Abstract

W. Shukun, C.Congjia, Y. Yunbo, K. Biao, and D. Baowei

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.