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saprophyticus from S. fleurettii. CONCLUSIONS These data give new insight into the epidemiology of veterinary methicillin-resistant staphylococci to inform future surveillance and zoonotic risk evaluation. Our data indicate that MRSA has likely decreased in prevalence since earlier survey work in England and Wales during 2011-12 and highlights the diversity of methicillin resistance and other resistance determinants among bovine-associated staphylococci with implications for veterinary and human medicine. OBJECTIVES Little attention has been paid to heavy metal resistance (HMR) to pathogenic bacteria with the wide use of heavy metals as feed additives in food animals. Therefore, present study was constructed to investigate the presence of HMR in Escherichia coli and Salmonella, and its correlation with disinfectant resistance genes (DRGs) and antibiotic resistance genes (ARGs). METHODS The heavy metal resistance genes (HMRGs) of 178 E. coli and 294 Salmonella isolated from chicken farms and retail meats were detected by polymerase chain reaction (PCR). The minimal inhibitory concentrations (MICs) of heavy metals were determined by broth micro-dilution method. The complete-genome of E. coli E308 which had indications of multi-resistance was recovered and assembled using third-generation sequencing. RESULTS Results showed that frequency of different HMRGs in E. coli and Salmonella ranged 0.60 – 77.0% and 0.30 – 87.1%, respectively. MICs of heavy metals for E. coli and Salmonella ranged widely from ≤ 12.5 mg/L to 1600 mg/L. Moreover, the HMRGs (zntA, arsB, merA, pcoR, pcoA, pcoC and chrA) were found to be significantly associated with one or more DRGs (sugE(c), emrE, mdfA, ydgE/ydgF, qacF, sugE(p) and qacEΔ1) and ARGs (sul1, sul2, sul3, tetA, tetB, tetC, blaTEM, blaSHV and blaCTX) (p  less then  0.05). CONCLUSIONS The present study demonstrated that HMRGs were widely present in E. coli and Salmonella isolated from chicken farm and retail meats, and the association between HMRGs with DRGs and ARGs may lead to the co-resistance of heavy metals and other antimicrobials. BACKGROUND Clostridium (Clostridioides) difficile infection (CDI) is recognized worldwide as a public health concern, related mainly with hypervirulent strains. In Brazil there are few studies about molecular epidemiology of C. difficile, for this reason, we aimed to characterize C. difficile isolates from a large cohort study of three different Brazilian states to identify virulence and resistance genes, specifically genes related to metronidazole and vancomycin resistance. METHODS All 153 fecal samples were submitted to C. difficile culture in CM0601 broth. Identification of suspected colonies was confirmed by matrix-assisted laser desorption/ionization (MALDI-TOF/MS, Brucker Daltonics, Germany). The tcdA and tcdB toxin were searched by PCR. The sequence type (ST) was determinate by multilocus sequencing typing (MLST) and susceptibility profile was performed by agar dilution method. RESULTS Among the 16 isolates, we identified fourteen different STs, five belonging to Clade 1, one to Clade 2 and eight news STs with high similarity levels. Resistance (ermB, tetM, VanW and nimB) and virulence genes (cwp84, cwp66, cwp2, fbpA and secA) were found in toxigenic strains. CONCLUSION Differently from other studies, we found high levels of resistance to vancomycin. These results suggest that the main circulating strains in Brazil belong to Clade 1 and have high pathogenicity and resistance profile. OBJECTIVES Multidrug-resistant (MDR) bacteria are a major concern in public health. Pancuronium dibromide purchase Endolysins (lysins) from bacteriophage can be used as a novel antimicrobial agent against bacterial infectious diseases. In this study, a novel endolysin (LysSS) containing a lysozyme-like domain was evaluated for its antibacterial activity against various bacterial species. METHODS LysSS-encoding gene was analyzed and cloned and LysSS recombinant protein was expressed and purified. Purified LysSS was used to determine antimicrobial activities against various bacterial speciesin vitro and to measure its protection rate against Acinetobacter baumannii systemic infection model in vivo. RESULTS Recombinant LysSS showed activity against MDRAcinetobacter baumannii, MDR Escherichia coli, MDR Klebsiella pneumoniae, MDR Pseudomonas aeruginosa, and Salmonella without pretreatment with an outer membrane permeabilizer. Moreover, LysSS inhibited the growth of methicillin-resistant Staphylococcus aureus (MRSA). The minimum inhibitory concentration of LysSS against 16 strains of MDR Acinetobacter baumannii ranged from 0.063 to 0.25 mg/mL. LysSS had no cytotoxic effect on A549 human lung cells under 250 µg/mL. In an animal model, mice infected with A. baumannii were protected with a 40% survival rate by intraperitoneal injection of LysSS. CONCLUSIONS Our current results demonstrated that LysSS can be a novel and promising antimicrobial agent against MRSA and MDR Gram-negative bacteria includingA. baumannii and P. aeruginosa. OBJECTIVES Tigecycline is an antibacterial restricted for use against carbapenem-resistant Klebsiella pneumoniae (CRKP). This study aimed to identify the tigecycline-resistance mechanism in clinical CRKP isolates obtained from a 60-year-old female during tigecycline treatment. METHODS Three K. pneumoniae isolates obtained during tigecycline treatment were subjected to antimicrobial susceptibility testing (AST), pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), whole-genome sequencing and analyzing. The function of ramR was confirmed by gene complementation. RESULTS Three K. pneumoniae isolates named W814, W112, and W113 were collected on days 0, 10 and 13 respectively, from an ongoing tigecycline treatment. The AST results showed resistance to all antibiotics except tigecycline and ceftazidime/avibactam. The tigecycline minimum inhibitory concentration (MIC) for W814 and W112 was 4 mg/L, compared to W113 MIC of 16 mg/L. These three strains belonged to ST11 and their PGFE analysis showed a similar pattern. The ISKpn18 insertion sequence (IS) in ramR was identified in W113. A parent strain transformed with the plasmid pCR2.1-Hyg carrying ramR enhanced tigecycline susceptibility, thus confirming that loss-of-function insertion in ramR contributes to tigecycline resistance. CONCLUSION ISKpn18 insertion in the ramR gene contributes to the tigecycline-resistance mechanism in the isolated K. pneumoniae strains.