Search Results (57)

The intensive farming of Pelodiscus sinensis (P. sinensis) for its medicinal and economic value has led to an increased incidence of bacterial skin infections, commonly treated with antibiotics. However, rising antibiotic resistance has reduced the effectiveness of these treatments, highlighting an urgent need for alternative therapeutic approaches. In this study, we isolated and identified pathogenic bacteria (Aeromonas and Morganella) from P. sinensis affected by skin ulcer disease at a turtle farm in Beijing. Antibiotic resistance was evaluated using the checkerboard microdilution method and the in vitro antibacterial efficacy of a florfenicol–doxycycline combination therapy was assessed. A total of 30 bacterial isolates were obtained, primarily Morganella and Aeromonas species. Among these, 83.3% of Morganella and 57.14% of Aeromonas isolates demonstrated multidrug-resistance. The florfenicol–doxycycline combination yielded lower fractional inhibitory concentration (FIC) values, indicating synergistic or additive effects. Animal experiments have shown that florfenicol in combination with doxycycline can achieve better therapeutic effects with less drug. These findings support that combination antibiotic therapies help in managing skin ulcer disease in P. sinensis and offer valuable insights for clinical applications. Full article

Bats (order Chiroptera) are increasingly recognized as important reservoirs and potential vectors of pathogenic and antimicrobial-resistant bacteria (ARB), with potential implications for human, animal, and environmental health. This study aimed to assess the presence and antimicrobial resistance profiles of bacterial isolates from bat populations in Sicily, an area for which data are currently limited. A total of 132 samples (120 rectal swabs and 12 guano samples) were collected at four sites in the provinces of Catania, Siracusa, and Ragusa. Bacteriological analysis yielded 213 isolates, including 161 Gram-negative and 52 Gram-positive strains, representing 55 different species. Among Gram-negative isolates, Escherichia coli, Citrobacter freundii, and Morganella morganii were most frequently detected, while Bacillus licheniformis and Staphylococcus xylosus were predominant among Gram-positive bacteria. Antimicrobial susceptibility testing revealed high resistance rates to colistin, amoxicillin, and ampicillin in Gram-negative strains, and to oxacillin, ceftazidime, and lincomycin in Gram-positive strains. Notably, 84.5% of isolates exhibited multidrug resistance. These findings highlight the potential role of bats as reservoirs of ARB and underline the importance of ongoing monitoring within a One Health framework to mitigate risks to public and animal health. Full article

Psychrotrophic Morganella spp. is a typical histamine producer commonly found in seafood, exhibiting a high histamine-producing capacity. In this study, two strains of Morganella (GWT 902 and GWT 904) isolated from yellowfin tuna were subjected to phenotypic and genotypic characterization. Phenotypic analysis reveals differences in growth temperature, NaCl tolerance, and D-galactose fermentation capacity between the two strains. Notably, the histamine production capacity of GWT 902 is significantly higher than that of GWT 904 at 4 °C. The complete genome sequences of strains GWT 902 and GWT 904 were sequenced, identifying GWT 902 as Morganella psychrotolerans and GWT 904 as Morganella morganii subsp. sibonii. Genomic analysis confirms the presence of histidine decarboxylase gene clusters (hdcT1, hdc, hdcT2, hisRS) in both strains, and sequence alignment shows that the amino acid sequence similarity of histidine decarboxylase encoded by the hdc gene was 95.24%. Gene function analysis further identified genes associated with putrescine biosynthesis, sulfur metabolism, lipase and protease secretion, and detected key genes in quorum sensing (QS), stress adaptation, and antibiotic resistance. This study provides valuable insights into the taxonomic analysis of psychrotrophic Morganella spp. and contributes to the development of efficient strategies for preventing histamine formation in seafood. Full article

Background: Disruption of the natural balance of the skin microbiota can impair wound healing and contribute to chronic infections. Identifying the bacterial species involved and understanding their antimicrobial susceptibility profiles are essential for guiding treatment, especially given the growing threat of antibiotic resistance. Methods: This study characterized the virulence and antibiotic resistance phenotypes of 43 bacterial strains isolated from chronic wounds. The antimicrobial activity of selected essential oils (sandalwood, ylang-ylang, sage, cajeput, and juniper), pharmaceutical products (propolis tinctures, usnic acid), and probiotic lactic acid bacteria strains (Lactobacillus spp., Lactococcus lactis) was assessed using qualitative and quantitative assays, including MIC, MICBA, and co-culture evaluations. Results: Gram-positive strains were more sensitive to essential oils than Gram-negative strains, with sandalwood, ylang-ylang, and propolis tincture showing the strongest antibacterial effects. These agents also showed significant biofilm inhibition. Probiotic strains exhibited antimicrobial activity against Staphylococcus aureus and Morganella morganii, with Lactobacillus paracasei and Lactobacillus rhamnosus being particularly effective in reducing bacterial growth and adhesion in vitro. Conclusions: Essential oils and probiotic strains demonstrate promising antimicrobial effects against chronic wound pathogens and may serve as alternative or adjunctive treatments to antibiotics. Further clinical research and standardization are necessary to establish their safety, efficacy, and optimal application protocols. Full article

The illegal treatment of tuna with nitrite is a significant food safety concern. The risk may be due to not only the high nitrite levels and the possible formation of N-Nitrosamines but also to the possible increase in biogenic amines and microbial load and also pathogens. This study optimized the treatment of red tuna (Thunnus thynnus) with nitrite solutions and then determined several chemical (histamine, total volatile basic nitrogen (TVBN), biogenic amines, nitrite/nitrate, ascorbic acid, and sulfites) and microbiological (total microbial count, Enterobacteriaceae, Vibrionaceae, coagulase-positive staphylococci, Salmonella, Escherichia coli) parameters, comparing the results obtained with fresh samples with those obtained with treated samples after 5 days of storage (4 °C). The effect of such treatment on samples voluntarily contaminated with some pathogens was also investigated. The results indicate that if the products are characterized by suitable hygienic quality, the total microbial load and the levels of histamine and TVBN after 5 days of storage are below the legal limits, and no health risk subsists. The growth of pathogens/histaminogens (Salmonella and Morganella morganii) was also substantially inhibited during storage. Thus, this work confirmed that the high nitrite amounts and the possible development of N-nitrosamines represent the only significant food safety concerns. Full article

Geckos are often considered to be reservoirs of zoonotic pathogens. This study was conducted to describe the prevalence and characteristics of pathogens isolated from fecal samples of crested geckos in South Korea. A total of 76 fecal samples were collected from 76 domesticated crested geckos in independent captivity. To determine bacterial profiles, matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), the disk diffusion method, PCR and direct sequencing, and the Kauffmann–White scheme for serotyping Salmonella species were performed. A total of 107 Gram-negative isolates were identified as belonging to 50 Citrobacter species, 33 Salmonella enterica subsp., 8 Serratia marcescens, 8 Klebsiella species, 3 Morganella morganii, 2 Enterobacter cloacae, 2 Pseudomonas aeruginosa, and 1 Acinetobacter species. Most of the isolates were susceptible to antibiotics tested in this study. The chloramphenicol acetyltransferase (cat) gene was detected in one M. morganii isolate, and the class C beta-lactamase (AZECL-14) gene was detected in one E. cloacae. The most prevalent somatic (O) antigens of the groups were C (n = 23) and D (n = 7), and 8 different serotypes were identified among the 33 Salmonella enterica subsp. isolates. Five of eight Salmonella serotypes have not been previously reported among clinical isolates in South Korea. Our results reveal that enteric bacteria have not been shared between crested geckos and humans, at least in South Korea. Full article

The present work aimed to evaluate and mathematically model the effect of temperature on Morganella morganii growth and histamine formation in farmed mullet (Mugil cephalus) during refrigerated storage (at constant temperatures, T = 0, 2.5, 5, 10, and 15 °C) and to validate the developed models at non-constant temperature conditions (effective temperature T_eff = 7.4 °C). Shelf life evaluation of chilled mullet was also carried out based on microbial spoilage, sensory degradation, and total volatile nitrogen (TVB-N) determination. Spoilage of mullet during refrigerated storage was co-dominated by Pseudomonas spp. and Enterobacteriaceae growth. Sensory rejection (score 5 for overall impression) and the end of shelf life coincided with a total microbial load of 8 log cfu/g. The shelf life of chilled mullet was estimated at 15, 11, 7, 3, and 1.5 days at 0, 2.5, 5, 10, and 15 °C, respectively. At T 0–5 °C, the time of sensory rejection coincided with TVB-N concentrations of 10.2–12.3 mg·100 g⁻¹, and at 10–15 °C, the samples were sensorially rejected before TVB-N development. At storage temperatures < 5 °C, sensory rejection was observed well before histamine levels reached a concentration of 50 mg/kg fish flesh. However, when abusive temperatures prevail, histamine should be considered as a risk factor for the human consumption of mullet. Full article

Four synthetic Schiff bases (PSB1 [(E)-2-(((4-aminopyridin-3-yl)imino)methyl)-4,6-dibromophenol], PSB2 [(E)-2-(((4-aminopyridin-3-yl)imino)methyl)-4,6-diiodophenol], PSB3 [(E)-2-(((4-aminopyridin-3-yl)imino)methyl)-4-iodophenol], and PSB4 [(E)-2-(((4-aminopyridin-3-yl)imino)methyl)-4-chloro-6-iodophenol]) were fully characterized. These compounds exhibit an intramolecular hydrogen bond between the hydroxyl group of the phenolic ring and the nitrogen of the azomethine group, contributing to their stability. Their antimicrobial activity was evaluated against various Gram-negative and Gram-positive bacteria, and it was found that the synthetic pyridine Schiff bases, as well as their precursors, showed no discernible antimicrobial effect on Gram-negative bacteria, including Salmonella Typhi (and mutant derivatives), Salmonella Typhimurium, Escherichia coli, and Morganella morganii. In contrast, a more pronounced biocidal effect against Gram-positive bacteria was found, including Bacillus subtilis, Streptococcus agalactiae, Streptococcus pyogenes, Enterococcus faecalis, Staphylococcus aureus, and Staphylococcus haemolyticus. Among the tested compounds, PSB1 and PSB2 were identified as the most effective against Gram-positive bacteria, with PSB2 showing the most potent biocidal effects. Although the presence of reactive oxygen species (ROS) was noted after treatment with PSB2, the primary mode of action for PSB2 does not appear to involve ROS generation. This conclusion is supported by the observation that antioxidant treatment with vitamin C only partially mitigated bacterial inhibition, indicating an alternative biocidal mechanism. Full article

AmpC enzymes are a class of beta-lactamases produced by Gram-negative bacteria, including several Enterobacterales. When produced in sufficient amounts, AmpCs can hydrolyze third-generation cephalosporins (3GCs) and piperacillin/tazobactam, causing resistance. In Enterobacterales, the AmpC gene can be chromosomal- or plasmid-encoded. Some species, particularly Enterobacter cloacae complex, Klebsiella aerogenes, and Citrobacter freundii, harbor an inducible chromosomal AmpC gene. The expression of this gene can be derepressed during treatment with a beta-lactam, leading to AmpC overproduction and the consequent emergence of resistance to 3GCs and piperacillin/tazobactam during treatment. Because of this phenomenon, the use of carbapenems or cefepime is considered a safer option when treating these pathogens. However, many areas of uncertainty persist, including the risk of derepression related to each beta-lactam; the role of piperacillin/tazobactam compared to cefepime; the best option for severe or difficult-to-treat cases, such as high-inoculum infections (e.g., ventilator-associated pneumonia and undrainable abscesses); the role of de-escalation once clinical stability is obtained; and the best treatment for species with a lower risk of derepression during treatment (e.g., Serratia marcescens and Morganella morganii). The aim of this review is to collate the most relevant information about the microbiological properties of and therapeutic approach to AmpC-producing Enterobacterales in order to inform daily clinical practice. Full article

In the context of global efforts to combat antimicrobial resistance (AMR), the importance of comprehensive AMR data is more crucial than ever. AMR surveillance networks, such as the European Antimicrobial Resistance Surveillance Network (EARS-Net) and the Central Asian and European Surveillance of Antimicrobial Resistance (CAESAR), support member states in obtaining high-quality AMR data. Nevertheless, data gaps persist in some countries, including those in the Western Balkans (WBs), a region with high AMR rates. This review analyzed existing research on carbapenem-resistant Enterobacterales (CRE) to better understand the AMR landscape in the WB countries. The most prevalent CRE was Klebsiella pneumoniae, followed by Escherichia coli, Enterobacter cloacae, and Proteus mirabilis, with sporadic cases of Morganella morganii, Providencia spp., Klebsiella oxytoca, and Citrobacter sedlakii. Carbapenemase production was identified as the most common mechanism of carbapenem resistance, but other resistance mechanisms were not investigated. An increasing trend in carbapenem resistance has been observed over the last decade, alongside a shift in carbapenemase epidemiology from the NDM type in 2013–2014 to the OXA-48 type in recent years. Few studies have applied whole-genome sequencing for CRE analysis, which has demonstrated the spread of resistance determinants across different niches and over time, emphasizing the importance of molecular-based research. The overall low number of studies in the WB countries can be attributed to limited resources, highlighting the need for enhanced support in education, training, technology, and equipment to improve data collection and evaluation. Full article

Introduction: Bloodstream infections caused by AmpC-producing Enterobacterales pose treatment challenges due to the risk of AmpC overproduction and treatment failure. Current guidelines recommend carbapenems or cefepime as optimal therapy. We aimed to evaluate empiric and definitive non-carbapenem regimens for these infections. Methods: In a retrospective study from June 2014 to March 2023, adult bacteremic patients with Enterobacter cloacae complex strains and Morganella morganii were evaluated. Demographic, clinical and lab data and outcomes were assessed. Results: The cohort comprised 120 bacteremic patients, 17 receiving empiric carbapenem and 103 non-carbapenem regimens. Both groups had similar Charlson and Norton scores and previous antimicrobial exposure. The most common sources of bacteremia were urinary, abdominal and central-line-associated sources. Empiric non-carbapenem regimens (primarily piperacillin–tazobactam and cephalosporins) were not associated with recurrent bacteremia or 30-day mortality. Definitive regimens included mainly carbapenems (n = 41) and ciprofloxacin (n = 46). Beta-lactams were administered to 25 patients. Recurrent bacteremia and 30-day mortality rates were similar among treatment groups. Ciprofloxacin showed comparable outcomes to carbapenems, however, severity of illness among these patients was lower. Conclusions: Empiric and definitive non-carbapenem regimens for bacteremia with AmpC-producing organisms were not associated with treatment failure or increased 30-day mortality. Ciprofloxacin appears promising for selected, stable patients, potentially enabling early discharge. Full article

5′-Phosphorylation of nucleosides is a reaction as important in nature and in industry as it is cumbersome to be performed. Whilst chemical phosphorylation relies on the use of harsh reagents, solvents, and conditions, as well as on the need for protection–deprotection steps, biocatalysis can be a tool to achieve one-step phosphorylation reactions, which are selective, protecting group-free, and occurring under mild and sustainable conditions. In this work, the wild-type non-specific acid phosphatase from Morganella morganii (PhoC-Mm) was expressed, purified, and used for the synthesis of inosine 5′-monophosphate (IMP), an important food additive, by using pyrophosphate (PPi) as an inexpensive phosphate donor in a fully aqueous medium at 30 °C. Via the fine-tuning of the reaction set-up taking into account the type of buffer, amount of PPi, mode/time of PPi addition, and enzyme and substrate concentration, PhoC-Mm could be used for catalyzing the phosphorylation of inosine (I) to IMP in a good yield and high purity (62% yield). The catalysis of the hydrolytic reaction direction, which is the primary function of phosphatases in nature, was here reversed to a certain extent by a reaction engineering approach, without the need for protein engineering strategies. Full article

Haemaphysalis longicornis is a common tick species that carries several pathogens. There are few reports on the influence of different hosts on the structure of midgut microflora in H. longicornis. In this study, midgut contents of fully engorged female H. longicornis were collected from the surface of tiger (Panthera tigris) and deer (Dama dama). The bacterial genomic DNA of each sample was extracted, and the V3–V4 regions of the bacterial 16S rRNA were sequenced using the Illumina NovaSeq sequencing. The diversity of the bacterial community of the fully engorged female H. longicornis on the surface of tiger was higher than that of deer. In total, 8 phyla and 73 genera of bacteria annotations were detected in the two groups. At the phylum level, the bacterial phyla common to the two groups were Proteobacteria, Firmicutes, and Actinobacteriota. At the genus level, there were 20 common bacterial genera, among which the relative abundances of Coxiella, Morganella, Diplorickettsia, and Acinetobacter were high. The Morganella species was further identified to be Morganella morganii. The alpha diversity index indicated that the bacterial diversity of the tiger group was higher than that of the deer group. Bacteroidota, Patescibacteria, Desulfobacterota, Verrucomicrobiota, and Cyanobacteria were solely detected in the tiger group. A total of 52 bacterial genera were unique in the tiger group, while one bacterial genus was unique in the deer group. This study indicates that there are differences in the structure of the gut bacteria of the same tick species among different hosts. Further culture-based methods are needed to provide a more comprehensive understanding of the tick microbiota parasitizing different hosts. Full article

Drug-resistant Morganella morganii, a rod-shaped, Gram-negative, facultatively anaerobic bacillus belonging to the Enterobacteriaceae family, is a growing worldwide health concern due to its association with high morbidity and mortality rates. Recent advancements in machine learning, particularly Alphafold 2’s protein structure prediction using local physics and pattern recognition, have aided research efforts. This study focuses on the enzymatic activity of aminoglycoside N6′-acetyltransferase (aacA7), a critical transferase enzyme in bacteria that confers resistance to aminoglycosides. AacA7 modifies aminoglycoside molecules by catalyzing the acetylation of their 6′-amino group using acetyl-CoA, rendering antibiotics like kanamycin, neomycin, tobramycin, and amikacin inactive. We propose that Doripenem and OncoglabrinolC can interact with aacA7, potentially modifying its enzymatic activity. Molecular docking analysis of aacA7 with 22 drug targets revealed OncoglabrinolC as the most promising candidate, exhibiting a binding energy of −12.82 kcal/mol. These two top candidates, OncoglabrinolC and Doripenem, were then subjected to 100 ns of molecular dynamic simulations to assess their dynamic conformational features. Furthermore, the PredictSNP consensus classifier was used to predict the impact of mutations on aacA7 protein functionality. The study also investigated the interaction of wild-type and mutant aacA7 proteins with both Doripenem and OncoglabrinolC. These findings provide valuable insights into the binding behavior of OncoglabrinolC and Doripenem as potential lead molecules for repurposing against aacA7, potentially reducing the pathogenicity of Morganella morganii. Full article

A bacterium was isolated and identified from the secretion of a rhesus monkey with endometritis. The morphological results showed that the strain exhibited round, convex, gray-white colonies with smooth surfaces and diameters ranging from 1 to 2 mm when cultured on Columbia blood agar at 37 °C for 24 h; on salmonella–shigella agar (S.S.) at 37 °C for 24 h, the colonies appeared round, flat, and translucent. Gram staining showed negative results with blunt ends and non-spore-forming characteristics. Molecular biology results showed that the 16S rRNA sequence of the strain revealed over 96.9% similarity with published sequences of M. morganii from different sources in the NCBI GenBank database. Morphological and molecular biology analysis confirmed that the strain (RM2023) isolated from cervical secretions of rhesus monkey was M. morganii. Drug sensitivity testing demonstrated that the isolated strain (RM2023) was sensitive to ceftriaxone, amikacin, gentamicin, cefazolin, cefuroxime, ceftazidime, levofloxacin, cotrimoxazole, norfloxacin, and tetracycline; moderately sensitive to ampicillin; and resistant to penicillin, vancomycin, ciprofloxacin, and clindamycin. The research findings provide valuable insights for disease prevention in rhesus monkeys and contribute to molecular epidemiological studies. Full article