Yaqun Qiu

Vibrio parahaemolyticus, Southern Coastal Region of China, 2007–2012

We analyzed the prevalence and characteristics of Vibrio parahaemolyticus among patients with acute infectious diarrhea in the southern coastal region of China. V. parahaemolyticus was the leading cause of bacterial infectious diarrhea in this region during 2007–2012. Serotype O3:K6 strains were most common, followed by serotypes O4:K8 and O3:K29.

Simultaneous Detection of Five Enteric Viruses Associated with Gastroenteritis by Use of a PCR Assay: a Single Real-Time Multiplex Reaction and Its Clinical Application

ABSTRACT We developed a highly sensitive reverse transcription and multiplex real-time PCR (rtPCR) assay that can identify five viruses, including six genogroups, in a single reaction: norovirus genogroups I and II; sapovirus genogroups I, II, IV, and V; human rotavirus A; adenovirus serotypes 40 and 41; and human astrovirus. In comparison to monoplex rtPCR assays, the sensitivities and specificities of the multiplex rtPCR ranged from 75% to 100% and from 99% to 100%, respectively, evaluated on 812 clinical stool specimens.

Risk Factors for Vibrio parahaemolyticus Infection in a Southern Coastal Region of China

OBJECTIVES The objectives of the study were to identify dietary and medical risk factors for Vibrio parahaemolyticus (VP) infection in the coastal city Shenzhen in China. METHODS In April-October 2012, we conducted a case-control study in two hospitals in Shenzhen, China. Laboratory-confirmed VP cases (N = 83) were matched on age, sex, and other social factors to healthy controls (N = 249). Subjects were interviewed using a questionnaire on medical history; contact with seawater; clinical symptoms and outcome; travel history over the past week; and dietary history 3 days prior to onset. Laboratory tests were used to culture, serotype, and genotype VP strains. We used logistic regression to calculate the odds ratios for the association of VP infection with potential risk factors. RESULTS In multivariate analysis, VP infection was associated with having pre-existing chronic disease (adjusted odds ratio [aOR], 6.0; 95% confidence interval [CI], 1.5-23.7), eating undercooked seafood (aOR, 8.0; 95% CI, 1.3-50.4), eating undercooked meat (aOR, 29.1; 95% CI, 3.0-278.2), eating food from a street food vendor (aOR, 7.6; 95% CI, 3.3-17.6), and eating vegetable salad (aOR, 12.1; 95% CI, 5.2-28.2). CONCLUSIONS Eating raw (undercooked) seafood and meat is an important source of VP infection among the study population. Cross-contamination of VP in other food (e.g., vegetables and undercooked meat) likely plays a more important role. Intervention should be taken to lower the risks of cross-contamination with undercooked seafood/meat, especially targeted at people with low income, transient workers, and people with medical risk factors.

Comparative Screening of Digestion Tract Toxic Genes in Proteus mirabilis.

Proteus mirabilis is a common urinary tract pathogen, and may induce various inflammation symptoms. Its notorious ability to resist multiple antibiotics and to form urinary tract stones makes its treatment a long and painful process, which is further challenged by the frequent horizontal gene transferring events in P. mirabilis genomes. Three strains of P. mirabilis C02011/C04010/C04013 were isolated from a local outbreak of a food poisoning event in Shenzhen, China. Our hypothesis is that new genes may have been acquired horizontally to exert the digestion tract infection and toxicity. The functional characterization of these three genomes shows that each of them independently acquired dozens of virulent genes horizontally from the other microbial genomes. The representative strain C02011 induces the symptoms of both vomit and diarrhea, and has recently acquired a complete type IV secretion system and digestion tract toxic genes from the other bacteria.

Genome Sequence of Proteus mirabilis Clinical Isolate C05028

ABSTRACT Genomic DNA of Proteus mirabilis C05028 was sequenced by an Illumina HiSeq platform and was assembled to 39 scaffolds with a total length of 3.8 Mb. Next, open reading frames (ORFs) were identified and were annotated by the KEGG, COG, and NR databases. Finally, we found special virulence factors only existing in P. mirabilis C05028.

The evaluation and application of multilocus variable number tandem repeat analysis (MLVA) for the molecular epidemiological study of Salmonella enterica subsp. enterica serovar Enteritidis infection

BackgroundSalmonella enterica subsp. enterica serovar Enteritidis (S. Enteritidis) is one of the most prevalent Salmonella serotypes that cause gastroenteritis worldwide and the most prevalent serotype causing Salmonella infections in China. A rapid molecular typing method with high throughput and good epidemiological discrimination is urgently needed for detecting the outbreaks and finding the source for effective control of S. Enteritidis infections.MethodsIn this study, 194 strains which included 47 from six outbreaks that were well-characterized epidemiologically were analyzed with pulse field gel electrophoresis (PFGE) and multilocus variable number tandem repeat analysis (MLVA). Seven VNTR loci published by the US Center for Disease Control and Prevention (CDC) were used to evaluate and develop MLVA scheme for S. Enteritidis molecular subtyping by comparing with PFGE, and then MLVA was applied to the suspected outbreaks detection. All S. Enteritidis isolates were analyzed with MLVA to establish a MLVA database in Shenzhen, Guangdong province, China to facilitate the detection of S. Enteritidis infection clusters.ResultsThere were 33 MLVA types and 29 PFGE patterns among 147 sporadic isolates. These two measures had Simpson indices of 0.7701 and 0.8043, respectively, which did not differ significantly. Epidemiological concordance was evaluated by typing 47 isolates from six epidemiologically well-characterized outbreaks and it did not differ for PFGE and MLVA. We applied the well established MLVA method to detect two S. Enteritidis foodborne outbreaks and find their sources successfully in 2014. A MLVA database of 491 S. Enteritidis strains isolated from 2004 to 2014 was established for the surveillance of clusters in the future.ConclusionsMLVA typing of S. Enteritidis would be an effective tool for early warning and epidemiological surveillance of S. Enteritidis infections.

Simultaneous Identification of Ten Bacterial Pathogens Using the Multiplex Ligation Reaction Based on the Probe Melting Curve Analysis

Pathogenic Vibrio spp., Aeromonas spp. and Plesiomonas shigelloides are associated with human gastroenteritis and wound infections, as well as fish diseases. The comprehensive and accurate identification of these pathogens is crucial for the current public health. The present study describes the development of a multiplex assay for the simultaneous identification of ten bacterial pathogens in a single reaction by using a multiplex ligation reaction based on probe melting curve analysis (MLMA). The specificity for target genes was 100%, as assessed with a panel of 67 bacterial pathogens, which indicated no cross-reactions. The detection limit of this assay ranged from 0.8 × 107 CFU/mL to 1.5 × 108 CFU/mL at the pure bacterial culture level and from 0.1 ng to 1.0 ng at the DNA level. The MLMA assay was used to detect ten species of pathogens in 269 clinical and seafood samples, and for further validation, the results were compared with the conventional culture method. The results indicated greater than 90% sensitivity and 100% specificity for each bacterial pathogen tested, and the kappa correlation for all the pathogens ranged from 0.95 to 1.00. Overall, this assay is well suited for public health laboratories for its high throughput, accuracy, and low cost.

Clinical characteristics, virulence factors and molecular typing of methicillin-resistant Staphylococcus aureus infections in Shenzhen City, China.

Methicillin-resistant Staphylococcus aureus (MRSA) has emerged as a serious hospital and community-acquired infection and some strains are associated with greater severity. We investigated the clinical variability and molecular characteristics of MRSA infections in Shenzhen, China through a study at nine sentinel hospitals from January to December 2014. MRSA infections were classified as community-associated (CA-MRSA), healthcare-associated (HA-MRSA), and healthcare-associated community-onset (HACO-MRSA). In total, 812 MRSA isolates were collected and 183 of these were selected for further study. Patients with HA-MRSA infections were generally of greater age compared to other groups. Distinct body site and clinical presentations were evident in infected patients, e.g. CA-MRSA (skin and soft tissue, 53%), HA-MRSA (respiratory tract, 22%; surgical site, 20%; trauma wounds, 20%) and HACO-MRSA (mastitis, 47%). In contrast to HA-MRSA, other categories of strains were significantly more susceptible to gentamicin, sulfamethoxazole/trimethoprim, and tetracycline. No resistance to vancomycin or linezolid was recorded. The predominant clonal lineage within each strain category was CC59-t437-SCCmec IV/V-agr I (CA, 51·4%; HA, 28·9%; HACO, 52·9%) which exhibited characteristics of a traditional CA clone together with agr I which is more often associated with HA clones. In conclusion, for the three categories of MRSA infections, there were significant differences in clinical characteristics of patients, but the predominant clone in each category shared a similar genetic background which suggests that transmission of MRSA strains has occurred between the community and hospitals in Shenzhen.

Clonal Expansion of Biofilm-Forming Salmonella Typhimurium ST34 with Multidrug-Resistance Phenotype in the Southern Coastal Region of China

To disclose the antibiotics susceptibility and wide adaptability of commonly occurring genotypes of Salmonella Typhimurium, the antibiotic resistance and biofilm formation of different multi-locus sequence typing (MLST) types of a collection of 240 S. Typhimurium isolates (33 food and 207 clinical ones) during 2010–2014 in Shenzhen were analyzed. Among these strains, 167 was ST34 (69.58%), and 57 was ST19 (23.75%), respectively. A total of 159 (95.21%) ST34 strains displayed the multidrug resistant phenotype (≥ three classes of antibiotic), whereas only 23 (40.35%) ST19 ones did (P < 0.01). Moreover, a relative high proportion (72.46%) of ST34 isolates was classified as moderate to strong biofilm-producers, while only 15.79% of ST19 (P < 0.01) was. Among the food isolates, more than half (51.52%) were from livestock products, among which 41.18% classified as moderate to strong biofilm-producers. In summary, this study highlights the expansion of S. Typhimurium ST34 of strong biofilm-forming ability and multidrug resistance in the southern coastal region of China. Therefore, monitoring the occurrence of ST34 S. Typhimurium in food sources, especially in livestock products, and taking appropriate measures to control Salmonella spp. infections via decreasing biofilm formation should be addressed.