Clonal expansion and genetic diversity of nalidixic acid-resistant Salmonella enterica serotype Paratyphi A in Yuxi city, China
- VernacularTitle:萘啶酸抗性甲型副伤寒病原菌的克隆扩散和遗传多样性
- Author:
Shukun WANG
;
Yunbo YAO
;
Congjia CHU
;
Desheng SHAN
;
Biao KAN
;
Baowei DIAO
;
Qiang WU
;
Rusong YANG
;
Hongyan LIU
;
Liping ZENG
- Publication Type:Journal Article
- Keywords:
Salmonella enterica serotype Paratyphi;
Antimicrobial susceptibility;
Pulsed-field gel electrophoresis;
Clonal expansion;
Genetic diversity
- From:
Chinese Journal of Microbiology and Immunology
2008;28(12):1109-1115
- CountryChina
- Language:Chinese
-
Abstract:
Objective To understand the elonal expansion and genetic diversity of Salmonella en-terica semtype Paratyphi A (SPA) and to construct a typing method to determine the epidemic clones of the isolates. Methods Antimicrobial susceptibility testing was performed with 3980 SPA isolates by the cen-trolled Kirby-Bauer disc diffusion technique on Muller-Hinton agar plates. A total of 15 SPA with nalidixie acid resistance for mutations in gyrA, gyrB, gyrC and gyrE genes within the quinolone-resistant determina-tion region (QRDR) were examined. Subtyping of 121 isolates of SPA from seven counties in Yuxi were studied using pulsed-field gel eleetrophoresis (PFGE) analysis following digestion of chromosomal DNA with restriction endanucleases Spe Ⅰ and Xba Ⅰ. PFGE patterns were analyzed by duster analysis. Results The nalidixic acid-susceptible isolates predominated in 1999 but was replaced by nalidixic acid -resistant (NAR) isolates after 2000. Amplification by PCR and sequencing of the genes with subsets of 15 NAR strains re-vealed that the resistance mechanisms had resulted from single point mutations in the gyrA gene. Spe Ⅰ and Xba Ⅰ digestion of 121 isolates gave five and four different PFGE patterns with the predominance of the Spe Ⅰ 01 and Spe Ⅰ 02 (or the Xba Ⅰ 01) epidemic patterns, respectively. Spe Ⅰ 01 and Spe Ⅰ 02 consisted of 37.2% and 57.9% of isolates, respectively, or Xba Ⅰ 01 consisted of 95.0% of isolates. Conclusion The incidence of resistance to nalidixic acid of the isolates increased during the study period. PFGE patterns Spe Ⅰ 01 and Spe Ⅰ 02 (or Xba Ⅰ 01), the main clones of the epidemics, are highly prevalent in Yuxi. PFGE with Spe Ⅰ and Xba Ⅰ is a useful technique to differentiate SPA.
