First isolation of ciprofloxacin-resistant Salmonella enterica serovar Typhi in Taiwan

Background/Purpose: Typhoid fever is a major cause of disease burden in developing countries. The use of fluoroquinolones, once considered the drugs of choice, should be re-evaluated due to the emergence of quinolone-resistant Salmonella enterica serovar Typhi. In Taiwan, typhoid fever is rare but constitutes an important public health concern. Methods: In August 2011, two ciprofloxacin-resistant S. Typhi isolates were identified from one patient who had recently travelled to India. The two isolates together with four other ciprofloxacin-susceptible S. Typhi isolates were subjected for molecular investigation. Polymerase chain reaction (PCR) and sequencing were used to analyze the resistance mechanisms. Pulsed-field gel electrophoresis (PFGE) was performed to delineate the genetic relatedness among the isolates. Results: In 2011, a total of 49 typhoid fever cases were reported to the Center for Disease Control in Taiwan, with a significant increase in indigenous cases in northern Taiwan from August to November. In the two S. Typhi isolates with complete resistance to ciprofloxacin [minimum inhibitory concentration (MIC) >32 mu g/mL], multiple point mutations in the quinolone resistance-determining regions (QRDRs) of gyrA and parC genes were identified. A unique PFGE pattern was found in the resistant isolates and was different from the other representative susceptible isolates. Conclusions: The first ciprofloxacin-resistant S. Typhi infection in Taiwan is reported. The emergence and spread of antimicrobial-resistant S. Typhi infection as a result of international travel may become a threat to public health in Taiwan. Clinicians should be well alert when treating patients who may have acquired resistant infections associated with international travel among endemic regions. Copyright (C) 2013, Taiwan Society of Microbiology. Published by Elsevier Taiwan LLC. All rights reserved.