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Antibiotics, Volume 11, Issue 5 (May 2022) – 168 articles

Cover Story (view full-size image): We conducted a comparative effectiveness study of ceftolozane/tazobactam vs. aminoglycoside- or polymyxin-based therapies among hospitalized patients with positive MDR P. aeruginosa cultures. Patients treated with ceftolozane/tazobactam (n = 57) were younger (mean age of 67.5 vs. 71.1, p = 0.03) and had a higher comorbidity burden (median Charlson of 5 vs. 3, p = 0.01) as well as higher rates of spinal cord injury (38.6% vs. 21.9%, p = 0.02) and P. aeruginosa-positive bone/joint cultures (12.3% vs. 0.7%, p < 0.0001) compared with patients treated with aminoglycoside- or polymyxin-based regimens (n = 155). Inpatient mortality was significantly lower in the ceftolozane/tazobactam group compared with aminoglycosides or polymyxins (15.8% vs. 27.7%, adjusted odds ratio of 0.39, and 95% confidence interval of 0.16–0.93). View this paper
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Article
Combined PK/PD Index May Be a More Appropriate PK/PD Index for Cefoperazone/Sulbactam against Acinetobacter baumannii in Patients with Hospital-Acquired Pneumonia
Antibiotics 2022, 11(5), 703; https://doi.org/10.3390/antibiotics11050703 - 23 May 2022
Viewed by 539
Abstract
Cefoperazone/sulbactam (CPZ/SUL) is a β-lactam and β-lactamase inhibitor combination therapy for the treatment of respiratory tract infections. Using data from a prospective, multiple-center, open-label clinical trial in 54 patients with hospital-acquired pneumonia or ventilator-associated pneumonia caused by multidrug-resistant Acinetobacter baumannii (Ab), we showed [...] Read more.
Cefoperazone/sulbactam (CPZ/SUL) is a β-lactam and β-lactamase inhibitor combination therapy for the treatment of respiratory tract infections. Using data from a prospective, multiple-center, open-label clinical trial in 54 patients with hospital-acquired pneumonia or ventilator-associated pneumonia caused by multidrug-resistant Acinetobacter baumannii (Ab), we showed that a combined PK/PD index %(T > MICcpz*T > MICsul) is a more appropriate PK/PD index against Ab, compared to the PK/PD index (%T > MIC) for a single drug. For a 2 h infusion, the PK/PD cutoff of CPZ/SUL (2 g/1 g, q8h) for clinical and microbiological efficacy was 4/2 and 1/0.5 mg/L, respectively. The corresponding cumulative fraction of response was 46.5% and 25.3%, respectively. Results based on the combined PK/PD index were quite similar to that based on the joint probability of target attainment. The two drugs have interaction from the viewpoint of PK/PD. When the dose of one drug was too high, the PK/PD cutoff was often determined by another drug in which the dose was maintained. In most cases, sulbactam exerted the main effect against infection by Ab in the complex CPZ/SUL, which was similar to the literature reports. When the MIC of CPZ was 8, 16, or 32 mg/L, a CPZ/SUL 2 g/1 g (q8h), 2 g/2 g (q8h), or 2 g/2 g (q6h) (infusion was all 3 h) was recommended, respectively. A clinical efficacy and safety study to confirm simulation results is warranted. Full article
(This article belongs to the Special Issue Pharmacokinetic/Pharmacodynamic Models of Antibiotics)
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Article
Clinical Efficacy and Safety of Vancomycin Continuous Infusion in Patients Treated at Home in an Outpatient Parenteral Antimicrobial Therapy Program
Antibiotics 2022, 11(5), 702; https://doi.org/10.3390/antibiotics11050702 - 23 May 2022
Cited by 1 | Viewed by 551
Abstract
Vancomycin is commonly used in outpatient parenteral antimicrobial therapy (OPAT) of Gram-positive infections. Therapeutic drug monitoring and adverse event monitoring pose a challenge. Outcome data of vancomycin in OPAT (vOPAT) are limited. The study aim was to report the safety and efficacy of [...] Read more.
Vancomycin is commonly used in outpatient parenteral antimicrobial therapy (OPAT) of Gram-positive infections. Therapeutic drug monitoring and adverse event monitoring pose a challenge. Outcome data of vancomycin in OPAT (vOPAT) are limited. The study aim was to report the safety and efficacy of a structured vOPAT program implemented in the University Hospitals Leuven. The program provides continuous elastomeric infusion of vancomycin at home with biweekly follow-up at the outpatient clinic. Demographics, clinical, biochemical and treatment parameters, target attainment parameters and clinical outcomes were recorded. An e-survey was conducted to assess patient satisfaction. Thirty-five vOPAT episodes in 32 patients were included. During 206 follow-up consultations, 203 plasma concentration measurements were registered with a median vancomycin plasma concentration of 22.5 mg/L (range 6.6–32.0). The majority of concentrations (68.5%) were within the therapeutic range (20.0–25.0 mg/L). Adverse event rates, including drug- (5.7%) and catheter-related (5.7%) events, were low. For 32 vOPAT episodes, a clinical cure rate of 100% was observed. All patients who completed the e-survey were satisfied with their vOPAT course. These findings show that a structured vOPAT program with rigorous follow-up provides safe and effective ambulatory treatment of patients with vancomycin in continuous infusion. Full article
(This article belongs to the Special Issue Therapeutic Drug Monitoring of Antimicrobials)
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Review
Ways to Improve Insights into Clindamycin Pharmacology and Pharmacokinetics Tailored to Practice
Antibiotics 2022, 11(5), 701; https://doi.org/10.3390/antibiotics11050701 - 21 May 2022
Cited by 1 | Viewed by 771
Abstract
Given the increase in bacterial resistance and the decrease in the development of new antibiotics, the appropriate use of old antimicrobials has become even more compulsory. Clindamycin is a lincosamide antibiotic approved for adults and children as a drug of choice for systemic [...] Read more.
Given the increase in bacterial resistance and the decrease in the development of new antibiotics, the appropriate use of old antimicrobials has become even more compulsory. Clindamycin is a lincosamide antibiotic approved for adults and children as a drug of choice for systemic treatment of staphylococcal, streptococcal, and gram-positive anaerobic bacterial infections. Because of its profile and high bioavailability, it is commonly used as part of an oral multimodal alternative for prolonged parenteral antibiotic regimens, e.g., to treat bone and joint or prosthesis-related infections. Clindamycin is also frequently used for (surgical) prophylaxis in the event of beta-lactam allergy. Special populations (pediatrics, pregnant women) have altered cytochrome P450 (CYP)3A4 activity. As clindamycin is metabolized by the CYP3A4/5 enzymes to bioactive N-demethyl and sulfoxide metabolites, knowledge of the potential relevance of the drug’s metabolites and disposition in special populations is of interest. Furthermore, drug–drug interactions derived from CYP3A4 inducers and inhibitors, and the data on the impact of the disease state on the CYP system, are still limited. This narrative review provides a detailed survey of the currently available literature on pharmacology and pharmacokinetics and identifies knowledge gaps (special patient population, drug–drug, and drug–disease interactions) to describe a research strategy for precision medicine. Full article
(This article belongs to the Special Issue Therapeutic Drug Monitoring of Antimicrobials)
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Article
Effects of Verapamil and Two Bisbenzylisoquinolines, Curine and Guattegaumerine Extracted from Isolona hexaloba, on the Inhibition of ABC Transporters from Pseudomonas aeruginosa
Antibiotics 2022, 11(5), 700; https://doi.org/10.3390/antibiotics11050700 - 21 May 2022
Viewed by 554
Abstract
The biological effects of alkaloids, curine, guattegaumerine, and verapamil, on Pseudomonas aeruginosa were investigated. These molecules did not inhibit P. aeruginosa growth but increased the sensitivity of this bacterium to carbenicillin, novobiocin, and erythromycin. The results of another study indicate that curine and [...] Read more.
The biological effects of alkaloids, curine, guattegaumerine, and verapamil, on Pseudomonas aeruginosa were investigated. These molecules did not inhibit P. aeruginosa growth but increased the sensitivity of this bacterium to carbenicillin, novobiocin, and erythromycin. The results of another study indicate that curine and guattegaumerine were competitors of verapamil and acted as inhibitors of eukaryotic ABCB1 efflux pump. A BLAST-P carried out between a bacterial MDR transporter LmrA from Lactococcus lactis, a human MDR1/P-glycoprotein (ABCB1), and ABC proteins of P.aeruginosa highlighted five potential candidates that have this bacterium. A study on the sensitivity to carbenicillin in the presence of verapamil allowed us to identify the product of gene PA1113 as the ABC transporter involved in the influx of carbenicillin. Similarly, novobiocin transport performed in the presence of verapamil and a docking analysis highlighted protein MsbA (Lipid A flippase, gene PA4997) as a potential candidate in novobiocin efflux. MsbA has previously been identified as a multidrug transporter in E. coli, and as P. aeruginosa MsbA presented 76% identity with E. coli MsbA, it is possible that novobiocin efflux involves this ABC transporter, accounting for about 30% of the bacterium resistance to this antibiotic. Full article
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Article
Antimicrobial Efficacy of an Ultraviolet-C Device against Microorganisms Related to Contact Lens Adverse Events
Antibiotics 2022, 11(5), 699; https://doi.org/10.3390/antibiotics11050699 - 21 May 2022
Viewed by 545
Abstract
The purpose of the study was to assess the antimicrobial activity of an ultraviolet-C (UVC) device against microorganisms implicated in contact lens related adverse events. An UVC device with an emitting 4.5 mm diameter Light Emitting Diode (LED; 265 nm; 1.93 mJ/cm2 [...] Read more.
The purpose of the study was to assess the antimicrobial activity of an ultraviolet-C (UVC) device against microorganisms implicated in contact lens related adverse events. An UVC device with an emitting 4.5 mm diameter Light Emitting Diode (LED; 265 nm; 1.93 mJ/cm2) was used. Pseudomonas aeruginosa, Staphylococcus aureus, Fusarium solani, and Candida albicans agar plate lawns were exposed to the device beams for 15 and 30 s at 8 mm distance. Following the exposure, the diameter of the growth inhibition zone was recorded. Contact lenses made of Delfilicon-A, Senofilicon-A, Comfilicon-A, Balafilicon-A, Samfilicon-A and Omafilicon-A and a commercially available contact storage case was used. They were exposed to bacterial and fungal strains for 18 h at 37 °C and 25 °C respectively. After this, the samples were exposed to UVC for 30 s at 8 mm distance to determine the antimicrobial efficacy. Samples were then gently washed and plated on appropriate agar for enumeration of colonies. The UVC exposure reduced microbial growth by 100% in agar lawns, and significantly (p < 0.05) reduced microbial contamination to contact lenses and cases, ranging between 0.90 to 4.6 log. Very short UVC exposure has high antimicrobial efficacy against most of the predominant causative microorganisms implicated in contact lens related keratitis. UVC could be readily used as a broad-spectrum antimicrobial treatment for lens disinfection. Full article
(This article belongs to the Special Issue Ocular Surface Infection and Antimicrobials)
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Article
Management of Helicobacter Pylori Infection and Effectiveness Rates in Daily Clinical Practice in Spain: 2010–2019
Antibiotics 2022, 11(5), 698; https://doi.org/10.3390/antibiotics11050698 - 20 May 2022
Viewed by 471
Abstract
The management and effectiveness of the treatment of Helicobacter pylori infection are heterogeneous worldwide, despite the publication of international consensus conferences and guidelines, which have been widely available for years. The aim of the study was to describe the clinical management and the [...] Read more.
The management and effectiveness of the treatment of Helicobacter pylori infection are heterogeneous worldwide, despite the publication of international consensus conferences and guidelines, which have been widely available for years. The aim of the study was to describe the clinical management and the eradication rates in a region of Southern Europe (Spain). Between 2010 and 2019, we conducted a retrospective analysis of patients with H. pylori infection attended by gastroenterologists in two defined areas of the National Health System in Aragón. We compared the appropriateness of therapies according to guidelines, and described the effectiveness of each treatment. A total of 1644 penicillin non-allergic patients were included. The most prescribed therapy between 2010 and 2013 was the ‘classic’ triple therapy PCA (80%), whereas the ’concomitant’ therapy PCAM was chosen by 90% of the gastroenterologists in 2015. After 2016, the use of the quadruple bismuth-containing therapy in a single capsule (Pylera®) quickly increased, representing almost half of the overall prescriptions in 2019. Throughout the decade, adherence to guidelines was 76.4% and global efficacy was 70.7% (ITT). Triple therapies’ eradication rates were lower than 70% (ITT), whereas eradication rates with quadruple therapies achieved or were over 80% (ITT). In conclusion, despite the use of quadruple therapies and optimized treatments, the effectiveness of H. pylori management in daily clinical practice is far from the target of 90%. Full article
(This article belongs to the Special Issue Helicobacter pylori Infection: Therapy Changes and Challenges)
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Review
The Role of Abdominal Drain Cultures in Managing Abdominal Infections
Antibiotics 2022, 11(5), 697; https://doi.org/10.3390/antibiotics11050697 - 20 May 2022
Viewed by 526
Abstract
Intra-abdominal infections (IAI) are common in hospitalized patients, both in and outside of the intensive care unit. Management principles include antimicrobial therapy and source control. Typically, these infections are polymicrobial, and intra-operative samples will guide the targeted antimicrobial therapy. Although the use of [...] Read more.
Intra-abdominal infections (IAI) are common in hospitalized patients, both in and outside of the intensive care unit. Management principles include antimicrobial therapy and source control. Typically, these infections are polymicrobial, and intra-operative samples will guide the targeted antimicrobial therapy. Although the use of prophylactic abdominal drains in patients undergoing abdominal surgery is decreasing, the use of drains to treat IAI, both in surgical and non-surgical strategies for abdominal infection, is increasing. In this context, samples from abdominal drains are often used to assist in antimicrobial decision making. In this narrative review, we provide an overview of the current role of abdominal drains in surgery, discuss the importance of biofilm formation in abdominal drains and the mechanisms involved, and review the clinical data on the use of sampling these drains for diagnostic purposes. We conclude that biofilm formation and the colonization of abdominal drains is common, which precludes the use of abdominal fluid to reliably diagnose IAI and identify the pathogens involved. We recommend limiting the use of drains and, when present, avoiding routine microbiological sampling. Full article
(This article belongs to the Special Issue Antibiotic Usage in Acute Situations)
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Article
Hesperidin-, Curcumin-, and Amphotericin B- Based Nano-Formulations as Potential Antibacterials
Antibiotics 2022, 11(5), 696; https://doi.org/10.3390/antibiotics11050696 - 20 May 2022
Viewed by 575
Abstract
To combat the public health threat posed by multiple-drug-resistant (MDR) pathogens, new drugs with novel chemistry and modes of action are needed. In this study, several drugs including Hesperidin (HES), curcumin (CUR), and Amphotericin B (AmpB) drug–nanoparticle formulations were tested for antibacterial strength [...] Read more.
To combat the public health threat posed by multiple-drug-resistant (MDR) pathogens, new drugs with novel chemistry and modes of action are needed. In this study, several drugs including Hesperidin (HES), curcumin (CUR), and Amphotericin B (AmpB) drug–nanoparticle formulations were tested for antibacterial strength against MDR Gram-positive bacteria, including Bacillus cereus, Streptococcus pyogenes, Methicillin-resistant Staphylococcus aureus (MRSA), and Streptococcus pneumoniae, and Gram-negative bacteria, including Escherichia coli K1, Pseudomonas aeruginosa, Salmonella enterica, and Serratia marcescens. Nanoparticles were synthesized and subjected to Atomic force microscopy, Fourier transform-infrared spectroscopy, and Zetasizer for their detailed characterization. Antibacterial assays were performed to determine their bactericidal efficacy. Lactate dehydrogenase (LDH) assays were carried out to measure drugs’ and drug–nanoparticles’ cytotoxic effects on human cells. Spherical NPs ranging from 153 to 300 nm were successfully synthesized. Results from antibacterial assays revealed that drugs and drug–nanoparticle formulations exerted bactericidal activity against MDR bacteria. Hesperidin alone failed to exhibit antibacterial effects but, upon conjugation with cinnamic-acid-based magnetic nanoparticle, exerted significant bactericidal activity against both the Gram-positive and Gram-negative isolates. AmpB-LBA-MNPs produced consistent, potent antibacterial efficacy (100% kill) against all Gram-positive bacteria. AmpB-LBA-MNPs showed strong antibacterial activity against Gram-negative bacteria. Intriguingly, all the drugs and their conjugated counterpart except AmpB showed minimal cytotoxicity against human cells. In summary, these innovative nanoparticle formulations have the potential to be utilized as therapeutic agents against infections caused by MDR bacteria and represent a significant advancement in our effort to counter MDR bacterial infections. Full article
(This article belongs to the Special Issue New Frontiers in Antimicrobial Discovery)
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Article
An Observational Study of MDR Hospital-Acquired Infections and Antibiotic Use during COVID-19 Pandemic: A Call for Antimicrobial Stewardship Programs
Antibiotics 2022, 11(5), 695; https://doi.org/10.3390/antibiotics11050695 - 20 May 2022
Cited by 1 | Viewed by 567
Abstract
The pandemic caused by the COVID-19 virus has required major adjustments to healthcare systems, especially to infection control and antimicrobial stewardship. The objective of this study was to describe the incidence of multidrug-resistant (MDR) hospital-acquired infections (HAIs) and antibiotic consumption during the three [...] Read more.
The pandemic caused by the COVID-19 virus has required major adjustments to healthcare systems, especially to infection control and antimicrobial stewardship. The objective of this study was to describe the incidence of multidrug-resistant (MDR) hospital-acquired infections (HAIs) and antibiotic consumption during the three waves of COVID-19 and to compare it to the period before the outbreak at Molinette Hospital, located in the City of Health and Sciences, a 1200-bed teaching hospital with surgical, medical, and intensive care units. We demonstrated an increase in MDR infections: particularly in K. pneumoniae carbapenemase-producing K. pneumoniae (KPC-Kp), A. baumannii, and MRSA. Fluoroquinolone use showed a significant increasing trend in the pre-COVID period but saw a significant reduction in the COVID period. The use of fourth- and fifth-generation cephalosporins and piperacillin–tazobactam increased at the beginning of the COVID period. Our findings support the need for restoring stewardship and infection control practices, specifically source control, hygiene, and management of invasive devices. In addition, our data reveal the need for improved microbiological diagnosis to guide appropriate treatment and prompt infection control during pandemics. Despite the infection control practices in place during the COVID-19 pandemic, invasive procedures in critically ill patients and poor source control still increase the risk of HAIs caused by MDR organisms. Full article
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Article
The Economic Impact of Carbapenem Resistant-Non Lactose Fermenter and Enterobacteriaceae Infections on Hospital Costs in Dr. Soetomo General Academic Hospital Surabaya, Indonesia
Antibiotics 2022, 11(5), 694; https://doi.org/10.3390/antibiotics11050694 - 20 May 2022
Viewed by 487
Abstract
Background: Carbapenem resistant-non lactose fermenter (CR-NLF) and Carbapenem resistant-Enterobacteriaceae (CR-E) bacterial infections are likely to be a global threat to people’s health. However, studies on the economic impacts according to the hospital setting are very scarce. The study aimed to explore the [...] Read more.
Background: Carbapenem resistant-non lactose fermenter (CR-NLF) and Carbapenem resistant-Enterobacteriaceae (CR-E) bacterial infections are likely to be a global threat to people’s health. However, studies on the economic impacts according to the hospital setting are very scarce. The study aimed to explore the impact of CR-NLF (Acinetobacter baumannii = CRAB) & Pseudomonas aeruginosa = CRPA) and CR-E (Escherichia coli = CREC) & Klebsiella pneumoniae = CRKP) infections on hospital costs from a payer perspective among patients admitted to Dr.Soetomo Hospital, Surabaya, Indonesia. Methods: In the retrospective case-control study, medical records of all included patients hospitalized during 2018–2021 were reviewed for CRAB, CRPA, CREC, CRKP, and carbapenem sensitive (CSAB, CSPA, CSEC, CSKP) were collected. We retrieved the data of age, gender, clinical specimen, dates of admission, and discharge status. The outcomes of interest were hospital length of stay and hospitalization cost. Results: The cost for CR-NLFs infections was higher than carbapenem sensitive, $3026.24 versus $1299.28 (p < 0.05). There was no significant difference between CR-E against carbapenem sensitive. It showed that the highest impact of the cost was CRAB, followed by CRPA, CRKP, and CREC. The bed, antibiotics, pharmacy, and diagnostic costs of CR-NLFIs were significantly higher than CR-E. Conclusion: This study showed that the hospital cost and expenditure of CR-NLFs per patient were higher than CS. The hospital cost per patient for CR-NLF was higher than CR-E. Full article
Article
TXH11106: A Third-Generation MreB Inhibitor with Enhanced Activity against a Broad Range of Gram-Negative Bacterial Pathogens
Antibiotics 2022, 11(5), 693; https://doi.org/10.3390/antibiotics11050693 - 20 May 2022
Viewed by 488
Abstract
The emergence of multi-drug-resistant Gram-negative pathogens highlights an urgent clinical need to explore and develop new antibiotics with novel antibacterial targets. MreB is a promising antibacterial target that functions as an essential elongasome protein in most Gram-negative bacterial rods. Here, we describe a [...] Read more.
The emergence of multi-drug-resistant Gram-negative pathogens highlights an urgent clinical need to explore and develop new antibiotics with novel antibacterial targets. MreB is a promising antibacterial target that functions as an essential elongasome protein in most Gram-negative bacterial rods. Here, we describe a third-generation MreB inhibitor (TXH11106) with enhanced bactericidal activity versus the Gram-negative pathogens Escherichia coli, Klebsiella pneumoniae, Acinetobacter baumannii, and Pseudomonas aeruginosa compared to the first- and second-generation compounds A22 and CBR-4830, respectively. Large inocula of these four pathogens are associated with a low frequency of resistance (FOR) to TXH11106. The enhanced bactericidal activity of TXH11106 relative to A22 and CBR-4830 correlates with a correspondingly enhanced capacity to inhibit E. coli MreB ATPase activity via a noncompetitive mechanism. Morphological changes induced by TXH11106 in E. coli, K. pneumoniae, A. baumannii, and P. aeruginosa provide further evidence supporting MreB as the bactericidal target of the compound. Taken together, our results highlight the potential of TXH11106 as an MreB inhibitor with activity against a broad spectrum of Gram-negative bacterial pathogens of acute clinical importance. Full article
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Article
Whole-Genome Characterisation of ESBL-Producing E. coli Isolated from Drinking Water and Dog Faeces from Rural Andean Households in Peru
Antibiotics 2022, 11(5), 692; https://doi.org/10.3390/antibiotics11050692 - 20 May 2022
Viewed by 550
Abstract
E. coli that produce extended-spectrum β-lactamases (ESBLs) are major multidrug-resistant bacteria. In Peru, only a few reports have characterised the whole genome of ESBL enterobacteria. We aimed to confirm the identity and antimicrobial resistance (AMR) profile of two ESBL isolates from dog faeces [...] Read more.
E. coli that produce extended-spectrum β-lactamases (ESBLs) are major multidrug-resistant bacteria. In Peru, only a few reports have characterised the whole genome of ESBL enterobacteria. We aimed to confirm the identity and antimicrobial resistance (AMR) profile of two ESBL isolates from dog faeces and drinking water of rural Andean households and determine serotype, phylogroup, sequence type (ST)/clonal complex (CC), pathogenicity, virulence genes, ESBL genes, and their plasmids. To confirm the identity and AMR profiles, we used the VITEK®2 system. Whole-genome sequencing (WGS) and bioinformatics analysis were performed subsequently. Both isolates were identified as E. coli, with serotypes -:H46 and O9:H10, phylogroups E and A, and ST/CC 5259/- and 227/10, respectively. The isolates were ESBL-producing, carbapenem-resistant, and not harbouring carbapenemase-encoding genes. Isolate 1143 ST5259 harboured the astA gene, encoding the EAST1 heat-stable toxin. Both genomes carried ESBL genes (blaEC-15, blaCTX-M-8, and blaCTX-M-55). Nine plasmids were detected, namely IncR, IncFIC(FII), IncI, IncFIB(AP001918), Col(pHAD28), IncFII, IncFII(pHN7A8), IncI1, and IncFIB(AP001918). Finding these potentially pathogenic bacteria is worrisome given their sources and highlights the importance of One-Health research efforts in remote Andean communities. Full article
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Article
Exploring the Antimicrobial Stewardship Educational Needs of Healthcare Students and the Potential of an Antimicrobial Prescribing App as an Educational Tool in Selected African Countries
Antibiotics 2022, 11(5), 691; https://doi.org/10.3390/antibiotics11050691 - 19 May 2022
Viewed by 556
Abstract
Antimicrobial resistance (AMR) is a global health threat and one of the top 10 global public health threats facing humanity. AMR contributes to 700,000 deaths annually and more deaths, as many as 10 million are projected to happen by 2050. Antimicrobial stewardship (AMS) [...] Read more.
Antimicrobial resistance (AMR) is a global health threat and one of the top 10 global public health threats facing humanity. AMR contributes to 700,000 deaths annually and more deaths, as many as 10 million are projected to happen by 2050. Antimicrobial stewardship (AMS) activities have been important in combating the ripple effects of AMR and several concerted efforts have been taken to address the issues of antimicrobial resistance. The Commonwealth Pharmacists Association through the Commonwealth Partnerships for Antimicrobial Stewardship (CwPAMS) programme has been enhancing the capacity of health institutions in Low-Middle-Income Countries (LMIC) to combat AMR. Through such efforts, an antimicrobial prescribing app (CwPAMS app) was launched and delivered to support antimicrobial prescribing and improve AMS practice in four African countries; Ghana, Uganda, Zambia, and Tanzania. The app provides easy access to infection management resources to improve appropriate use of antimicrobials in line with national and international guidelines. This study aimed to identify and explore the potential for the usability of the CwPAMS app among healthcare students across selected African countries that are part of the Commonwealth. The study equally evaluated the healthcare students’ understanding and attitudes towards antimicrobial resistance and stewardship. Despite 70% of the respondents indicating that they had been taught about prudent use of antibiotics, diagnosis of infections and their management using antibiotics in their universities, notable knowledge gaps were discovered: 52.2% of the respondents had no prior information on the term AMS, 50.6% of them reported a lack of resources for accessing up-to-date information on drugs, for instance only 36% had had an opportunity to access an app as a learning resource even when 70% of the respondents thought that a mobile app would support in increasing their knowledge. Those challenges reveal an opportunity for the CwPAMS App as a potential option to address AMR and AMS gaps among healthcare students. Full article
(This article belongs to the Special Issue Antimicrobial Prescribing and Stewardship, 2nd Volume)
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The Implementation of National Action Plan (NAP) on Antimicrobial Resistance (AMR) in Bangladesh: Challenges and Lessons Learned from a Cross-Sectional Qualitative Study
Antibiotics 2022, 11(5), 690; https://doi.org/10.3390/antibiotics11050690 - 19 May 2022
Viewed by 575
Abstract
This study explored the current situation of the National Action Plan (NAP) on Antimicrobial Resistance (AMR) implementation in Bangladesh and examined how different sectors (human, animal, and environment) addressed the AMR problem in policy and practice, as well as associated challenges and barriers [...] Read more.
This study explored the current situation of the National Action Plan (NAP) on Antimicrobial Resistance (AMR) implementation in Bangladesh and examined how different sectors (human, animal, and environment) addressed the AMR problem in policy and practice, as well as associated challenges and barriers to identifying policy lessons and practices. Informed by a rapid review of the available literature and following the World Health Organization (WHO) AMR situation analysis framework, a guideline was developed to conduct in-depth interviews with selected stakeholders from January to December 2021. Data were analysed using an adapted version of Anderson’s governance framework. Findings reveal the absence of required inter-sectoral coordination essential to a multisectoral approach. There was substantial coordination between the human health and livestock/fisheries sectors, but the environment sector was conspicuously absent. The government initiated some hospital-based awareness programs and surveillance activities, yet no national Monitoring and Evaluation (M&E) framework was established for NAP activities. Progress of implementation was slow, constrained by the shortage of a trained health workforce and financial resources, as well as the COVID-19 pandemic. To summarise, five years into the development of the NAP in Bangladesh, its implementation is not up to the level that the urgency of the situation requires. The policy and practice need to be cognisant of this fact and do the needful things to avoid a catastrophe. Full article
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Article
Epidemiology of Plasmids in Escherichia coli and Klebsiella pneumoniae with Acquired Extended Spectrum Beta-Lactamase Genes Isolated from Chronic Wounds in Ghana
Antibiotics 2022, 11(5), 689; https://doi.org/10.3390/antibiotics11050689 - 19 May 2022
Viewed by 479
Abstract
Little information is available on the local epidemiology of mobile genetic elements such as plasmids harboring acquired beta-lactamase genes in Western African Ghana. In the present study, we screened for plasmids in three Escherichia coli and four Klebsiella pneumoniae isolates expressing extended spectrum [...] Read more.
Little information is available on the local epidemiology of mobile genetic elements such as plasmids harboring acquired beta-lactamase genes in Western African Ghana. In the present study, we screened for plasmids in three Escherichia coli and four Klebsiella pneumoniae isolates expressing extended spectrum beta-lactamases (ESBL) mediated by the blaCTX-M-15 gene from chronically infected wounds of Ghanaian patients. Bacterial isolates were subjected to combined short-read and long-read sequencing to obtain the sequences of their respective plasmids. In the blaCTX-M-15-gene-carrying plasmids of the four ESBL-positive K. pneumoniae isolates, IncFIB/IncFII (n = 3) and FIA (n = 1) sequences were detected, while in the blaCTX-M-15-gene-carrying plasmids of the three ESBL-positive E. coli isolates, IncFIA/IncFIB (n = 2) and IncFIB (n = 1) sequences were found. The three IncFIB/IncFII sequence-containing plasmids were almost identical to a K. pneumoniae plasmid reported from France. They belonged to the clonal lineages ST17, ST36 and ST39 of K. pneumoniae, suggesting transversal spread of this obviously evolutionary successful plasmid in Ghana. Other resistance gene-encoding plasmids observed in the assessed Enterobacterales harbored IncFIA/IncR and IncFII sequences. International spread was confirmed by the high genetic similarity to resistance-mediating plasmids published from Asia, Australia, Europe and Northern America, including a blaCTX-M-15-gene-carrying plasmid isolated from a wild bird in Germany. In conclusion, the study contributed to the scarcely available information on the epidemiology of third-generation cephalosporine resistance-mediating plasmids in Ghana. Furthermore, the global spread of resistance-mediating plasmids provided hints on the evolutionary success of individual resistance-harboring plasmids by transversal spread among K. pneumoniae lineages in Ghana. Full article
(This article belongs to the Special Issue Global Spread of Antibiotics)
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Article
Phenotypic Adaptation to Antiseptics and Effects on Biofilm Formation Capacity and Antibiotic Resistance in Clinical Isolates of Early Colonizers in Dental Plaque
Antibiotics 2022, 11(5), 688; https://doi.org/10.3390/antibiotics11050688 - 19 May 2022
Viewed by 541
Abstract
Despite the wide-spread use of antiseptics in dental practice and oral care products, there is little public awareness of potential risks associated with antiseptic resistance and potentially concomitant cross-resistance. Therefore, the aim of this study was to investigate potential phenotypic adaptation in 177 [...] Read more.
Despite the wide-spread use of antiseptics in dental practice and oral care products, there is little public awareness of potential risks associated with antiseptic resistance and potentially concomitant cross-resistance. Therefore, the aim of this study was to investigate potential phenotypic adaptation in 177 clinical isolates of early colonizers of dental plaque (Streptococcus, Actinomyces, Rothia and Veillonella spp.) upon repeated exposure to subinhibitory concentrations of chlorhexidine digluconate (CHX) or cetylpyridinium chloride (CPC) over 10 passages using a modified microdilution method. Stability of phenotypic adaptation was re-evaluated after culture in antiseptic-free nutrient broth for 24 or 72 h. Strains showing 8-fold minimal inhibitory concentration (MIC)-increase were further examined regarding their biofilm formation capacity, phenotypic antibiotic resistance and presence of antibiotic resistance genes (ARGs). Eight-fold MIC-increases to CHX were detected in four Streptococcus isolates. These strains mostly exhibited significantly increased biofilm formation capacity compared to their respective wild-type strains. Phenotypic antibiotic resistance was detected to tetracycline and erythromycin, consistent with the detected ARGs. In conclusion, this study shows that clinical isolates of early colonizers of dental plaque can phenotypically adapt toward antiseptics such as CHX upon repeated exposure. The underlying mechanisms at genomic and transcriptomic levels need to be investigated in future studies. Full article
(This article belongs to the Special Issue Antimicrobial Strategies against Oral Pathogenic Bacteria and Biofilm)
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Review
The Emergence and Dissemination of Multidrug Resistant Pseudomonas aeruginosa in Lebanon: Current Status and Challenges during the Economic Crisis
Antibiotics 2022, 11(5), 687; https://doi.org/10.3390/antibiotics11050687 - 19 May 2022
Viewed by 621
Abstract
Pseudomonas aeruginosa is a common cause of healthcare-associated infections and chronic airway diseases in non-clinical settings. P. aeruginosa is intrinsically resistant to a variety of antimicrobials and has the ability to acquire resistance to others, causing increasingly recalcitrant infections and elevating public health [...] Read more.
Pseudomonas aeruginosa is a common cause of healthcare-associated infections and chronic airway diseases in non-clinical settings. P. aeruginosa is intrinsically resistant to a variety of antimicrobials and has the ability to acquire resistance to others, causing increasingly recalcitrant infections and elevating public health concerns. We reviewed the literature on multidrug-resistant (MDR) P. aeruginosa isolated from humans (nosocomial and community-associated), animals, and the environment in Lebanon, a country that has been suffering from a surge in antimicrobial resistance (AMR). We identified 24 studies that described the epidemiology and antimicrobial susceptibility profiles of P. aeruginosa. Our analysis showed that the bacterium was predominant in lesions of patients on mechanical ventilation and in burn patients and those with diabetic foot infections and hematological malignancies. We also found that carbapenem resistance in P. aeruginosa isolates in Lebanon involved both enzymatic and non-enzymatic mechanisms but depended predominantly on VIM-2 production (40.7%). Additionally, MDR P. aeruginosa was detected in animals, where a recent study reported the emergence of carbapenemase-producing P. aeruginosa in livestock in Lebanon. Notably, no studies evaluated the contribution of MDR P. aeruginosa in the environment to human infections. Taken together, our findings highlight the need for AMR surveillance programs and a national action plan to combat resistance in Lebanon. Full article
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Article
Impact of Three Nonsurgical, Full-Mouth Periodontal Treatments on Total Bacterial Load and Selected Pathobionts
Antibiotics 2022, 11(5), 686; https://doi.org/10.3390/antibiotics11050686 - 19 May 2022
Viewed by 466
Abstract
For the treatment of periodontitis stage III/IV, a quadrant/week-wise debridement (Q-SRP) was compared with three full-mouth approaches: full-mouth scaling (FMS, accelerated Q-SRP within 24 h), full-mouth scaling with chlorhexidine-based disinfection (FMD), and FMD with adjuvant erythritol air polishing (FMDAP). The objective of this [...] Read more.
For the treatment of periodontitis stage III/IV, a quadrant/week-wise debridement (Q-SRP) was compared with three full-mouth approaches: full-mouth scaling (FMS, accelerated Q-SRP within 24 h), full-mouth scaling with chlorhexidine-based disinfection (FMD), and FMD with adjuvant erythritol air polishing (FMDAP). The objective of this prospective, randomized study (a substudy of ClinicalTrials.gov, identifier: NCT03509233) was to compare the clinical and microbiological effects of the treatments. In total, 105 patients were randomized to one of the four aforementioned treatment groups, with n = 25, 28, 27, and 25 patients allocated to each group, respectively. At baseline and 3 and 6 months after treatment, the clinical parameters, including the pocket probing depths, clinical attachment level, and bleeding on probing, were recorded, and the prevalence of the total bacteria and four periodontal pathobionts (Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, and Tannerella forsythia) was determined using real-time quantitative PCR. Concerning the clinical outcomes, all the treatment modalities were effective, but the full-mouth approaches, especially FMDAP, were slightly superior to Q-SRP. Using the FMD approach, the reduction in the bacterial load and the number of pathobionts was significantly greater than for FMS, followed by Q-SRP. FMDAP was the least effective protocol for microbial reduction. However, after a temporary increase 3 months after therapy using FMDAP, a significant decrease in the key pathogen, P. gingivalis, was observed. These findings were not consistent with the clinical results from the FMDAP group. In conclusion, the dynamics of bacterial colonization do not necessarily correlate with clinical outcomes after full-mouth treatments for periodontitis stage III/IV. Full article
(This article belongs to the Special Issue Antibacterial Treatment in Periodontal and Endodontic Therapy)
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Article
Co-Delivery of Nano-Silver and Vancomycin via Silica Nanopollens for Enhanced Antibacterial Functions
Antibiotics 2022, 11(5), 685; https://doi.org/10.3390/antibiotics11050685 - 18 May 2022
Viewed by 526
Abstract
Infectious diseases caused by bacteria have led to a great threat to public health. With the significant advances in nanotechnology in recent decades, nanomaterials have emerged as a powerful tool to boost antibacterial performance due to either intrinsic bactericidal properties or by enhancing [...] Read more.
Infectious diseases caused by bacteria have led to a great threat to public health. With the significant advances in nanotechnology in recent decades, nanomaterials have emerged as a powerful tool to boost antibacterial performance due to either intrinsic bactericidal properties or by enhancing the delivery efficiency of antibiotics for effective pathogen killing. Vancomycin, as one of the most widely employed antimicrobial peptides, has a potent bactericidal activity, but at the same time shows a limited bioavailability. Silver nanoparticles have also been extensively explored and were found to have a well-recognized antibacterial activity and limited resistance potential; however, how to prevent nanosized Ag particles from aggregation in biological conditions is challenging. In this study, we aimed to combine the advantages of both vancomycin and nano-Ag for enhanced bacterial killing, where both antibacterial agents were successfully loaded onto a silica nanoparticle with a pollen-like morphology. The morphology of nano-Ag-decorated silica nanopollens was characterized using transmission electron microscopy and elemental mapping through energy dispersive spectroscopy. Silver nanoparticles with a size of 10–25 nm were observed as well-distributed on the surface of silica nanoparticles of around 200 nm. The unique design of a spiky morphology of silica nano-carriers promoted the adhesion of nanoparticles towards bacterial surfaces to promote localized drug release for bacterial killing, where the bacterial damage was visualized through scanning electron microscopy. Enhanced bactericidal activity was demonstrated through this co-delivery of vancomycin and nano-Ag, decreasing the minimum inhibition concentration (MIC) towards E. coli and S. epidermidis down to 15 and 10 µg/mL. This study provides an efficient antimicrobial nano-strategy to address potential bacterial infections. Full article
(This article belongs to the Special Issue Antibiotic-Free Antibacterial Strategies Enabled by Nanomaterials)
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Article
Multi Evaluation of a Modified GoldNano Carb Test for Carbapenemase Detection in Clinical Isolates of Gram-Negative Bacilli
Antibiotics 2022, 11(5), 684; https://doi.org/10.3390/antibiotics11050684 - 18 May 2022
Viewed by 368
Abstract
Carbapenemase-producing Gram-negative bacteria have been increasingly reported. Simple and sensitive methods for carbapenemase detection are still needed. In this study, a gold nanoparticle (AuNP) solution was modified by the addition of zinc sulfate (ZnSO4) for improving the conventional GoldNano Carb (cGoldC) [...] Read more.
Carbapenemase-producing Gram-negative bacteria have been increasingly reported. Simple and sensitive methods for carbapenemase detection are still needed. In this study, a gold nanoparticle (AuNP) solution was modified by the addition of zinc sulfate (ZnSO4) for improving the conventional GoldNano Carb (cGoldC) test, and the modified GoldC (mGoldC) test was then evaluated for phenotypic detection of carbapenemase production in Gram-negative bacilli clinical isolates. ZnSO4 was added to give final concentrations of 0.25, 0.5, 0.75, and 1 mM. The performance of the mGoldC test was evaluated in Enterobacterales, Acinetobacter spp., and Pseudomonas aeruginosa isolates from six hospitals in different regions using polymerase chain reaction (PCR) as a gold standard. The AuNP solution with 0.25 mM ZnSO4 was used for the mGoldC test. Evaluation of the mGoldC test in 495 Enterobacterales, 212 Acinetobacter spp., and 125 P. aeruginosa isolates (including 444 carbapenemase producers and 388 non-carbapenemase producers) revealed sensitivity, specificity, a positive likelihood ratio, and a negative likelihood ratio of 98.6%, 98.2%, 54.7, and 0.01, respectively. This test is fast, easy to perform, cost-effective (~0.25 USD per test), and highly sensitive and specific for routine carbapenemase detection, thus leading to effective antimicrobial therapy and infection control measures. Full article
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Article
Leucyl-tRNA Synthetase Inhibitor, D-Norvaline, in Combination with Oxacillin, Is Effective against Methicillin-Resistant Staphylococcus aureus
Antibiotics 2022, 11(5), 683; https://doi.org/10.3390/antibiotics11050683 - 18 May 2022
Viewed by 408
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) is a pathogenic bacterium that causes severe diseases in humans. For decades, MRSA has acquired substantial resistance against conventional antibiotics through regulatory adaptation, thereby posing a challenge for treating MRSA infection. One of the emerging strategies to combat MRSA [...] Read more.
Methicillin-resistant Staphylococcus aureus (MRSA) is a pathogenic bacterium that causes severe diseases in humans. For decades, MRSA has acquired substantial resistance against conventional antibiotics through regulatory adaptation, thereby posing a challenge for treating MRSA infection. One of the emerging strategies to combat MRSA is the combinatory use of antibacterial agents. Based on the dramatic change in phospholipid fatty acid (PLFA) composition of MRSA in previous results, this study investigated branched-chain amino acid derivatives (precursors of fatty acid synthesis of cell membrane) and discovered the antimicrobial potency of D-norvaline. The compound, which can act synergistically with oxacillin, is among the three leucine-tRNA synthetase inhibitors with high potency to inhibit MRSA cell growth and biofilm formation. PLFA analysis and membrane properties revealed that D-norvaline decreased the overall amount of PLFA, increasing the fluidity and decreasing the hydrophobicity of the bacterial cell membrane. Additionally, we observed genetic differences to explore the response to D-norvaline. Furthermore, deletion mutants and clinically isolated MRSA strains were treated with D-norvaline. The study revealed that D-norvaline, with low concentrations of oxacillin, was effective in killing several MRSA strains. In summary, our findings provide a new combination of aminoacyl-tRNA synthetase inhibitor D-norvaline and oxacillin, which is effective against MRSA. Full article
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Article
Exploration of Trends in Antimicrobial Use and Their Determinants Based on Dispensing Information Collected from Pharmacies throughout Japan: A First Report
Antibiotics 2022, 11(5), 682; https://doi.org/10.3390/antibiotics11050682 - 18 May 2022
Viewed by 483
Abstract
The purpose of this study was to evaluate the defined daily doses (DDD)/1000 prescriptions/month (DPM) as a new indicator that can be used in pharmacies, and to describe antimicrobial use patterns in pharmacies nationwide in Japan. Dispensing volumes, number of prescriptions received, and [...] Read more.
The purpose of this study was to evaluate the defined daily doses (DDD)/1000 prescriptions/month (DPM) as a new indicator that can be used in pharmacies, and to describe antimicrobial use patterns in pharmacies nationwide in Japan. Dispensing volumes, number of prescriptions received, and facility information were obtained from 2638 pharmacies that participated in a survey. DPM was calculated based on the dispensing volume and number of prescriptions, which are routinely collected data that are simple to use. Use of third-generation cephalosporins, quinolones, and macrolides in pharmacies that received prescriptions primarily from hospitals or clinics decreased from January 2019 to January 2021. In particular, the antimicrobial use was higher in otorhinolaryngology departments than in other departments, despite a decrease in the antimicrobial use. In the linear multiple regression analysis, otorhinolaryngology department was independently associated with the third-generation cephalosporin, quinolone, and macrolide prescription in all periods. This study reveals for the first-time trends in antimicrobial use through a new indicator using the volume of drugs dispensed in pharmacies throughout Japan. Antimicrobial use differed by the medical department, suggesting the need to target interventions according to the department type. Full article
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Article
Phytochemical Composition, Antioxidant and Antifungal Activity of Thymus capitatus, a Medicinal Plant Collected from Northern Morocco
Antibiotics 2022, 11(5), 681; https://doi.org/10.3390/antibiotics11050681 - 18 May 2022
Viewed by 512
Abstract
Thymus capitatus is a Mediterranean endemic plant commonly known as “Zaïtra” in northern Morocco. As T. capitatus is widely used in traditional medicine and food, this present work aims to investigate the chemical compositions and biological activities of the T. capitatus leaves essential [...] Read more.
Thymus capitatus is a Mediterranean endemic plant commonly known as “Zaïtra” in northern Morocco. As T. capitatus is widely used in traditional medicine and food, this present work aims to investigate the chemical compositions and biological activities of the T. capitatus leaves essential oil (TcLEO), acetonic (TcLAE), and methanolic extract (TcLME). The spectrophotometric determination demonstrated that T. capitatus is a natural source rich in phenolic contents (TPC) and flavonoid contents (TFC) and that TcLME revealed the highest TPC and TFC than TcLAE and TcLEO. The LC-MS analysis of phenolic compounds showed that paraben acid was predominant in both TcLME and TcLAE, followed by cinnamic acid and p-hydroxybenzoic acid. GC-MS analysis of the TcLEO revealed the presence of a total of 10 compounds, which were predominated by carvacrol. The antioxidant activity by ORAC was observed to be significantly higher in TcLEO and TcLAE than in TcLME. All samples used to assess DNA degradation effectively prevented DNA oxidation and, at the same time, had a prooxidant effect. The genotoxicity test showed that the T. capitatus were devoid of any mutagenic activity. Concerning antifungal activity, all samples were able to inhibit the growth of all microorganisms tested at low concentrations. TcLAE showed higher activity than TcLME, and in general, dermatophytes were more susceptible, being Microsporum canis the most sensitive one. Overall, the results obtained from this study confirm the wide uses of T. capitatus. Furthermore, the finding results suggest that the T. capitatus essential oil and extracts can be highly useful for pharmaceutical industries. Full article
(This article belongs to the Special Issue Recent Advances in Antimicrobial Drug Discovery)
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Article
Identification of Therapeutic Targets in an Emerging Gastrointestinal Pathogen Campylobacter ureolyticus and Possible Intervention through Natural Products
Antibiotics 2022, 11(5), 680; https://doi.org/10.3390/antibiotics11050680 - 18 May 2022
Viewed by 484
Abstract
Campylobacter ureolyticus is a Gram-negative, anaerobic, non-spore-forming bacteria that causes gastrointestinal infections. Being the most prevalent cause of bacterial enteritis globally, infection by this bacterium is linked with significant morbidity and mortality in children and immunocompromised patients. No information on pan-therapeutic drug targets [...] Read more.
Campylobacter ureolyticus is a Gram-negative, anaerobic, non-spore-forming bacteria that causes gastrointestinal infections. Being the most prevalent cause of bacterial enteritis globally, infection by this bacterium is linked with significant morbidity and mortality in children and immunocompromised patients. No information on pan-therapeutic drug targets for this species is available yet. In the current study, a pan-genome analysis was performed on 13 strains of C. ureolyticus to prioritize potent drug targets from the identified core genome. In total, 26 druggable proteins were identified using subtractive genomics. To the best of the authors’ knowledge, this is the first report on the mining of drug targets in C. ureolyticus. UDP-3-O-acyl-N-acetylglucosamine deacetylase (LpxC) was selected as a promiscuous pharmacological target for virtual screening of two bacterial-derived natural product libraries, i.e., postbiotics (n = 78) and streptomycin (n = 737) compounds. LpxC inhibitors from the ZINC database (n = 142 compounds) were also studied with reference to LpxC of C. ureolyticus. The top three docked compounds from each library (including ZINC26844580, ZINC13474902, ZINC13474878, Notoginsenoside St-4, Asiaticoside F, Paraherquamide E, Phytoene, Lycopene, and Sparsomycin) were selected based on their binding energies and validated using molecular dynamics simulations. To help identify potential risks associated with the selected compounds, ADMET profiling was also performed and most of the compounds were considered safe. Our findings may serve as baseline information for laboratory studies leading to the discovery of drugs for use against C. ureolyticus infections. Full article
(This article belongs to the Special Issue Clinical Pharmacology and Pharmacy of Antimicrobial Agents)
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Article
A Soil-Isolated Streptomyces spororaveus Species Produces a High-Molecular-Weight Antibiotic AF1 against Fungi and Gram-Positive Bacteria
Antibiotics 2022, 11(5), 679; https://doi.org/10.3390/antibiotics11050679 - 18 May 2022
Viewed by 521
Abstract
The overuse of antibiotics has resulted in the emergence of antibiotic resistance, not only in bacteria but also in fungi. Streptomyces are known to produce numerous secondary metabolites including clinically useful antibiotics. In this study, we screened for antibiotic-producing actinobacteria from soils in [...] Read more.
The overuse of antibiotics has resulted in the emergence of antibiotic resistance, not only in bacteria but also in fungi. Streptomyces are known to produce numerous secondary metabolites including clinically useful antibiotics. In this study, we screened for antibiotic-producing actinobacteria from soils in Taipei and discovered a Streptomyces strain SC26 that displayed antimicrobial activities against Gram-positive bacteria and fungi, but the compounds are heat-labile. Upon UV mutagenesis, a late-sporulation mutant SC263 was isolated with the same antibiotic spectrum but increased in thermostability. The nature of the antibiotic is not clear, but its activity was resistant to proteolytic, nucleolytic and pancreatic digestions, and was retained by the 100 kDa membrane during filtration. To gather more information on SC263, the genome was sequenced, which produced three contigs with a total of 8.2 Mb and was assigned to the species of Streptomyces spororaveus based on the average nucleotide identity to the reference species S. spororaveus NBRC 15456. Full article
(This article belongs to the Special Issue Anti-microbial Activity of Metabolites Isolated from Fungi)
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Editorial
Multi-Drug-Resistant Gram-Negative Microorganisms: Epidemiology, Treatment and Alternative Approach
Antibiotics 2022, 11(5), 678; https://doi.org/10.3390/antibiotics11050678 - 18 May 2022
Viewed by 534
Abstract
The presence of enzymes such as Extended-Spectrum β-lactamase (ESBL) and carbapenemases (KPCs, Metallo β-lactamases and OXA) constitutes the principal resistance mechanism to antibiotics [...] Full article
Article
The Specific Capsule Depolymerase of Phage PMK34 Sensitizes Acinetobacter baumannii to Serum Killing
Antibiotics 2022, 11(5), 677; https://doi.org/10.3390/antibiotics11050677 - 17 May 2022
Viewed by 726
Abstract
The rising antimicrobial resistance is particularly alarming for Acinetobacter baumannii, calling for the discovery and evaluation of alternatives to treat A. baumannii infections. Some bacteriophages produce a structural protein that depolymerizes capsular exopolysaccharide. Such purified depolymerases are considered as novel antivirulence compounds. [...] Read more.
The rising antimicrobial resistance is particularly alarming for Acinetobacter baumannii, calling for the discovery and evaluation of alternatives to treat A. baumannii infections. Some bacteriophages produce a structural protein that depolymerizes capsular exopolysaccharide. Such purified depolymerases are considered as novel antivirulence compounds. We identified and characterized a depolymerase (DpoMK34) from Acinetobacter phage vB_AbaP_PMK34 active against the clinical isolate A. baumannii MK34. In silico analysis reveals a modular protein displaying a conserved N-terminal domain for anchoring to the phage tail, and variable central and C-terminal domains for enzymatic activity and specificity. AlphaFold-Multimer predicts a trimeric protein adopting an elongated structure due to a long α-helix, an enzymatic β-helix domain and a hypervariable 4 amino acid hotspot in the most ultimate loop of the C-terminal domain. In contrast to the tail fiber of phage T3, this hypervariable hotspot appears unrelated with the primary receptor. The functional characterization of DpoMK34 revealed a mesophilic enzyme active up to 50 °C across a wide pH range (4 to 11) and specific for the capsule of A. baumannii MK34. Enzymatic degradation of the A. baumannii MK34 capsule causes a significant drop in phage adsorption from 95% to 9% after 5 min. Although lacking intrinsic antibacterial activity, DpoMK34 renders A. baumannii MK34 fully susceptible to serum killing in a serum concentration dependent manner. Unlike phage PMK34, DpoMK34 does not easily select for resistant mutants either against PMK34 or itself. In sum, DpoMK34 is a potential antivirulence compound that can be included in a depolymerase cocktail to control difficult to treat A. baumannii infections. Full article
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Article
Genetic Resistance Determinants in Clinical Acinetobacter pittii Genomes
Antibiotics 2022, 11(5), 676; https://doi.org/10.3390/antibiotics11050676 - 17 May 2022
Viewed by 607
Abstract
Antimicrobial-resistant pathogenic bacteria are an increasing problem in public health, especially in the healthcare environment, where nosocomial infection microorganisms find their niche. Among these bacteria, the genus Acinetobacter which belongs to the ESKAPE pathogenic group harbors different multi-drug resistant (MDR) species that cause [...] Read more.
Antimicrobial-resistant pathogenic bacteria are an increasing problem in public health, especially in the healthcare environment, where nosocomial infection microorganisms find their niche. Among these bacteria, the genus Acinetobacter which belongs to the ESKAPE pathogenic group harbors different multi-drug resistant (MDR) species that cause human nosocomial infections. Although A. baumannii has always attracted more interest, the close-related species A. pittii is the object of more study due to the increase in its isolation and MDR strains. In this work, we present the genomic analysis of five clinically isolated A. pittii strains from a Spanish hospital, with special attention to their genetic resistance determinants and plasmid structures. All the strains harbored different genes related to β-lactam resistance, as well as different MDR efflux pumps. We also found and described, for the first time in this species, point mutations that seem linked with colistin resistance, which highlights the relevance of this comparative analysis among the pathogenic species isolates. Full article
(This article belongs to the Special Issue Diversity of Antimicrobial Resistance Genes in Clinical Settings)
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Article
An Evolutionary Conservation and Druggability Analysis of Enzymes Belonging to the Bacterial Shikimate Pathway
Antibiotics 2022, 11(5), 675; https://doi.org/10.3390/antibiotics11050675 - 17 May 2022
Viewed by 470
Abstract
Enzymes belonging to the shikimate pathway have long been considered promising targets for antibacterial drugs because they have no counterpart in mammals and are essential for bacterial growth and virulence. However, despite decades of research, there are currently no clinically relevant antibacterial drugs [...] Read more.
Enzymes belonging to the shikimate pathway have long been considered promising targets for antibacterial drugs because they have no counterpart in mammals and are essential for bacterial growth and virulence. However, despite decades of research, there are currently no clinically relevant antibacterial drugs targeting any of these enzymes, and there are legitimate concerns about whether they are sufficiently druggable, i.e., whether they can be adequately modulated by small and potent drug-like molecules. In the present work, in silico analyses combining evolutionary conservation and druggability are performed to determine whether these enzymes are candidates for broad-spectrum antibacterial therapy. The results presented here indicate that the substrate-binding sites of most enzymes in this pathway are suitable drug targets because of their reasonable conservation and druggability scores. An exception was the substrate-binding site of 3-deoxy-D-arabino-heptulosonate-7-phosphate synthase, which was found to be undruggable because of its high content of charged residues and extremely high overall polarity. Although the presented study was designed from the perspective of broad-spectrum antibacterial drug development, this workflow can be readily applied to any antimicrobial target analysis, whether narrow- or broad-spectrum. Moreover, this research also contributes to a deeper understanding of these enzymes and provides valuable insights into their properties. Full article
(This article belongs to the Special Issue Design and Preparation of Antimicrobial Agents)
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Article
The Class A β-Lactamase Produced by Burkholderia Species Compromises the Potency of Tebipenem against a Panel of Isolates from the United States
Antibiotics 2022, 11(5), 674; https://doi.org/10.3390/antibiotics11050674 - 17 May 2022
Viewed by 416
Abstract
Tebipenem-pivoxil hydrobromide, an orally bioavailable carbapenem, is currently in clinical development for the treatment of extended-spectrum β-lactamase- and AmpC-producing Enterobacterales. Previously, tebipenem was found to possess antimicrobial activity against the biothreat pathogens, Burkholderia pseudomallei and Burkholderia mallei. Thus, herein, tebipenem was evaluated [...] Read more.
Tebipenem-pivoxil hydrobromide, an orally bioavailable carbapenem, is currently in clinical development for the treatment of extended-spectrum β-lactamase- and AmpC-producing Enterobacterales. Previously, tebipenem was found to possess antimicrobial activity against the biothreat pathogens, Burkholderia pseudomallei and Burkholderia mallei. Thus, herein, tebipenem was evaluated against a panel of 150 curated strains of Burkholderia cepacia complex (Bcc) and Burkholderia gladioli, pathogens that infect people who are immunocompromised or have cystic fibrosis. Using the provisional susceptibility breakpoint of 0.12 mg/L for tebipenem, 100% of the Bcc and B. gladioli tested as being provisionally resistant to tebipenem. Bcc and B. gladioli possess two inducible chromosomal β-lactamases, PenA and AmpC. Using purified PenA1 and AmpC1, model β-lactamases expressed in Burkholderia multivorans ATCC 17616, PenA1 was found to slowly hydrolyze tebipenem, while AmpC1 was inhibited by tebipenem with a k2/K value of 1.9 ± 0.1 × 103 M−1s−1. In addition, tebipenem was found to be a weak inducer of blaPenA1 expression. The combination of the slow hydrolysis by PenA1 and weak induction of blaPenA1 likely compromises the potency of tebipenem against Bcc and B. gladioli. Full article
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