Laboratory-Based Surveillance of NontyphoidalSalmonellaInfections in China

Abstract

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.

Analysis of Bacterial Pathogens Causing Acute Diarrhea on the Basis of Sentinel Surveillance in Shanghai, China, 2006–2011

“…The isolation rate of Salmonella in the present study (0.8z) was lower than that reported previously from China (7,19) as well as developed countries such as the United States and Italy, where a much higher incidence of diarrhea was caused by Salmonella (20). More than 2,000 serotypes of Salmonella have been discovered globally; however, only a limited number of serotypes are known to cause human disease (21).…”

Salmonella Serotype Determination Utilizing High-Throughput Genome Sequencing Data

“…For O-group determination, two databases were built: (i) sequences from the entire rfb cluster were used for O-group determination from genome assemblies and (ii) wzx (O-antigen flippase), wzy (O-antigen polymerase), and other genes or markers from the rfb cluster useful for O-group determination (see Table S4 in the supplemental material) were used when the input data were raw sequencing reads. Two O-antigen groups, those that possess O9 (O9,O2, O9,46, and O9,46,27) and those that possess O3 (O3,10 and O1, 3,19), require additional markers for differentiation, including the rfb sequence specific to serotype O3,10 and a frameshift mutation in tyv (see Table S4). The combined use of the six markers allowed the differentiation of 273 (O3,10) and 72 (O1, 3,19) strains (data not shown).…”

“…Two O-antigen groups, those that possess O9 (O9,O2, O9,46, and O9,46,27) and those that possess O3 (O3,10 and O1, 3,19), require additional markers for differentiation, including the rfb sequence specific to serotype O3,10 and a frameshift mutation in tyv (see Table S4). The combined use of the six markers allowed the differentiation of 273 (O3,10) and 72 (O1, 3,19) strains (data not shown). In the two O-group databases, each of the 46 O antigens was represented by a single rfb cluster (26) or a single allele of the wzx or wzy gene (27).…”

IncI1 Plasmids Carrying Various bla CTX-M Genes Contribute to Ceftriaxone Resistance in Salmonella enterica Serovar Enteritidis in China

“…Salmonella enterica subsp. enterica serovar Enteritidis is the most common serotype that causes human infections in China (1). In the United States, S. Enteritidis has become the most clinically prevalent serotype since 2008, accounting for ϳ17% of all salmonellosis cases (2).…”