ABSTRACT
Objective To investigate molecular types and drug resistance of methicillin-resistant Staphylococcus aureus (MRSA) in Zhejiang province.Methods One hundred and fourty-seven clinical MRSA isolates were collected from 11 grade A tertiary hospitals during January 2009 and December 2010 in Zhejiang province.Minimal inhibitory concentrations (MICs) of 13 antimicrobial agents were determined by agar dilution.Multilocus sequence typing (MLST),staphylococcal cassette chromosome mec (SCCmec) typing and spa typing were used to examine the homology of the strains,and drug resistance patterns were compared among different molecular types.Simpson index was used to determine the discriminatory power of three typing methods.Results Fourteen STs were identified in 147 MRSA isolates,of which ST239 (75 isolates),ST5 (24 isolates) and ST59 (23 isolates) were the most prevalent clones.Four SCCmec types (types Ⅱ to Ⅴ) were identified in 141 isolates,and 6 isolates were not typed.SCCmec type Ⅲ was the predominant type (76 isolates),which was followed by type Ⅳ (32 isolates),type Ⅱ (24 isolates) and type Ⅴ (9 isolates).All MRSA isolates yielded 23 spa types,in which t030 (57 strains),t437 (17 strains),t002 (15 strains) and t037 (12 strains) were the predominant spa types.MRSA strains were sensitive to linezolid,teicoplanin,vancomycin and norvancomycin,but were highly resistant to other antibacterial agents,especially in strains carrying clone ST239 or of SCCmec type Ⅲ.The discriminatory power of MLST,SCCmec and spa typing were 0.6885,0.6577 and 0.8165,respectively.Conclusion The predominant clone of MRSA strains in Zhejiang province was ST239-SCCmec Ⅲ-t030-MRSA,and these strains are highly resistant to most antibacterial agents,so that the surveillance of MRSA in hospital should be strengthened.
ABSTRACT
Objective To investigate the genotypes of β-lactamases produced by Klebsiella pneumoniae.Methods Plasmid conjugation,PCR amplification,gene cloning and DNA sequencing,isoelectric focusing electrophoresis and extended-spectrum β-lactamase(ESBLs)confirmatory test were carried out for analyzing the encoding gene of β-lactamases in clinical strains of Klebsiella pneumoniae collected from hospital wards.Results Totally 75 clinical strains of Klebsiella pneumoniae were collected,in which 48 strains were confirmed to produce genotype of β-laetamases(64.0%),including 39 ESBLs-producing Btraim(52.0%).Among 48 strains,17 isolates(35.4%)carried 2 types of ESBLs genes,7(14.6%)carried 3 types of ESBL8 genes,and 5(10.4%)carried 4 types of ESBLs genes.CTX-M was the most comon type(30/48,62.5%),followed by TEM(26/48,54.2%)and SHV(25/48,52.1%).Among 9 isolates with DHA-1 AmpC β-laetamase,8 produced AmpC β-lactamases and ESBLs.Class A carbapenemase KPC-2 was produced in 3 isolates.False negative rate of ESBLs confirmatory test was 23.1%(9/39).Condusion Genotypes of β-lactamases produced by Klebsiella pneumoniae are complicated,which results in multi-drug resistance in clinic.