[The fundamental role of stage control technology on the detectability for Salmonella networking laboratory].

OBJECTIVE: To evaluated the fundamental role of stage control technology (SCT) on the detectability for Salmonella networking laboratories. METHODS: Appropriate Salmonella detection methods after key point control being evaluated, were establishment and optimized. Our training and evaluation networking laboratories participated in the World Health Organization-Global Salmonella Surveillance Project (WHO-GSS) and China-U.S. Collaborative Program on Emerging and Re-emerging infectious diseases Project (GFN) in Shanghai. Staff members from the Yunnan Yuxi city Center for Disease Control and Prevention were trained on Salmonella isolation from diarrhea specimens. Data on annual Salmonella positive rates was collected from the provincial-level monitoring sites to be part of the GSS and GFN projects from 2006 to 2012. RESULTS: The methodology was designed based on the conventional detection procedure of Salmonella which involved the processes as enrichment, isolation, species identification and sero-typing. These methods were simultaneously used to satisfy the sensitivity requirements on non-typhoid Salmonella detection for networking laboratories. Public Health Laboratories in Shanghai had developed from 5 in 2006 to 9 in 2011, and Clinical laboratories from 8 to 22. Number of clinical isolates, including typhoid and non-typhoid Salmonella increased from 196 in 2006 to 1442 in 2011. The positive rate of Salmonella isolated from the clinical diarrhea cases was 2.4% in Yuxi county, in 2012. At present, three other provincial monitoring sites were using the SBG technique as selectivity enrichment broth for Salmonella isolation, with Shanghai having the most stable positive baseline. CONCLUSION: The method of SCT was proved the premise of the network laboratory construction. Based on this, the improvement of precise phenotypic identification and molecular typing capabilities could reach the level equivalent to the national networking laboratory.

[Assessment of the application of variable-number tandem repeat loci of Salmonella Enteritidis in subtyping multiple-locus variable-number tandem repeat analysis].

OBJECTIVE: To evaluate the feasibility of the application of variable-number tandem repeat (VNTR) loci of Salmonella Enteritidis (S. enteritidis) in subtyping mutiple-locus variable-number tandem repeat analysis (MLVA). METHODS: A total of 16 isolates of S.enteritidis from different place and time in China were preliminarily assessed by choosing 11 reported VNTR loci, the loci with single amplified bands were picked to subtype all 104 S. enteritidis isolates. The isolates were also analyzed by pulse field gel electrophoresis (PFGE) to compare the superiority or inferiority of MLVA method and PFGE method. RESULTS: Seven VNTR loci were selected from the preliminary screening to expand the analysis, and the 7 VNTR loci had grouped 104 of S.enteritidis isolates into either 16 MLVA subtypes or 22 PFGE subtypes, with the D value at 0.7222 and 0.7974, respectively. Comparing with the isolates in MLVA subtypes, the isolates in PFGE showed a stronger resolving power. Meanwhile the results in PFGE showed a more disperse frequency distribution than those in MLVA. CONCLUSION: These results indicate that some VNTR locus which have shown a good polymorphism internationally, may fail to show polymorphism in China, thereby, more VNTR loci should be included in MLVA and the wide screening may benefit the unity of global laboratorial methods.