Publications by authors named "Dazhi Jin"

33 Publications

Comparative Whole Genome Sequence Analysis and Biological Features of Sequence Type 2.

Front Microbiol 2021 5;12:651520. Epub 2021 Jul 5.

School of Laboratory Medicine, Hangzhou Medical College, Hangzhou, China.

sequence type 2 (ST2) has been increasingly recognized as one of the major genotypes in China, while the genomic characteristics and biological phenotypes of Chinese ST2 strains remain to be determined. We used whole-genome sequencing and phylogenetic analysis to investigate the genomic features of 182 ST2 strains, isolated between 2011 and 2017. PCR ribotyping (RT) was performed, and antibiotic resistance, toxin concentration, and sporulation capacity were measured. The core genome Maximum-likelihood phylogenetic analysis showed that ST2 strains were distinctly segregated into two genetically diverse lineages [L1 (67.0% from Northern America) and L2], while L2 further divided into two sub-lineages, SL2a and SL2b (73.5% from China). The 36 virulence-related genes were widely distributed in ST2 genomes, but in which only 11 antibiotic resistance-associated genes were dispersedly found. Among the 25 SL2b sequenced isolates, RT014 (40.0%, = 10) and RT020 (28.0%, = 7) were two main genotypes with no significant difference on antibiotic resistance (χ = 0.024-2.667, > 0.05). A non-synonymous amino acid substitution was found in (Y1975D) which was specific to SL2b. Although there was no significant difference in sporulation capacity between the two lineages, the average toxin B concentration (5.11 ± 3.20 ng/μL) in SL2b was significantly lower in comparison to those in L1 (10.49 ± 15.82 ng/μL) and SL2a (13.92 ± 2.39 ng/μL) (χ = 12.30, < 0.05). This study described the genomic characteristics of ST2, with many virulence loci and few antibiotic resistance elements. The Chinese ST2 strains with the mutation in codon 1975 of the gene clustering in SL2b circulating in China express low toxin B, which may be associated with mild or moderate infection.
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http://dx.doi.org/10.3389/fmicb.2021.651520DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8287029PMC
July 2021

Genomic evolution and virulence association of sequence type 37 (ribotype 017) in China.

Emerg Microbes Infect 2021 Dec;10(1):1331-1345

School of Laboratory Medicine, Hangzhou Medical College, Hangzhou, People's Republic of China.

sequence type (ST) 37 (ribotype 017) is one of the most prevalent genotypes circulating in China. However, its genomic evolution and virulence determinants were rarely explored. Whole-genome sequencing, phylogeographic and phylogenetic analyses were conducted for ST37 isolates. The 325 ST37 genomes from six continents, including North America ( = 66), South America ( = 4), Oceania ( = 7), Africa ( = 9), Europe ( = 138) and Asia ( = 101), were clustered into six major lineages, with region-dependent distributions, harbouring an array of antibiotic-resistance genes. The ST37 strains from China were divided into four distinct sublineages, showing five importation times and international sources. Isolates associated with severe infections exhibited significantly higher toxin productions, mRNA levels, and sporulation capacities ( < 0.001). Kyoto Encyclopedia of Genes and Genomes analysis showed 10 metabolic pathways were significantly enriched in the mutations among isolates associated with severe CDI ( < 0.05). Gene mutations in glycometabolism, amino acid metabolism and biosynthesis virtually causing instability in protein activity were correlated positively to the transcription of and negatively to the expression of toxin repressor genes, and Y. In summary, our study firstly presented genomic insights into genetic characteristics and virulence association of ST37 in China. Gene mutations in certain important metabolic pathways are associated with severe symptoms and correlated with higher virulence in ST37 isolates.
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http://dx.doi.org/10.1080/22221751.2021.1943538DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8253194PMC
December 2021

Research progress on gut microbiota in patients with gastric cancer, esophageal cancer, and small intestine cancer.

Appl Microbiol Biotechnol 2021 Jun 26;105(11):4415-4425. Epub 2021 May 26.

School of Laboratory Medicine, Hangzhou Medical College, Zhejiang, 310053, Hangzhou, China.

The pathogenesis of gut microbiota in humans can be indicated due to the wide application of techniques, such as 16S rRNA sequencing. Presently, several studies have found a significant difference in fecal flora between normal individuals and patients with gastric cancer. Although clinical research on the feedback mechanism of gastric flora and gut microbiota is lacking, clarifying the relationship between gut microbiota and the characteristics of cancer is significant for the early diagnosis of gastric cancer. This study was conducted to review the results of several studies in the past 5 years and analyze the intestinal bacteria in patients with gastric cancer and compare them with those in patients with esophageal and small intestine cancers. It was found that the gut microbiota in patients with gastric cancer was similar to that in patients with esophageal cancer. However, making an analysis and comparing the gut microbiota in patients with small intestine and gastric cancers was impossible due to the low incidence of small intestinal cancer. Our review summarized the research progress on using the gut microbiota for early screening for gastric cancer, and the results of this study will provide a further direction in this field. KEY POINTS: • We reviewed several relative mechanisms of the gut microbiota related to gastric cancer. • The gut microbiota in gastric, esophageal, and small intestine cancers are significantly different in types and quantity, and we have provided some tips for further research. • A prospective review of sequencing methods and study results on the gut microbiota in gastric, esophageal, and small intestine cancers was described.
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http://dx.doi.org/10.1007/s00253-021-11358-zDOI Listing
June 2021

Population Structure and Multidrug Resistance of Non-O1/Non-O139 Vibrio cholerae in Freshwater Rivers in Zhejiang, China.

Microb Ecol 2021 Jan 7. Epub 2021 Jan 7.

School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW, 2052, Australia.

To understand the environmental reservoirs of Vibrio cholerae and their public health significance, we surveyed freshwater samples from rivers in two cities (Jiaxing [JX] and Jiande [JD]) in Zhejiang, China. A total of 26 sampling locations were selected, and river water was sampled 456 times from 2015 to 2016 yielding 200 V. cholerae isolates, all of which were non-O1/non-O139. The average isolation rate was 47.3% and 39.1% in JX and JD, respectively. Antibiotic resistance profiles of the V. cholerae isolates were examined with nonsusceptibility to cefazolin (68.70%, 79/115) being most common, followed by ampicillin (47.83%, 55/115) and imipenem (27.83%, 32/115). Forty-two isolates (36.52%, 42/115) were defined as multidrug resistant (MDR). The presence of virulence genes was also determined, and the majority of the isolates were positive for toxR (198/200, 99%) and hlyA (196/200, 98%) with few other virulence genes observed. The population structure of the V. cholerae non-O1/non-O139 sampled was examined using multilocus sequence typing (MLST) with 200 isolates assigned to 128 STs and 6 subpopulations. The non-O1/non-O139 V. cholerae population in JX was more varied than in JD. By clonal complexes (CCs), 31 CCs that contained isolates from this study were shared with other parts of China and/or other countries, suggesting widespread presence of some non-O1/non-O139 clones. Drug resistance profiles differed between subpopulations. The findings suggest that non-O1/non-O139 V. cholerae in the freshwater environment is a potential source of human infections. Routine surveillance of non-O1/non-O139 V. cholerae in freshwater rivers will be of importance to public health.
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http://dx.doi.org/10.1007/s00248-020-01645-zDOI Listing
January 2021

Comparison of xMAP Serotyping Assay With Traditional Serotyping and Discordance Resolution by Whole Genome Sequencing.

Front Cell Infect Microbiol 2020 7;10:452. Epub 2020 Sep 7.

School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW, Australia.

spp. are a major cause of foodborne illness throughout the world. Traditional serotyping by antisera agglutination has been used as a standard identification method for many years but newer nucleic acid-based tests have become available that may provide advantages in workflow and test turnaround time. In this study, we evaluated the Luminex® xMAP® Serotyping Assay (SSA), a multiplex nucleic acid test capable of identifying 85% of the most common serotypes, in comparison to the traditional serum agglutination test (SAT) on 4 standard strains and 255 isolates from human (224), environmental, and food (31) samples. Of the total of 259 isolates, 256 could be typed by the SSA. Of these, 197 (77.0%) were fully typed and 59 (23.0%) were partially typed. By SAT, 246 of the 259 isolates (95%) were successfully typed. Sixty isolates had discrepant results between SAT and SSA and were resolved using whole genome sequencing (WGS). By SAT, 80.0% (48/60) of the isolates were consistent with WGS while by SSA 91.7% (55/60) were partially consistent with WGS. By serovar, all 30 serovars except one tested were fully or partially typable. The workflow comparison showed that SSA provided advantages over SAT with a hands-on time (HOT) of 3.5 min and total turnaround time (TAT) of 6 h, as compared to 1 h HOT and 2-6 days TAT for SAT. Overall, this study showed that molecular serotyping is promising as a rapid method for serotyping with good accuracy for typing most common serovars circulating in China.
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http://dx.doi.org/10.3389/fcimb.2020.00452DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7504902PMC
June 2021

Subtyping analysis reveals new variants and accelerated evolution of Clostridioides difficile toxin B.

Commun Biol 2020 07 3;3(1):347. Epub 2020 Jul 3.

Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang, 310024, China.

Clostridioides difficile toxins (TcdA and TcdB) are major exotoxins responsible for C. difficile infection (CDI) associated diseases. The previously reported TcdB variants showed distinct biological features, immunoactivities, and potential pathogenicity in disease progression. Here, we performed global comparisons of amino acid sequences of both TcdA and TcdB from 3,269 C. difficile genomes and clustered them according to the evolutionary relatedness. We found that TcdB was much diverse and could be divided into eight subtypes, of which four were first described. Further analysis indicates that the tcdB gene undergoes accelerated evolution to maximize diversity. By tracing TcdB subtypes back to their original isolates, we found that the distribution of TcdB subtypes was not completely aligned with the phylogeny of C. difficile. These findings suggest that the tcdB genes not only frequently mutate, but also continuously transfer and exchange among C. difficile strains.
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http://dx.doi.org/10.1038/s42003-020-1078-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7335066PMC
July 2020

Molecular characteristics of Clostridium difficile in children with acute gastroenteritis from Zhejiang.

BMC Infect Dis 2020 May 13;20(1):343. Epub 2020 May 13.

School of Laboratory Medicine, Hangzhou Medical College, No. 481, Binwen Road, Hangzhou, Zhejiang, China.

Background: Clostridium difficile infection (CDI) has an increasing pediatric prevalence worldwide. However, molecular characteristics of C. difficile in Chinese children with acute gastroenteritis have not been reported.

Methods: A five-year cross-sectional study was conducted in a tertiary children's hospital in Zhejiang. Consecutive stool specimens from outpatient children with acute gastroenteritis were cultured for C. difficile, and isolates then were analyzed for toxin genes, multi-locus sequence type and antimicrobial resistance. Diarrhea-related viruses were detected, and demographic data were collected.

Results: A total of 115 CDI cases (14.3%), and 69 co-infected cases with both viruses and toxigenic C. difficile, were found in the 804 stool samples. The 186 C. difficile isolates included 6 of toxin A-positive/toxin B-positive/binary toxin-positive (ABCDT), 139 of ABCDT, 3 of ABCDT, 36 of ABCDT and 2 of ABCDT. Sequence types 26 (17.7%), 35 (11.3%), 39 (12.4%), 54 (16.7%), and 152 (11.3%) were major genotypes with significant differences among different antimicrobial resistances (Fisher's exact test, P < 0.001). The AB isolates had significantly higher resistance, compared to erythromycin, rifampin, moxifloxacin, and gatifloxacin, than that of the AB (χ = 7.78 to 29.26, P < 0.01). The positive CDI rate in infants (16.2%) was significantly higher than that of children over 1 year old (10.8%) (χ = 4.39, P = 0.036).

Conclusions: CDI has been revealed as a major cause of acute gastroenteritis in children with various genotypes. The role of toxigenic C. difficile and risk factors of CDI should be emphatically considered in subsequent diarrhea surveillance in children from China.
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http://dx.doi.org/10.1186/s12879-020-05030-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7222317PMC
May 2020

Discovery of seven novel mutations of gyrB, parC and parE in Salmonella Typhi and Paratyphi strains from Jiangsu Province of China.

Sci Rep 2020 04 30;10(1):7359. Epub 2020 Apr 30.

Xuzhou Medical University School of Medical Technology, Xuzhou, 221004, China.

Objective: To investigate the prevalence of Salmonella Typhi and Paratyphi resistance to quinolones and characterize the underlying mechanism in Jiangsu Province of China.

Methods: Antimicrobial susceptibility testing was performed using Kirby-Bauer disc diffusion system. Quinolone resistance-determining region (QRDR), plasmid-mediated quinolone resistance (PMQR) determinant genes were detected by PCR and sequencing.

Results: Out of 239 Salmonella isolates, 164 were S. Typhi and 75 were S. Paratyphi. 128 (53.6%) Salmonella isolates were resistant to nalidixic acid; 11 (4.6%) isolates to ciprofloxacin and 66 (27.6%) isolates were intermediate to ciprofloxacin. QRDR were present in 69 S. Typhi isolates, among which mutation at codon 83 (n = 45) and 133 (n = 61) predominated. In S. Paratyphi, the most common mutations were detected in gyrA at codon 83(n = 24) and parC: T57S (n = 8). Seven mutations were first reported in Salmonella isolates including gyrB: S426G, parC: D79G and parE: [S498T, E543K, V560G, I444S, Y434S]. PMQR genes including qnrD1, qnrA1, qnrB4, aac (6')-Ib-cr4 and qnrS1 were detected in 1, 2, 3, 7 and 9 isolates, relatively.

Conclusions: High resistance to quinolones in Salmonella remains a serious problem in Jiangsu, China. The presence of the novel mutations increases the complexity of quinolone-resistant genotypes and poses a threat to public health. Subject terms: Salmonella Typhi, Salmonella Paratyphi, antimicrobial resistance, QRDR, PMQR.
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http://dx.doi.org/10.1038/s41598-020-64346-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7193621PMC
April 2020

High-Level Resistance of Toxigenic Genotype to Macrolide-Lincosamide- Streptogramin B in Community Acquired Patients in Eastern China.

Infect Drug Resist 2020 17;13:171-181. Epub 2020 Jan 17.

Centre of Laboratory Medicine, Zhejiang Provincial People Hospital, People's Hospital of Hangzhou Medical College, Hangzhou, Zhejiang, People's Republic of China.

Background: resistant to macrolide-lincosamide-streptogramin B (MLS) has not been reported in China.

Methods: In a cross-sectional study in two tertiary hospitals, isolates from stool specimens from community-onset, hospital-associated diarrheal patients were analyzed for toxin genes, genotype, and antibiotic resistance, and the patients' clinical charts were reviewed.

Results: A total of 190 (15.2%) isolates (102 AB and 88 AB) from 1250 community acquired (CA) patients were recovered and all were susceptible to vancomycin and metronidazole. High-level resistance (minimum inhibitory concentration > 128 mg/L) to erythromycin and clindamycin was recorded in 77.9% and 88.4% of the tested isolates, respectively. Furthermore, 89.3% (159/178) of the isolates resistant to MLS carried the erythromycin resistance methylase gene (). The statistically significant factors associated with infection (CDI) induced by AB isolates with MLS resistance included a severity score of >2 (odds ratio [95% confidence interval], 7.43 [2.31-23.87]) and platelet count (cells × 10 cells/L) < 100 [5.19 (1.58-17.04)]. The proportion of AB increased with enhanced CDI severity ( = 21.62, 0.001), which was significantly higher than that of -positive AB in severity score of 4 ( = 8.61, = 0.003). The average severity score of -positive isolates was significantly higher than that of -negative isolates in AB ( = -2.41, = 0.016).

Conclusion: The -positive AB with MLS resistance is described for the first time as a potential epidemic clone inducing severe CDI in CA diarrheal patients in Eastern China.
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http://dx.doi.org/10.2147/IDR.S238916DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6974413PMC
January 2020

Different molecular characteristics and antimicrobial resistance profiles of in the Asia-Pacific region.

Emerg Microbes Infect 2019 ;8(1):1553-1562

Department of Microbiology, Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, People's Republic of China.

Molecular epidemiology of infection (CDI) has been extensively studied in North America and Europe; however, limited data on CDI are available in the Asia-Pacific region. A multicentre retrospective study was conducted in this region. isolates were subjected to multilocus sequence typing (ST) and antimicrobial susceptibility testing. Totally, 394 isolates were collected from Hangzhou, Hong Kong, China; Busan, South Korea; Fukuoka, Japan; Singapore; Perth, Sydney, Australia; New York, the United States. isolates included 337 toxin A-positive/B-positive/binary toxin-negative (ABCDT), 48 ABCDT, and nine ABCDT. Distribution of dominant STs varied geographically with ST17 in Fukuoka (18.6%), Busan (56.0%), ST2 in Sydney (20.4%), Perth (25.8%). The antimicrobial resistance patterns were significantly different among the eight sites ( = 325.64, < 0.001). Five major clonal complexes correlated with unique antimicrobial resistances. Healthcare-associated (HA) CDI was mainly from older patients with more frequent antimicrobial use and higher AB positive rates. Higher resistance to gatifloxacin, tetracycline, and erythromycin were observed in HA-CDI patients ( = 4.76-7.89, = 0.005-0.029). In conclusion, multiple genotypes with varied antimicrobial resistance patterns have been circulating in the Asia-Pacific region. AB isolates from older patients with prior antimicrobial use were correlated with HA-CDI.
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http://dx.doi.org/10.1080/22221751.2019.1682472DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6830245PMC
January 2020

MALDI-TOF mass spectrometry-based serotyping of V. parahaemolyticus isolated from the Zhejiang province of China.

BMC Microbiol 2018 11 13;18(1):185. Epub 2018 Nov 13.

Graduate College, Anhui Medical University, No.81 Meishan Road, Hefei, 230032, Anhui, China.

Background: Vibrio parahaemolyticus is as an important food-borne pathogen circulating in China. Since 1996, the core serotype has become O3:K6, which has specific genetic markers. This serotype causes the majority of outbreaks worldwide. Until now, nearly 21 serotypes were considered as serovariants of O3:K6. Among these, O4:K68, O1:K25 and O1:KUT have caused pandemic outbreaks. O4:K8, a serovariant of O3:K6, has become the second most dominant serotype circulating in China after O3:K6. In this study, we report the use of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) to analyze and characterize 146 V. parahaemolyticus isolates belonging to 23 serotypes.

Results: Upon mass spectral analysis, isolates belonging to O4:K8 formed a distinct group among the five main pandemic groups (O3:K6, O4:K8, O4:K68, O1:K25 and O1:KUT). Two major protein peaks (m/z 4383 and 4397) were significantly different between serotype O4:K8 and the four other pandemic strains. Both of these peaks were present in 32 out of 36 O4:K8 isolates, but were absent in 105 out of 110 non-O4:K8 isolates. These peaks were also absent in all 74 pandemic serotypes (O3:K6, O4:K68, O1:K25 and O1:KUT).

Conclusion: Our results highlight the threat of O4:K8 forming a distinct group, which differs significantly from pandemic serotypes on the proteomic level. The use of MALDI-TOF MS has not been reported before in a study of this nature. Mass spectrum peaks at m/z 4383 and 4397 may be specific for O4:K8. However, we cannot conclude that MALDI-TOF MS can be used to serotype V. parahaemolyticus.
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http://dx.doi.org/10.1186/s12866-018-1328-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6234682PMC
November 2018

Evaluation of an UltraFast LabChip V280 assay for detection of toxigenic Clostridium difficile.

Diagn Microbiol Infect Dis 2018 Dec 30;92(4):279-283. Epub 2018 Jun 30.

Department of Microbiology, Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, Zhejiang, 310051, China. Electronic address:

In this study, we compared the performance of an UltraFast LabChip (UL) V280 system for Clostridium difficile detection in stool with that of Xpert C. difficile/Epi and VIDAS CDAB. Among 176 stool specimens, UL V280 detected toxigenic C. difficile in 22 (22/176, 12.5%) with a sensitivity, specificity, positive predictive value, negative predictive value (NPV) of 100.0%, 99.4%, 99.5% and 100.0%, respectively, which were higher than 95.2%, 97.4%, 83.3%, and 99.3% of Xpert C. difficile/Epi (P > 0.05). Notably, the sensitivity and NPV of ULV280 were significantly higher than those of VIDAS CDAB 52.4% (P < 0.001, odds ratio [OR] = 20.0, 95% confidence interval [CI] = 2.26-176.81) and 93.8% (P = 0.002, OR = 10.27, 95% CI = 1.30-81.17). UL V280 turnaround time (35 min) and cost (6.24 Dollars [$]) per specimen were less than those for Xpert C. difficile/Epi (47 min, 59.26 $) and VIDAS CDAB (65 min, 11.70 $). UL V280 possessed an analytical sensitivity limit of 2500 CFU/ml, 95% [CI] = (Ct: 30.76-34.90), and no cross-reactions with other pathogens were found. The study demonstrates that UL V280 based on a microfluidic chip is a rapid, accurate, easy, and cost-effective diagnostic test for toxigenic C. difficile in stool.
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http://dx.doi.org/10.1016/j.diagmicrobio.2018.06.021DOI Listing
December 2018

Coinfection with 2 Clostridium difficile ribotypes in China: A case report.

Medicine (Baltimore) 2018 Mar;97(13):e9946

Department of Laboratory Medicine, Zhejiang Chinese Medical University Affiliated Hangzhou First Hospital Department of Microbiology, Zhejiang Provincial Center for Disease Control and Prevention Department of Laboratory Medicine, Hangzhou First Hospital, Huansha road, Hangzhou, Zhejiang, China.

Rationale: Clostridium difficile infections (CDIs) have been reported in China, but detailed clinical symptoms of coinfection by 2 C difficile ribotypes have not been documented.

Patients Concerns: An 83-year-old male with a 10-day history of diarrhea and urinary tract infection was admitted to the hospital. The patient had received ofloxacin for several days, but his clinical response was poor. Laboratory workup revealed high white blood cell (WBC), serum creatinine (Scr), and C-reactive protein (CRP) levels. Based on these abnormal lab results, rapid detection of glutamate dehydrogenase and toxin A and B was performed.

Diagnosis: Severe CDI.

Interventions: Oral vancomycin was administered for 8 days.

Outcomes: Diarrhea symptoms improved and C difficile culture was negative after oral vancomycin administration for 8 days. Clostridium difficile was isolated from 3 consecutive stool samples at 2-day intervals because the patient was admitted to the hospital. Polymerase chain reaction ribotyping revealed ribotype (RT) 017 in the first 2 samples and RT 001 in the third sample. RT 017 caused significantly higher increases in the levels of WBC, Scr, and CRP than RT 001.

Lessons: It is necessary to improve clinicians' awareness of CDI and reduce the severity of CDI caused by RT 017 in China.
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http://dx.doi.org/10.1097/MD.0000000000009946DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5895390PMC
March 2018

Identification and Characterization of Clostridium difficile Sequence Type 37 Genotype by Matrix-Assisted Laser Desorption IonizationTime of Flight Mass Spectrometry.

J Clin Microbiol 2018 05 25;56(5). Epub 2018 Apr 25.

Department of Clinical Microbiology, Second Hospital of Hebei Medical University, Hebei Provincial Center for Clinical Laboratories, Shijiazhuang, Hebei, China

multilocus sequence type 37 (ST37), which mainly corresponds to ribotype 017, has been a dominant genotype circulating in China. In this study, we report the use of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) to analyze and characterize 204 clinical isolates, including 49 ST37 and 155 non-ST37 isolates collected in China and other countries. The distributions of two major protein peaks ( 3,242 and 3,286) were significantly different between ST37 and non-ST37 prototype strains and clinical isolates. This difference was reproducible when analysis was performed on different colonies in different runs. This finding was repeated and confirmed by both bioMérieux Vitek MS and Bruker Microflex LT systems on isolates recovered from a variety of geographic regions worldwide. The combination of the two peaks was present in 47 of 49 ST37 isolates, resulting in a sensitivity of 95.9%. In contrast, the peak combination was absent in 153 of 155 non-ST37 isolates, resulting in a specificity of 98.7%. Our results suggest that MALDI-TOF MS is a rapid and reliable tool to identify genotype ST37. Work is in progress to characterize the two molecules having peaks at 3,242 and 3,286, which appear to be specific to genotype ST37.
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http://dx.doi.org/10.1128/JCM.01990-17DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5925732PMC
May 2018

Simultaneous detection and characterization of toxigenic Clostridium difficile directly from clinical stool specimens.

Front Med 2018 Apr 17;12(2):196-205. Epub 2017 Oct 17.

Department of Microbiology, Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, 310051, China.

We employed a multiplex polymerase chain reaction (PCR) coupled with capillary electrophoresis (mPCR-CE) targeting six Clostridium difficile genes, including tpi, tcdA, tcdB, cdtA, cdtB, and a deletion in tcdC for simultaneous detection and characterization of toxigenic C. difficile directly from fecal specimens. The mPCR-CE had a limit of detection of 10 colony-forming units per reaction with no cross-reactions with other related bacterial genes. Clinical validation was performed on 354 consecutively collected stool specimens from patients with suspected C. difficile infection and 45 isolates. The results were compared with a reference standard combined with BD MAX Cdiff, real-time cell analysis assay (RTCA), and mPCR-CE. The toxigenic C. difficile species were detected in 36 isolates and 45 stool specimens by the mPCR-CE, which provided a positive rate of 20.3% (81/399). The mPCR-CE had a specificity of 97.2% and a sensitivity of 96.0%, which was higher than RTCA (x = 5.67, P = 0.017) but lower than BD MAX Cdiff (P = 0.245). Among the 45 strains, 44 (97.8%) were determined as nonribotype 027 by the mPCR-CE, which was fully agreed with PCR ribotyping. Even though ribotypes 017 (n = 8, 17.8%), 001 (n = 6, 13.3%), and 012 (n = 7, 15.6%) were predominant in this region, ribotype 027 was an important genotype monitored routinely. The mPCR-CE provided an alternative diagnosis tool for the simultaneous detection of toxigenic C. difficile in stool and potentially differentiated between RT027 and non-RT027.
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http://dx.doi.org/10.1007/s11684-017-0560-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6750768PMC
April 2018

Update on Antimicrobial Resistance in Clostridium difficile: Resistance Mechanisms and Antimicrobial Susceptibility Testing.

J Clin Microbiol 2017 07 12;55(7):1998-2008. Epub 2017 Apr 12.

Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida, USA

Oral antibiotics such as metronidazole, vancomycin and fidaxomicin are therapies of choice for infection. Several important mechanisms for antibiotic resistance have been described, including the acquisition of antibiotic resistance genes via the transfer of mobile genetic elements, selective pressure resulting in gene mutations, altered expression of redox-active proteins, iron metabolism, and DNA repair, as well as via biofilm formation. This update summarizes new information published since 2010 on phenotypic and genotypic resistance mechanisms in and addresses susceptibility test methods and other strategies to counter antibiotic resistance of .
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http://dx.doi.org/10.1128/JCM.02250-16DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5483901PMC
July 2017

Clostridium difficile colonization in preoperative colorectal cancer patients.

Oncotarget 2017 Feb;8(7):11877-11886

Cancer Biotherapy Center, First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China.

The entire process of Clostridium difficile colonization to infection develops in large intestine. However, the real colonization pattern of C. difficile in preoperative colorectal cancer patients has not been studied. In this study, 33 C. difficile strains (16.1%) were isolated from stool samples of 205 preoperative colorectal cancer patients. C. difficile colonization rates in lymph node metastasis patients (22.3%) were significantly higher than lymph node negative patients (10.8%) (OR=2.314, 95%CI=1.023-5.235, P =0.025). Meanwhile, patients positive for stool occult blood had lower C. difficile colonization rates than negative patients (11.5% vs. 24.0%, OR=0.300, 95%CI=0.131-0.685, P =0.019). A total of 16 sequence types were revealed by multilocus sequence typing. Minimum spanning tree and time-space cluster analysis indicated that all C. difficile isolates were epidemiologically unrelated. Antibiotic susceptibility testing showed all isolates were susceptible to vancomycin and metronidazole. The results suggested that the prevalence of C. difficile colonization is high in preoperative colorectal cancer patients, and the colonization is not acquired in the hospital. Since lymph node metastasis colorectal cancer patients inevitably require adjuvant chemotherapy and C. difficile infection may halt the ongoing treatment, the call for sustained monitoring of C. difficile in those patients is apparently urgent.
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http://dx.doi.org/10.18632/oncotarget.14424DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5355311PMC
February 2017

Molecular Epidemiology of Clostridium difficile Infection in Hospitalized Patients in Eastern China.

J Clin Microbiol 2017 03 14;55(3):801-810. Epub 2016 Dec 14.

Department of Laboratory Medicine, Memorial Sloan Kettering Cancer Center, New York, New York, USA

Few studies on risk factors for and transmission of infection (CDI) in China have been reported. A cross-sectional study was conducted for 3 years in eastern China. Consecutive stool specimens from hospitalized patients with diarrhea were cultured for isolates from these patients then were analyzed for toxin genes, genotypes, and antimicrobial resistance. A severity score for the CDI in each patient was determined by a blinded review of the medical record, and these scores ranged from 1 to 6. A total of 397 out of 3,953 patients (10.0%) with diarrhea were found to have CDI. Severity of CDI was mild to moderate, and the average (± standard deviation) severity score was 2.61 ± 1.01. was isolated from stool specimens in 432 (10.9%) of all the patients who had diarrhea. genotypes were determined by multilocus sequence analysis and PCR ribotyping; sequence type 37 (ST37)/ribotype 017 (RT017) ( = 68, 16.5%) was the dominant genotype. Eleven patients (16.2%) with this genotype had a CDI severity score of 5. Overall, three RTs and four STs were predominant; these genotypes were associated with significantly different antimicrobial resistance patterns in comparison to all genotypes (χ = 79.56 to 97.76; < 0.001). Independent risk factors associated with CDI included age greater than 55 years (odds ratio [95% confidence interval], 26.80 [18.76 to 38.29]), previous hospitalization (12.42 [8.85 to 17.43]), previous antimicrobial treatment within 8 weeks (150.56 [73.11 to 310.06]), hospital stay more than 3 days before sampling (2.34 [1.71 to 3.22]), undergoing chemotherapy (3.31 [2.22 to 4.92]), and undergoing abdominal surgery (4.82 [3.54 to 6.55]). CDI is clearly a problem in eastern China and has a prevalence of 10.0% in hospitalized patients. Among risk factors for CDI, the advanced age threshold was younger for Chinese patients than that reported for patients in developed countries.
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http://dx.doi.org/10.1128/JCM.01898-16DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5328448PMC
March 2017

US Gulf-like toxigenic O1 Vibrio cholerae causing sporadic cholera outbreaks in China.

J Infect 2016 May 23;72(5):564-72. Epub 2016 Feb 23.

School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia. Electronic address:

Objectives: Cholera is potentially a life threatening disease caused by toxigenic Vibrio cholerae. Here we report the identification and characterisation of 76 non-7th pandemic clone O1 V. cholerae isolates including 65 clinical isolates from diarrhoeal patients from 2005 to 2014 in Zhejiang Province, China.

Methods: We used multilocus sequence typing (MLST) to characterise 65 V. cholerae isolates. Pulse-Field Gel Electrophoresis (PFGE) was performed on a subset of the isolates and whole-genome sequencing was done on 13 isolates.

Results: MLST separated 65 isolates into 19 sequence types (STs). Thirty three isolates belonged to ST75 which also contains the US Gulf Coast clone. PFGE separated the 33 isolates into 16 pulsotypes. Whole genome sequencing of 10 ST75 isolates showed that the US Gulf Coast clone and the Chinese ST75 isolates can be separated into two distinct lineages, ST75a and ST75b. All Zhejiang ST75 isolates were ST75b.

Conclusion: PFGE and genome sequencing confirmed the linked cases and identified small outbreaks caused by ST75b. The emergence and potential spread of ST75b may pose significant threat to public health. Epidemiological surveillance is required to further understand its epidemic potential.
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http://dx.doi.org/10.1016/j.jinf.2016.02.005DOI Listing
May 2016

Genome Sequence and Analysis of Peptoclostridium difficile Strain ZJCDC-S82.

Evol Bioinform Online 2016 24;12:41-9. Epub 2016 Jan 24.

Department of Microbiology, Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, Zhejiang, China.

Peptoclostridium difficile (Clostridium difficile) is the major pathogen associated with infectious diarrhea in humans. Concomitant with the increased incidence of C. difficile infection worldwide, there is an increasing concern regarding this infection type. This study reports a draft assembly and detailed sequence analysis of C. difficile strain ZJCDC-S82. The de novo assembled genome was 4.19 Mb in size, which includes 4,013 protein-coding genes, 41 rRNA genes, and 84 tRNA genes. Along with the nuclear genome, we also assembled sequencing information for a single plasmid consisting of 11,930 nucleotides. Comparative genomic analysis of C. difficile ZJCDC-S82 and two other previously published strains, such as M120 and CD630, showed extensive similarity. Phylogenetic analysis revealed that genetic diversity among C. difficile strains was not influenced by geographic location. Evolutionary analysis suggested that four genes encoding surface proteins exhibited positive selection in C. difficile ZJCDC-S82. Codon usage analysis indicated that C. difficile ZJCDC-S82 had high codon usage bias toward A/U-ended codons. Furthermore, codon usage patterns in C. difficile ZJCDC-S82 were predominantly affected by mutation pressure. Our results provide detailed information pertaining to the C. difficile genome associated with a strain from mainland China. This analysis will facilitate the understanding of genomic diversity and evolution of C. difficile strains in this region.
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http://dx.doi.org/10.4137/EBO.S32476DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4727486PMC
January 2016

[Establishment and evaluation of identification method for Yersinia pestis and Yersinia pseudotuberculosis].

Zhonghua Liu Xing Bing Xue Za Zhi 2015 May;36(5):496-500

Institute for Communicable Disease Prevention and Control, Chinese Center for Disease Control and Prevention; Email:

Objective: To establish a gene identification method of Yersinia pestis and Yersinia pseudotuberculosis for plague surveillance.

Methods: According to the specific genomic sequences of Y. pestis and Y. pseudotuberculosis, i.e. "pestis Island (PeI)" and "pseudotuberculosis Island (PsI)" and the published genomic sequences of 12 strains of Y. pestis and 4 strains of Y. pseudotuberculosis, the specific identification primers of these sequences were designed.

Results: A total of 52 strains of Y. pestis and 57 strains of Y. pseudotuberculosis and other intestinal bacteria strains were tested with PCR. Of the 5 pairs of Y. pestis identification primers, PeI2 and PeI11 were specific for Y. pestis. Besides Y. pestis, the primers PeI1, PeI3 and PeI12 could detect part of 57 Y. pseudotuberculosis strains. Of the 5 pairs of Y. pseudotuberculosis identification primers, PsI1 could detect all the 52 strains of Y. pestis and 57 strains of Y. pseudotuberculosis. PsI7, PsI16, PsI18 and PsI19 were specific for Y. pseudotuberculosis.

Conclusion: The primers PsI1, PeI 2 and PeI11, PsI7, PsI16, PsI18 and PsI19 can be used in the rapid identification of Y. pestis and Y. pseudotuberculosis, which can be also used to explore the circulation of atypical Y. pestis in quiescent plague foci.
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May 2015

Real-time cell analysis for monitoring cholera toxin-induced human intestinal epithelial cell response.

Curr Microbiol 2015 Apr 16;70(4):536-43. Epub 2014 Dec 16.

Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, 310051, Zhejiang, China.

The pathogenic mechanism of Vibrio cholerae manifests as diarrhea and causes life-threatening dehydration. Here, we observe the human intestinal epithelial cells (HIEC) response to Cholera toxin (CT) by a real-time cell analysis (RTCA) platform, and disclose the difference from CT-induced cytotoxicity and others in HIEC. An HIEC cell of 1.0 × 10(5) cells/mL was characterized as the suitable concentration for each well. For experimentation, the assay requires an inoculation of CT dissolved in Dulbecco's phosphate-buffered saline with 0.1 % gelatin for a period of 18-25 h. The dimensionless impedance cell index curve presented characteristic dose- and time-dependent drop responses at the first stage, and the CT-induced cytotoxicity was the most remarkable following exposure for 18-25 h (P = 0.0002). Following the obvious cytotoxic reaction, the CI curve gradually increased over time until the original CI value, indicating that self-recovery occurred. The CT-induced CI curve for HIEC was different from that induced by other toxins, including diphtheria and Clostridium difficile toxin. Collectively, these results suggest that the CT-induced cytotoxicity in HIEC was absolutely different from that induced by C. difficile and other toxins because of the different pathogeneses that were correlated with the specific CI curve generated by the RTCA system. In summary, our data show that the assay described here is a convenient and rapid high-throughput tool for real-time monitoring of host cellular responses to CT on the basis of the characteristic CI curve.
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http://dx.doi.org/10.1007/s00284-014-0752-zDOI Listing
April 2015

Crystal structure of the novel di-nucleotide cyclase from Vibrio cholerae (DncV) responsible for synthesizing a hybrid cyclic GMP-AMP.

Cell Res 2014 Oct 23;24(10):1270-3. Epub 2014 Sep 23.

1] Structural Biology Laboratory and MOE laboratory of Protein Science, School of Medicine and Life Science, Tsinghua University, Beijing 100084, China [2] Collaborative Innovation Center for Biotherapy, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, West China Medical School, Sichuan University, Chengdu, Sichuan 610207 China.

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http://dx.doi.org/10.1038/cr.2014.123DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4185349PMC
October 2014

Real-time cellular analysis for quantitative detection of functional Clostridium difficile toxin in stool.

Expert Rev Mol Diagn 2014 Apr;14(3):281-91

Department of Laboratory Medicine, First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China.

Rapid and accurate diagnosis and monitoring of Clostridium difficile infection (CDI) is critical for patient care and infection control. We will briefly review current laboratory techniques for the diagnosis of CDI and identify aspects needing improvement. We will also introduce a real-time cellular analysis (RTCA) assay developed for the diagnosis and monitoring of CDI using electronic impedance to assess the cell status. The RTCA assay uses impedance measurement to detect minute physiological changes in cells cultured on gold microelectrodes embedded in glass substrates in the bottom of microtiter wells. This assay has been adapted for quantitative detection of C. difficile functional toxin directly from stool specimens. Compared to conventional techniques and molecular assays, the RTCA assay provides a valuable tool for the diagnosis of CDI as well as for the assessment of clinical severity and for monitoring therapeutic efficacies.
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http://dx.doi.org/10.1586/14737159.2014.900442DOI Listing
April 2014

Real-time cellular analysis coupled with a specimen enrichment accurately detects and quantifies Clostridium difficile toxins in stool.

J Clin Microbiol 2014 Apr 22;52(4):1105-11. Epub 2014 Jan 22.

Department of Laboratory Medicine, First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China.

We describe here the use of an immunomagnetic separation enrichment process coupled with a modified real-time cellular analysis (RTCA) system (RTCA version 2) for the detection of C. difficile toxin (CDT) in stool. The limit of CDT detection by RTCA version 2 was 0.12 ng/ml. Among the consecutively collected 401 diarrheal stool specimens, 53 (13.2%) were toxin-producing C. difficile strains by quantitative toxigenic culture (qTC); bacterial loads ranged from 3.00 × 10(1) to 3.69 × 10(6) CFU/ml. The RTCA version 2 method detected CDT in 51 samples, resulting in a sensitivity of 96.2%, a specificity of 99.7%, and positive and negative predictive values of 98.1% and 99.4%, respectively. The positive step time ranged from 1.43 to 35.85 h, with <24 h for 80% of the samples. The CDT concentrations in stool samples determined by RTCA version 2 correlated with toxigenic C. difficile bacterial load (R(2) = 0.554, P = 0.00002) by qTC as well as the threshold cycle (R(2) = 0.343, P = 0.014) by real-time PCR. A statistically significant correlation between the CDT concentrations and the clinical severity of CDI was observed (P = 0.015). The sensitivity of the RTCA version 2 assay for the detection of functional toxins in stool specimens was significantly improved when the immunomagnetic separation enrichment process was incorporated. More than 80% positive results can be obtained within 24 h. The stool specimen CDT concentration derived using the RTCA version 2 assay correlates with clinical severity and may be used as a marker for monitoring the status of CDI.
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http://dx.doi.org/10.1128/JCM.02601-13DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3993479PMC
April 2014

Molecular characterization and antibiotic susceptibility of Vibrio vulnificus in retail shrimps in Hangzhou, People's Republic of China.

J Food Prot 2013 Dec;76(12):2063-8

College of Life Sciences, Zhejiang University, Hangzhou 310058, People's Republic of China; Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou 310051, People's Republic of China.

Vibrio vulnificus is a gram-negative bacterium that occurs naturally in estuarine and marine water and is associated with wound infections or septicemia related to the consumption of raw shellfish in humans. The molecular characteristics and antibiotic susceptibilities of V. vulnificus strains in shrimps from retail markets in Hangzhou, People's Republic of China, were investigated in this study. Thirty-three samples were positive for V. vulnificus in 78 shrimp samples which were collected from 15 retail markets between July and August 2012; the most-probable-number values ranged from 3 to 1,600 g(-1) in these positive samples, with a median most-probable-number value of 72 g(-1). Twenty-five biotype 1 strains and eight biotype 2 strains were identified by biochemical tests, and all strains could be definitively genotyped. By 16S rRNA genotyping, 21.2% (7 of 33) were classified as genotype A, 63.6% (21 of 33) as genotype B, and 15.2% (5 of 33) as genotype AB, while by virulence-correlated gene (vcg) typing, 21.2% (7 of 33) were characterized as genotype E and 78.8% (26 of 33) were genotype C. More than 50% of those isolates were identified as the potentially virulent type vcg type C-16S rRNA B (CB). The antibiotic susceptibilities of the V. vulnificus strains to 21 antimicrobial agents were tested as well. Some strains showed resistance or intermediate resistance to cefepime (3.03%), tetracycline (6.06%), aztreonam (24.24%), streptomycin (45.45%), gentamicin (93.94%), tobramycin (100%), and cefazolin (100%). Multiple-locus variable-number tandem repeat-based fingerprinting analysis (MLVA) was successfully applied to these 33 isolates and yielded 30 patterns that clustered into two MLVA groups; with a calculated Simpson's index of diversity of 0.994, this revealed that MLVA had great discriminating power for V. vulnificus. To minimize the potential risk of V. vulnificus infections due to the consumption of raw shrimp, it is necessary to monitor the hygiene status of seafood.
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http://dx.doi.org/10.4315/0362-028X.JFP-13-161DOI Listing
December 2013

Quantitative detection of Vibrio cholera toxin by real-time and dynamic cytotoxicity monitoring.

J Clin Microbiol 2013 Dec 18;51(12):3968-74. Epub 2013 Sep 18.

Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, China.

We report here the quantitative detection of Vibrio cholerae toxin (CT) in isolates and stool specimens by dynamic monitoring of the full course of CT-mediated cytotoxicity in a real-time cell analysis (RTCA) system. Four cell lines, including Y-1 mouse adrenal tumor cells, Chinese hamster ovary (CHO) cells, small intestine epithelial (FHs74Int) cells, and mouse adrenal gland (PC12-Adh) cells, were evaluated for their suitability for CT-induced cytotoxicity testing. Among them, the Y-1 line was demonstrated to be the most sensitive for CT-mediated cytotoxicity, with limits of detection of 7.0 pg/ml for purified CT and 0.11 ng/ml for spiked CT in pooled negative stool specimens. No CT-mediated cytotoxicity was observed for nontoxigenic V. cholerae, non-V. cholerae species, or non-V. cholerae enterotoxins. The CT-RTCA assay was further validated with 100 stool specimens consecutively collected from patients with diarrhea and 200 V. cholerae isolates recovered from patients and the environment, in comparison to a reference using three detection methods. The CT-RTCA assay had sensitivities and specificities of 97.5% and 100.0%, respectively, for V. cholerae isolates and 90.0% and 97.2% for stool specimens. For stool specimens spiked with CT concentrations ranging from 3.5 pg/ml to 1.8 ng/ml, the inoculation-to-detection time was 1.12 ± 0.38 h, and the values were inversely correlated with CT concentrations (ρ = -1; P = 0.01). The results indicate that the CT-RTCA assay with the Y-1 cell line provides a rapid and sensitive tool for the quantitative detection of CT activities in clinical specimens.
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http://dx.doi.org/10.1128/JCM.01959-13DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3838090PMC
December 2013

T85C polymorphisms of the dihydropyrimidine dehydrogenase gene detected in gastric cancer tissues by high-resolution melting curve analysis.

Turk J Gastroenterol 2012 ;23(6):652-7

Department of Medical Oncology, The First Affiliated Hospital, College of Medicine, Zhejiang University, Zhejiang, China

Background/aims: Dihydropyrimidine dehydrogenase is a key enzyme acting on the metabolic pathway of medications for gastric cancer. High-resolution melting curve technology, which was developed recently, can distinguish the wild-type dihydropyrimidine dehydrogenase gene from multiple polymorphisms by fluorescent quantitative polymerase chain reaction products in a direct and effective manner.

Materials And Methods: T85C polymorphisms of dihydropyrimidine dehydrogenase in the peripheral blood of 112 Chinese gastric cancer patients were detected by real-time polymerase chain reaction combined with high-resolution melting curve technology. Primer design, along with the reaction system and conditions, was optimized based on the GenBank sequence.

Results: Seventy nine cases of wild-type (TT, [70.5%]), 29 cases of heterozygous (TC, [25.9%]), and 4 cases of homozygous mutant (CC, [3.6%]) were observed. The result was completely consistent with the results of the sequencing.

Conclusions: Real-time polymerase chain reaction combined with high-resolution melting curve technology is a rapid, simple, reliable, direct-viewing, and convenient method for the detection and screening of polymorphisms.
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http://dx.doi.org/10.4318/tjg.2012.0469DOI Listing
February 2014

Molecular analysis of non-O1/non-O139 Vibrio cholerae isolated from hospitalised patients in China.

BMC Microbiol 2013 Mar 4;13:52. Epub 2013 Mar 4.

Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, Zhejiang, China.

Background: Cholera is still a significant public health issue in developing countries. The aetiological agent is Vibrio cholerae and only two serogroups, O1 and O139, are known to cause pandemic or epidemic cholera. In contrast, non-O1/non-O139 V. cholerae has only been reported to cause sporadic cholera-like illness and localised outbreaks. The aim of this study was to determine the genetic diversity of non-O1/non-O139 V. cholerae isolates from hospitalised diarrhoeal patients in Zhejiang Province, China.

Results: In an active surveillance of enteric pathogens in hospitalised diarrhoeal patients, nine non-O1/non-O139 V. cholerae isolates were identified from 746 diarrhoeal stool samples at a rate of 1.2%. These isolates and an additional 31 isolates from sporadic cases and three outbreaks were analysed using pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). PFGE divided the isolates into 25 PFGE types while MLST divided them into 15 sequence types (STs). A single ST, ST80, was predominant which persisted over several years in different cities and caused two outbreaks in recent years. Antibiotic resistance varied with the majority of the isolates resistant to sulphamethoxazole/trimethoprim and nearly all isolates either resistant or intermediate to erythromycin and rifampicin. None of the isolates carried the cholera toxin genes or toxin co-regulated pilus genes but the majority carried a type III secretion system as the key virulence factor.

Conclusions: Non-O1/non-O139 V. cholerae is an important contributor to diarrhoeal infections in China. Resistance to commonly used antibiotics limits treatment options. Continuous surveillance of non-O1/non-O139 V. cholerae is important for control and prevention of diarrhoeal infections.
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http://dx.doi.org/10.1186/1471-2180-13-52DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3605376PMC
March 2013

Comparison of multiple-locus variable-number tandem-repeat analysis with pulsed-field gel electrophoresis typing of Acinetobacter baumannii in China.

J Clin Microbiol 2013 Apr 23;51(4):1263-8. Epub 2013 Jan 23.

State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China.

A panel of seven variable-number tandem-repeat (VNTR) markers was selected for Acinetobacter baumannii typing analysis (MLVA-7). Compared with pulsed-field gel electrophoresis (PFGE), MLVA-7 provided greater discrimination. We modified the criteria for MLVA complex assignments proposed previously, and a remarkable congruence between MLVA-7- and PFGE-based strain clustering was observed.
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http://dx.doi.org/10.1128/JCM.03108-12DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3666804PMC
April 2013
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