Objective To understand the antibiotic resistance and molecular characteristics of Salmonella typhimurium and Salmonella 1,4,［5］,12:i:– isolated in Zhuhai, Guangdong province, and provide reference data for molecular epidemiological investigation of food borne diseases.
Methods Disk diffusion method was used for antibiotic susceptibility test. Pulsed-field gel electrophoresis (PFGE) and multiple loci variable number tandem repeat analysis (MLVA) were conducted for 121 strains of S. typhimurium and S. 1,4,［5］,12:i:– isolated from diarrhea patients in Zhuhai by using the protocols published on PulseNet International Network and European Food-borne Disease Surveillance Network.
Results The antibiotic susceptibility test showed that 45 strains of S. typhimurium (45/51, 88.24%) and 51 strains of S. 1,4,［5］,12:i:– (51/70,72.86%) were multidrug resistant, the difference was significant (χ2＝4.256, P＝0.039). The antibiotics to which two serotypes strains' resistant rates were ＞50% were ampicillin, tetracycline, compound sulfamethizole and chloramphenicol. PFGE results indicated that the 121 isolates belonged to 88 types. There was no obvious clustering characteristics in two serotypes, but the types of S. typhimurium were more dispersed, the predominant 11 PT15 isolates had two serotypes. MLVA results indicated that STTR5 and STTR6 had highest repeat number (11 and 14), followed by STTR9 and STTR3. Up to 95.87% of the strains had no PCR amplification products. MLVA typing showed that there were 50 types. The predominant types were MT18 and MT10, which contained 23 and 11 isolates respectively, in two serotypes. Analysis with the minimum spanning tree (MST) found that 111 isolates (91.74%) were distributed in group I.
Conclusion The multidrug resistant rates of two serotypes Salmonella in Zhuhai were high, their molecular types were diverse, but the type of S. typhimurium was more dispersed. They had similar genetic characteristics.
Home
DownLoad: