Isolation,Identification and Drug Resistance Genes of 34 Riemerella anatipestifer Isolates
To better guide the clinical medication of farms and explore the mechanism of multi-drug resistance about Riemerella anatipestifer,bacteria were isolated from moribund ducks in Anhui province in this study.Total 34 RA isolates were obtained by biochemical reaction and tested for drug susceptibility.Then aminoglycoside resistance genes and class I integrons were identified according to the results of drug susceptibility.Drug susceptibility test showed that these 34 isolates were more sensitive to cefradine,ceftriaxone,florfenicol,spectinomycin and sulfisoxazole but strong resistant to kanamycin,gentamicin,amikacin,streptomycin and azithromycin.In addition,97%RA isolates were multi-drug resistant and the highest resistance reached up to 19 antibiotics.Examination of 15 aminoglycoside resistance genesrevealed varying detection rates of aac(6')Ib gene(94.1%,32/34),aac(6')Ⅱ gene(82.4%,28/34),rmtC gene(73.5%,25/34)and aph(3')Ⅱa gene(70.6%,24/34).Other drug resistant genes were not detected.At the same time,all 34 isolates carried class I integrons,the size of which was 1 kb and the gene cassette type was aadA 1(streptomycin resistance gene).The coincidence rate of drug resistance phenotype and drug resistance genes was greater than 69%.Therefore,the multi-drug resistance was severe among RA isolates in Anhui province indicating a necessity to strengthen the standardization of the antibiotic use and pay special attention to aminoglycoside antibiotics.
Riemerella anatipestiferdrug susceptibilitydrug resistance geneclass I integron