Clinical distribution, virulence factors, and molecular epidemiology of hypervirulent Klebsiella pneumoniae in Hainan Province in 2016 / 中国感染控制杂志

Objective To investigate clinical distribution,capsular serotyping,molecular typing,virulence gene carriage,and antimicrobial susceptibility of hypervirulent Klebsiella pneumoniae (hvKP) strains isolated from a hospital in Hainan Province in 2016.Methods Klebsiella pneumoniae(K.pneumoniae) isolated from the hospital between January and December 2016 were analyzed retrospectively,hvKP strains were selected through string test,antimicrobial susceptibility testing was performed and compared with classic K.pneumoniae(cKP);capsular serotyping,virulence genes,and drug resistance genes of hvKP strains were detected with polymerase chain reaction,molecular typing was performed with pulsed-field gel electrophoresis (PFGE) and multiloeus sequence typing.Results A total of 84 hvKP strains were isolated,the main specimen source was sputum(45 strains);K1 and K2 were the major capsular serotypes of hvKP,while ST23,ST65,and ST86 were the main sequence types of hvKP.The carriage rates of rmpA,aerobatin,allS,kfuBC,and cf29a in hvKP were 90.48％,96.43％,42.86％,66.67％,and 53.57％ respectively,all of them were statistically higher than those of cKP strains,PFGE found that allS was positive only among K1 strains;most antimicrobial resistance rates of hvKP were lower than those of the cKP.Conclusion Sputum is the main specimen source of hvKP,especially K1 serotype;more than 90％ of hvKP strains carry rmpA and aerobatin genes,allS gene only exists in K1 type hvKP.

PCR-based detection of enterotoxigenic isolates of Bacillus cereus from tropical seafood.

Background & objectives: Bacillus cereus is an important enterotoxigenic food borne pathogen. The present study was undertaken to assess the occurrence of B. cereus in tropical fish and evaluation of virulent gene specific PCR for differentiation of diarrhoeal enterotoxin producing isolates of B. cereus from non enterotoxigenic isolates. Methods: Selective plating on polymixin-pyruvate-egg yolk-mannitol-bromocresol purple agar (PEMPA) was used for isolation of B. cereus from finfish, prawn and clams. Enterotoxin producing ability of all 42 isolates obtained from the samples was judged by reverse passive latex agglutination (RPLA) test and the presence of different virulent genes i.e. hbla, bceT and entFM was screened by PCR. Results: B. cereus and enterotoxigenic B. cereus were found to be in 36.7 and 29.41 per cent of fish samples, respectively. All the diarrhoeal enterotoxin producing isolates showed the presence of hbla gene, but hbla gene was not present in any of the non-enterotoxigenic isolates tested in this study. Interpretation & conclusions: Our findings indicated that hbla gene specific PCR can be employed for differentiation of enterotoxigenic B. cereus isolates from non-enterotoxigenic isolates.

Carriage prevalence and distribution of virulence genes of diarrheagenic Escherichia coli isolated from healthy children under 5 years of age in community

Introduction: Diarrheagenic Escherichia Coli (DEC) is getting more and more important as a cause of diarrhea in children under 5 years of age. Detection of DEC prevalence and distribution of their virulent genes plays an important role in prevention and treatment for E.coli-related diseases and vaccine development. Objectives: This study was conducted with the aim to detect DEC prevalence and the distribution of virulent genes of DEC isolated from healthy children under 5 who were living in the community. Subjects and method: 826 children under-5 living in Ba Vi District, Ha Tay Province were selected. Polymerase chain reactions using specific primers to virulent genes of DEC were used. Results. The study found that the prevalence of DEC was 9.8%, among this EAEC accounted for 3.1%, EHEC 1.8%, EIEC 0.1%, EPEC 1.1%, ETEC 0.1% and two DECs 3.5%. Combinations of virulent genes of EHEC and EHEC+ETEC accounted for 50% of total virulent genes. Conclusion: Five types of DEC were isolated from subjects with the prevalence of 9.8%. The most common virulent genes were combinations of EHEC and ETEC. Further studies are needed to investigate the transmission pathway of DEC in children living in the community.

Detection of Virulent Gene Distribution of Diarrheagenic Escherichia Coli (DEC)

Introduction: There are 5 identified DEC including EAEC, EHEC, EIEC, EPEC and ETEe. Virulent genes (for adherrnee, toxin, antibiotic resistance ...) play important roles in pathogenesis of DEe. Detection of DEC is very important in diagnosis, epidemiology survey and vaccine development. \r\n', u'Objectives: Detection of virulent gene distribution of DEC and non - DEe.\r\n', u'Object and methods: 161 strains of DEC (EAEC, EIEC, EPEC, TEC) and 100 strains of non - DEC were subjected to this study. PCR with specific primers were used to test these genes. \r\n', u'Results: EAEC that accounted for 50% of DEC, was identified and isolated. Aap gene was the highest prevalence in EAEC (96.5%), followed by aggR (79.1 %) and astA (60.5%). 37.2% of the strains harbor all three genes. None of strains had PCR results negative for these 3 genes. ETEC, EPEC and EIEC had aap, and astA gene at the prevalence from 7% to 72.7%. The highest prevalence of aap was seen in EIEC 72.7%), aggR in EIEC (45.5%), and astA in ETEC (50%). 14% of non - DEC had aggR and more than 30% of E. coli had aap and astA gene. \r\n', u'Conclusion: EAEC is prevalent at 50% among Diarreagenic E. coli. Aap is the most prevalent and the most commonly seen among EAEC isolates. The other three genes are at different prevalence. The findings contribute towards the vaccine development against diarrhea caused by E. coli. \r\n', u'