Antimicrobial Drug Resistance of Salmonella enterica Serovar Typhi in Asia and Molecular Mechanism of Reduced Susceptibility to the Fluoroquinolones

摘要: This study describes the pattern and extent of drug resistance in 1,774 strains Salmonella enterica serovar Typhi isolated across Asia between 1993 2005 characterizes molecular mechanisms underlying reduced susceptibilities to fluoroquinolones these strains. For 1,393 collected southern Vietnam, proportion multidrug has remained high since (50% 2004) there was a dramatic increase nalidixic acid (4%) (97%). In cross-sectional sample 381 from 8 Asian countries, Bangladesh, China, India, Indonesia, Laos, Nepal, Pakistan, central 2002 2004, various rates (16 37%) (5 51%) were found. The eight countries involved this are home approximately 80% world's typhoid fever cases. These results document scale Asia. Ser83-->Phe substitution GyrA predominant alteration Vietnam (117/127 isolates; 92.1%). No mutations gyrB, parC, or parE detected 55 vitro time-kill experiments showed reduction efficacy ofloxacin against harboring single-amino-acid at codon 83 87 GyrA; effect more marked strain with double substitution. 8-methoxy fluoroquinolone gatifloxacin rapid killing both single- double-amino-acid substitutions.