Search

Aim This study aimed to compare and characterize the resistance profile and the presence of extended-spectrum beta-lactamase (ESBL) related genes in Escherichia coli isolated from healthy finishing pigs fed with or without antibiotics in their diets. Methods and results A total of 27 ceftiofur-resistant E. coli isolates were obtained from 96 healthy pigs. The antibiotic resistance profile was tested, and all 27 isolates were classified as multidrug-resistant (MDR). A high proportion of isolates were resistant to cephalosporins, ampicillin, ciprofloxacin, and tetracyclines. The ESBL production was observed in 85% of isolates by double-disc synergy test. The MDR- E. coli isolates harbored ESBL genes, such as bla TEM, bla CTX-M-1, bla CTX-M-2, and bla CTX-M-8,25. In addition, other antibiotics resistance genes (ARGs) were also detected, such as sul2, ant(3″)-I, tetA , and mcr-1. The mobilization of the bla CTX-M gene was confirmed for nine E. coli isolates by conjugation assays. The presence of bla CTX-M on mobile genetic elements in these isolates was demonstrated by Southern blot hybridization, and the resistance to cephalosporins was confirmed in the transconjugants. Our results indicate the prevalence of CTX-M-producing E. coli strains harboring mobile genetic elements in the normal microbiota of healthy pigs. Conclusions These findings highlight the significance of ESBL genes as a global health concern in livestock and the potential spread of antimicrobial resistance to other members of the gastrointestinal tract microbiota. [ABSTRACT FROM AUTHOR]

Aim The objective of this study was to investigate the antimicrobial resistance genes (ARGs) in plasmids of Enterobacteriaceae from soil, sewage, and feces of food-producing animals and humans. Methods and results The plasmid sequences were obtained from the NCBI database. For the identification of ARG, comprehensive antibiotic resistance database (CARD), and ResFinder were used. Gene conservation and evolution were investigated using DnaSP v.6. The transfer potential of the plasmids was evaluated using oriTfinder and a MOB-based phylogenetic tree was reconstructed using Fastree. We identified a total of 1064 ARGs in all plasmids analyzed, conferring resistance to 15 groups of antibiotics, mostly aminoglycosides, beta-lactams, and sulfonamides. The greatest number of ARGs per plasmid was found in enterobacteria from chicken feces. Plasmids from Escherichia coli carrying multiple ARGs were found in all ecosystems. Some of the most abundant genes were shared among all ecosystems, including aph(6)-Id, aph(3′')-Ib, tet(A) , and sul2. A high level of sequence conservation was found among these genes, and tet(A) and sul2 are under positive selective pressure. Approximately 62% of the plasmids carrying at least one ARG were potentially transferable. Phylogenetic analysis indicated a potential co-evolution of Enterobacteriaceae plasmids in nature. Conclusion The high abundance of Enterobacteriaceae plasmids from diverse ecosystems carrying ARGs reveals their widespread distribution and importance. [ABSTRACT FROM AUTHOR]

The RNA chaperone Hfq regulates diverse processes in numerous bacteria. In this study, we compared phenotypes (growth rate, adherence, response to different stress conditions and virulence in Galleria mellonella) of wild-type (WT) and isogenic hfq mutants of three serovars (1, 8 and 15) of the porcine pathogen Actinobacillus pleuropneumoniae. Similar growth in rich broth was seen for all strains except Ap1∆ hfq , which showed slightly reduced growth throughout the 24 h time course, and the complemented Ap8∆ hfq C mutant had a prolonged lag phase. Differences were seen between the three serovar WT strains regarding adherence, stress response and virulence in G. mellonella , and deletion of hfq affected some, but not all of these phenotypes, depending on serovar. Complementation by expression of cloned hfq from an endogenous promoter only restored some WT phenotypes, indicating that complex regulatory networks may be involved, and that levels of Hfq may be as important as presence/absence of the protein regarding its contribution to gene regulation. Our results support that Hfq is a pleiotropic global regulator in A. pleuropneumoniae , but serovar-related differences exist. These results highlight the importance of testing multiple strains/serovars within a given species when determining contributions of global regulators, such as Hfq, to expression of complex phenotypes. [ABSTRACT FROM AUTHOR]

The larva of the greater wax moth Galleria mellonella is an increasingly popular model for assessing the virulence of bacterial pathogens and the effectiveness of antimicrobial agents. In this review, we discuss details of the components of the G. mellonella larval immune system that underpin its use as an alternative infection model, and provide an updated overview of the state of the art of research with G. mellonella infection models to study bacterial virulence, and in the evaluation of antimicrobial efficacy. Emphasis is given to virulence studies with relevant human and veterinary pathogens, especially Escherichia coli and bacteria of the ESKAPE group. In addition, we make practical recommendations for larval rearing and testing, and overcoming potential limitations of the use of the model, which facilitate intra- and interlaboratory reproducibility. [ABSTRACT FROM AUTHOR]

The Núcleo de Estudos em Microbiologia Agrícola (NEMA) is an academic-scientific group created by graduate students in the Post Graduate in Agricultural Microbiology in the Department of Microbiology at Universidade Federal de Viçosa, Brazil. NEMA's purposes include promoting and sharing research and knowledge on microbiology in different fields of application. Here, we will comment on our experience in organizing the Summer School on Microbiology and teaching microbiology to undergraduate students during the program. NEMA offers this annual event to disseminate and stimulate knowledge about microbiology for undergraduate students in a participatory, collaborative and interactive way. [ABSTRACT FROM AUTHOR]