Serogroups Investigation Of Escherichia Coli Associated With Piglet Diarrhea In Partial Regions Of East China And Detection Of Aminoglycoside N-acetyltransferases Genes

Enterotoxigenic Escherichia coli (ETEC) is main pathogen of the piglet diarrhea, which can cause economic loss due to higher morbidity and mortality in yellow scour of newborn piglets, higher morbidity and lower mortality in while scour of piglets, poor growth rates, and decrease feed efficiency. The first purposes of this study was to determine the present distribution of O-serogroups among pathogenic Escherichia coli isolates collected from piglets with yellow and white diarrhea in partial regions of eastern China. Among 508 E.coli isolates, serogroups of 341 strains were determined while 145 were unable to be classified as certain groups, and 22 were self-agglutinated. These isolates distributed in 71 serogroups and main of which belonging to 6 O-serogroups : O101, 09, 020, O149, O107 and O91.In order to guide the clinical medication, antibiotic susceptibility of E. coil isolates was determined with t4 kinds of antibiotics. Among 173 E.eoli isolates, which were collected form 1995 to 2006 and stored in the laboratory, 161 strains were sensitive to Ceftriaxone, and 142 and 126 strains were sensitive to Polymyxin B and Kanamycin, respectively. These isolates show little sensitivity to Gentamicin, Ciprofloxacin, Norfloxacin, and Chloramphenicol, whereas resistant to Doxycycline, Ampicillin, Streptomycin, Tetracycline, and Sulfamethoxazole . A novel strain isolated in 1998 shows no drug resistance, meanwhile the others show drug resistance to almost 10～12 antibiotics. These data suggested that there is close correlation between the antibiotic resistance and the frequence of agents prescribed in clinic.To investigate the relationship between the presence of N-acetyltransferases (AAC) genes and the resistance of aminoglycoside of E.coli isolates, two pairs of primers of AAC genes were designed and PCR was performed. Among ninety strains of E.coli isolates which resistant to Gentamicin, 71.1% of isolates were aac(3)-Ⅱpositive, while 16.7% of isolates were aac(6')-Ⅰb positive. The results suggested that aae(3)-Ⅱmaybe the main modifying enzyme of aminoglycoside in E.coli.