Objective  To investigate the epidemic characteristics, drug resistance, multi-locus sequence typing (MLST) and genetic evolution background of Pseudomonas aeruginosa in Guangdong Province, and provide a reference for clinical rational drug use.

Method  Samples from dead embryos of pheasant and their surrounding environment were collected for separation and identification of P. aeruginosa. The K-B paper disk diffusion method was used to analyze P. aeruginosa sensitivity to 22 kinds of antimicrobials. The MLST method was applied to analyze the molecular epidemiology of P. aeruginosa strains. Seven house-keeping genes of each ST type were spliced sequentially, and we used MEGA7 software to conduct genetic evolution analysis to the spliced sequence.

Result  A total of 145 P. aeruginosa strains (isolation rate 28.2%) were isolated from the collected 514 samples (405 dead embryo samples and 109 environment samples), including 24 strains from environmental samples (isolation rate 22.0%, 24/109) and 121 strains from dead embryos (isolation rate 29.9%, 121/405). Antibiotic drug sensitivity test showed that 145 strains of P. aeruginosa were naturally resistant to ampicillin, kanamycin and nalidixic acid, strongly resistant to complex sulfamethoxazole, chloramphenicol, tetracycline, followed by cefotaxime, with the drug resistance rates of 100%, 80.0%, 77.2% and 23.4% respectively. Except the natural drug resistance, the proportion of multiple drug resistant P. aeruginosa was up to 73.1% (106/145), and a certain proportion of P. aeruginosa strains which were resistant to imipenem appeared. MLST analysis showed that 89 P. aeruginosa strains with a broad spectrum of resistance were divided into 18 ST types, presenting high diversity. Among them, six ST types were the new types discovered in this study. The dead embryo isolates of P. aeruginosa were mainly ST-260, and the environmental sample isolates were mainly ST-2100 and ST-3202. Genetic evolution analysis showed that P. aeruginosa strains in environment were closely related to those in dead embryos.

Conclusion  There are different degrees of P. aeruginosa infection or contamination in dead embryos and surrounding environment of three pheasant farms, and the isolates have strong drug resistance. Therefore, it is recommended that we should not only strengthen the breeding management and raise the awareness of bio-safety in the process of breeding, but also use antibacterial drugs reasonably according to the results of the drug sensitivity test.