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Antibiotics, Volume 9, Issue 7 (July 2020) – 69 articles

Cover Story (view full-size image): Just as a caterpillar turns into a butterfly, bacteria sensitive to antibiotics acquire resistance and often become multiresistant, and just as a butterfly that spreads pollen from flower to flower, antibiotic-resistant bacteria spread resistance through various environmental sectors. The rapid dissemination of antimicrobial-resistant determinants in hospital settings leads to the development of multidrug-resistant species. Methicillin-resistant Staphylococcus aureus (MRSA) is considered one of the most important and common pathogens causing hospital-acquired bloodstream infections. Despite adequate treatment, this condition is responsible for mortality rates between 20% and 40% in a period of 30 days. Therefore, it is extremely important to study the genetic characteristics of the most prevalent strains causing bacteremia to more effectively target the strategies for controlling these [...] Read more.
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Open AccessArticle
Environmental Dissemination of Selected Antibiotics from Hospital Wastewater to the Aquatic Environment
Antibiotics 2020, 9(7), 431; https://doi.org/10.3390/antibiotics9070431 - 21 Jul 2020
Cited by 4 | Viewed by 917
Abstract
The environmental dissemination of selected antibiotics from hospital wastewater into municipal wastewater and lastly to a receiving water body was investigated. Selected antibiotics (azithromycin (AZM), ciprofloxacin (CIP), clindamycin (CDM), doxycycline (DXC) and sulfamethoxazole (SMZ)) present in effluents of academic hospital wastewater, influents, sewage [...] Read more.
The environmental dissemination of selected antibiotics from hospital wastewater into municipal wastewater and lastly to a receiving water body was investigated. Selected antibiotics (azithromycin (AZM), ciprofloxacin (CIP), clindamycin (CDM), doxycycline (DXC) and sulfamethoxazole (SMZ)) present in effluents of academic hospital wastewater, influents, sewage sludge, and effluents of municipal wastewater, receiving water, and its benthic sediment samples were quantified using the Acquity® Waters Ultra-Performance Liquid Chromatography System hyphenated with a Waters Synapt G2 coupled to a quadrupole time-of-flight mass spectrometer. The overall results showed that all assessed antibiotics were found in all matrices. For solid matrices, river sediment samples had elevated concentrations with mean concentrations of 34,834, 35,623, 50,913, 55,263, and 41,781 ng/g for AZM, CIP, CDM, DXC, and SMZ, respectively, whereas for liquid samples, hospital wastewater and influent of wastewater had the highest concentrations. The lowest concentrations were observed in river water, with mean concentrations of 11, 97, 15, and 123 ng/L, except for CDM, which was 18 ng/L in the effluent of wastewater. The results showed that the highest percentages of antibiotics removed was SMZ with 90%, followed by DXC, AZM and CIP with a removal efficiency of 85%, 83%, and 83%, respectively. The antibiotic that showed the lowest removal percentage was CDM with 66%. However, the calculated environmental dissemination analysis through the use of mass load calculations revealed daily release of 15,486, 14,934, 1526, 922, and 680 mg/d for SMZ, CIP, AZM, DXC, and CDM, respectively, indicating a substantial release of selected antibiotics from wastewater to the river system, where they are possibly adsorbed in the river sediment. Further research into the efficient removal of antibiotics from wastewater and the identification of antibiotic sources in river sediment is needed. Full article
(This article belongs to the Special Issue Antibiotics and Environment)
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Open AccessArticle
Antiviral Action of Native and Methylated Lactoferrin and β-Lactoglobulin against Potato Virus Y (PVY) Infected into Potato Plants Grown in an Open Field
Antibiotics 2020, 9(7), 430; https://doi.org/10.3390/antibiotics9070430 - 21 Jul 2020
Cited by 2 | Viewed by 590
Abstract
Potato plants are liable to PVY infection without efficient control. Therefore, they were cultivated under greenhouse and open field conditions, artificially infected with PVY and then treated after 15 days of infection with native lactoferrin (LF) and native β-lactoglobulin (BL) and their esterified [...] Read more.
Potato plants are liable to PVY infection without efficient control. Therefore, they were cultivated under greenhouse and open field conditions, artificially infected with PVY and then treated after 15 days of infection with native lactoferrin (LF) and native β-lactoglobulin (BL) and their esterified forms, MLF (methylated lactoferrin) and BLM (methylated β-lactoglobulin) to test the efficiency of this approach. Viral replication was inhibited by the applied substances, particularly the methylated forms, in a concentration-dependent manner, where the concentration of 500 μg·mL−1 was sufficient for plant protection against the PVY infection. An open field experiment showed that one single application of the antiviral substance was enough for maximum inhibitory action against PVY. The modified milk proteins induced higher inhibitory action on PVY virus replication in the plants, compared to their native forms, which was reflected by potato growth and yield. Using the dot blot hybridization and RT-PCR techniques to detect PVY in the experimental plants showed the supremacy of native and esterified LF in inhibiting the targeted virus. The generally observed scanning electronic microscopy (SEM) structural deformations and irregular appearance in PVY particles when treated with MLF and BLM revealed their direct action. BLM, MLF and LF are efficient antiviral agents against PVY. They can not only abolish the observed PVY-induced reduction in potato growth and tuber yield, but also further increase them to higher levels than negative control. Full article
(This article belongs to the Special Issue Antimicrobial Action of Biomaterials)
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Open AccessArticle
Antibiotic-Antiapoptotic Dual Function of Clinacanthus nutans (Burm. f.) Lindau Leaf Extracts against Bovine Mastitis
Antibiotics 2020, 9(7), 429; https://doi.org/10.3390/antibiotics9070429 - 21 Jul 2020
Viewed by 744
Abstract
Mastitis caused by bacterial infection has negative impacts on milk quality and animal health, and ultimately causes economic losses to the dairy industry worldwide. Gram-negative bacteria and their component lipopolysaccharide (LPS) can trigger the inflammatory response of endothelial cells (ECs) and subsequently promote [...] Read more.
Mastitis caused by bacterial infection has negative impacts on milk quality and animal health, and ultimately causes economic losses to the dairy industry worldwide. Gram-negative bacteria and their component lipopolysaccharide (LPS) can trigger the inflammatory response of endothelial cells (ECs) and subsequently promote EC dysfunction or injury, which is a critical pathogenesis of mastitis-causing sepsis shock. To control the bacterial infection and to minimise the LPS negative effects on ECs, we thus aimed to identify the potential herb extracts that comprised antibacterial activity and protective ability to inhibit LPS-induced cell death. Extracts from seven types of herbs derived from antibacterial screening were investigated for their protective effects on LPS-stimulated bovine endothelial cell line. Clinacanthus nutans (Burm. f.) Lindau (C. nutans) extract appeared to be the most effective antiapoptotic extract against LPS stimulation. Treatment of C. nutans extract in LPS-stimulated cells significantly lowered apoptotic cell death through modulating pro-survival Bcl-2 and pro-apoptotic Bax expression. The investigation of bioactive compounds using solvent fractionation, HPLC, and LC-MS/MS analysis revealed glyceryl 1,3-disterate (C39H76O5), kaempferol 3-O-feruloyl-sophoroside 7-O-glucoside (C43H48O24), and hydroxypthioceranic acid (C46H92O3) as the candidate components. Our findings indicated that C. nutans extract has great potential to be further developed as an alternative therapeutic agent for mastitis treatment. Full article
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Open AccessArticle
In Vitro Evaluation of the Antimicrobial and Immunomodulatory Activity of Culinary Herb Essential Oils as Potential Perioceutics
Antibiotics 2020, 9(7), 428; https://doi.org/10.3390/antibiotics9070428 - 21 Jul 2020
Cited by 4 | Viewed by 834
Abstract
Due to their antimicrobial, immunomodulatory, antioxidant, and regenerative activities, culinary herbs have multiple medicinal uses, among which to prevent and treat oral diseases. The whole essential oils (EOs) have multiple advantages over purified components, such as a low probability to select for antimicrobial [...] Read more.
Due to their antimicrobial, immunomodulatory, antioxidant, and regenerative activities, culinary herbs have multiple medicinal uses, among which to prevent and treat oral diseases. The whole essential oils (EOs) have multiple advantages over purified components, such as a low probability to select for antimicrobial resistance, synergic effects of different components, and multi-pharmacological activities. In this study, we aimed to evaluate essential oils from Salvia officinalis (sage), Satureja hortensis (summer savory), and Anethum graveolens (dill) using an in vitro analysis of their antimicrobial activity against Gram-positive and Gram-negative bacterial strains isolated from the oral cavity of patients with periodontitis; the assays addressed both the planktonic and biofilm growth states and used culture-based approaches. Some of the tested EOs exhibited excellent bactericidal and antibiofilm activity, being active at concentrations as low as 0.08–1.36 mg/mL. Flow cytometry was used to investigate the potential mechanisms of their antibacterial activity and confirmed that the tested EOs act by permeabilizing the bacterial membrane and by inhibiting the activity of the efflux pumps. The immunomodulatory effect of the three EOs was determined by analyzing the gene expression profiles for pro- and anti-inflammatory cytokines of the THP-1 cells. The summer savory EO induced a clear proinflammatory effect, while the others did not significantly influence the cytokines profile of the tested cells. Taken together, our results indicate that summer savory EO and, to a lesser extent, sage and dill EOs could be used to inhibit bacteria involved in oral plaque formation and to reduce the expression of genes known to contribute to the inflammatory response using cell culture assessment. Full article
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Open AccessCase Report
Monitoring of Hydrogen Emission from Bacteria in Food, Animals and in the Blood of Humans Suffering from Lyme Disease by A Specific Hydrogen Sensor
Antibiotics 2020, 9(7), 427; https://doi.org/10.3390/antibiotics9070427 - 21 Jul 2020
Cited by 1 | Viewed by 626
Abstract
A novel straightforward analytical technique was developed to monitor the emission of hydrogen from anaerobic bacteria cultured in sealed headspace vials using a specific hydrogen sensor. The results were compared with headspace gas chromatography carried out in parallel. This technique was also applied [...] Read more.
A novel straightforward analytical technique was developed to monitor the emission of hydrogen from anaerobic bacteria cultured in sealed headspace vials using a specific hydrogen sensor. The results were compared with headspace gas chromatography carried out in parallel. This technique was also applied to investigate the efficacy of chemical antibiotics and of natural compounds with antimicrobial properties. Antibiotics added to the sample cultures are apparently effective if the emission of hydrogen is suppressed, or if not, are either ineffective or the related bacteria are even resistant. The sensor approach was applied to prove bacterial contamination in food, animals, medical specimens and in ticks infected by Borrelia bacteria and their transfer to humans, thus causing Lyme disease. It is a unique advantage that the progress of an antibiotic therapy can be examined until the emission of hydrogen is finished. The described technique cannot identify the related bacteria but enables bacterial contamination by hydrogen emitting anaerobes to be recognized. The samples are incubated with the proper culture broth in closed septum vials which remain closed during the whole process. The personnel in the lab never come into contact with pathogens and thus safety regulations are guaranteed. Full article
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Open AccessArticle
Occurrence, Virulence and Antimicrobial Resistance-Associated Markers in Campylobacter Species Isolated from Retail Fresh Milk and Water Samples in Two District Municipalities in the Eastern Cape Province, South Africa
Antibiotics 2020, 9(7), 426; https://doi.org/10.3390/antibiotics9070426 - 21 Jul 2020
Cited by 1 | Viewed by 835
Abstract
Campylobacter species are among the major bacteria implicated in human gastrointestinal infections and are majorly found in faeces of domestic animals, sewage discharges and agricultural runoff. These pathogens have been implicated in diseases outbreaks through consumption of contaminated milk and water in some [...] Read more.
Campylobacter species are among the major bacteria implicated in human gastrointestinal infections and are majorly found in faeces of domestic animals, sewage discharges and agricultural runoff. These pathogens have been implicated in diseases outbreaks through consumption of contaminated milk and water in some parts of the globe and reports on this is very scanty in the Eastern Cape Province. Hence, this study evaluated the occurrence as well as virulence and antimicrobial-associated makers of Campylobacter species recovered from milk and water samples. A total of 56 water samples and 72 raw milk samples were collected and the samples were processed for enrichment in Bolton broth and incubated for 48 h in 10% CO2 at 42 °C under microaerobic condition. Thereafter, the enriched cultures were further processed and purified. After which, presumptive Campylobacter colonies were isolated and later confirmed by PCR using specific primers for the detection of the genus Campylobacter, target species and virulence associated genes. Antimicrobial resistance profiles of the isolates were determined by disk diffusion method against a panel of 12 antibiotics and relevant genotypic resistance genes were assessed by PCR assay. A total of 438 presumptive Campylobacter isolates were obtained; from which, 162 were identified as belonging to the genus Campylobacter of which 36.92% were obtained from water samples and 37.11% from milk samples. The 162 confirmed isolates were further delineated into four species, of which, 7.41%, 27.16% and 8.64% were identified as C. fetus, C. jejuni and C. coli respectively. Among the virulence genes screened for, the iam (32.88%) was most prevalent, followed by flgR (26.87%) gene and cdtB and cadF (5.71% each) genes. Of the 12 antibiotics tested, the highest phenotypic resistance displayed by Campylobacter isolates was against clindamycin (95.68%), while the lowest was observed against imipenem (21.47%). Other high phenotypic resistance displayed by the isolates were against erythromycin (95.06%), followed by ceftriaxone (93.21%), doxycycline (87.65%), azithromycin and ampicillin (87.04% each), tetracycline (83.33%), chloramphenicol (78.27%), ciprofloxacin (77.78%), levofloxacin (59.88%) and gentamicin (56.17%). Relevant resistance genes were assessed in the isolates that showed high phenotypic resistance, and the highest resistance gene harbored by the isolates was catII (95%) gene while VIM, KPC, Ges, bla-OXA-48-like, tetC, tetD, tetK, IMI and catI genes were not detected. The occurrence of this pathogen and the detection of virulence and antimicrobial resistance-associated genes in Campylobacter isolates recovered from milk/water samples position them a risk to human health. Full article
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Open AccessArticle
Detection of Carbapenem-Resistance Genes in Klebsiella Species Recovered from Selected Environmental Niches in the Eastern Cape Province, South Africa
Antibiotics 2020, 9(7), 425; https://doi.org/10.3390/antibiotics9070425 - 21 Jul 2020
Cited by 1 | Viewed by 765
Abstract
Carbapenemase-producing Enterobacteriaceae (CPE) have been heavily linked to hospital acquired infections (HAI) thereby leading to futility of antibiotics in treating infections and this have complicated public health problems. There is little knowledge about carbapenemase-producing Klebsiella spp. (CPK) in South Africa. This study aimed [...] Read more.
Carbapenemase-producing Enterobacteriaceae (CPE) have been heavily linked to hospital acquired infections (HAI) thereby leading to futility of antibiotics in treating infections and this have complicated public health problems. There is little knowledge about carbapenemase-producing Klebsiella spp. (CPK) in South Africa. This study aimed at determining the occurrence of CPK in different samples collected from selected environmental niches (hospitals, wastewater treatment plants, rivers, farms) in three district municipalities located in the Eastern Cape Province, South Africa. Molecular identification and characterization of the presumptive isolates were determined using polymerase chain reaction (PCR) and isolates that exhibited phenotypic carbapenem resistance were further screened for the possibility of harbouring antimicrobial resistance genes. One hundred (43%) of the 234 confirmed Klebsiella spp. isolates harboured carbapenem-resistance genes; 10 isolates harboured blaOXA-48-like; 17 harboured blaKPC; and 73 isolates harboured blaNDM-1. The emergence of blaKPC, blaOXA-48-like, and blaNDM-1 carbapenem-resistance genes in Klebsiella species associated with environmental sources is of great concern to public health. Full article
(This article belongs to the Special Issue Antibiotics and Environment)
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Open AccessArticle
Non-Tuberculous Mycobacteria in Respiratory Specimens of Patients with Obstructive Lung Diseases—Colonization or Disease?
Antibiotics 2020, 9(7), 424; https://doi.org/10.3390/antibiotics9070424 - 20 Jul 2020
Cited by 1 | Viewed by 688
Abstract
Non-tuberculous mycobacteria (NTM) are increasingly a cause of human respiratory tract colonization and mycobacterial lung disease (NTM-LD), especially in patients with chronic lung diseases. The aim of the present study was to find the factors predictive of NTM-LD in patients with obstructive lung [...] Read more.
Non-tuberculous mycobacteria (NTM) are increasingly a cause of human respiratory tract colonization and mycobacterial lung disease (NTM-LD), especially in patients with chronic lung diseases. The aim of the present study was to find the factors predictive of NTM-LD in patients with obstructive lung diseases and NTM respiratory isolates. A total of 839 isolates of NTM, obtained from 161 patients between 2010 and 2020 in a single pulmonary unit, have been retrospectively reviewed. Of these isolates, 73 concerned 36 patients with obstructive lung diseases (COPD-26, asthma-3, COPD/asthma overlap syndrome-7). NTM-LD was recognized according to the American Thoracic Society (ATS) and the Infectious Diseases Society of America (IDSA) criteria in 17 patients, colonization in 19. Lower BMI, elevated body temperature on admission, infiltrative/cavitary lesions on chest CT, and NTM species other than Mycobacterium gordonae were the significant predictors of NTM-LD recognition. Based on the above-mentioned predictive factors, an original scoring system was implemented. The diagnostic utility of the scoring system was higher than that of single parameters. We conclude that NTM-LD prediction in patients with obstructive lung diseases and positive respiratory isolates is difficult. A scoring system based on clinical, radiological and microbiological characteristics was capable of facilitating the differential diagnosis, but it needs further validation in a larger study group. Full article
(This article belongs to the Special Issue Mycobacterial Infections and Therapy)
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Open AccessArticle
Policies to Reduce Antibiotic Consumption: The Impact in the Basque Country
Antibiotics 2020, 9(7), 423; https://doi.org/10.3390/antibiotics9070423 - 19 Jul 2020
Viewed by 649
Abstract
In 2013, a change in copayment rate was introduced in the Basque Country (one year later than in the other regions in Spain), and improvements were made to drug packaging. In 2014, a National Program Against Bacterial Resistance (Spanish abbreviation: PRAN) was approved. [...] Read more.
In 2013, a change in copayment rate was introduced in the Basque Country (one year later than in the other regions in Spain), and improvements were made to drug packaging. In 2014, a National Program Against Bacterial Resistance (Spanish abbreviation: PRAN) was approved. The aim of this study is to analyze the impact of change to the copayment rate, the adjustment of drug packaging, and the approval of PRAN on the consumption of antibiotics. Raw monthly data on the consumption of antibiotics (costs, packages, and daily defined doses per thousand people (DID)) were collected from January 2009 to December 2018 in the Basque Country. Counterfactual and intervention analysis (Autoregressive integrated moving average (ARIMA) model) was performed for the total series, disaggregated by group of antibiotics (2019 WHO Access, Watch, and Reserve (AWaRe) Classification) and active substances with the highest cost per prescription (cefditoren and moxifloxacin), the lowest cost per prescription (doxycycline and cloxacillin), and the most prescribed active ingredients (amoxicillin, azithromycin, and levofloxacin). Introduction of copayment led to a ‘stockpiling effect’ one month before its implementation, equal to 8% in the three consumption series analyzed. Only the adjustment of drug packaging significantly reduced the number of packages dispensed (−12.19%). PRAN approval reduced consumption by 0.779 DID (−4.51%), representing a significant decrease for both ’access’ and ’watch’ group antibiotics. Despite the delay in implementing changes to copayment, there was a ‘stockpiling effect’. With the adjustment of packaging, fewer packs were prescribed but with a higher drug load and price. PRAN approval reduced both the consumption of ’access group antibiotics’ (first-line treatment) and ’watch group antibiotics’ (second-line treatment). Full article
(This article belongs to the Special Issue Antibiotics Use in Primary Care)
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Open AccessArticle
Antibacterial and Anti-Inflammatory Effects of Novel Peptide Toxin from the Spider Pardosa astrigera
Antibiotics 2020, 9(7), 422; https://doi.org/10.3390/antibiotics9070422 - 19 Jul 2020
Viewed by 862
Abstract
The prevalence of antibiotic-resistant bacteria has become an immediate threat to public health. Antimicrobial peptides are attracting attention as a new source of antibiotics due to their ability to prevent drug-resistances with fewer side effects. Spider venom is composed of various bioactive substances [...] Read more.
The prevalence of antibiotic-resistant bacteria has become an immediate threat to public health. Antimicrobial peptides are attracting attention as a new source of antibiotics due to their ability to prevent drug-resistances with fewer side effects. Spider venom is composed of various bioactive substances with multiple functionalities such as antimicrobial and anti-inflammatory effects. Here, RNA sequencing was conducted on the venom gland of the spider Pardosa astrigera, and a potential toxin peptide with antibacterial properties was selected via homology and in silico analysis. A novel toxin, Lycotoxin-Pa4a, inhibited both gram-negative and gram-positive bacteria by disrupting the outer and bacterial cytoplasmic membrane. Moreover, the peptide downregulated the expression of pro-inflammatory mediators while upregulating the level of anti-inflammatory cytokine by inactivating mitogen-activated protein kinase signaling in a lipopolysaccharide-stimulated murine macrophage cell line. In this research, we identified a novel peptide toxin, Lycotoxin-pa4a, with antibacterial and anti-inflammatory properties, suggesting its potential for the development of a new antibiotics, as well as offering insights into the utilization of biological resources. Full article
(This article belongs to the Special Issue Peptide Antibiotics from Microbes and Venomous Animals)
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Open AccessArticle
Analysing the Initial Bacterial Adhesion to Evaluate the Performance of Antifouling Surfaces
Antibiotics 2020, 9(7), 421; https://doi.org/10.3390/antibiotics9070421 - 17 Jul 2020
Cited by 1 | Viewed by 696
Abstract
The aim of this work was to study the initial events of Escherichia coli adhesion to polydimethylsiloxane, which is critical for the development of antifouling surfaces. A parallel plate flow cell was used to perform the initial adhesion experiments under controlled hydrodynamic conditions [...] Read more.
The aim of this work was to study the initial events of Escherichia coli adhesion to polydimethylsiloxane, which is critical for the development of antifouling surfaces. A parallel plate flow cell was used to perform the initial adhesion experiments under controlled hydrodynamic conditions (shear rates ranging between 8 and 100/s), mimicking biomedical scenarios. Initial adhesion studies capture more accurately the cell-surface interactions as in later stages, incoming cells may interact with the surface but also with already adhered cells. Adhesion rates were calculated and results shown that after some time (between 5 and 9 min), these rates decreased (by 55% on average), from the initial values for all tested conditions. The common explanation for this decrease is the occurrence of hydrodynamic blocking, where the area behind each adhered cell is screened from incoming cells. This was investigated using a pair correlation map from which two-dimensional histograms showing the density probability function were constructed. The results highlighted a lower density probability (below 4.0 × 10−4) of the presence of cells around a given cell under different shear rates irrespectively of the radial direction. A shadowing area behind the already adhered cells was not observed, indicating that hydrodynamic blocking was not occurring and therefore it could not be the cause for the decreases in cell adhesion rates. Afterward, cell transport rates from the bulk solution to the surface were estimated using the Smoluchowski-Levich approximation and values in the range of 80–170 cells/cm2.s were obtained. The drag forces that adhered cells have to withstand were also estimated and values in the range of 3–50 × 10−14 N were determined. Although mass transport increases with the flow rate, drag forces also increase and the relative importance of these factors may change in different conditions. This work demonstrates that adjustment of operational parameters in initial adhesion experiments may be required to avoid hydrodynamic blocking, in order to obtain reliable data about cell-surface interactions that can be used in the development of more efficient antifouling surfaces. Full article
(This article belongs to the Special Issue New Insights on Biofilm Antimicrobial Strategies)
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Open AccessArticle
Unveiling the Properties of Thai Stingless Bee Propolis via Diminishing Cell Wall-Associated Cryptococcal Melanin and Enhancing the Fungicidal Activity of Macrophages
Antibiotics 2020, 9(7), 420; https://doi.org/10.3390/antibiotics9070420 - 17 Jul 2020
Viewed by 725
Abstract
Cryptococcus neoformans, a life-threatening human yeast pathogen, has the ability to produce melanin, which is one of the common virulence factors contributing to cryptococcal pathogenesis. This virulence factor is closely associated with the cryptococcal cell wall, specifically chitin and chitosan polysaccharides, a [...] Read more.
Cryptococcus neoformans, a life-threatening human yeast pathogen, has the ability to produce melanin, which is one of the common virulence factors contributing to cryptococcal pathogenesis. This virulence factor is closely associated with the cryptococcal cell wall, specifically chitin and chitosan polysaccharides, a complex structure that is essential for maintaining cellular structure and integrity. In this study, we aim to investigate the effects of two stingless bee (SLB) propolis from Tetragonula laeviceps and Tetrigona melanoleuca against cell wall-associated melanin in C. neoformans, and its immune response in RAW 264.7 macrophage. The ethanolic extract of SLB propolis (EEP) has strongly exhibited anti-cryptococcal activity. Moreover, EEP from both sources reduced chitin/chitosan and melanin production against C. neoformans in a dose-dependent manner. Likewise, the mRNA expression level of CDA1, IPC1-PKC1 and LAC1 genes involved in the cryptococcal melanization pathway was significantly decreased at 2 mg/mL in EEP treatment. Additionally, pretreatment with EEP prior to yeast infection dramatically reduced intracellular replication of C. neoformans in RAW 264.7 macrophages in a dose-dependent manner. This study might be a new insight to use a natural powerful source, not only acting to target cell wall-associated molecules, but also being capable to explore a novel strategy by which dysregulation of these molecules leads to promote immunomodulatory activity. Full article
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Open AccessArticle
Optimising Interventions for Catheter-Associated Urinary Tract Infections (CAUTI) in Primary, Secondary and Care Home Settings
Antibiotics 2020, 9(7), 419; https://doi.org/10.3390/antibiotics9070419 - 17 Jul 2020
Viewed by 2006
Abstract
Catheter-associated urinary tract infections (CAUTI) are common yet preventable. Healthcare professional behaviours, such as reducing unnecessary catheter use, are key for preventing CAUTI. Previous research has focused on identifying gaps in the national response to CAUTI in multiple settings in England. This study [...] Read more.
Catheter-associated urinary tract infections (CAUTI) are common yet preventable. Healthcare professional behaviours, such as reducing unnecessary catheter use, are key for preventing CAUTI. Previous research has focused on identifying gaps in the national response to CAUTI in multiple settings in England. This study aimed to identify how national interventions could be optimised. We conducted a multi-method study comprising: a rapid review of research on interventions to reduce CAUTI; a behavioural analysis of effective research interventions compared to national interventions; and a stakeholder focus group and survey to identify the most promising options for optimising interventions. We identified 37 effective research interventions, mostly conducted in United States secondary care. A behavioural analysis of these interventions identified 39 intervention components as possible ways to optimise national interventions. Seven intervention components were prioritised by stakeholders. These included: checklists for discharge/admission to wards; information for patients and relatives about the pros/cons of catheters; setting and profession specific guidelines; standardised nationwide computer-based documentation; promotion of alternatives to catheter use; CAUTI champions; and bladder scanners. By combining research evidence, behavioural analysis and stakeholder feedback, we identified how national interventions to reduce CAUTI could be improved. The seven prioritised components should be considered for future implementation. Full article
(This article belongs to the Special Issue Antimicrobial Stewardship in Primary Care)
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Open AccessCommentary
Narrow-Spectrum Antibacterial Agents—Benefits and Challenges
Antibiotics 2020, 9(7), 418; https://doi.org/10.3390/antibiotics9070418 - 17 Jul 2020
Cited by 1 | Viewed by 1242
Abstract
The number of antibacterial agents in clinical and preclinical development possessing activity against a narrow spectrum of bacterial pathogens is increasing, with many of them being nontraditional products. The key value proposition hinges on sparing antibiotic use and curtailing the emergence of resistance, [...] Read more.
The number of antibacterial agents in clinical and preclinical development possessing activity against a narrow spectrum of bacterial pathogens is increasing, with many of them being nontraditional products. The key value proposition hinges on sparing antibiotic use and curtailing the emergence of resistance, as well as preventing the destruction of a beneficial microbiome, versus the immediate need for effective treatment of an active infection with a high risk of mortality. The clinical use of a targeted spectrum agent, most likely in combination with a rapid and robust diagnostic test, is a commendable goal with significant healthcare benefits if executed correctly. However, the path to achieving this will come with several challenges, and many scientific and clinical development disciplines will need to align their efforts to successfully change the treatment paradigm. Full article
Open AccessReview
Isolation and Biological Properties of the Natural Flavonoids Pectolinarin and Pectolinarigenin—A Review
Antibiotics 2020, 9(7), 417; https://doi.org/10.3390/antibiotics9070417 - 16 Jul 2020
Cited by 2 | Viewed by 954
Abstract
Flavonoids are metabolites widely distributed in plants and commonly present in foods, such as fruits and vegetables. Pectolinarin, which belongs to the flavone subclass, has attracted considerable attention due to its presence in many medicinal plants. It has turned out to be a [...] Read more.
Flavonoids are metabolites widely distributed in plants and commonly present in foods, such as fruits and vegetables. Pectolinarin, which belongs to the flavone subclass, has attracted considerable attention due to its presence in many medicinal plants. It has turned out to be a good biological agent especially due to its antioxidant, anti-inflammatory, antidiabetic, and antitumor activities, evaluated both in vitro and in vivo. Its aglycone, the metabolite pectolinarigenin, is also known for a series of biological properties including anti-inflammatory and antidiabetic effects. In the first overview on the two metabolites here presented, their collection, isolation and the results of their biological evaluation are reported. Full article
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Open AccessArticle
Genetic Subtyping, Biofilm-Forming Ability and Biocide Susceptibility of Listeria monocytogenes Strains Isolated from a Ready-to-Eat Food Industry
Antibiotics 2020, 9(7), 416; https://doi.org/10.3390/antibiotics9070416 - 16 Jul 2020
Cited by 3 | Viewed by 658
Abstract
Listeria monocytogenes is a foodborne pathogen of special concern for ready-to-eat food producers. The control of its presence is a critical step in which food-grade sanitizers play an essential role. L. monocytogenes is believed to persist in food processing environments in biofilms, exhibiting [...] Read more.
Listeria monocytogenes is a foodborne pathogen of special concern for ready-to-eat food producers. The control of its presence is a critical step in which food-grade sanitizers play an essential role. L. monocytogenes is believed to persist in food processing environments in biofilms, exhibiting less susceptibility to sanitizers than planktonic cells. This study aimed to test the susceptibility of L. monocytogenes in planktonic culture and biofilm to three commercial food-grade sanitizers and to benzalkonium chloride; together with the genetic subtyping of the isolates. L. monocytogenes isolates were collected from raw materials, final products and food-contact surfaces during a 6-year period from a ready-to-eat meat-producing food industry and genetically characterized. Serogrouping and pulsed-field gel electrophoresis (PFGE) revealed genetic variability and differentiated L. monocytogenes isolates in three clusters. The biofilm-forming ability assay revealed that the isolates were weak biofilm producers. L. monocytogenes strains were susceptible both in the planktonic and biofilm form to oxidizing and ethanol-based compounds and to benzalkonium chloride, but not to quaternary ammonium compound. A positive association of biofilm-forming ability and LD90 values for quaternary ammonium compound and benzalkonium chloride was found. This study highlights the need for preventive measures improvement and for a conscious selection and use of sanitizers in food-related environments to control Listeria monocytogenes. Full article
(This article belongs to the Special Issue Antimicrobial Resistance and Virulence Mechanisms)
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Open AccessArticle
Application of Bacteriophages to Control Vibrio alginolyticus Contamination in Oyster (Saccostrea glomerata) Larvae
Antibiotics 2020, 9(7), 415; https://doi.org/10.3390/antibiotics9070415 - 16 Jul 2020
Cited by 3 | Viewed by 1092
Abstract
Mortalities of bivalve larvae and spat linked with Vibrio spp. infection have been described in hatcheries since 1959, causing potential development of resistant bacteria. A reliable and sustainable solution to this problem is yet to be developed. Potential treatment of bacterial infection with [...] Read more.
Mortalities of bivalve larvae and spat linked with Vibrio spp. infection have been described in hatcheries since 1959, causing potential development of resistant bacteria. A reliable and sustainable solution to this problem is yet to be developed. Potential treatment of bacterial infection with bacteriophages is gaining interest in aquaculture as a more sustainable option for managing Vibrio spp. infection. This study assessed the effectiveness of bacteriophages (Φ-5, Φ-6, and Φ-7) against pathogenic Vibrio isolates (USC-26004 and USC-26005). These phage isolates were found to belong to the Myoviridae viral family. A total of 212 ORFs of Φ-5 were identified and annotated. The genome of this phage contained putative thymidine kinase and lysin enzyme. During infections with phages, the OD values of the isolates USC-26005 and USC-26004 remained stable at a much lower reading compared to the control after 9 h of incubation. Mortality rate of oyster (Saccostrea glomerata) larvae was 28.2 ± 3.5% in the bacteriophage treatment group, compared to 77.9 ± 9.1% in the bacterial treatment group after 24 h incubation. Findings of this study indicate that lytic phages might be utilized as potential bio-control agents of luminescent bacterial disease in oyster hatcheries. Full article
(This article belongs to the Special Issue Phage Diversity for Research and Application)
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Open AccessReview
Bacteriophages and the One Health Approach to Combat Multidrug Resistance: Is This the Way?
Antibiotics 2020, 9(7), 414; https://doi.org/10.3390/antibiotics9070414 - 16 Jul 2020
Cited by 2 | Viewed by 1030
Abstract
Antimicrobial resistance necessitates action to reduce and eliminate infectious disease, ensure animal and human health, and combat emerging diseases. Species such as Acinetobacter baumanniii, vancomycin resistant Enterococcus, methicillin resistance Staphylococcus aureus, and Pseudomonas aeruginosa, as well as other WHO [...] Read more.
Antimicrobial resistance necessitates action to reduce and eliminate infectious disease, ensure animal and human health, and combat emerging diseases. Species such as Acinetobacter baumanniii, vancomycin resistant Enterococcus, methicillin resistance Staphylococcus aureus, and Pseudomonas aeruginosa, as well as other WHO priority pathogens, are becoming extremely difficult to treat. In 2017, the EU adopted the “One Health” approach to combat antibiotic resistance in animal and human medicine and to prevent the transmission of zoonotic disease. As the current therapeutic agents become increasingly inadequate, there is a dire need to establish novel methods of treatment under this One Health Framework. Bacteriophages (phages), viruses infecting bacterial species, demonstrate clear antimicrobial activity against an array of resistant species, with high levels of specificity and potency. Bacteriophages play key roles in bacterial evolution and are essential components of all ecosystems, including the human microbiome. Factors such are their specificity, potency, biocompatibility, and bactericidal activity make them desirable options as therapeutics. Issues remain, however, relating to their large-scale production, formulation, stability, and bacterial resistance, limiting their implementation globally. Phages used in therapy must be virulent, purified, and well characterized before administration. Clinical studies are warranted to assess the in vivo pharmacokinetics and pharmacodynamic characteristics of phages to fully establish their therapeutic potential. Full article
(This article belongs to the Special Issue Phage Diversity for Research and Application)
Open AccessArticle
Structural and Bioactivity Characterization of Filipin Derivatives from Engineered Streptomyces filipinensis Strains Reveals Clues for Reduced Haemolytic Action
Antibiotics 2020, 9(7), 413; https://doi.org/10.3390/antibiotics9070413 - 16 Jul 2020
Viewed by 616
Abstract
The rise in the number of immunocompromised patients has led to an increased incidence of fungal infections, with high rates of morbidity and mortality. Furthermore, misuse of antifungals has boosted the number of resistant strains to these agents; thus, there is urgent need [...] Read more.
The rise in the number of immunocompromised patients has led to an increased incidence of fungal infections, with high rates of morbidity and mortality. Furthermore, misuse of antifungals has boosted the number of resistant strains to these agents; thus, there is urgent need for new drugs against these infections. Here, the in vitro antifungal activity of filipin III metabolic intermediates has been characterized against a battery of opportunistic pathogenic fungi—Candida albicans, Candida glabrata, Candida krusei, Cryptococcus neoformans, Trichosporon cutaneum, Trichosporon asahii, Aspergillus nidulans, Aspergillus niger, and Aspergillus fumigatus—using the Clinical and Laboratory Standards Institute broth microdilution method. Structural characterization of these compounds was undertaken by mass spectrometry (MS) and nuclear magnetic resonance (NMR) following HPLC purification. Complete NMR assignments were obtained for the first time for filipins I and II. In vitro haemolytic assays revealed that the haemolytic action of these compounds relies largely on the presence of a hydroxyl function at C26, since derivatives lacking such moiety show remarkably reduced activity. Two of these derivatives, 1′-hydroxyfilipin I and filipin I, show decreased toxicity towards cholesterol-containing membranes while retaining potent antifungal activity, and could constitute excellent leads for the development of efficient pharmaceuticals, particularly against Cryptococcosis. Full article
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Open AccessCommunication
Antibacterial Drug Development: A New Approach Is Needed for the Field to Survive and Thrive
Antibiotics 2020, 9(7), 412; https://doi.org/10.3390/antibiotics9070412 - 15 Jul 2020
Cited by 3 | Viewed by 1092
Abstract
It is often said that the marketplace for new antibiotics is broken. This notion is supported by the observation that many recently-approved antibiotics to treat drug-resistant bacteria have failed commercially in a spectacular fashion. Today, companies with peak market-cap values in excess of [...] Read more.
It is often said that the marketplace for new antibiotics is broken. This notion is supported by the observation that many recently-approved antibiotics to treat drug-resistant bacteria have failed commercially in a spectacular fashion. Today, companies with peak market-cap values in excess of USD 500 million to 1 billion prior to product launch regularly sell for pennies on the dollar a few years after market introduction. It is possible, however, that the market is not as broken as we perceive. That is, in the collective mind of the clinician, recently-approved antibiotics may be too-poorly differentiated to justify their broad use and inordinate cost relative to those already existing. Perhaps we in the antibacterial drug development field must change our way of thinking if we are to survive and thrive. Rather than reflexively developing new β-lactam-β-lactamase inhibitor combinations for every new enzyme that evades our current inhibitors, we should focus discovery and development efforts on agents that revolutionize how we potentiate antibiotics. To this end, there has been renewed interest in phage therapies, virulence inhibitors, bacterial growth rate modulators, monoclonal antibodies, and other approaches to augment antibiotic effects. Herein, we suggest that the unmet medical need is less about adding poorly-differentiated antibiotics to our armamentarium and more about the need for innovation in how we augment antibiotic regimen effects. Full article
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Open AccessArticle
Antibacterial Activity of Bacteriocinogenic Commensal Escherichia coli against Zoonotic Strains Resistant and Sensitive to Antibiotics
Antibiotics 2020, 9(7), 411; https://doi.org/10.3390/antibiotics9070411 - 15 Jul 2020
Cited by 2 | Viewed by 758
Abstract
Antibiotic resistance concerns various areas with high consumption of antibiotics, including husbandry. Resistant strains are transmitted to humans from livestock and agricultural products via the food chain and may pose a health risk. The commensal microbiota protects against the invasion of environmental strains [...] Read more.
Antibiotic resistance concerns various areas with high consumption of antibiotics, including husbandry. Resistant strains are transmitted to humans from livestock and agricultural products via the food chain and may pose a health risk. The commensal microbiota protects against the invasion of environmental strains by secretion of bacteriocins, among other mechanisms. The present study aims to characterize the bactericidal potential of bacteriocinogenic Escherichia coli from healthy humans against multidrug-resistant and antibiotic-sensitive strains from pigs and cattle. Bacteriocin production was tested by the double-layer plate method, and bacteriocin genes were identified by the PCR method. At least one bacteriocinogenic E. coli was detected in the fecal samples of 55% of tested individuals, adults and children. Among all isolates (n = 210), 37.1% were bacteriocinogenic and contained genes of colicin (Col) Ib, ColE1, microcin (Mcc) H47, ColIa, ColM, MccV, ColK, ColB, and single ColE2 and ColE7. Twenty-five E. coli carrying various sets of bacteriocin genes were further characterized and tested for their activity against zoonotic strains (n = 60). Strains with ColE7 (88%), ColE1-ColIa-ColK-MccH47 (85%), MccH47-MccV (85%), ColE1-ColIa-ColM (82%), ColE1 (75%), ColM (67%), and ColK (65%) were most active against zoonotic strains. Statistically significant differences in activity toward antibiotic-resistant strains were shown by commensal E. coli carrying MccV, ColK-MccV, and ColIb-ColK. The study demonstrates that bacteriocinogenic commensal E. coli exerts antagonistic activity against zoonotic strains and may constitute a defense line against multidrug-resistant strains. Full article
(This article belongs to the Special Issue Pathogenic Escherichia coli: Infections and Therapies)
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Open AccessArticle
Profile of Enterobacteria Resistant to Beta-Lactams
Antibiotics 2020, 9(7), 410; https://doi.org/10.3390/antibiotics9070410 - 15 Jul 2020
Cited by 1 | Viewed by 851
Abstract
A serious emerging problem worldwide is increased antimicrobial resistance. Acquisition of coding genes for evasion methods of antimicrobial drug mechanisms characterizes acquired resistance. This phenomenon has been observed in Enterobacteriaceae family. Treatment for bacterial infections is performed with antibiotics, of which the most [...] Read more.
A serious emerging problem worldwide is increased antimicrobial resistance. Acquisition of coding genes for evasion methods of antimicrobial drug mechanisms characterizes acquired resistance. This phenomenon has been observed in Enterobacteriaceae family. Treatment for bacterial infections is performed with antibiotics, of which the most used are beta-lactams. The aim of this study was to correlate antimicrobial resistance profiles in Enterobacteriaceae by phenotypic methods and molecular identification of 14 beta-lactamase coding genes. In this study, 70 exclusive isolates from Brazil were used, half of which were collected in veterinary clinics or hospitals Phenotypic methodologies were used and real-time PCR was the molecular methodology used, through the Sybr Green system. Regargding the results found in the tests it was observed that 74.28% were resistant to ampicillin, 62.85% were resistant to amoxicillin associated with clavalunate. The mechanism of resistance that presented the highest expression was ESBL (17.14%). The genes studied that were detected in a greater number of species were blaGIM and blaSIM (66.66% of the samples) and the one that was amplified in a smaller number of samples was blaVIM (16.66%). Therefore, high and worrying levels of antimicrobial resistance have been found in enterobacteria, and a way to minimize the accelerated emergence of their resistance includes developing or improving techniques that generate diagnoses with high efficiency and speed. Full article
(This article belongs to the Special Issue Antibiotic Resistance: From the Bench to Patients)
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Open AccessArticle
The Variability of Thymol and Carvacrol Contents Reveals the Level of Antibacterial Activity of the Essential Oils from Different Accessions of Oliveria decumbens
Antibiotics 2020, 9(7), 409; https://doi.org/10.3390/antibiotics9070409 - 14 Jul 2020
Viewed by 820
Abstract
Oliveria decumbens (Apiaceae) is an aromatic herb traditionally employed in the Persian medicine for the treatment of infectious and gastrointestinal disorders. In the present study, we analyzed the chemical composition of essential oils obtained from different Iranian populations and evaluated their efficacy on [...] Read more.
Oliveria decumbens (Apiaceae) is an aromatic herb traditionally employed in the Persian medicine for the treatment of infectious and gastrointestinal disorders. In the present study, we analyzed the chemical composition of essential oils obtained from different Iranian populations and evaluated their efficacy on a panel of human pathogens (Staphylococcus aureus and Escherichia coli), probiotic (Bacillus subtilis), and phytopathogens (Clavibacter michiganensis, Curtobacterium flaccumfaciens, Xanthomonas citri, and Agrobacterium tumefaciens). The gas chromatographic-mass spectrometry analysis put in evidence four main volatile constituents such as thymol (20.3–36.4%), carvacrol (18.8–33.1%), γ-terpinene (10.6–25.9%), and p-cymene (9.5–17.3%), though with significant variability from an essential oil to another. Notably, the oils from the populations sited in Nourabad Mamasani and Dehdasht showed the highest amount of the phenolic monoterpenes thymol (36.4 and 35.2%, respectively) and carvacrol (33.1 and 30.6%, respectively). The antibacterial activity of O. decumbens essential oils was assessed by the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) methods, showing high activity for the samples from Nourabad Mamasani and Dehdasht populations exhibiting high level of the above phenolics. The obtained MIC and MBC values (mg/ml) were in the ranges 0.0625–2 mg/ml and 1–16 mg/ml, respectively. Noteworthy, in some cases, the antibacterial activity of O. decumbens essential oils was higher than that of chloramphenicol used as positive control. The average MBCs displayed by the O. decumbens samples showed that C. flaccumfaciens had the highest sensitivity to the essential oils. Based on these results, our work shed light on selected O. decumbens populations deserving proper breeding and cultivation strategies in order to warrantee production of bioactive essential oils to be used at pharmaceutical and agricultural level to combat several pathogens. Full article
(This article belongs to the Special Issue Antibacterial Activity of Plant Extracts and Essential Oils)
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Open AccessArticle
Kinetic Fingerprinting Links Bacteria-Phage Interactions with Emergent Dynamics: Rapid Depletion of Klebsiella pneumoniae Indicates Phage Synergy
Antibiotics 2020, 9(7), 408; https://doi.org/10.3390/antibiotics9070408 - 14 Jul 2020
Cited by 1 | Viewed by 1148
Abstract
The specific temporal evolution of bacterial and phage population sizes, in particular bacterial depletion and the emergence of a resistant bacterial population, can be seen as a kinetic fingerprint that depends on the manifold interactions of the specific phage–host pair during the course [...] Read more.
The specific temporal evolution of bacterial and phage population sizes, in particular bacterial depletion and the emergence of a resistant bacterial population, can be seen as a kinetic fingerprint that depends on the manifold interactions of the specific phage–host pair during the course of infection. We have elaborated such a kinetic fingerprint for a human urinary tract Klebsiella pneumoniae isolate and its phage vB_KpnP_Lessing by a modeling approach based on data from in vitro co-culture. We found a faster depletion of the initially sensitive bacterial population than expected from simple mass action kinetics. A possible explanation for the rapid decline of the bacterial population is a synergistic interaction of phages which can be a favorable feature for phage therapies. In addition to this interaction characteristic, analysis of the kinetic fingerprint of this bacteria and phage combination revealed several relevant aspects of their population dynamics: A reduction of the bacterial concentration can be achieved only at high multiplicity of infection whereas bacterial extinction is hardly accomplished. Furthermore the binding affinity of the phage to bacteria is identified as one of the most crucial parameters for the reduction of the bacterial population size. Thus, kinetic fingerprinting can be used to infer phage–host interactions and to explore emergent dynamics which facilitates a rational design of phage therapies. Full article
(This article belongs to the Special Issue Phage Diversity for Research and Application)
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Open AccessArticle
Substandard Quality of the Antimicrobials Sold in the Street Markets in Haiti
Antibiotics 2020, 9(7), 407; https://doi.org/10.3390/antibiotics9070407 - 14 Jul 2020
Viewed by 1510
Abstract
This pilot study was conducted to analyze the quality of the antimicrobials sold in the street markets in Port-au-Prince, Haiti. A total of 258 packs containing antimicrobials were bought in 28 street markets in Port-au-Prince (Haiti). Tablets and contents of capsules included in [...] Read more.
This pilot study was conducted to analyze the quality of the antimicrobials sold in the street markets in Port-au-Prince, Haiti. A total of 258 packs containing antimicrobials were bought in 28 street markets in Port-au-Prince (Haiti). Tablets and contents of capsules included in 196 packs were analyzed using a Raman handheld spectrometer (NanoRAM of BWTEK, Model: BWS456-785) during the first quarter of 2019. Three out of 11 antimicrobials (Amoxicillin, Metronidazole, and Cotrimoxazole) had a high spectral match with an HQI ≥ 90 to the respective authentic medicine for more than 95% of their tablets/capsules. For six antimicrobials (Tetracycline, Erythromycin, Cloxacillin, Azithromycin, Clarithromycin, and the combination Amoxicillin + Clavulanic Acid) none of their tablets/capsules showed a sufficient spectral match with the authentic medicine. This finding indicates that these products sold in the markets did not contain the labeled drug and/or contained a degraded drug. In addition to the fact that prescription antimicrobials can be purchased in street markets, the present field study found that for most of them (including “Watch” antimicrobials according to the AWaRe classification) were substandard, which contributes to the present antimicrobials resistance epidemic. Full article
Open AccessReview
The Antimicrobial Activity of Cannabinoids
Antibiotics 2020, 9(7), 406; https://doi.org/10.3390/antibiotics9070406 - 13 Jul 2020
Cited by 6 | Viewed by 2613
Abstract
A post-antibiotic world is fast becoming a reality, given the rapid emergence of pathogens that are resistant to current drugs. Therefore, there is an urgent need to discover new classes of potent antimicrobial agents with novel modes of action. Cannabis sativa is an [...] Read more.
A post-antibiotic world is fast becoming a reality, given the rapid emergence of pathogens that are resistant to current drugs. Therefore, there is an urgent need to discover new classes of potent antimicrobial agents with novel modes of action. Cannabis sativa is an herbaceous plant that has been used for millennia for medicinal and recreational purposes. Its bioactivity is largely due to a class of compounds known as cannabinoids. Recently, these natural products and their analogs have been screened for their antimicrobial properties, in the quest to discover new anti-infective agents. This paper seeks to review the research to date on cannabinoids in this context, including an analysis of structure–activity relationships. It is hoped that it will stimulate further interest in this important issue. Full article
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Open AccessArticle
Functional Analysis of the Acinetobacter baumannii XerC and XerD Site-Specific Recombinases: Potential Role in Dissemination of Resistance Genes
Antibiotics 2020, 9(7), 405; https://doi.org/10.3390/antibiotics9070405 - 13 Jul 2020
Cited by 3 | Viewed by 886
Abstract
Modules composed of a resistance gene flanked by Xer site-specific recombination sites, the vast majority of which were found in Acinetobacter baumannii, are thought to behave as elements that facilitate horizontal dissemination. The A. baumannii xerC and xerD genes were cloned, and [...] Read more.
Modules composed of a resistance gene flanked by Xer site-specific recombination sites, the vast majority of which were found in Acinetobacter baumannii, are thought to behave as elements that facilitate horizontal dissemination. The A. baumannii xerC and xerD genes were cloned, and the recombinant clones used to complement the cognate Escherichia coli mutants. The complemented strains supported the resolution of plasmid dimers, and, as is the case with E. coli and Klebsiella pneumoniae plasmids, the activity was enhanced when the cells were grown in a low osmolarity growth medium. Binding experiments showed that the partially purified A. baumannii XerC and XerD proteins (XerCAb and XerDAb) bound synthetic Xer site-specific recombination sites, some of them with a nucleotide sequence deduced from existing A. baumannii plasmids. Incubation with suicide substrates resulted in the covalent attachment of DNA to a recombinase, probably XerCAb, indicating that the first step in the recombination reaction took place. The results described show that XerCAb and XerDAb are functional proteins and support the hypothesis that they participate in horizontal dissemination of resistant genes among bacteria. Full article
(This article belongs to the Special Issue Bacterial Pathogens Resistance and Virulence)
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Open AccessArticle
Antimicrobial Susceptibility and Characterization of Resistance Mechanisms of Corynebacterium urealyticum Clinical Isolates
Antibiotics 2020, 9(7), 404; https://doi.org/10.3390/antibiotics9070404 - 13 Jul 2020
Viewed by 966
Abstract
Corynebacterium urealyticum is a non-diphtherial urease-producing clinically relevant corynebacterial, most frequently involved in urinary tract infections. Most of the C. urealyticum clinical isolates are frequently resistant to several antibiotics. We investigated the susceptibility of 40 C. urealyticum isolated in our institution during the [...] Read more.
Corynebacterium urealyticum is a non-diphtherial urease-producing clinically relevant corynebacterial, most frequently involved in urinary tract infections. Most of the C. urealyticum clinical isolates are frequently resistant to several antibiotics. We investigated the susceptibility of 40 C. urealyticum isolated in our institution during the period 2005–2017 to eight compounds representative of the main clinically relevant classes of antimicrobial agents. Antimicrobial susceptibility was determined by the Epsilometer test. Resistance genes were searched by PCR. All strains were susceptible to vancomycin whereas linezolid and rifampicin also showed good activity (MICs90 = 1 and 0.4 mg/L, respectively). Almost all isolates (39/40, 97.5%) were multidrug resistant. The highest resistance rate was observed for ampicillin (100%), followed by erythromycin (95%) and levofloxacin (95%). Ampicillin resistance was associated with the presence of the blaA gene, encoding a class A β-lactamase. The two rifampicin-resistant strains showed point mutations driving amino acid replacements in conserved residues of RNA polymerase subunit β (RpoB). Tetracycline resistance was due to an efflux-mediated mechanism. Thirty-nine PFGE patterns were identified among the 40 C. urealyticum, indicating that they were not clonally related, but producing sporadic infections. These findings raise the need of maintaining surveillance strategies among this multidrug resistant pathogen. Full article
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Open AccessArticle
Phytochemical Composition and In Vitro Biological Activity of Iris spp. (Iridaceae): A New Source of Bioactive Constituents for the Inhibition of Oral Bacterial Biofilms
Antibiotics 2020, 9(7), 403; https://doi.org/10.3390/antibiotics9070403 - 11 Jul 2020
Cited by 5 | Viewed by 977
Abstract
The inhibition and eradication of oral biofilms is increasingly focused on the use of plant extracts as mouthwashes and toothpastes adjuvants. Here, we report on the chemical composition and the antibiofilm activity of 15 methanolic extracts of Iris species against both mono-(Pseudomonas [...] Read more.
The inhibition and eradication of oral biofilms is increasingly focused on the use of plant extracts as mouthwashes and toothpastes adjuvants. Here, we report on the chemical composition and the antibiofilm activity of 15 methanolic extracts of Iris species against both mono-(Pseudomonas aeruginosa, Staphylococcus aureus) and multi-species oral biofilms (Streptococcus gordonii, Veillonella parvula, Fusobacterium nucleatum subsp. nucleatum, and Actinomyces naeslundii). The phytochemical profiles of Iris pallida s.l., Iris versicolor L., Iris lactea Pall., Iris carthaliniae Fomin, and Iris germanica were determined by ultra-high performance liquid chromatography-high-resolution tandem mass spectroscopy (UHPLC-HRMS/MS) analysis, and a total of 180 compounds were identified among Iris species with (iso)flavonoid dominancy. I. pallida, I. versicolor, and I. germanica inhibited both the quorum sensing and adhesion during biofilm formation in a concentration-dependent manner. However, the extracts were less active against maturated biofilms. Of the five tested species, Iris pallida s.l. was the most effective at both inhibiting biofilm formation and disrupting existing biofilms, and the leaf extract exhibited the strongest inhibitory effect compared to the root and rhizome extracts. The cytotoxicity of the extracts was excluded in human fibroblasts. The inhibition of bacterial adhesion significantly correlated with myristic acid content, and quorum sensing inhibition correlated with the 7-β-hydroxystigmast-4-en-3-one content. These findings could be useful for establishing an effective tool for the control of oral biofilms and thus dental diseases. Full article
(This article belongs to the Special Issue New Insights on Biofilm Antimicrobial Strategies)
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Open AccessArticle
Antimicrobial Susceptibility Pattern of Porcine Respiratory Bacteria in Spain
Antibiotics 2020, 9(7), 402; https://doi.org/10.3390/antibiotics9070402 - 11 Jul 2020
Cited by 3 | Viewed by 1022
Abstract
The monitoring of antimicrobial susceptibility of pig pathogens is critical to optimize antimicrobial treatments and prevent development of resistance with a one-health approach. The aim of this study was to investigate the antimicrobial susceptibility patterns of swine respiratory pathogens in Spain from 2017 [...] Read more.
The monitoring of antimicrobial susceptibility of pig pathogens is critical to optimize antimicrobial treatments and prevent development of resistance with a one-health approach. The aim of this study was to investigate the antimicrobial susceptibility patterns of swine respiratory pathogens in Spain from 2017 to 2019. Bacterial isolation and identification were carried out following standardized methods from samples coming from sacrificed or recently deceased pigs with acute clinical signs compatible with respiratory tract infections. Minimum inhibitory concentration (MIC) values were determined using the broth microdilution method containing a total of 10 and 7–8 antimicrobials/concentrations respectively, in accordance with the recommendations presented by the Clinical and Laboratory Standards Institute (CLSI). The obtained antimicrobial susceptibility varies between pig respiratory pathogens. Actinobacillus pleuropneumoniae (APP) and Pasteurella multocida (PM) were highly susceptible (≥90%) to ceftiofur, florfenicol and macrolides (tilmicosin, tildipirosin and tulathromycin). However, the antimicrobial susceptibility was intermediate (>60% but <90%) for amoxicillin and enrofloxacin in the case of APP and sulfamethoxazole/trimethropim and tiamulin in the case of PM. Both bacteria showed low (<60%) antimicrobial susceptibility to doxycycline. Finally, Bordetella bronchiseptica was highly susceptible only to tildipirosin and tulathromycin (100%) and its susceptibility for florfenicol was close to 50% and <30% for the rest of the antimicrobial families tested. These results emphasize the need of determining antimicrobial susceptibility in pig respiratory cases in order to optimize the antimicrobial treatment in a case-by-case scenario. Full article
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