Microbiological features of indigenous typhoid cases in Taiwan and relatedness to imported cases, 2001–2014: A cross-sectional analysis

Abstract Background Typhoid fever was rare in Taiwan but approximately two-thirds of the cases were indigenous. The transmission source of the indigenous cases and the relatedness to the imported cases remained unknown. Methods Patients with any site culture positive for Salmonella enterica serovar Typhi were identified in a teaching hospital during 2001–2014. The isolates were determined for antibiotic susceptibilities, pulsed-field gel electrophoresis (PFGE) types and single nucleotide polymorphisms (SNP) types. Results A total of 64 typhoid episodes were identified in 63 patients. Seventeen episodes (26.6%) were imported and a majority (10, 58.8%) of them were from Indonesia. The clinical manifestations, outcomes of patients and antibiograms of isolates were similar between indigenous and imported cases. 63.3% of the isolates were ciprofloxacin-resistant. The distributions of PFGE and SNP types did not differ significantly between indigenous and imported isolates, either ( P  = 0.191 and 0.124, respectively). Identical PFGE pattern could be identified in indigenous isolates appearing at certain time frames, indicating outbreaks due to local transmission of certain Typhi strains. Conclusions The imported cases of typhoid fever from Southeast Asia were the major sources of indigenous S. Typhi infections in Taiwan. Small-scale outbreaks occurred due to local transmission of the strains after their importation.