Objective To investigate the prevalence and dissemination mechanism of 16S rRNA methylase genes in extended-spectrum beta-lactamases(ESBLs)-producing Enterobacteriaceae in China.Methods PCR amplification and DNA sequencing were used for screening and identifing 16S rRNA methylase genes and ESBLs genes.Minimal inhibitory concentrations(MICs)of the antimicrobial agents were detected by Etest.Conjugation and plasmid extract were performed to study dissemination mechanism of 16S rRNA methylase genes and ESBLs genes.Results Only one strain.Klebsiella oxytoca strain ZJ157 was screened as positive for armA gene from 447 ESBLs-producing isolates,which also contained CTX-M-15 and TEM-1 genes.It was resistant to aminoglycesides,ciprofloxacin,and most β-lactams,except carbapenems,polymyxin E and tigecyeline.Resistance to amikacin and β-lactams was transferred to a recipient Escherichia coli 600 by conjugation experiment.arntA.CTX-M-15 and TEM-1 genes were detected in the transconjugant.A plasmid about 55 kb was extracted from Klebsiella oxytoca ZJl57 and the transconjugant.Conclusions A 16S rRNA methylase gene armA was detected in an isolate of Klebsiella oxytoca.armA,CTX-M-15 and TEM-1 genes can be co-transferred in the same plasmid leading to multi-drug resistance.

Objective To investigate the biological characteristics of rpoS gene deleted mutation in Salmonella typhi under different stress conditions,so as to explore the target gene for the prevention and treament of Salmonella typhi infection.Methods rpoS gene deleted mutant of Salmonella typhi was prepared by homologious recombination.rpoS mutant and parental strains were incubated under iso-osmia and various stress conditions:acid stress(pH 4.2),high osmolarity stress(NaCl 300 mmol/L),bile stress (1.5 mmol/L sodiumdeoxycbolate)and oxidative stress(1 mmol/L H2O2).The growth curves were compared between mutant and parental strains under different incubation conditions(t test).Results rpoS gene deleted mutant of Salmonella typhi Was successfully generated.Compared with the parental strain,the survival ability of rpoS mutant was significantly compromised under the acid stress,high osmolarity stress and oxidative stress(t values at4 h were 12.864,3.594 and 12.979;t values at 14 h were6.497,3.039 and 10.440,P<0.05 or<0.01).Conclusion rpoS is important for Salmonella typhi to overcome the acid,high osmolarity and oxidative stresses,and it may be a target gene for the prevention and treatment of Salmonella typhi infection.

Objective To evaluate the plasma levels of adrenomedullin (ADM) and urotensin Ⅱ ( U-Ⅱ ) in children with capillary bronchiolitis, and their clinical significance. Methods One hundred and fifty three children with capillary bronchiolitis and 36 healthy children were recruited. Plasma levels of ADM and U- Ⅱ were measured at acute stage ( <7days) and convalescent stage (>14days) of airway inflammation. The relationship of plasma ADM and U-Ⅱ levels with symptom scores was evaluated. Results Plasma levels of ADM and U-Ⅱ in acute stage of capillary bronchiolitis were significantly higher than those in convalescent stage and healthy controls ( ADM: t = 20. 57 and 26. 26, P < 0. 01; U-Ⅱ: t = 14. 27 and 7. 61, P < 0. 01 ) , and there were significant differences among mild, moderate and severe capillary bronohiolitis (F = 245. 94 and 304. 79, P <0. 01). Plasma level of U-Ⅱ in convalescent stage of capillary bronchiolitis was lower than that of healthy controls (t = 6. 99, P <0. 01 ) , but ADM was still in a higher level ( t = 8. 98, P < 0. 01 ). In the convalescent stage, there was significant difference on U-Ⅱ levels among mild, moderate and severe capillary bronchiolitis ( F = 25.69, P < 0. 01 ) , but no significant difference was observed for ADM levels (F = 2. 25 , P > 0. 05 ) . Plasma levels of ADM and U- Ⅱ in acute stage showed positive correlation with symptom scores, and the regression coefficients were 0.884 (P =0. 000) for ADM and 0. 943 (P = 0. 000) for U-Ⅱ . Conclusion Plasma ADM and U-Ⅱ levels in children with capillary bronchiolitis are increased in acute stage and correlated with the symptom scores, which may serve as laboratory indicators for assessing the severity of the disease.

Objective To investigate the prevalence of mobile genetic elements in Acinetobacter baumannii strains isolated from burn patients. Methods Polymerase chain reaction (PCR) was used to detect the genes encoding the integron, transposon, conjugative plasmid and insertion sequence in 20 strains of Acinetobacter baumannii isolated from burn patients. Results tnpU and ISaba1 genes were detected in all 20 strains, and int Ⅰ gene was detected in 19 strains (95.0%). Other genes were all negative. Conclusion Mobile genetic elements carrying multi-drug resistant genes are found in Acinctobacter baumannii strains isolated from bum patients.

Objective To survey on the prevalence of schistosomiasis among floating population in Zhejiang province. Methods A survey on prevalence of schistosomiasis among floating population was conducted from September to November 2008, and the stratified cluster sampling method was adopted in the survey. Totally 129 villages of 19 counties or districts were selected as survey sites, and 100 samples of migrants aged 6 to 65 from schistosomiasis-endemic areas were taken in each selected village. All selected individuals were surveyed by questionnaire and underwent serum indirect hemagglutination (IHA) test. For individuals with positive serum IHA testing the fecal examination was carried out to detect the eggs by nylon sedimentation method. SPSS 13.0 software was used for data processing. Results The number of migrants in survey sites was 3 357 420, among whom 303 219 were from schistosomiasis-endemic areas (9.03%).The positive rate in serum IHA test was 2.06% (286/13 898), 276 IHA-positives individuals received fecal examination, and 7 cases were positive (2.52%). Based on above data it was estimated that there would be potentially about 33 500 serum IHA-positive cases and 845 egg-positive cases among floating population in Zhejiang province. Conclusion The risk of schistosomiasis transmission still exists in Zhejiang province due to the infected migrants from endemic areas, and a surveillance system and quick response are required for prevention of re-emergence of the disease.

Objective To evaluate hepatitis B virus large surfsce protein(LHBs) in monitoring of antiviral treatment.Methods LHBs.HBV serum markers and HBV DNA loads in 46 patients with adefovir dipivoxil(ADV) therapy were monitored for the whole course(60 weeks).Enzyme linked immunosorbent assay(ELISA),time differentiate immunofluoresence assay and real.time polymerase chain reaction(RT-PCR)were performed to detect LHBs,HBV serum markers and HBV DNA loads,respectively.And correlation analysis was also performed.Results Both LHBs and HBV DNA declined during the ADV treatment.and the correlation coefficient was 0.97.but LHBs declined after HBV DNA.There were 20 patients with HBV DNA<5×102/mL at 60th week.in which 8 were LHBs negative;in 14 recurrent patients,the HBV DNA turned to negative and became positive again,3 with negative LHBs;while in 12 patients resistant to the ADV therapy.2 were LHBs negative.Conclusion Dynamic monitoring of LHBs is useful in the evaluation of antiviral treatment.

Objective To investigate the predictive value of TNFα,ALT,HBV DNA loads and HBV serological markers in response to adefovir dipivoxil (ADV) treatment for patients with chronic hepatitis B(CHB).Methods Two hundred and three HBeAg.positive CHB patients were administered with ADV 10 mg/d for 48 weeks.HBV serological markers and TNFα at the baseline were determined by enzyme linked immunosorbent assay(EUSA),and HBV DNA loads were detected by PCR.Logistic regression was used to identify predictive factors for serological response at 48th week after the treatment.Results The rates of HBV DNA clearance,ALT normalization,HBeAg lOSS,HBeAg seroconversion and response at 24th week were 31.5%(64/203),59.1%(120/203),15.8%(32/203).8.9%(18/203)and 13.3%(27/203)respectively,while those at 48th week were 58.6%(119/203),78.3%(159/203),29.6%(60/203),16.7%(34/203)and 25.6%(52/203),respectively.Patients who achieved HBeAS loss at 48th week were found to have higher rates of HBV DNA clearance.HBeAg loss and seroconversion at 24th week and higher TNFα at baseline(P=0.017,0.ooI,0.029 and 0.040),while those who achieved HBeAg seroconversion at 48th week were found to have higher rate of HBeAg seroconversion at 24th week.and lower baseline HBV DNA loads(P=0.000 and 0.004).Conclusion For HBeAg.positive CHBpatients with ADV treatment,the rate of HBV DNA clearanee,HBeAg loss and seroeonversion at 24th week and TNFα at baseline may be used to predict the rate of HBeAg 1088 at 48th week:the rate of HBeAgseroconversion at 24th week and baseline HBV DNA loads may be used to predict the rate of HBeAgseroeonversion at 48th week.

Objective To investigate the distribution of acquired resistance-related genes and markers of mobile genetic elements, and their relationships in multidrug-resistant Escherichia coli. Methods From October 2008 to March 2009, 28 strains of multidrug-resistant Escherichia coli isolated from urine were collected from the Ningbo First Hospital. Then, 47 kinds of acquired resistance genes to beta-lactams, aminoglycosides, quinolones, 2 kinds of acquired drug efflux gene and 13 kinds of genetic markers of mobile genetic elements: conjugal plasmids, transposons, insertion sequences, and integrons were analyzed by PCR. The index cluster analysis was used to investigate their relationships. Results In 28 strains of Escherichia coli, 7 kinds of acquired beta-lactam-resistance genes, 8 kinds of acquired aminoglycosideresistance genes, 1 kind of acquired drug efflux gene, 2 kinds of genetic markers of conjugal plasmids, 3 kinds of genetic markers of transposon and insertion sequences, 1 kind of genetic marker of integron were detected; but other 46 kinds of genes were not detected. Two clusters, A and B, were divided by index cluster analysis depending on positive genes. Conclusions In this group of Escherichia coli, acquired resistance related genes may be associated with resistant phenotypes of antimicrobial agents. Horizontal transfer of mobile genetic elements may bring rapid spread of resistance of bacterial pathogens, not only among the same kind of pathogens, but also among the different kinds. In addition, index cluster analysis suggests that correlation might exist between acquired resistance-related genes and mobile genetic elements.

ObjectiveTo investigate the prevalence of 16S rRNA methylase genes, aminoglycoside modifying enzymes (AMEs) genes and small multidrug resistance efflux pump gene smr-2 in Klebsiella pneumoniae. MethodsTotally 138 Klebsiella pneumoniae isolates were collected in the First Affiliated Hospital, college of medicine, Zhejiang University from January 2007 to December 2009. Polymerase chain reaction (PCR) and DNA sequencing were performed to screen the presence of six 16S rRNA methylase genes ( rmtA, rmtB, rmtC, rmtD, armA and npmA), seven AMEs genes[aac ( 3 )- Ⅰ , aac ( 3 )- Ⅱ,aac(6′)- Ⅰ b, aac(6′)-Ⅱ, ant(2″)- Ⅰ , ant(3″)- Ⅰ , aph(3′)-Ⅵa]and small multidrug resistance efflux pumps gene (smr-2).Results Thirteen (9. 4％) isolates were found to carry rmtB gene, whereas 87 (63.0％) isolates were found to carry at least one kind of AMEs genes but no smr-2 was detected. The positive rates of aac(3)-Ⅱ, aac(6′)- Ⅰ b, ant (3″)- Ⅰ and ant(2″)- Ⅰ were 40.6％ (56/138), 31.9％ (44/138), 28.3％ (39/138) and 2.2％ (3/138), respectively. All strains harboring rmtB gene carried one to three AMEs genes. Among 44 aac(6′)- Ⅰ b positive strains, 37 (84. 1％ ) were confirmed to carryaac(6′)- Ⅰ b-cr. ConclusionFor Klebsiella pneumoniae, rmtB is the predominant subtype in 16S rRNA methylase genes, accompanying with several AMEs genes.

Objective To investigate the correlation between drug-resistant genes and mobile genetic elements in multi-drug resistant Escherichia coli,and to explore phylogeny among the strains.MethodsTotally 20 strains of multi-drug resistant Escherichia coli were collected from Pan' an Hospital,Zhejiang Province during June 2009 and June 2010.Beta-lactam-resistance genes,aminoglycoside-resistance genes,genetic markers of mobile genetic elements were analyzed by PCR.Index and sample cluster analysis were performed on above results. Results In 20 strains of Escherichia coli,4 kinds of beta-lactamresistance genes,4 kinds of aminoglycoside-resistance genes,and 5 kinds of genetic markers of mobile genetic elements were detected.Index cluster analysis showed that correlation existed between resistance genes TEM,CTX-M-1,aadA5 and mobile genetic elements traA,IS26,ISEcpl; and correlation also existed between resistance genes OXA-1,aac(6′)-Ⅰ b,ant(3)-Ⅰ,rmtB and mobile genetic elements trbC,IS903.Sample cluster analysis showed that this group of Escherichia coli could be divided into 2 groups which were genetically different.ConclusionsDrug-resistant genes in multi-drug resistant Escherichia coli are correlated with mobile genetic elements.Sample cluster analysis can reveal phylogeny among the strains,which is important for hospital infection control.