Insertion sequences mediate clinical ST34 monophasic Salmonella enterica serovar Typhimurium plasmid polymorphism.

Hybrid plasmids can combine the genetic elements of multiple plasmids, with the potential to carry a variety of antibiotic resistance genes and virulence genes, causing a great public health concern. Hybrid plasmids formed by fusion events may further exacerbate the spread of antibiotic resistance genes as well as plasmid evolution. Salmonella enterica serovar 4,[5],12:i:- is a monophasic variant of S. Typhimurium, which is one of the major causes of foodborne disease outbreaks worldwide. To assess the risk of transmission due to plasmid structure changes, we investigated the structural diversity of plasmids in two S. 4,[5],12:i:- isolates. Nanopore long-read sequencing was performed for plasmid comparison between original plasmids (donor isolates) and reorganized plasmids. We found that the IncHI2-IncHI2A multidrug resistance (MDR) plasmids in S. 4,[5],12:i:- possessed high plasticity, and could undergo recombination with other plasmids to form fusion plasmids of different sizes. Plasmid structural polymorphisms were mainly mediated by insertion sequences such as IS26 and ISPa40, and led to the rearrangement of the plasmid internal structures. To the best of our knowledge, this is the first report of the fusion of the IncHI2-IncHI2A and IncB/O/K/Z plasmids in S. 4,[5],12:i:- mediated by IS26. In addition, we also found that the mcr-1 gene was able to generate duplication during conjugation. Polymorphic changes in MDR plasmids during conjugation may further reduce the choice of clinical therapeutic agents. Therefore, continuous monitoring regarding plasmid polymorphic changes during transmission in both in vitro and in vivo is urgently needed to decipher the MDR plasmid evolution.

A large outbreak of acute gastroenteritis caused by the human norovirus GII.17 strain at a university in Henan Province, China.

BACKGROUND: Human noroviruses are a major cause of viral gastroenteritis and are the main etiological agents of acute gastroenteritis outbreaks. An increasing number of outbreaks and sporadic cases of norovirus have been reported in China in recent years. There was a large acute gastroenteritis outbreak at a university in Henan Province, China in the past five years. We want to identify the source, transmission routes of the outbreak by epidemiological investigation and laboratory testing in order to provide the effective control measures. METHODS: The clinical cases were investigated, and analysed by descriptive epidemiological methods according to factors such as time, department, grade and so on. Samples were collected from clinical cases, healthy persons, the environment, water, and food at the university. These samples were tested for potential bacteria and viruses. The samples that tested positive for norovirus were selected for whole genome sequencing and the sequences were then analysed. RESULTS: From 4 March to 3 April 2015, a total of 753 acute diarrhoea cases were reported at the university; the attack rate was 3.29%. The epidemic curve showed two peaks, with the main peak occurring between 10 and 20 March, accounting for 85.26% of reported cases. The rates of norovirus detection in samples from confirmed cases, people without symptoms, and environmental samples were 32.72%, 17.39%, and 9.17%, respectively. The phylogenetic analysis showed that the norovirus belonged to the genotype GII.17. CONCLUSIONS: This is the largest and most severe outbreak caused by genotype GII.17 norovirus in recent years in China. The GII.17 viruses displayed high epidemic activity and have become a dominant strain in China since the winter of 2014, having replaced the previously dominant GII.4 Sydney 2012 strain.

[Surveillance on the etiology and molecular epidemiology of Shigella sonnei isolated in Henan province from 2011 to 2014].

OBJECTIVE: To detect and analyze the distribution of virulence factors, antimicrobial resistance and pulsed field gel electrophoresis (PFGE) patterns of Shigella sonnei, isolated in Henan province from 2011 to 2014. METHODS: Samples of diarrhea patients were collected and isolated with SS selective culture medium in 37 ℃ for 18-24 hours. All strains were identified under the Kligler iron agar/motility-indol-urea biochemical action and API20E biochemical system. Serological typing and prepared DNA template were carried out with thermal cracking method and multiplex PCR, to detect the virulence genes of Shigella sonnei. According to the molecular typing method and K-B drug susceptibility testing method published by the international PulseNet bacterial infectious disease monitoring network and USA clinical and Laboratory Standards Institute, antimicrobial susceptibility tests and PFGE molecular characteristics of these positive strains isolated from sentinel hospitals patients stool samples were analyzed. RESULTS: Among the 98 strains of Sonnei type Ⅰ and 118 strains of Sonnei type Ⅱ, all the strains carried carry different virulence genes including SHET-1B, SHET-2, ial, ipaH genes, with 4 kinds of virulence gene combination types. All the 216 strains of Shigella sonnei belonged to the multi-drug resistant strains, including 34 isolates resistant to 2-4 kinds of antibiotics(15.7%), 147 isolates to 5-8 kinds of antibiotics (68.1%), 24 to 9-10 kinds of antibiotics (11.1%), 7 to 11 kinds of antibiotics (3.2%), and 4 to 13 kinds of antibiotics (1.9%). A total of 100 strains of Shigella sonnei were divided into 31 molecular patterns, digested by XbaⅠ and PFGE. Each pattern contained 1-13 strains with similarities ranged from 68.6%-100.0%. CONCLUSIONS: All the Shigella sonnei strains carried virulence pathogenic factors, presenting serious status on drug resistance. PFGE fingerprinting patterns showed high polymorphism and dominant characteristics. PFGE patterns of partial strains and corresponding antidrug spectrum presented certain relevance and with same aggregation relationship.

[Characteristics of drug resistance and molecular typing research for Salmonella Enteritidis isolated in Henan province from 2011 to 2013].

OBJECTIVE: To investigate the antimicrobial resistance status and pulsed field gel electrophoresis (PFGE) patterns of Salmonella Enteritidis (S.Enteritidis) strains in Henan province. METHODS: S. Enteritidis strains were isolated from seven sentinel hospitals from March 2011 to December 2013. According to molecular typing and Salmonella (Kirby-Bauer, K-B) drug susceptibility testing method published by the international PulseNet bacterial infectious disease monitoring network and USA Clinical and Laboratory Standards Institute (CLSI), we analyzed drug sensitivity of 8 kinds antibiotics and PFGE molecule characteristics of 120 S. Enteritidis isolates from seven sentinel hospitals. RESULTS: Among 120 strains of S. Enteritidis, 77 were isolated from male patients, 43 from female patients. A total of 78 strains S. Enteritidis were isolated from young children ranged from 0 to 5 years old (65.0%), including 57 strains isolated from 6 months to 2 years old (47.5%). The isolated time mainly centralized on May to October of the year, 11 strains isolated in March-April (9.2%), 48 were in May-July (40.0%),54 in August-October (45.0%), 7 in other months, with a typical summer seasonal characteristics. The resistance rate of 120 strains S. Enteritidis to ampicillin was 50.0% (n=60); to ceftazidime was 14.2% (n=17), to cefotaxime was 18.3% (n=22); to cefepime was 5.8% (n=7); to nalidixic acid was 61.7% (n=74); to ciprofloxacin was 8.3% (n=10), to norfloxacin was 5.8% (n=7); to gentamicin was 42.5% (n=51); to streptomycin was 21.7% (n=26); to chloramphenicol was 30.0% (n=36); resistance to methicillin benzyl ammonium was 11.7% (n=14), compound sulfamethoxazole resistance rate was 71.7% (n=86); the tetracycline resistant rate was 47.5% (n=57). All 120 strains of S. Enteritidis had different levels of resistance to 8 kinds of antibiotics, all strains were multidrug resistant strains, 28 isolates were resistant to 3-4 kinds of antibiotics (23.3%), 38 isolates were resistant to 5-6 kinds of antibiotics (31.7%), 39 isolates were resistant to 7-8 kinds of antibiotics (32.5%). All 120 strains of S. Enteritidis were divided into 44 molecular patterns by digestion with XbaI and pulsed field gel electrophoresis. each pattern contained 1-35 strains with similarity ranged from 54.3%-100%. EN14 and EN19 were the main PFGE types, including 35 and 29 strains respectively. CONCLUSION: The status of drug resistance of clinical isolates of Salmonella in Henan province was rather serious, PFGE patterns showed advantages and partial strain's corresponding resistant spectrum have certain relevance and the same aggregation relationship.

[Characteristics of drug resistance and molecular type of Salmonella typhi and Salmonella paratyphi isolated in Henan province, 2009-2011].

OBJECTIVE: To investigate the antibiotic resistance and pulsed field gel electrophoresis (PFGE) patterns of clinical isolates of Salmonella (S.) typhi and S. paratyphi in Henan province during 2009-2011. METHODS: According to molecular typing and Salmonella K-B drug susceptibility test method published by international PulseNet bacterial infectious disease monitoring network and USA Clinical and Laboratory Standards Institute (CLSI), the drug susceptibility and PFGE molecule characteristics of 78 S. typhi and S. paratyphi strains isolated from sentinel hospitals in Henan were analyzed. RESULTS: The 78 strains of S. typhi and S. paratyphi were resistant to 13 kinds of antibiotics, in which 62 were multidrug resistant (79.5%), 4 were resistant to 2-3 kinds of antibiotics (5.1%), 41 were resistant to 5-8 kinds of antibiotics (52.6%), 14 were resistant to 9-10 kinds of antibiotics (17.9%), 3 were resistant to 11-12 kinds of antibiotics (3.8%). The resistant rate to cephalosporins, quinolones and other 3 kinds of antibiotic showed an increase trends. Seventy two strains of S. typhi and S. paratyphi could be divided 14 molecular patterns by digestion with XbaⅠ and PFGE, each pattern contains 1-47 strains which shared the similarity of 66.03%-100.00%. CONCLUSIONS: The drug resistance of clinical isolates of S. typhi and S. paratyphi was serious in Henan. The PFGE patterns showed diversity, but the predominant patterns could be still found. The PFGE patterns of some strains were associated with their drug resistance.

[Investigation on distribution of Yersinia enterocolitica in Henan province between 2005 and 2011].

OBJECTIVE: To investigate the distribution of Yersinia enterocolitica in Henan province from 2005 to 2011. METHODS: A total of 6700 samples of stool specimen were collected from diarrhea patients and different domestic animals between 2005 and 2011 from Zhengzhou, Suixian and Dengfeng, as well as flies and the daub specimens of raw and cooked meat products. The bacteria were isolated by cold enrichment method, analyzed by the systematic biochemistry to determine the serotypes and bio-types, and tested the virulence genes by PCR method. RESULTS: A total of 216 strains of Yersinia enterocolitica were isolated from 11 kinds of animal hosts and foods, while 29.63% (64/216) of them were from swine. The dominant epidemic serotypes of the Yersinia enterocolitica were O: 5 and O: 8, accounted for 23.2% (50/216) and 20.4% (44/216), respectively; type 1A was the dominant bio-type, accounted for 84.7% (183/216). The dominant serotype and bio-type differed a lot among various hosts.16 pathogenic strains were isolated from swine, followed by diarrhea patients (6 strains) and dogs (6 strains). CONCLUSION: The distribution of the host of Yersinia enterocolitica was widespread, while swine was the dominant animal host.

Detection of a novel bunyavirus associated with fever, thrombocytopenia and leukopenia syndrome in Henan Province, China, using real-time reverse transcription PCR.

A novel bunyavirus associated with fever, thrombocytopenia and leukopenia syndrome (FTLS) was discovered in Henan Province, China. Here, we report the development of an assay for this novel bunyavirus based on real-time reverse transcription PCR (RT-PCR). The assay exhibited high sensitivity and specificity without cross-reactivity towards 13 other viruses that cause similar symptoms. To evaluate the performance of this assay in detecting clinical samples, we analysed 261 serum samples from patients in Henan Province between 2007 and 2010. Of these samples, 91.95 % were bunyavirus positive. Compared with serological assays, the real-time PCR assay was much more sensitive in identifying infected patients 1 to 7 days after the onset of symptoms.

[Analysis of etiological surveillance results of Shigella spp between 2009 and 2010 in Henan province].

OBJECTIVE: To explore the etiologic characteristics of bacillary dysentery found in Henan province, between year 2009 and 2010. METHODS: In order to explore the distribution of bacterial types, drug susceptibility and the virulence gene carrier situation, 482 strains of Shigella isolated in Henan province between 2009 and 2010 were pathogen-detected and analyzed by serotype screening, anti microbial sensitivity test and PCR methods. RESULTS: The 482 isolated strains were confirmed to be Shigella by both morphological and biochemical tests. The Shigella strains were divided into 13 serotypes in 2 groups, namely Shigella flexneri (B group) accounting for 72.0% (347/482) and Shigella sonnei (D group), accounting for 28.0% (135/482). The detection rate of Serotype F2a, as the dominant type of Shigella flexneri, decreased from 43.4% (106/245) in 2009 to 33.8% (80/237) in 2010; while the detection rate of Shigella sonnei increased from 13.1% (32/245) to 43.5% (103/237) in the same period. The results of microbial sensitivity tests carried out in year 2009 and 2010, both showed that over 98% of the 185 studied strains were resistant to ampicillin (AMP), trimethoprim-pyrimidine (TMP), tetracycline (TE), streptomycin (S) and nalidixic acid (NA).182 strains were recruited in the virulence factors detection, 67.6% (123/182) of which carried Shigella Enterotoxin 1B (set1B), Shigella Enterotoxin 2 (set2), invasive plasmid antigen H (ipaH) or invasion-related virulence factors (ial) and 24.2% (44/182) of which carried 3 virulence factors mentioned above. CONCLUSION: The prevalent serotypes of Shigella in Henan province have changed in recent years. The isolated strains showed high resistance to common antibacterial drugs and generally carried virulence factors.

[Etiology survey on an outbreak of viral encephalitis].

OBJECTIVE: To isolate and identify the pathogen that caused an outbreak of viral encephalitis in Henan province in 2010; and to analyze the genetic characteristic of gene viral protein1(VP1) on the viral strains isolated. METHODS: During the period of the outbreak of viral encephalitis in Lushan county, Pingdingshan city, Henan province, eight hospitalized patients were recruited in the study. All the patients' feces samples were collected. Three patients' cerebrospinal fluids samples and another four patients' serum samples were collected separately. The virus in the samples were isolated and identified by enterovirus (EV) combined serum. The VP1 gene of the positive isolate was amplified by reverse transcriptase PCR method, and its nucleotide sequence was detected and the genetic evolution was analyzed. RESULTS: Fifteen samples were collected in total, including 8 feces samples, 3 cerebrospinal fluids samples and 4 serum samples. The results of Fluorescence Quota PCR detection showed that 11 out of 15 samples were positive; 2 strains of virus were isolated from 2 feces samples and the serotype were all Coxsackie-positive identified by the EV combined serum. The full-length VP1 genetic sequences were all 849 bp, and showed 77.1% - 96.9% similar to the nucleotide and 95.8% - 100% similar to the amino acid of CoxB5. The analysis showed that the genetic evolution tree was just the same with Genotype-D. CONCLUSION: CoxB5 whose genotype was Genotype-D, was the pathogen that caused the outbreak of viral encephalitis in Lushan county, Pingdingshan city, Henan province.