Impact of the Use of b-Lactam Antimicrobials on the Emergence of @entity526 Isolates Resistant to Cephalosporins under Standard XXXX -Rearing Conditions.

@entity1707 @entity21563 @entity2756 @entity115 @entity50672 @entity5898 @entity50673 @entity526
The aim of this study was to evaluate if the treatments with @entity21563 and @entity115 are risk factors for the emergence of cephalosporin resistant (CR) @entity526 in a @entity1707 farm during the rearing period. One hundred 7-day-old piglets were divided into two groups, a control (n = 50) group and a group parenterally treated with @entity21563 (n = 50). During the fattening period, both groups were subdivided in two. A second treatment with @entity115 was administered in feed to two of the four groups, as follows: group 1 (untreated, n = 20), group 2 (treated with @entity115 , n = 26), group 3 (treated with @entity21563 , n = 20), and group 4 (treated with @entity21563 and @entity115 , n = 26). During treatment with @entity21563 , fecal samples were collected before treatment (day 0) and at days 2, 7, 14, 21, and 42 posttreatment, whereas with @entity115 , the sampling was extended 73 days posttreatment. CR @entity526 bacteria were selected on MacConkey agar with @entity2756 (1 mg/liter). Pulsed-field gel electrophoresis (PFGE), MICs of 14 antimicrobials, the presence of @entity5898 resistance genes, and replicon typing of plasmids were analyzed. Both treatments generated an increase in the prevalence of CR @entity526 , which was statistically significant in the treated groups. Resistance diminished after treatment. A total of 47 CR @entity526 isolates were recovered during the study period; of these, 15 contained blaCTX-M-1, 10 contained @entity50673 , 4 contained blaCTX-M-9, 2 contained @entity50672 , and 5 contained blaSHV-12. The treatment with @entity21563 and @entity115 was associated with the emergence of CR @entity526 during the course of the treatment. However, by the time of finishing, CR @entity526 bacteria were not recovered from the animals.
