Abstract: In order to understand the pathogenic characteristics and drug resistance of Lohmann Pink chickens in a farm in Guizhou province,a Gram-negative strain was isolated from dead chickens,named GZ2019,and the isolated bacteria were purified and cultured,biochemical test,16S rRNA sequence analysis,drug susceptibility test and animal regression test.The isolated bacteria showed round raised,smooth surface,translucent small gray colonies on the ordinary agar medium,and the colony morphology on the blood-nourishing agar medium was consistent with that on the ordinary agar medium,without hemolysis.Microscopic examination of Gram staining results showed that the isolates were diplicate negative coccidiobacteria,with occasional single presence or chain arrangement.The results of biochemical tests showed that citrate utilization and catalase reaction of isolated bacteria were positive,while nitric acid reduction,oxidase and glucose fermentation were negative,with no movement.The 16S rRNA sequence analysis results showed that the homology between the isolated strain and acinetobacter was between 72.6% and 99.9%,and the homology with Acinetobacter schindleri LUH 4760 (GenBank accession No.:AJ275041),SNSK 752 (GenBank accession No.:MG584984),MCDA01 (GenBank accession No.:KY385627) and RP1 (GenBank accession No.:MG461636) was 99.9%.The results of drug susceptibility test showed that the isolate were sensitive to ceftriaxone and furazolidone,moderately sensitive to five drugs,such as cefoperazone,cefuroxime and ceftazidine,and resistant to 17 drugs,such as neomycin,ciprofloxacin,carboxylbenzicillin.The results of the animal regression test showed that only one mouse in the experimental group died after 1 week of isolation,with a mortality rate of 20%,indicating that the pathogenicity of the isolates was weak.This study successfully isolated a strain of low pathogenicity Acinetobacter schindleri GZ2019,which could provide certain reference for the prevention and treatment of Acinetobacter schindleri in chickens.

Key words: Lohmann Pink chickens; Acinetobacter schindleri; drug resistance analysis