Surveillance of diarrhea case cluster caused by Salmonella Agona

Objective To find out the possible clustering of sporadic diarrhea cases occurred in same period by using pulse field gel electrophoresis assay and conduct epidemiological survey and tracing. Methods Through PulseNet established in Beijing, the stool samples were collected from diarrhea patients to conduct pathogen isolation, biochemical identification, serotyping, drug susceptibility test and PFGE subtyping. Results From 2 to 7 May 2012,9 strains of Salmonella Agona were isolated from 22 stool samples of intestinal outpatients in a district in Beijing. The 9 strains of S. Agona showed same PFGE pattern by XbaⅠ enzyme digestion. In comparison with PulseNet China central database and local network laboratory database, the pattern was confirmed as a new type, encoded as JABX01.CN0072. Conclusion It suggested that 9 S. Agona isolates might be from same clone considering the highly concentrated infection time and place distribution of the cases and the clustering of PFGE pattern. Although common exposure factors were not found by the subsequent epidemiological survey and analysis of infection source, PFGE subtyping can improve the sensitivity of the surveillance. It is necessary to conduct consecutive molecular typing surveillance of pathogens and further improve PulseNet system and operation mechanism.