HEMOLYTIC ESCHERICHIA-COLI STRAINS ISOLATED FROM STOOLS OF HEALTHY CATS PRODUCE CYTOTOXIC NECROTIZING FACTOR TYPE-1 (CNF1)

A total of 159 Escherichia coil colonies isolated from the stools of 2 3 healthy cats were studied for production of cr-haemolysin (Hly), ent erohaemolysin (EntHly), cytotoxic necrotizing factors (CNF1 and CNF2), verotoxins (VT) and heat-labile enterotoxin (LT). Hly(+)CNF1(+),Hly()CNF2(+),Hly(+)VT(+) and Hly(+) E. coil colonies were isolated from 12 (48%), 1 (4%), 1 (4%) and 2 (8%) respectively of the cats sampled. No ne of the 159 E. coli colonies produced LT or EntHly. Nine of 12 Hly()CNF1(+) strains from the cats belonged to serogroup O6 and eleven to serotypes (O4:K?:H5 or H-, O6:K13:H1, O6:K53:H-, O6:K53:H1, O6:K53:H7 and O6:K14:H31) found among Hly(+)CNF1(+) E. coil that cause urinary t ract infections and sepsis in humans. Furthermore, 10 Hly(+)CNF1(+) st rains from the cats expressed the mannose-resistant haemagglutination (MRHA) type III. By contrast, the majority of nontoxigenic E. coil str ains were MRHA negative and belonged to different O groups. We conclud e that cats are a important reservoir of Hly(+)CNF1(+) E. coil strains that possess similar characteristics to strains that can cause extrai ntestinal infections in humans and that Hly(+) E. coil from cats usual ly do not produce shiga-like toxins with cytotoxic activity on Vero ce lls.