Identification, virulence gene and antibiotic resistance analysis of Escherichia coli isolated from diarrheic piglets

To gain insight into the prevalence of infection and drug resistance profiles of Escherichia coli isolated from diarrheic piglets in parts of western region of Guangdong Province, the present study was aimed at isolation and identification of E. coli from 114 rectal swabs in diarrheic piglets through differential media, Gram staining and rapid biochemical characterization, and then to identify virulence genes and antibiotic resistance of pathogenic E. coli through PCR and agar disk diffusion methods. The identification results showed that the predominant E. coli could be isolated from each sample, and the biochemical characteristics of isolated E. coli were consistent with that of E. coli ATCC 25922. A total of nive virulence genes were detected in all the E. coli isolates（114 strains）. The results showed that the overall detection rates of virulence genes were 90.35%（103/114）, among which the detection rates were 71.93%（82/114） for STa, 61.40%（70/114） for STb, 11.40%（13/114） for LT,7.02%（8/114） for K99, 6.14%（7/114） for F41, 5.26%（6/114） for F18ac, 0.88% for K88（1/114） and 0%（0/114） for 987P and 3.51%（4/114） for Stx2e. The results of drug sensitivity testing revealed that the E.coli isolates displayed high rates of resistance to sulfamethoxazole（100%, 114/114）, ampicillin（97.37%,111/114） and tetracycline（96.49%, 110/114）. The rates of resistance to other antibiotics were observed for: neomycin（48.25%, 55/114）, levofloxacin（43.86%, 50/114）, polymyxin B（42.98%, 49/114）,gentamicin（42.11%, 48/114）, cipro-floxacin（39.47%, 45/114）, and ceftiofur（24.56%, 28/114）. The present research obtained basic data of virulence gene distribution and drug resistance profiles of E. coli isolated from diarrheic piglets in parts of western region of Guangdong Province.