Diarrhea pathogens in rotavirus-negative infants in Hangzhou / 中华检验医学杂志

Objective To investigate the distribution of diarrhea pathogens in infants without rotavirus-detection in Hangzhou. Methods 605 stool samples of children with rotavirus-negative diarrhea were collected from Hangzhou First People's Hospital of Zhejiang University, Children's Hospital of Zhejiang University and Hangzhou Children's Hospital from March 2017 to June 2018. The routine test results were analyzed retrospectively and Bristol score was used for the characteristics of stool samples. DNA and/or RNA were extracted from fecal samples with DNA and RNA extraction kit. The extracted DNA and RNA-reversed cDNA were used as templates. 7 common pathogens DNA and/or RNA were amplified by polymerase chain reaction (PCR). The amplified products were detected by agarose gel electrophoresis. The positive rates of pathogens were analyzed by chi-square test. Results Among 605 children, 375 were male (28±11) months and 230 were female (29±10) months. Bristol score of stool samples was mainly in type 6 (496, 82％), followed by type 7 (85, 14％) and type 5 (24, 4％). Among 605 results 97 cases were occult blood positive (positive rate 16％) and 170 cases were white blood cell positive (positive rate 28％).452 of 605 stool samples were positive for pathogen target genes. The positive rate was 74.7％. 319 cases detected single pathogen gene fragments. 127 cases detected two pathogen genes and 6 cases detected three pathogen gene fragments. The positive rate of Clostridium difficile toxin B (48.9％, 296/605)was the highest than the others, followed by Salmonella (20.0％, 121/605) and Norovirus (10.9％, 66/605). The positive rate of Clostridium difficile toxin A was 1.0％ (6/605). The positive rates of pathogens in male and female children were 86.7％(325 / 375) and 86.5％ (199 / 230) respectively, with (χ2 =0.002, P=0.959). Conclusions Salmonella and Norovirus were the main pathogens in children with diarrhea who were negative for rotavirus detection in Hangzhou. The high positive rate of Clostridium difficile toxin B may be related to the colonization of Clostridium difficile in the gastrointestinal tract of infants rather than the pathogen of diarrhea because of the low positive rate of Clostridium difficile toxin A. There was no gender difference in the detection rate of diarrhea pathogens.

Establishment and application of DPO-based quadruple real-time PCR for detection of mycobacteria / 中华检验医学杂志

Objective To establish a rapid,accurate and specific method to detect the common mycobacteria based on multiplex real-time PCR.Methods The dual priming oligonucleotide ( DPO)primers and TaqMan probes labeled with FAM,ROX,HEX or JOE fluoresceins at 5' end and eclipse at 3' end respectively were designed to detect the 16S rRNA of mycobacteria.Both specificity and sensitivity were estimated on multiplex real-time PCR detecting genome DNA from 4 mycobacterial model species.Sixty eight early morning sputum specimens collected from hospitalized patients in the Red Cross Hospital of Hangzhou were detected by multiplex real-time PCR,bacterial culture and smear microscopy simultaneously.The positive rates were analyzed by chi-square.Results Mycobacteria including Mycobacterium tuberculosis and three common non-tuberculosis mycobacteria spp.were identified by multiplex real-time PCR accurately and specifically,with the limited load at 101 cfu/ml.In 68 sputum specimens,31 were positive (positive rate 45.6％ ) by this method,which was significant higher than that by smear microscopy ( positive rate 14.7％,x2 =15.4,P ＜0.05 ).The positive cases were identified as 28 Mycobacterium tuberculosis,1 Mycobacterium avium and 2 Mycobacterium intracellulare in agreement with the culture results.One case,which is detected by culture,but not by PCR,was identified as Mycobacterium chelonae by sequencing.Conclusion The multiplex real-time PCR characterizing as sensitive,specific and time-saving for Mycobacterium tuberculosis and common non-tuberculosis mycobacteria could be chosen as the rapid laboratory test of mycobacterial infection.

Simultaneous detection of four types of human herpes virus by AllGlo quadruple fluorescence quantitatve PCR / 中华微生物学和免疫学杂志

ObjectiveTo optimize the condition of multiple fluorescence quantitative PCR and establish a new assay of four human herpes virus (HHV) detected by AllGlo quadruple fluorescence quantitative PCR.MethodsFour HHV including HSV-1,HSV-2,EBV and CMV were identified by sequence analysing the qualitative PCR production.Furthermore,they were quantitatively detected by AllGlo and TaqMan multiple fluorescence quantitative PCR respectively.ResultsBoth the positive rate and specificity of AllGlo and TaqMan in detecting single HHV achieved 100％.And AllGlo single fluorescence quantitative PCR prevailed over TaqMan's by Ct of 1-3.Four HHV can be simultaneously detected by AllGlo quadruple fluorescence quantitative PCR,comparing to the only two by TaqMan.ConclusionAllGlo fluorescence quantitative PCR assay allows a higher throughput,sensitivity and specificity than TaqMan in detection and thus provides a board prospect.

HBV subgenotype C2 infection, A1762T/G1764A mutations may contribute to hepatocellular carcinoma with cirrhosis in southeast China

To glean insights into the relationship among hepatitis B virus [HBV] genotype/subgenotypes, A1762T/G1764A mutations and advanced liver disease such as liver cirrhosis [LC] and hepatocellular carcinoma [HCC] in Southeast China. Methods: A case-control study was performed, consisting of chronic hepatitis B [CHB] patients [n=160], LC patients [n=150], and HCC patients [n=156]. Fluorescence quantitative polymerase chain reaction [FQ-PCR] was used to detect A1762T/G1764A mutations. HBV genotypes/subgenotypes were determined by multiplex PCR. All patients' clinical data was systematically collected from the hospital records. Results: Our study revealed HBV genotypes C [63.95%] and B [33.69%] were predominant in chronically infected patients, subgenotype B2, C2 and C1 were the major subgenotypes. Both subgenotype C2 infection and A1762T/G1764A mutations were associated with LC and HCC with cirrhosis, subgenotype C2 [OR=2.033, 95%CI=1.246-3.323, P=0.003 for LC vs CHB; OR=3.247, 95%CI=1.742-6.096, P=0.001 for HCC with cirrhosis vs CHB; respectively], and A1762T/G1764A mutations [OR=1.914, 95%CI=1.188-3.085, P=0.005 for LC vs CHB; OR=2.996, 95%CI=1.683-5.353, P=0.002 for HCC with cirrhosis vs CHB; respectively], but no differences in the frequencies of both variants between LC and HCC with cirrhosis groups were found. Conclusions: HBV subgenotype C2 infection and A1762T/G1764A mutations are both risk factors of LC and HCC with cirrhosis development in the patients with CHB in Southeast China, but all no helpful for predicting HCC development in LC patients

Fluorescence PCR for detecting ureA gene of Helicobacter pylori in feces / 中华临床感染病杂志

Objective To evaluate the application of fluorescence PCR in detecting ureA gene of Helicobacter pylori(HP)in feces.Methods Fluorescence PCR was used to detect ureA gene of HP in feces from 50 patients,including 23 confirmed by gastric biopsy urease test and histological staining.Bacterium culture and serum antibody detection were also performed, and chi-square test was used to compare the sensitivity,specificity,positive predictive value and negative predictive value among three methods.Results The sensitivity,specificity,positive predictive value and negative predictive value of fluorescence PCR were 1.00,0.96,96.O%and 100.0%,while those for HP culture were 0.78,1.00,100.0%and 84.0%,and thee for serum antibody detection Was 0.96,0.74,76.O%and 95.0%.There were significant differences in sensitivity and negative predictive value between PCR and bacterium culture (X2=5.60 and 4.44,P<0.05),and significant differences in specificity and positive predictive value between PCR and serum antibody detection(X2=5.28 and 4.08,P<0.05).Conclusion ureA gene detection in feces by fluorescence PCR is of value for the diagnosis of HP infection.

Role of Helicobacter pylori cheA gene in chemotaxis in vitro and colonizationin vivo / 中华微生物学和免疫学杂志

Objective To determine the effect of cheA gene of Helicobacter pylori in the bacterial chemotaxis in vitro and colonization in vivo. Methods The entire cheA and cheY genes were amplified and cloned from genomic DNA of H. pylori NCTC11637 strain. Subsequently, the prokaryotic expression systems of cheA and cheY genes were generated and the target recombinant proteins rCheA and rCheY were extracted by Ni-NTA affinity chromatography. Rabbits were immunized with either rCheA or rCheY for obtaining antisera, and rCheA-IgG and rCheY-IgG in the antisera were prepared using ammonium sulfate precipitation plus DEAE-52 column chromatography. A suicide plasmid of cheA gene was constructed and then a cheA gene knock-out mutant ( cheA - ) was generated based on homologous recombinant exchange using the suicide plasmid. The cheA- mutant was identified using PCR and sequencing. The phosphorylation levels of CheA and CheY molecules of cheA - and wild-type strain were determined by using rCheA-IgG and rCheY-IgG anchoring the target proteins and protein phosphorylation detection kit. The differences of chemotaxis in vitro and colonization in vivo between cheA- mutant and wild-type strain were compared using chemotactic model and BALB/c infection model of H. pylori. Results The cheA gene knock-out in genome of cheA- mutant was confirmed by the results of PCR and sequencing. After treated with 0. 001-0. 1 mol/L HCI for 10 min, the phosphorylation levels of CheA and CheY molecules of wild-type strain were rapidly descended from ( 59.6 ±11.5) μmol and (55.5 ± 10.2) μmol to ( 10.8 ± 2.6) and (5. 5 ± 1.2) μmol (P ＜ 0.05 ), while the phosphorylation of CheY molecule of cheA - mutant was no markedly changed with a persistent lower level ( P ＞0.05). The diameters [(10-20) ± (2-3) mm] of chemotactic aggregative rings of cheA- mutant were significantly less than those [(16-24) ± (2-3)mm] of wild-type strain (P ＜0.05). The positive isolation rate (90%) of H. pylori in gastric biopsy specimens of mice that infected with wild-type strain was remarkably higher than that (40%) of mice that infected with cheA- mutant (P ＜0.05). The result of fluorescence quantitative was also showed that the numbers (6.3 × 103 ±2.1 × 103 copies/mg) of H. pylori in gastric biopsy specimens of wild-type strain infected mice were significantly larger than those (8.3 × 101 ±3. 1 × 101 copies/mg) in gastric biopsy specimens ofcheA- mutant infected mice (P＜0.05). Conclusion The cheA gene of H. pylori has an important role in the bacterial chemotaxis in vitro and colonization in vivo.

Prokaryotic expression of Helicobacter pylori cheA and cheY genes and correlation among the expressed products and bacterial chemotactic behavior / 中华微生物学和免疫学杂志

Objective To clone the cheA and cheY genes of Helicobacter pylori for construction of their prokaryotic expression systems, and to establish chemotactic model in vitro of H. pylori for determing chemotaxis-inducing substances and to understand the effects of specific antibody and closantel on inhibiting chemotactic behavior of the microbe. Methods The segments of entire cheA and cheY genes were amplified by PGR and then sequenced after T-A cloning. Prokaryotic expression systems of the genes were subsequent-ly constructed. SDS-PAGE plus Bio-Rad Gel Image Analyzer were used to examine the expression of target recombinant proteins rCheA and rCheY, and Ni-NTA affinity chromatography was performed to extract rCheA and rCheY. Rabbits were immunized with rCheA and rCheY to obtain antisera and IgG in each of the anti-sera was extracted by saturated ammonium sulfate precipitation and DEAE-32 ion exchange chromatography. Immunodiffusion assay was performed to measure the titers of antisera and their IgGs. Chemotactic model in vitro of H. pylori based on hard-agar plus method was established to determine the chemotaxis-inducing effects of eleven candidate substances. Simultaneously, the effects of rCheA-lgG and closantel sodium on blocking the bacterial chemotactic behavior were also observed. Results The segments with expected sizes of cheA and cheY genes were obtained by PCR, and their nucleotide and putative amino acid sequences were 100% idenities to the reports. The constructed prokaryotic systems could efficiently express rCheA and rCheY. The two rabbit antisera and IgG aginst rCheA and rCheY had 1 : 4 and 1 : 2 immunodiffusion titers, respectively. Hydrochloric acid, sulfuric acid and acetic acid were able to induce chemotactic movement of H. pylori. Both rCheA-IgG and closantel sodium with certain concentrations could weaken the chemotactic ability of H. pylori(P<0.05). Conclusion The prokaryotic expression systems of H. pylori cheA and cheY genes were successfully generated in this study. Hydrogen ion (H~+) is the inducer for chemotaxis of H. py-lori. rCheA-IgG, as well as closantel sodium can inhibit H~+-induced chemotaxis of H. pylori.