Objective:To understand the etiological characteristics of 2 serotypes of Salmonella strains isolated from a foodborne disease outbreak. Methods:A total of 11 anal swabs of the cases, 13 suspected contaminated food and 10 environmental samples were collected from a foodborne disease outbreak occurred on September 8, 2022 in a school. The anal swabs were enriched with selenite brilliant green enrichment broth (SBG) and brain heart infusion broth (BHI) respectively. PCR detection and culture of common intestinal pathogens were carried out. The suspected food samples were tested according to national standards for food safety. Multiple suspected Salmonella colonies were obtained and selected for serotype determination and whole genome sequencing. Serotypes were determined based on the whole-genome sequence, and clustering analysis was performed based on core genome single nucleotide polymorphism (SNP). Results:The positive rates of Salmonella in anal swabs and suspected food samples were 9/11 and 5/13 respectively. Both Salmonella Uganda and Salmonella Idikan were isolated from 4 anal swabs and 4 suspected food samples. For the remaining samples, only Salmonella Uganda or Salmonella Idikan was isolated in each sample. The positive rate of Salmonella in 11 anal swabs of the cases after BHI enrichment for 12 h and 24 h were all 9/11 in real-time PCR, same to the culture results. Salmonella Uganda and Salmonella Idikan formed two independent and genetically distant lineages in the clustering tree based on core genome SNP, and 0-14 and 0-23 SNP were observed in Salmonella Uganda and Salmonella Idikan respectively. Conclusions:This foodborne disease outbreak was probably caused by Salmonella Uganda and Salmonella Idikan, which both exhibited strong genetic diversity. The PCR based pathogen screening strategy plus pathogen enrichment for cases' annal swabs can be used in the routine outbreak investigation.

OBJECTIVETo analyze the polio immunity level of persistent population in Beijing, 2012.

METHODSA total of 1 676 subjects residing more than 6 months in Beijing were selected by stratified random cluster sampling design in 2012. Demographic characteristics, history of oral poliovirus vaccine (OPV) immunization were investigated by questionnaire. All 5 ml blood sample were collected for testing of polio neutralizing antibody using the method of microcell neutralization. The positive rate and the geometric mean titer (GMT) of polio neutralizing antibody type I, II and III were analyzed in different groups.

RESULTSThe positive rate of type I, II and III were 98.2% (1 645/1 676), 98.1% (1 644/1 676), 97.6% (1 635/1 676); The GMT were 1:130.2, 1: 113.4 and 1: 79.7. Three types of positive rates in<15 years group (99.7% (664/666), 99.8% (665/666), 99.5% (663/666)) were higher than those of ≥ 15 years group (97.1% (981/1 010), 96.9% (979/1 010), 96.2% (972/1 010)), the differences were significant (all the values of P < 0.01); The GMT in<15 years group (1:325.9, 1:250.5, 1:190.7) were higher than that of ≥ 15 years group (1: 71.1, 1: 67.2, 1: 44.8), the difference was significant (all the values of P < 0.01). The positive rate (99.0%-100%) and GMT (1: 128.8-1: 300.7) in vaccination information confirmed population were higher. The highest positive rate (all were 100%) and GMT(1: 409.7-1: 636.7) were observed in children who vaccinated three times.

CONCLUSIONThe polio antibody of healthy population was at a high level in Beijing in 2012; Especially the age groups of < 15 years which were covered by vaccines.Immunization barrier had been formed firmly to interrupt the transmission of wild poliovirus and vaccine-derived poliovirus.

Adaptive Immunity ; Adolescent ; Antibodies, Neutralizing ; Antibodies, Viral ; Child ; Humans ; Poliomyelitis ; Poliovirus ; Poliovirus Vaccine, Oral ; Vaccination ; statistics & numerical data

Objective To analyze the polio immunity level of persistent population in Beijing , 2012.Methods A total of 1 676 subjects residing more than 6 months in Beijing were selected by stratified random cluster sampling design in 2012.Demographic characteristics , history of oral poliovirus vaccine ( OPV) immunization were investigated by questionnaire.All 5 ml blood sample were collected for testing of polio neutralizing antibody using the method of microcell neutralization.The positive rate and the geometric mean titer ( GMT ) of polio neutralizing antibody type Ⅰ,Ⅱ and Ⅲ were analyzed in different groups.Results The positive rate of type Ⅰ,Ⅱ and Ⅲ were 98.2%( 1 645/1 676 ) , 98.1%( 1 644/1 676),97.6%(1 635/1 676);The GMT were 1∶130.2,1∶113.4 and 1∶79.7.Three types of positive rates in<15 years group(99.7%(664/666),99.8%(665/666),99.5%(663/666)) were higher than those of≥15 years group (97.1%(981/1 010),96.9%(979/1 010),96.2%(972/1 010)),the differences were significant(all the values of P<0.01); The GMT in<15 years group(1∶325.9,1∶250.5,1∶190.7)were higher than that of ≥15 years group (1∶71.1,1∶67.2,1∶44.8),the difference was significant (all the values of P<0.01).The positive rate(99.0%-100%) and GMT(1∶128.8-1∶300.7) in vaccination information confirmed population were higher.The highest positive rate (all were 100%) and GMT(1∶409.7-1∶636.7) were observed in children who vaccinated three times.Conclusion The polio antibody of healthy population was at a high level in Beijing in 2012; Especially the age groups of <15 years which were covered by vaccines.Immunization barrier had been formed firmly to interrupt the transmission of wild poliovirus and vaccine-derived poliovirus.

Objective To analyze the polio immunity level of persistent population in Beijing , 2012.Methods A total of 1 676 subjects residing more than 6 months in Beijing were selected by stratified random cluster sampling design in 2012.Demographic characteristics , history of oral poliovirus vaccine ( OPV) immunization were investigated by questionnaire.All 5 ml blood sample were collected for testing of polio neutralizing antibody using the method of microcell neutralization.The positive rate and the geometric mean titer ( GMT ) of polio neutralizing antibody type Ⅰ,Ⅱ and Ⅲ were analyzed in different groups.Results The positive rate of type Ⅰ,Ⅱ and Ⅲ were 98.2%( 1 645/1 676 ) , 98.1%( 1 644/1 676),97.6%(1 635/1 676);The GMT were 1∶130.2,1∶113.4 and 1∶79.7.Three types of positive rates in<15 years group(99.7%(664/666),99.8%(665/666),99.5%(663/666)) were higher than those of≥15 years group (97.1%(981/1 010),96.9%(979/1 010),96.2%(972/1 010)),the differences were significant(all the values of P<0.01); The GMT in<15 years group(1∶325.9,1∶250.5,1∶190.7)were higher than that of ≥15 years group (1∶71.1,1∶67.2,1∶44.8),the difference was significant (all the values of P<0.01).The positive rate(99.0%-100%) and GMT(1∶128.8-1∶300.7) in vaccination information confirmed population were higher.The highest positive rate (all were 100%) and GMT(1∶409.7-1∶636.7) were observed in children who vaccinated three times.Conclusion The polio antibody of healthy population was at a high level in Beijing in 2012; Especially the age groups of <15 years which were covered by vaccines.Immunization barrier had been formed firmly to interrupt the transmission of wild poliovirus and vaccine-derived poliovirus.