Occurrence of enterotoxigenic Escherichia coli and Salmonella sp in calves in the southern Agreste region of the state of Pernambuco, Brazil

The diarrheic processes caused by pathogenic enterobacteria are of great economic-sanitary importance, with limiting effects on cattle raising. In the present study 106 fecal samples from 52 diarrheic and 54 non-diarrheic calves aged 1 to 90 days were analyzed, in order to determine the occurrence of enterotoxigenic Escherichia coli (ETEC) and Salmonella sp among calves reared in the agreste region of the state of Pernambuco and to determine the behavior of the isolates in response to 16 antimicrobial agents. The strains were cultured in selective media and submitted to biochemical characterization, serologic identification and detection of heat-stable enterotoxin. E. coli was isolated from all 106 calves studied and five of these strains (4,7%) were producers of heat-stable enterotoxin. Salmonellasp was isolated from six (4,7%) samples belonging to serovars Dublin, Muenchen and Infantis. The Salmonella strains were highly sensitive to the drugs tested, whereas the E. colistrains were more resistent to tetracycline (50,9%), sulfonamide (40,6%), streptomycin (35,9%) and ampicillin (22,6%). Particularly outstanding in the general analysis was the multiresistance of E. coli (52,0%), with a predominance of the tetracycline-sulfonamide association. The present results serve as a warning regarding the indiscriminated use of antimicrobial agents. Low percentages of ETEC and Salmonella in calves show the. necessity of other diagnostic procedures to clarify the etiology.