International Journal of Medical Advances and Discoveries

International Journal of Medical Advances and Discovery ISSN 2756-3812 Vol. 3 (6), pp. 001-007, June, 2012. © International Scholars Journals

Full Length Research paper

Nalidixic acid resistance and clonal expansion of SALMONELLA  ENTERICA  serotype Paratyphi A Isolates in Yuxi city, China

W. Shukun¹, C.Congjia², Y. Yunbo¹, K. Biao³, and D. Baowei³

¹Centre for Disease Control and prevention of Yuxi city, Yuxi 653100, China.

²People^，s Hospital of Yuxi city, Yuxi 653100, China.

³National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, P.O. Box 5, Changping, Beijing 102206, China

Accepted 08 May, 2012

Abstract

Antimicrobial susceptibility tests were performed with 4060 strains of SALMONELLA ENTERICA serotype Paratyphi A (SPA) isolated from patients at Yuxi City from 1999 to 2008. The incidence of resistance to nalidixic acid of the isolates increased from 12.5% in 1999 to 82.2% in 2000, 93.0% in 2001, and 100% in 2008. The frequencies of intermediary and susceptibility (Kirby-Bauer disc diffusion technique) to ciprofloxacin were 17.0% and 83.0% before 2005, 65.3% and 34.7% in 2008, respectively. A group of 166 NAR and 20 NAS isolates of SPA were typed by pulsed-field gel electrophoresis (PFGE) using SpeI into nine different PFGE patterns with predominance of the SpeI01 and SpeI02. All NAR isolates had higher MICs for fluoroquinolone. We validate the use of the nalidixic acid screening test for detection of decreased fluoroquinolone susceptibility in SPA.

Keywords: Paratyphoid fever, Salmonella enterica serotype Paratyphi, antimicrobial susceptibility, resistance to nalidixic acid, PFGE, clonal expansion.