Isolation and Association of Escherichia Coli AIDA-I/STb, Rather than EAST1 Pathotype, with Diarrhea in Piglets and Antibiotic Sensitivity of Isolates

Autor: Dorothy M. Middleton, Musangu Ngeleka, John M. Fairbrother, Jane Pritchard, Greg D. Appleyard
Rok vydání: 2003
Předmět:
Zdroj: Journal of Veterinary Diagnostic Investigation. 15:242-252
ISSN: 1943-4936
1040-6387
DOI: 10.1177/104063870301500305
Popis: To identify emerging Escherichia coli that have the potential to cause diarrhea in pigs, the prevalence of E. coli pathotypes was determined among 170 and 120 isolates from diarrheic and nondiarrheic piglets, respectively. The isolates were tested for F4, F5, F6, F18, and F41 fimbriae, for E. coli attaching and effacing (EAE), porcine attaching and effacing-associated (Paa), and adhesin involved in diffuse adherence (AIDA-I) factors, for LT, STa, STb, and enteroaggregative heat-stable (EAST1) enterotoxins, and for Shiga toxins (Stx1, Stx2, and Stx2e), using DNA hybridization and polymerase chain reaction. All isolates were O- serotyped and tested for antibiotic resistance against 10 drugs. Seventeen different pathotypes, accounting for 40.0% of the isolates, were recovered from diarrheic piglets. The main pathotypes included EAST1 (13.5%), F4/LT/STb/EAST1 (6.5%), AIDA-I/STb/EAST1 (4.1%), F5/STa (2.9%), EAE/EAST1 (2.9%), and AIDA-I/F18 (2.3%). Only 3 pathotypes, EAE (11.7%), EAST1 (10.8%), and EAE/EAST1 (3.3%), were recovered from nondiarrheic piglets. Paa factor was detected in 8.8% and 7.5% of isolates from diarrheic and nondiarrheic piglets, respectively, and always was associated with other virulence determinants. Overall, 22.9% of isolates from diarrheic piglets appeared to be enteropathogens: enterotoxigenic E. coli (11.7%), enteropathogenic E. coli (3.5%), and E. coli isolates (3.0%) for which none of the above adherence factors was detected. Pathotypes AIDA-I/STb/EAST1 and AIDA-I/STb were isolated only from diarrheic piglets and accounted for 4.7% of isolates. Strains of these pathotypes induced diarrhea when inoculated into newborn colostrum-deprived pigs, in contrast to an isolate positive only for EAST1, which did not induce diarrhea. Antibiotic sensitivity test showed that isolates of the AIDA-I/STb/EAST1 and AIDA-I/STb pathotypes were the only strains sensitive to enrofloxacin, gentamicin, neomycin, and trimethoprim-sulfamethoxazole. This study showed that at least 20.5% of isolates from diarrheic piglets appeared to be associated with AIDA-I/STb pathotype and that EAST1 path- otype is probably not an important marker for diarrhea in piglets. Diarrhea remains an important cause of morbidity and mortality in livestock and is one of the most common diseases of suckling and postweaning piglets worldwide. Among preweaning diseases in swine, diarrhea has the highest morbidity and is responsible for approximately 10.8% of preweaning mortality in certain geographic re- gions. 29 Infection can occur at any time during suckling, but the highest incidence of disease occurs during the first 3-5 days of life. EnterotoxigenicE. coli (ETEC) has been commonly incriminated as one of the most impor- tant etiological agents of the disease. 8 In addition, other groups of E. coli such as Shiga toxin-producing E. coli (STEC) and enteropathogenic E. coli (EPEC) are also important enteric pathogens in piglets. Strains of ETEC express F4, F5, F6, F18, or F41 fimbriae and can pro- duce heat-labile (LTI and LTII) or heat-stable (STa (or STI) and STb (or STII)) enterotoxins (or both). 8 Strains of STEC, of which enterohemorrhagic E. coli is a subset, express the E. coli attaching and effacing (EAE) factor
Databáze: OpenAIRE
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