Serotypes, toxins and antibiotic resistance of Escherichia coli strains isolated from diarrhoeic and healthy rabbits in Spain

One hundred and ten Escherichia coli strains isolated from diarrhoeic and healthy rabbits from 50 Spanish commercial farms were serotyped and investigated for production of enterotoxins (LT and STa), verotoxins (VT), cytotoxic necrotizing factors (CNF1 and CNF2), α-haemolysin (Hly) and enterohaemolysin (EntHly), for necrotic and lethal activities and for antibiotic resistance. Six sero-groups (O2, O26, O49, O92, O103 and O128) accounted for 81% (67 of 83) and 26% (7 of 27) respectively of E. coli strains isolated from diarrhoeic and healthy rabbits ( P < 0.001). The most common serotypes found among E. coli strains associated with diarrhoeic rabbits in order of frequency were: O103:K−:H2, O49:K?:H2, O26:K−:H−, O26:K−:H11, O128:K?:H−,O92:K−:H2 and O2:K5:H6. E. coli strains belonging to the same serotype but from different farms usually showed a distint antibiotic resistance pattern. Only one strain, of serotype O2:K5:H6 was toxigenic (CNF1 +, Hly +, necrotic and lethal).