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Objective To investigate the fosfomycin resistance and its mechanism in extended‐spectrum β‐lactamases (ESBL) producing K lebsiellapneumoniae (K .pneumoniae) from clinical samples . Methods Seventy‐nine isolates of ESBL‐producing clinical K .pneumoniae were collected at Sir Run Run Shaw Hospital ,Zhenjiang University School of Medicine from July 2014 to December 2014 .Minimal inhibitory concentration (MIC ) of fosfomycin was determined by the agar dilution method , and the susceptibility breakpoint was interpreted as ≤32 mg/L according to European Committee on Antimicrobial Susceptibility Testing (EUCAST ) . Phylogenetic clonal patterns were analyzed by pulse‐field gel electrophoresis (PFGE) ,and plasmid size and similarity were revealed by nuclease assay .Filter membrane conjugation assay was carried out for determination of resistance transfer by plasmid .All the isolates were screened for plasmid‐mediated fosfomycin resistance genes by polymerase chain reaction ( PCR ) amplification ,and the structures of up‐and down‐stream resistance genes were analyzed .Results Nine of 79 isolates of ESBL‐producers were resistant against fosfomycin ,and the resistance rate was 11 .4% . PFGE and S1‐PFGE revealed that all the 9 f osA3‐harboring isolates were not clone related and not plasmid similar .All of the 9 resistant isolates were fosA3 positive ,which was one of the plasmid mediated fosfomycin resistance genes .No other fosA or fosC2‐positive resistant genes were found . fosA3 gene coded by resistant isolates was found to be flanked by two copies of IS26 .Conclusions Fosfomycin resistant isolates are emerged in ESBL‐producing clinical K .pneumoniae .Producing fosfomycin‐modifying enzyme fosA3 coded by plasmid is the major mechanism in fosfomycin resistant isolates .The IS26 element accelerates the resistance genes dissemination .
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Objective To investigate the distribution and antibiotic resistance of the K lebsiella pneumoniae strains isolated from clinical infections in terms of serotypes K1 ,K2 and virulence factor rmpA gene .Methods The hypermucoviscous phenotype of K .pneumoniae isolate was determined by string test .K1 and K2 serotypes and rmpA gene were detected using multiplex polymerase chain reaction .Results Of the 144 strains of K .pneumoniae ,the prevalence of hypermucoviscous phenotype ,K1 , K2 serotypes and rmpA gene was 62 .5% (90/144) ,52 .1% (75/144) and 65 .3% (94/144) ,respectively .The prevalence of K1 ,K2 and rmpA K .pneumoniae strains was 90 .7% (68/75) in K1 ,K2 serotypes .The prevalence of K1 ,K2 isolates and rmpA in hypermucoviscous or non‐hypermucoviscous phenoype was 63 .3% (57/90) ,85 .6% (77/90) and 33 .3% (18/54) , 31 .5% (17/54) ,respectively .The prevalence of serotype K1 ,K2 with or without rmpA gene was 72 .3% (68/94) and 14 .0% (7/50 ) respectively . Of the 42 K . pneumoniae strains isolated from liver abscess ,85 .7% (36/42) were hypermucoviscous phenotype and 88 .1% (37/42 ) were serotypes K1 , K2 . For the strains from other abscess , bacteremia ,community acquried pneumonia (CAP) ,urinary tract infection (UTI) and biliary tract infection ,the prevalence of hypermucoviscous phenotype was 81 .3% (13/16) ,40 .5%(15/37) ,85 .7% (12/14) ,52 .4% (11/21) and 21 .4% (3/14) ,respectively ,and the prevalence of serotypes K1 ,K2 was 56 .3% (9/16) ,29 .7% (11/37) ,64 .3% (9/14) ,38 .1% (8/21) and 7 .1% (1/14) ,respectively .K1 serotype isolate accounted for 61 .9% of the strains from liver abscess .The ratio between serotype K1 and K2 was similar in the isolates from other abscess ,CAP ,UTI or bacteremia .Non‐K1 ,K2 serotype isolates were common in biliary tract infection .The prevalence of extended‐spectrum beta‐lactamases (ESBLs ) was 5 .5% in hypermucoviscous phenotypes and 33 .3% in the non‐hypermucoviscous phenotypes .Conclusions rmpA gene is associated with the hypermucoviscous phenotype of K .pneumoniae strains and commonly identified in K1 ,K2 serotype isolates .Serotypes K1 ,K2 isolates are important pathogens in liver abscess and CAP ,and also common in other abscess ,UTI and bacteremia .K1 serotype isolate was most common in liver abscess .The prevalence of K1 or K2 serotype was similar in other infections . The prevalence of ESBLs is lower in hypermucoviscous strains than in non‐hypermucoviscous strains and is associated with lower resistance rate to most of the antibiotics tested .
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Objective To analyze the resistant profile and genotypes ,as well as susceptibility to tigecycline in carbapenemase‐producing K lebsiella pneumoniae for better clinical management of such infections .Methods Nine strains of carbapenemase‐producing K .pneumoniae were isolated from clinical specimens during the period from February 2012 to May 2013 in our hospital .Bacterial identification and antimicrobial susceptibility testing were carried out with VITEK 2 Compact automatic microbiological assay systems .The phenotype of carbapenemase‐producing K . pneumoniae was detected by modified Hodges test .The genotype of carbapenemase was identified by PCR method .The susceptibility to tigecycline was tested by E‐test . Results All the 9 strains of carbapenemase‐producing K . pneumoniae were resistant to the 19 antibiotics tested .Modified Hodges test was positive for 7 strains (77 .8% ) .Target band of carbapenemase gene was identified in all the 9 strains of K . pneumoniae ,and all were confirmed as KPC‐2 gene .All the 9 strains were susceptible to tigecycline .Conclusions The resistance of carbapenemase‐producing K .pneumoniae is still serious .Tigecycline has shown good in vitro activity against such strains .
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To investigate the prevalence and gene types of KPC in Enterobacteriaceae strains isolated from 4 tertiary general hospitals in Hainan area ,a total 43 isolates which were resistant or intermediate to imipenem or ertapenem were collected from sterile sites between August 2012 and June 2013 from 4 tertiary general hospitals in Hainan area .Modified Hodge Tests (M HT ) were performed for KPC phenotype screening .PCR amplification and DNA sequence were performed to analyze the encoding genes of KPC .Results showed that in the 43 isolates ,21 strains were positive in M HT .PCR and DNA sequence analysis confirmed that 3 isolates produced KPC‐2 .It's suggested that there were the Enterobacteriaceae carrying KPC in Hain‐an area .The encoding genes were KPC‐2 .The KPC gene could be horizontally transmitted by plasmid among different groups of bacteria .It is important to control the transmission of these Enterobacteriaceae carrying KPC .
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Objective To investigate the drug-resistance of Pseudomonas aeruginosa which producing K lebsiella pneumoniae carbapenemases(KPC) .Methods Pseudomonas aeruginosa strains were derived from two sputum samples .VITEK 2 COMPACT Automated Microbial Identification/Susceptibility Analyzer was employed to identify the bacterial strains .Polymerase chain reaction (PCR) and gene sequencing were adopted to identify the genotypes of KPC enzyme ,Broth dilution method was used to measure the minimal inhibitory concentration(MIC) of antimicrobial agents .Results Both Pseudomonas aeruginosa strains were resistant to β-lactam antibiotic and levofloxacin ,and were intermediary to ciprofloxacin ,and sensitive to gentamicin ,netilmicin ,tobramycin ,colistin and multi-polymyxin B .One of them was sensitive to tigecycline .Carbapenemase produced by the two stains was not metal β-lacta-mase ,with the subtype of KPC-2 .Mating experiments failed to prove the bla K PC gene could be transferred to E .coli J53 .Conclu-sion Appearance of KPC-producing Pseudomonas aeruginosa poses serious challenges to clinical anti-infective therapy .