[Epidemiological and etiological characteristics of typhoid and paratyphoid fever in Ningbo during 1988 - 2007].

OBJECTIVE: To study the epidemiological and etiological characteristics of typhoid and paratyphoid fever in high epidemic areas. METHODS: Reported data on typhoid and paratyphoid fever during 1988-2007 in Ningbo were analyzed epidemiologically. Shellfish from the market was collected for laboratory testing and Salmonella typhi strains collected from the patients were also studied. RESULTS: Number of reported cases on both typhoid and paratyphoid fever was 19 404 with 7 deaths, from 1988 to 2007. The annual mean incidence was 17.68 per one hundred thousand with the fatality rate as 0.36 per thousand. Most cases were among adults aged 20-50 years and an obvious regional distribution was observed with high incidence seen in winter and spring. Since 1990s, the advantage strain had changed from Salmonella typhi to Salmonella paratyphi A. Etiologic studies showed that raw Anadara subcrenata and oyster were the main risk factors. One Salmonella paratyphi A strain was detected in both Anadara subcrenata and oysters collected from the market, which contained TEM-1 drug resistance gene. PFGE genotyping showed that PFGE-X2 was the strain which causing pandemic in Ningbo. CONCLUSION: Eating contaminated raw shellfish like oysters and hairy clams was the primary risk factor, responsible for the outbreaks. Salmonella paratyphi A was the advantages pandemic strain in Ningbo. Strategies as supervision on personal hygiene and health education should be strengthened.

[Analysis of beta-lactams-resistance genes in Pseudomonas aeruginosa in burn ward].

OBJECTIVE: To investigate the resistance genes and antibiotic resistance patterns against beta-lactams in Pseudomonas aeruginosa prevalent in burn ward. METHODS: K-B method was performed to test bacterial resistance patterns against 9 species of beta-lactams in Pseudomonas aeruginosa isolated from wounds and dressings of the patient in burn wards. Seven species of resistance genes against beta-lactams were detected with PCR. Tazobactam-inhibited piperacillin resistance test was performed to study whether the above strains produce extended spectrum beta-lactams. RESULTS: All 12 strains of bacteria with resistance genes detected were resistant to penicillin and cephalosporins (100%), among them 11 were resistant to all antibiotics. Tazobactam-inhibited piperacillin resistance test demonstrated that all strains with resistance genes were ESBLs. CONCLUSION: High incidence of beta-lactams resistance genes is found in Pseudomonas aeruginosa isolated from burn ward, and they have close relationship with the occurrence of multiple drug-resistance.