Laboratory-based surveillance of nontyphoidal Salmonella infections in China

Foodborne infections are an important public health problem in China. In 2008, we conducted surveillance for laboratory-confirmed nontyphoidal Salmonella to monitor trends for this infection in China and to build capacity for rapid detection and response to foodborne outbreaks. Salmonella isolates from patients with diarrhea were sent from hospitals to local public health laboratories for confirmation, serotyping, and antimicrobial susceptibility testing. A total of 126 hospitals in 44 cities and counties from 8 provinces provided isolates and epidemiologic data for analysis. Of 23,140 stool specimens submitted to clinical laboratories, 662 (3%) grew Salmonella enterica. Salmonella were most commonly detected between April and October. The median age of infected patients was 27 years; 34% of infections occurred in patients <5 years old. Of the 662 isolates, we found 73 serotypes, of which serotype Enteritidis (31%) and serotype Typhimurium (26%) were the most common. The prevalence of resistance was high for clinically important antimicrobial agents, including ampicillin (41%) and ciprofloxacin (6%). More than 60% of isolates, including 35% of all Typhimurium, were resistant to three or more antimicrobial agents. In this first multiprovince surveillance report of laboratory-confirmed Salmonella infections in China, we found that Enteritidis and Typhimurium are the most common serotypes and that efforts to reduce antimicrobial resistance among Salmonella in China are needed. Although no outbreaks were detected using this system, efforts to improve this system's capacity to do so are underway.