OBSERVATIONS ON PRODUCTION OF HEMOLYSIN, HEAT-LABILE ENTEROTOXIN AND ANTIMICROBIAL DRUG-RESISTANCE AMONG ENTEROTOXIGENIC ESCHERICHIA-COLI FROM PIGS

A total of 52 isolates of Escherichia coli belonging to enterotoxigenic serotypes from piglets with diarrhea were examined for hemolysis, production of cholera-like enterotoxin (LT) and susceptibility to 10 antimicrobial drugs. A strong association between production of LT and hemolysis was seen. Ninety percent of 29 hemolylic isolates were LT+ whereas 100% of 23 nonhemolytic isolates were LT- in a commercial latex agglutination assay. Antimicrobial susceptibility tests employing disc diffusion showed that resistance to trimethoprim-sulfamethoxazole (TMS), neomycin and tetracycline was significantly less among LT+ isolates compared to LT- ones. Enrofloxacin was the only antimicrobial drug to which all the 52 isolates were susceptible.