[Epidemiologic characteristics of typhoid and paratyphoid fever on related drug resistance and molecular types regarding Salmonella typhi and S. paratyphi, in Jiangsu province].

Objective: To explore the distribution of prevalence rates of typhoid and paratyphoid, with drug resistance and molecular types of Salmonella (S.) typhi and S. paratyphi in Jiangsu province.

Methods: Data, collected by the national infectious disease reporting system in Jiangsu province from 2007 to 2011, was analyzed. K-B method was used to test the sensibility to 9 kinds of antibiotics among 210 stains of S. typhi and S. paratyphi. 81 strains of S. typhi were classified by pulse-field gel electrophoresis (PFGE).

Results: The annual average incidence of typhoid and paratyphoid was 0.47 per 100 000 in the last five years, showing a decreasing trend. Highest incidence (1.70 per 100 000) was seen in the < 1 year age group, with S. typhi and S. paratyphi A accounted for 66.19% and 23.81% among the 210 stains. The rate of drug resistance to nalidixic acid appeared to be the highest as 66.19%. The drug resistant rates to 6 kinds of antibiotics were on average, lower than 10.00%. The multi-drug resistant rate of S. typhi and S. paratyphi was 30.00%. In the last 3 years, 37 types from 81 S. typhi strains had been classified into 4 clusters by PFGE. The predominant type was JPPX01. JS0027, accounted for 11.11%. JPPX01.JS0001 type had a specific regional distribution, but JPPX01.JS0014, JPPX01.JS0018 and JPPX01.JS0024 strains were widely spread. Results from the clustering analysis showed that cases in the 3 events tended to have a clustering nature.

Conclusion: The morbidity of typhoid and paratyphoid was in a relatively low level in Jiangsu province. Although S. typhi and S. paratyphi were sensitive to most of the commonly used antibiotics, the resistance rates to some kinds of antibiotics were increasing. The distribution of typhoid was sporadic in Jiangsu and without the dominant strain, it was unlikely that typhoid could become epidemic in the future, in Jiangsu.