Multilocus variable-number tandem-repeat analysis for molecular subtypes of Shigella isolates in Beijing / 中华预防医学杂志

<p><b>OBJECTIVE</b>Selecting variable-number tandem-repeat (VNTR) loci for different serogroups of Shigella spp to explore and establish multilocus variable-number tandem-repeat analysis (MLVA) method, in order to study the molecular characteristic of the isolated strains.</p><p><b>METHODS</b>Of the Shigella strains found by dysentery surveillance in Beijing from 2001 to 2009, 180 strains were selected for this study, according to the number and serotypes of the surveillant strains, at the ratio of 15%; including 50 strains of Shigella sonnei and 130 strains of Shigella flexneri. After screening the polymorphism of the 18 VNTR loci, 10 VNTR loci (sh1-sh10) were retained and constructed three groups of multi-PCR methods to detect all he 180 strains and analyze MLVA molecular subtypes using capillary segments.</p><p><b>RESULTS</b>A range of 2 to 11 alleles were found on the 10 VNTR loci among the 180 Shigella strains, with a diversity index value between 0.158 and 0.766. The 10 loci showed diversity in different serogroups, such as only one allele found in sh6 of Shigella flexneri, sh2 and sh3 of Shigella sonnei individually. The isolated 180 strains were divided into 84 MLVA subtypes, with a resolution ratio D value at 0.967 (95%CI: 0.956 - 0.978). The 130 strains of Shigella flexneri were divided into 63 subtypes, named as TF001-TF063; among which TF001, TF002 and TF 005 were the dominant subtypes, accounting to 17, 16 and 15 strains respectively. The 50 strains of Shigella sonnei were divided into 21 subtypes, named as TS001-TS021; among which TS002 (14 strains) and TS001 (7 strains) were the dominant subtypes.</p><p><b>CONCLUSION</b>MLVA subtyping method including 10 VNTR loci was preliminarily developed. The MLVA cluster analysis revealed that the subtypes of Shigella strains isolated in Beijing were diverse, and suggested the possibility of multiple-clone source.</p>

Etiological surveillance and analysis of infectious diarrhea in Beijing in year 2010 / 中华预防医学杂志

<p><b>OBJECTIVE</b>To explore the pathogenic form, epidemic features and serotype distribution of the pathogenic bacteria causing infectious diarrhea in Beijing.</p><p><b>METHODS</b>A total of 2118 samples of rectal swabs and stool specimens of diarrheal patients were collected from 6 surveillant intestinal tract clinics during the period between April and October, 2010. Enteric multiple pathogens including Vibrio cholerae, Vibrio parahaemolyticus, Salmonella, Shigella and diarrheagenic Escherichia coli were detected by the isolation culture, biochemical identification and serotyping methods. The population distribution, temporal distribution and serotype distribution of the above pathogenic bacteria were analyzed by descriptive statistical methods.</p><p><b>RESULTS</b>478 strains isolated from the total 2118 specimens were positive for pathogen detection, accounting to 22.6%. Among the 478 strains of pathogenic bacteria, Shigella accounting for 40.8% (195/478) was the most frequent pathogen, followed by Vibrio parahaemolyticus accouting for 23.8% (114/478), Salmonella accounting for 19.0% (91/478) and diarrheagenic Escherichia coli accounting for 4.8% (23/478). Enteric pathogenic bacteria spread mainly among adults aging between 20 and 39; and the distribution was different among different age groups, while the highest detected rate was in 30 - 39 age group, accounting for 27.2% (92/338). The detected rate of pathogenic bacteria showed evident seasonal variations, with a peak from July to October, whose detected rates were 23.5% (114/486), 32.8% (176/536), 36.1% (90/249) and 25.9% (29/112) respectively. The detected rates in other months were all under 16.0%. Shigella Sonnei was the dominant serotype, accounting for 83.1% (162/195). O3:K6 was the dominant serotype among Vibrio parahaemolyticus, accounting for 63.2% (72/114). Salmonella Enteritidis and Salmonella Typhimurium were dominant serotypes among Salmonella, accounting for 13.2% (12/91) and 12.1% (11/91) separately. Enterpathogenic Escherichia coli and enterotoxigenic Escherichia coli were the dominant serotypes among Diarrheagenic Escherichia coli, accounting for 69.6% (16/23) and 30.4% (7/23) respectively.</p><p><b>CONCLUSION</b>The three main pathogenic bacteria causing infectious diarrhea in Beijing are Shigella, Vibrio parahaemolyticus, Salmonella; and there are obvious changes in the serotype distribution of Shigella and Samonella compared to previous years.</p>

Analysis on the etiological and molecular epidemiological characteristics of Vibrio parahaemolyticus in Beijing / 中华流行病学杂志

Objective To understand the etiological and molecular-epiderniological characteristics of Vibrio parahaemolyticus in Beijing.Methods Stool specimens from sporadic diarrheal patients were collected during April to December,2010.Culture and serotyping were used to detect the Vibrio parahaemolyticus from the 2118 specimens.All the positive strains were tested for drug sensitivity by Kirby-Bauer method.Real-time PCR was used to detect the existence of three virulence genes tlh,tdh and trh.Molecular typing on Vibrio parahaerrolyticus isolates was completed by pulsed field gel electrophoresis(PFGE).Results 114 out of the 2118 specimens were Vibrio parahaemolyticus positive,with the positive rate as 5.38％.114 isolates belonged to 23 serotypes,with the dominant (63.16％)serotype as O3:K6.Strains isolated from clinical manifestation patients were resistant to antibiotics-ampicillin and gentamicin,while with high sensitivity to amoxicillin,ceftriaxone,chloromycetin,imipenem,nalidixic acid and tetracycline.Virulence gene detection was positive to tlh for all the strains,but most to tdh,while only one strain to trh.The positive rate oftdh among O3:K6 strains(98.61％)was higher than that in those non-O3:K6 strains(85.71％)(P=0.0098).114 isolates were discriminated into 54 different PFGE patterns,while 72 O3:K6 strains into 34 patterns without the clustering characteristic.Conclusion Vibrio parahaemolyticus strains isolated from diarrheal patients in Beijing were dominated by O3:K6 strains,with stronger virulence.The positive rates of genes tlh and tdh were high.Vibrio parahaemolyticus strains showed high sensitivity to most antibiotics.The prevalent Vibrio parahaemolyticus strains in Beijing had various sources of clones.

Etiology of hand-foot-and-mouth disease and genetic characteristics of Coxsackievirus A16 in Beijing, 2009 / 病毒学报

This study aimed to reveal the pathogen spectrum of hand-foot-and-mouth disease (HFMD) and genetic characteristics of Coxsackievirus A16 (CoxA16) isolates in Beijing in 2009. From 1044 clinical specimens collected from 975 HFMD cases at Beijing Pediatrics Hospital, Beijing You'an Hospital and Beijing Ditan Hospital in 2009, viral nucleic acids of enterovirus were detected by reverse transcriptase polymerase chain reaction (RT-PCR). Enterovirus isolations were conducted with rhabdomyosarcoma (RD) cell line on 200 throat swabs having positive RT-PCR results. Sequencing and analyses of VP1 encoding gene were performed on 9 CoxA16 isolates in this study. The results showed that CoxA16 (49.4%) and EV71 (36.4%) were the major pathogens for the epidemics of HFMD in 2009 in Beijing, and CoxA16 was the predominant serotype, while there were also other enterovirus co-circulating, such as CoxA4, CoxA10, and CoxA9; the CoxA16 strains prevalent in Beijing in 2009 belonged to subgenotype B1a and B1b.

Logistic analysis on risk factors related to smear positive pulmonary tuberculosis / 中华流行病学杂志

<p><b>OBJECTIVE</b>To explore the risk factors on relapsing tuberculosis related to smear positive pulmonary tuberculosis which had been cured for five years.</p><p><b>METHODS</b>Patients with smear positive pulmonary tuberculosis registered in 1995 from ten countries in Hubei province were studied and logistic regression was used for data analysis.</p><p><b>RESULTS</b>The 5-year relapse rate of smear positive pulmonary tuberculosis was 3.85 percent. Risk factors related to relapse would include being non-modeled county, negative smear after treated for three months, the class of retreatment, management of non-DOTS, method of chemotherapy and patients that did not get treated by the tuberculosis institute, with odds ratios of 0.15, 4.62, 3.68, 5.88 and 6.47, respectively.</p><p><b>CONCLUSION</b>Effect standard, regulation DOTS and the centralized management measure might have had effects on decreasing the relapse rate.</p>