BRUNA RIBEIRO ARRAIS
TÍTLE: SUBTYPES AND RESISTANCE TO ANTIMICROBIALS FROM Escherichia coli TOXIN PRODUCERS SHIGA (STEC) ISOLATED FROM CATTLE AND SHEEP FEES
Profa. Dra. CECILIA NUNES MOREIRA
DEFENSE DATE: 04/26/2019
Escherichia coli producing of toxin Shiga (STEC) is among the main ones E. coli pathogenic of the group of the diarrhealogenic. 10 different subtypes exist, each one of them associate the a pathogenic degree for the human being. The ruminant ones are considered the main reservoirs of that microorganism, eliminating him/it, constantly, for the feces. Due to treatment mistakes and exhibition excess to antibiotics, it is known that the bacterial resistance found in those animals is big. It was aimed at to accomplish the subtyping and to determine the susceptibility to the antimicrobials in 106 stumps of E. coli previously isolated of feces of bovine (59) and sheep (47) and characterized as producing of toxin Shiga (STEC), verifying the distribution of the subtypes among the stumps. The identification of the subtypes of the genes stx1 and stx2 was made by PCR. Also, they were made sensibility tests the antimicrobials for the disk-diffusion method, with ten antibiotics of five different classes. Of the bovine stumps, two stx1 subtypes were detected: stx1a and stx1c; and four stx2 subtypes: stx2a, stx2b, stx2c and stx2d. Already in the sheep feces, just the subtypes stx1a and stx1c, and four stx2 subtypes: stx2a, stx2b, stx2c and stx2g. The obtained results suggest the presence high variability in the genes of the type stx1 and stx2. 96,6% (57/59) of the stumps of bovine feces and 89,4% (42/47) of sheep feces presented resistance the at least a tested antibiotic. Adult animals possessed eight times more chances of they present STEC of high pathogenic. In the two species of animals most of the strains multiresistant (MDR) were considered, 67,8% in bovine and 59,6% in sheep, not having significant difference among the species. STEC of high pathogenic possessed three times more chances of they be MDR. The largest resistance frequency went to cefazolin, 86,4% (51/59) in bovine and 74,5% (35/47) in sheep, and smaller for cefoxitin and ciprofloxacin, both 6,8% (4/59) in bovine, and any resistant stump for sulfazotrim in sheep. STEC of high pathogenic possessed three times more chances of they be multiresistant to the tested antimicrobials, that STEC of low pathogenic. The data found in this study suggest stumps with high pathogenic potential, offering risk of unchaining serious infections to the population.
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