ABSTRACT
BACKGROUND: Carbapenem-resistant Klebsiella pneumoniae (CRKP) is considered a serious global threat. However, little is known regarding the multidrug resistance (MDR) mechanisms of CRKP. This study investigated the phenotypes and MDR mechanisms of CRKP and identified their clonal characteristics. METHODS: PCR and sequencing were utilized to identify antibiotic resistance determinants. Integron gene cassette arrays were determined by restriction fragment length polymorphism (RFLP) analysis. Multi-locus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE) were used for epidemiological analysis. Plasmids were typed by using a PCR-based replicon typing and analyzed by conjugation and transformation assays. RESULTS: Seventy-eight strains were identified as resistant to at least one carbapenem; these CRKP strains had a high prevalence rate (38.5%, 30/78) of carbapenemase producers. Additionally, most isolates harbored MDR genes, including Extended spectrum β-lactamases (ESBLs), AmpC, and quinolone and aminoglycoside resistance genes. Loss of porin genes was observed, and Class 1 integron was detected in 66.7% of the investigated isolates. PFGE and MLST results excluded the occurrence of clonal dissemination among these isolates. CONCLUSIONS: A high prevalence of NDM-1 genes encoding carbapenem resistance determinants was demonstrated among the K. pneumoniae isolates. Importantly, this is the first report of bla(NDM-1) carriage in a K. pneumoniae ST1383 clone in China and of a MDR CRKP isolate co-harboring bla(NDM-1), bla(KPC-2), bla(CTX-M), bla(SHV), acc(6′)-Ib, rmtB, qnrB, and acc(6′)-Ib-cr.
Subject(s)
China , Clone Cells , Drug Resistance, Bacterial , Drug Resistance, Microbial , Drug Resistance, Multiple , Electrophoresis, Gel, Pulsed-Field , Genes, MDR , Integrons , Klebsiella pneumoniae , Klebsiella , Molecular Epidemiology , Phenotype , Plasmids , Pneumonia , Polymerase Chain Reaction , Polymorphism, Restriction Fragment Length , Prevalence , RepliconABSTRACT
Objective To investigate the molecular epidemiology and infectious risk factors of linezolid-resistant Enterococci (LRE) isolates in the First Affiliated Hospital of Chongqing Medical University.Methods Thirteen LRE isolates were collected from 2011 to 2013 and confirmed by broth dilution susceptibility testing.The minimum inhibitory concentrations (MIC) of twelve antimicrobial agents were analyzed using Vitek 2 compact.The molecular epidemiology of LRE isolates was determined by multilocus sequence typing (MLST), pulsed-field gel electrophoresis (PFGE) and the Diversilab.A casecontrol study was conducted for the analysis of risk factors, and Logistic regression was performed to evaluate the independent risk factors.Results All thirteen LRE isolates showed low-level resistance to linezolid, and most of these isolates were resistant to tetracycline, erythromycin and ciprofloxacin.However, they had high sensitivity to penicillin, ampicillin and tigecycline.Sequence type 480 was predominant in the hospital, and three isolates (isolates 3, 4, and 5) from July to September 2013 were found to have the same ST, PFGE pattern and rep-PCR group, indicating the same resistance clone.Admission to intensive care unit (ICU), peripheral vascular disease, males, hypoalbuminaemia, enema and linezolid therapy were identified as significant risk factors for LRE infections.Among these factors, admission to ICU, enema and linezolid therapy were independent risk factors for the acquisition of LRE.Conclusions Thirteen LRE isolates collected in the hospital showed a multidrug-resistant phenotype, and a small-scale prevalence was detected from 2011 to 2013.Therefore, attention should be paid to monitor the LRE in the hospital to decrease the prevalence of LRE infections.