Veterinary Archives, Vol. 86 No. 4, 2016.
Original scientific paper
Investigation of tetracycline resistance genes in Escherichia coli isolates from broiler chickens during a rearing period in Iran.
Soodabeh Zibandeh
; Graduated student, School of Veterinary Medicine, Shiraz University, Shiraz, Iran
Hassan Sharifiyazdi
; Department of Clinical Sciences, School of Veterinary Medicine, Shiraz University, Shiraz, Iran
Keramat Asasi
; Poultry Diseases Research Center, School of Veterinary Medicine, Shiraz University, Shiraz, Iran
Bahman Abdi-Hachesoo
; Poultry Diseases Research Center, School of Veterinary Medicine, Shiraz University, Shiraz, Iran
Abstract
The tetracycline resistance of E. coli isolates (n = 300) from broiler chickens was investigated in three stages of the rearing period (one-day-old chicks, thirty-day-old chickens and one day before slaughter). Tetracycline resistance genes (tet(A), tet(M), tet(O) and tet(S)) were investigated among 120 tetracycline resistant E. coli isolates. Tetracycline resistance at the three stages of sampling was 67, 90 and 94%, respectively. Of the 120 tetracycline resistant E. coli isolates, 68 (59%) carried the tet(A) resistance gene. The tet(A) resistance gene was present in 32.5% (13/40) of E. coli isolated from one-day-old chicks, 65% (26/40) of E. coli isolated from thirty-day-old chickens and 72.5% (29/40) of E. coli isolated from the chickens on the day before slaughter. None of the tested isolates contained tet(M), tet(O) or tet (S). Tetracycline resistance was relatively high in E. coli isolated from one-day-old chicks, suggesting a high prevalence of tetracycline resistance in the preliminary gut flora of these broiler chicks. Significant increases in the resistance rate of E. coli isolates were found during the 2nd and 3rd rearing period. Tet(A) was the only detected tet resistance gene in these E. coli isolates. The rise of the tet(A) resistance gene during the rearing of broilers is alarming because this plasmid mediated tet gene can be transmitted to other pathogenic and commensal bacteria in the poultry industry.
Keywords
Escherichia coli; tetracycline resistance; tet(A); broiler chickens
Hrčak ID:
166039
URI
Publication date:
12.8.2016.
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