Molecular epidemiological survey on aminoglycoside antibiotics-resistant genotype and phenotype of avian Escherichia coli in North China.

Monitoring drug resistance in Escherichia coli is important for prevention and treatment of colibacillosis. To choose effective drugs to prevent and control avian colibacillosis in North China, we investigated resistance of 205 E. coli isolates (from Beijing, Tianjin, inner Mongolia, Shanxi, and Hebei regions) to commonly used clinical aminoglycoside antibiotics using a drug susceptibility test. The results show that the isolates had varying degrees of resistance to kanamycin, gentamicin, streptomycin, amikacin, neomycin, and spectinomycin. Particularly, the resistance rates of the former 3 antibiotics exceeded 40%. To explore the reasons for wide drug resistance, aminoglycosides modifying enzymes (AME) genes, which are important in generation of aminoglycoside resistance, were detected by PCR. Of the isolates, 60.98% carried AME genes and 38.05% carried commensal multidrug resistance genes. Therefore, resistance of avian E. coli to aminoglycoside antibiotics is very serious in North China, perhaps due to the existence of resistance genes.