Evaluation of different samples pretreatment method of MALDI-TOF MS on the identification of common foodborne pathogens / 上海预防医学

Objective To evaluate the effects of different sample pretreatment methods of MALDI-TOF MS on the identification of common foodborne pathogens. Methods A total of 51 common foodborne pathogens were collected, covering Salmonella, Staphylococcus, Listeria, Vibrio, Escherichia, and Shigella.Then the effects of three sample treatment methods including direct smear method, in-situ formic acid extraction method and formic acid acetonitrile extraction method of MALDI-TOF MS on the identification of common foodborne pathogens were evaluated. Results There were no significant differences in the identification results of Salmonella, Shigella, and Escherichia by three sample pretreatment methods; Staphylococcus captis, Staphylococcus cohnii, Vibrio parahaemolyticus and Vibrio vulnificus could not be identified effectively by direct smear method, but these strains could be accurately identified by other methods.Non-listeria monocytogenes strains of listeria genus were often mistakenly identified by using direct smear method and in-situ formic acid extraction method, and the use of formic acid and acetonitrile extraction could improve the identification accuracy for different species of listeria. Conclusion Different sample pretreatment methods of MALDI-TOF MS have certain influence on the identification of common foodborne pathogenic bacteria.Therefore, selecting appropriate sample pretreatment methods is important to obtain reliable and accurate identification results.

Human rhinovirus with different genotypes in children with acute respiratory tract infections in Beijing / 病毒学报

To understand the infections and molecular biological characteristics of different human rhinovirus (HRV) genotypes -A, B, C, especially C in children with acute respiratory tract infections (ARI) in Beijing. Seven hundreds and three respiratory tract specimens were collected from children with ARI during Jan. 2011 to Dec. 2011. Semi-nested PCR was developed for detecting HRVs. Gene fragment of VP4/VP2 capsid protein amplified from HRV positive specimens was sequenced and analyzed by software DNAStar, the phylogenetic tree was then constructed by MEGA 5. 05. Among these 703 specimens tested, 54 (7.7%, 54/703) were HRV positive, including 25 (46.3%, 25/54) positive for HRV-A, 8 (14. 8%, 8/54) for HRV-B, 21 (38. 9%, 21/54) for HRV-C determined by sequence analysis. Most of these children (94. 4%00, 51/54) infected with HRVs were younger than 5 years old, and the highest positive rate was shown in group younger than 1 year (11. 4%). These patients positive for HRVs were diagnosed as bronchiolitis (23.1%), asthma (20.0%), pneumonia (1.0%), bronchitis (4.4%) and upper respiratory tract infections (4. 1%). Sequence analysis of VP4/VP2 gene fragment revealed that 70. 0% to 100. 0% nucleotide identity was shown among the sequences within the same HRV genotype, and 55. 5% to 65. 8% nucleotide identity among the sequences from different HRV genotypes. In conclusion, HRVs, especially HRV-C, are important pathogens for children with ARI in Beijing. The prevalence of HRV-C is similar to that of HRV-A, higher than that of HRV-B. High sequence variation among different HRV genotypes was indicated in this study.

Different species of human rhinovirus infection in children with acute respiratory tract infections in Beijing / 中华儿科杂志

<p><b>OBJECTIVE</b>To understand the clinical characteristics of different groups human rhinovirus (HRV)-A, B and C infection in children with acute respiratory tract infections (ARI) in Beijing.</p><p><b>METHOD</b>Respiratory tract specimens (n = 1412) collected from children with ARI during Jan. 2011 to Dec. 2012 were tested for HRV by using semi-nested PCR. Gene fragments of VP4/VP2 capsid protein amplified from HRV positive specimens were sequenced for HRV genotype confirmation. Then epidemiological characteristics of these HRV-positive cases were analyzed.</p><p><b>RESULT</b>Among these 1412 specimens tested, 103 (7.3%) were HRV positive, including 54 (52.4%) positive for HRV-A, 14 (13.6%) for HRV-B, 35 (34.0%) for HRV-C determined by sequence analysis. The positive rates of HRV-A, B and C (2.5%, 16/638; 0.3%, 2/638 and 1.3%, 8/638) in children with acute upper respiratory tract infections (URI) were lower than those (5.8%, 36/623; 1.8%, 11/623 and 3.9%, 24/623) in children with acute lower respiratory tract infections (LRI) (P = 0.003, 0.011, 0.003). In children with LRI, the positive rates of HRV-A, C were similar to each other (P = 0.112), and both were higher than that of HRV-B (P = 0.000, P = 0.026). The severity of ARI among children positive for different groups HRV showed no significant difference evaluated by Kruskal-Wallis H test (Hc = 0.044, P > 0.05), as well as that between children co-infected with HRV and other viruses and those infected with HRV only evaluated by Wilcoxon rank sum test (Zc = 0.872, P > 0.05).</p><p><b>CONCLUSION</b>HRV is one of important pathogens for children with ARI, especially LRI in Beijing. The positive rates of HRV-A and HRV-C are similar to each other, and both are higher than that of HRV-B. No significant difference was shown among children with different HRV genotypes by evaluation of the severity of ARI, and co-infections of HRV with other viruses do not significantly increase the severity of ARI.</p>