Serotype-specific clinical tropism and antimicrobial resistance trends of non-typhoidal Salmonella in Taiwan, 2014-2023.

BACKGROUND

Non-typhoidal Salmonella (NTS) is an important pathogen causing gastroenteritis and extra-intestinal infections. This study aimed to comprehensively characterize the epidemiological features of NTS infections in Taiwan and to dissect the distinct clinical characteristics associated with different serotypes.

METHODS

During 2014‒2023, 4429, 1178 and 243 non-duplicate, culture-confirmed NTS isolates were collected from stool, blood, and urine from Chang Gung Memorial Hospitals, Taiwan, which represent gastroenteritis, bacteremia, and bacteriuria cases. Serotyping and antimicrobial susceptibility testing were conducted.

RESULTS

Serotypes Panama, Muenster and Enteritidis showed the highest odds ratios in causing bacteremia, while Muenster, Goldcoast and Agona were most prone to bacteriuria. Enteritidis and Goldcoast predominantly infected the elderly but Panama and Muenster primarily affected children. Antimicrobial resistance varied substantially across serotypes. Moreover, within the same serotype, blood isolates exhibited higher susceptibility than stool and urine isolates. NTS causing gastroenteritis underwent a compositional shift towards highly-resistant serotypes, but the composition for bacteremia remained constant. Anatum and Goldcoast constituted 75.6% of isolates resistant to both ciprofloxacin and ceftriaxone. Goldcoast caused more critical care unit admission in the elderly patients than other serotypes.

CONCLUSIONS

The study has uncovered novel clinical features, serotype composition, and antimicrobial resistance trends of NTS. Not all Salmonella serotypes are equal in contributing to disease pathogenesis. Blood isolates exhibited higher susceptibility than stool and urine isolates. The emergence of highly resistant serotypes, such as Anatum, and Goldcoast, poses a considerable threat to the elderly in disease burden and severity.