pap-and pil-related DNA sequences and other virulence determinants associated with Escherichia coli isolated from septicemic chickens and turkeys

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Abstract
Escherichia coli isolates from septicemic or healthy chickens and turkeys from Quebec were serotyped, examined genotypically by using DNA probes specific for the pil and pap fimbrial systems and the aerobactin siderophore system, and examined phenotypically for lethality in day-old chicks, hemagglutination, serum resistance, and aerobactin production. Serogroups O78 and O1 were most common in septicemic chickens and turkeys. pap+ isolates from chickens were associated with septicemia, and pap+ isolates from turkeys were associated with lethality in day-old chicks. Four of nine pap+ isolates from septicemic turkeys expressed P adhesin, whereas all pap+ isolates from septicemic chickens were negative for P adhesin. The pil+ genotype was associated with septicemia in chickens and with serum resistance in isolates from turkeys. Mannose-sensitive hemagglutination of guinea pig erythrocytes was associated with septicemia in chickens and turkeys, although this phenotype was not associated with pil+ isolates from turkeys. Serum resistance was associated with isolates from septicemic turkeys and with lethality in isolates from chickens. The aerobactin system was associated with isolates from septicemic chickens and turkeys. Overall, results indicated that (i) genotypic examination may reveal virulence-associated traits which differ from the typically expected phenotype and/or are not readily expressed in vitro, and (ii) certain phenotypic and genotypic traits associated with E. coli causing extraintestinal disease in humans and animals are also associated with E. coli causing avian septicemia.