Objective: To understand the clinical epidemiology and manifestation of nontyphoidal Salmonella (NTS)enteric infections and serotypes and antibiotic resistance patterns of NTS in children.
Method: All cases with probable acute bacterial inflammatory diarrhea were included into this study from the Children's Hospital of Fudan University during January 2012 through December 2014. Salmonella species and other major enteric bacteria were routinely isolated from the fresh stool sample of the enrolled patients at their first visit to the enteric clinic. Salmonella isolates were serotyped and tested for antimicrobial susceptibility testing using Kirby-Bauer method at the reference laboratory of Shanghai Municipal Center for Disease Control and Prevention. All enrolled cases had clinical records. The enumeration data were described by constituent ratio.
Result: Of the enrolled 3 143 patients, 742 (23.6%) were confirmed to have Salmonella infections, and NTS was identified in 738 (23.5%) cases and Salmonella Paratyphi B was identified in 4 (0.1%) cases, respectively. The isolation rate of NTS exceeded diarrheagenic Escherichia coli (6.7%, 182/2 727), Campylobacter (4.1%, 129/3 143) and Shigella (2.4%, 77/3 143). Nine serogroups and 41 serovars were identified in 742 salmonella isolates. Salmonella Enteritidis and Salmonella Typhimurium were the most common serovars, representing 42.6% (316/742) and 28.2% (209/742) of isolates, respectively.NTS infections were prevalent year-round with a seasonal peak from May to October. The common symptoms included fever (57.5%, 424/738) and blood-in-stool (31.0%, 229/738). Antimicrobial susceptibility showed only 8 (1.1%) of 742 isolates sensitive to 16 tested antibiotics.Resistance to the current first-line antibiotics such as the third-generation and(or) fourth-generation cephalosporins (cefotaxime and cefepime), ciprofloxacin was detected in 10.0%(74/738), 8.1%(60/738) and 1.1%(8/738), respectively.
Conclusion: NTS is the leading causative agent responsible for bacterial inflammatory diarrhea in Shanghainese children. The prevalence of NTS enteric infections show an increasing trend year by year. It is essential to continuously monitor the antimicrobial resistance of NTS and trace the source of infection to prevent and treat NTS infections in Shanghai.