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Purpose: Class 1 integrons are among the main vehicles that facilitate the spread of antibiotic-resistance genes, with serious public health consequences. The aim of this cross-sectional study was to investigate the presence of class 1 integrons and to characterize their variable regions, as well as the antimicrobial resistance profiles and phylogenetic groups of a collection of Escherichia coli isolates recovered from healthy subjects (n=42) and those with urinary infection (n=40)., Methodology: The methods used included PCR, sequencing and antimicrobial susceptibility testing., Results: PCR screening for the integrase gene (intI1) revealed a higher incidence of class 1 integrons in uropathogenic E. coli (65 %, UPEC) than in commensal isolates (11.9 %). Eight of 31 intI1-positive isolates, all of them UPEC, harboured empty integrons. The variable regions of the other 23 contained gene cassettes encoding resistance to β-lactams (blaOXA-1), aminoglycosides (aadA1 and aadA5), trimethoprim (dfrA1 and dfrA17) and an ORF. To our knowledge this is the first report of an ORF identified as a putative phage tail protein associated with a class 1 integron. The aadA1 and dfrA17-addA5 arrays prevailed in commensal E. coli and UPEC, respectively. UPEC isolates were highly resistant to the antimicrobials tested, in contrast to commensal isolates. The E. coli isolates carrying gene cassettes associated with class 1 integrons were found to be unrelated to any phylogroup or multiresistance., Conclusion: Co-resistance to clinically relevant fluoroquinolone and trimethoprim-sulfamethazole in all UPEC isolates is a cause for concern. These results expand the current knowledge of gene cassettes in both commensal and pathogenic E. coli.

Antagonistic and synergistic substances are important for interactions between micro-organisms associated with human body surfaces, either in healthy or in diseased conditions. In the present study, such compounds produced by Gardnerella vaginalis strains isolated from women with bacterial vaginosis (BV) were detected in vitro and the antagonistic ones were partially characterized. Among 11 G. vaginalis strains tested, all showed antagonistic activity against at least one of the 22 indicator bacteria assayed. Interestingly, for some of these strains, antagonism reverted to synergism, favouring one of the indicator strains (Peptostreptococcus anaerobius) when the growth medium was changed. Partial characterization of antagonistic substances suggested a bacteriocin-like chemical nature. Depending on growth conditions, G. vaginalis isolated from women with BV produced antagonistic or synergistic compounds for other bacterial components of the vaginal ecosystem. This is the first report to our knowledge of the production of antagonistic and/or synergistic substances by G. vaginalis. This ability may be a pivotal factor in understanding BV and the ecological role of this bacterium in the vaginal environment.

Previous results in the laboratory of the authors showed that Saccharomyces cerevisiae strain 905, isolated during 'cachaça' production, was able to colonize and survive in the gastrointestinal tract of germ-free and conventional mice, and to protect these animals against oral challenge with Salmonella enterica serotype Typhimurium or Clostridium difficile. In the present work, the effects of S. cerevisiae 905 on the translocation of Salm. Typhimurium (mesenteric lymph nodes, Peyer's patches, spleen, liver) as well as on the immune system (number of Küpffer cells, immunoglobulin production, clearance of Escherichia coli B41) were evaluated in gnotobiotic and/or conventional mice. The treatment with the yeast reduced significantly the translocation of Salm. Typhimurium to liver in gnotobiotic animals and to all the organs tested in conventional mice. The number of Küpffer cells per 100 hepatocytes in liver was significantly higher (P<0.05) in yeast mono-associated mice (52.9+/-15.7) than in germ-free controls (38.1+/-9.0). Probably as a consequence, clearance of E. coli B41 from the bloodstream was more efficient in yeast mono-associated animals when compared to germ-free mice. Higher levels (P<0.05) of secretory IgA in intestinal content and of IgA and IgM in serum were observed in yeast mono-associated mice when compared to germ-free group. Concluding, the protection against pathogenic bacteria observed in a previous study was probably due to a modulation of both local and systemic immunity of mice treated with S. cerevisiae 905.