Abstract:
In order to understand the drug resistance characteristics of Gallibacterium anatis from chickens, ducks, geese and other poultry in Jiangsu, Guangxi, Shandong Provinces and other places, in this experiment, the liver, heart, fallopian tube and other tissues of dead birds were collected for isolation of Gallibacterium anatis from above regions. Biochemical identification, 16S rDNA gene PCR identification and sequencing analysis, drug sensitivity test, drug resistance gene detection and 18 types of incompatible(Inc) plasmids detection were performed. The correlation between the drug-sensitive phenotypes of the isolated bacteria and its drug-resistance genes, and the correlation between the drug-resistance genes carried by the isolated bacteria and Inc plasmids were analyzed. The results showed that a total of 17 isolates with the characteristics of Gallibacterium anatis were obtained. The results of biochemical identification of the 17 isolates were consistent with the characteristics of Gallibacterium anatis. The nucleotide similarity between the 16S rDNA gene sequences of 17 isolates and the reference strains reached more than 97%,which was further confirmed that all the 17 isolates were Gallibacterium anatis,and named as 2021GA01-2021GA17,respectively. The resistance rates of 17 isolates to cotrimoxazole, doxycycline, amoxicillin, norfloxacin, levofloxacin, ciprofloxacin and kanamycin were high, which were 88%, 82%, 76%, 76%, 76%, 71% and 65%, respectively. Among the 17 isolates, 14 isolates were resistant to three or more antibiotics, accounting for 82.35%; 7 isolates were resistant to more than 10 kinds of antibiotics, accounting for 41.18%. Only isolates 2021GA10 was resistant to both cefotaxime and ceftriaxone sodium. Among the 17 isolates, a total of 3 isolates(17.65%), 2021GA04, 2021GA05, 2021GA12, carried aminoglycoside resistance gene aac(3)-Ⅱ; 14 isolates(82.35%) of 2021GA01, 2021GA02 and 2021GA03,etc., carried the β-lactam resistance gene TEM; 6 isolates(35.29%) of 2021GA01, 2021GA03 and 2021GA04, etc., carried the β-lactam resistance gene CTX-M-65. No quinolone resistance genes were detected. Only 8 isolates of 2021GA09, 2021GA10 and 2021GA11, etc., carried IncFreP plasmid, and the detection rate of IncFreP plasmid was 47.06%. The other 17 plasmids were not detected. The coincidence rate between the resistance of 17 isolates to aminoglycoside drug gentamicin and the carrying resistance gene aac(3)-Ⅱ was 75%, and there was a significant correlation between them(P<0.05). Although the drug resistance of the aminoglycoside amikacin was 100% consistent with the carrying resistance gene aac(3)-Ⅱ, there was no correlation between them(P>0.05). The coincidence rate between the resistance to β-lactam drug mezlocillin and the carrying resistance gene TEM was 50%, and there was a significant correlation between them(P<0.05). There was no correlation between the resistance to other antibiotics and the carrying resistance genes(P>0.05). There was no correlation between the carrying resistance genes aac(3)-Ⅱ, TEM, CTX-M-65 and IncFreP plasmid in 17 isolates(P>0.05). The results suggested that Gallibacterium anatis isolated from multiple locations showed strong resistance to various antibiotics, but the IncFreP plasmid was not associated with the transmission of resistance genes in Gallibacterium anatis.