title: A combined multi-virulence-locus sequence typing and Staphylococcal Cassette Chromosome mec typing scheme possesses enhanced discriminatory power for genotyping MRSA.
abstract: Methicillin-resistant Staphylococcus aureus (MRSA) remains a major threat to human populations worldwide. Knowing the extent of MRSA genetic diversity within a healthcare facility may provide important insights into the epidemiology of this important pathogen. MRSA isolates recovered from nasal swabs of patients entering the Intensive Care Unit of the Penn State Milton S. Hershey Medical Center, USA, from 2008 to 2009 were genotyped using Staphylococcal Cassette Chromosome mec (SCCmec), multilocus sequence typing (MLST) and a newly developed multi-virulence-locus sequence typing (MVLST) scheme. Sequence data for seven housekeeping genes (arcC, aroE, glpF, gmk, pta, tpi and yqiL) and six virulence genes (alt, essC, geh, hlgA, htrA and sdrC) were used for MLST and MVLST analyses, respectively. MLST identified 12 sequence types (STs) within the hospital isolates. One ST designated ST5 was the most common subtype (38.8%) followed by ST105 (22.4%) and ST8 (16.4%). In contrast, MVLST identified 29 STs (Virulence Types, VTs) from the same set of isolates, with VT6 (32.8%) being the predominant subtype followed by VT9 (8.9%) and VT2 (8.9%). Subsequent analysis of 25 MRSA isolates associated with an outbreak at a Pennsylvania state prison revealed all isolates were VT2 and SCCmec type IVa. These results suggest that a combination of MVLST and SCCmec typing may clarify the epidemiology of MRSA. Additional research with a more diverse set of strains and correlation with conventional epidemiologic data are needed to validate this new subtyping strategy.
authors.affiliation: Department of Food Science, The Pennsylvania State University, University Park, PA 16802, USA.
authors.forename: Bindhu
authors.initials: B
authors.lastname: Verghese
authors.forename: Nathan D
authors.initials: ND
authors.lastname: Schwalm
authors.forename: Edward G
authors.initials: EG
authors.lastname: Dudley
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Knabel
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics*; D016000:Cluster Analysis; D005798:Genes, Bacterial; D014644:Genetic Variation; D006801:Humans; D007362:Intensive Care Units; D015810:Linkage Disequilibrium; D055624:Methicillin-Resistant Staphylococcus aureus / Q000145:classification / Q000235:genetics* / Q000472:pathogenicity*; D058885:Multilocus Sequence Typing; D009296:Nasal Cavity / Q000382:microbiology; D046915:Penicillin-Binding Proteins; D010414:Pennsylvania / Q000453:epidemiology; D015203:Reproducibility of Results; D012641:Selection, Genetic; D013203:Staphylococcal Infections / Q000453:epidemiology / Q000382:microbiology; D014774:Virulence / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D046915:Penicillin-Binding Proteins; C487789:mecA protein, Staphylococcus aureus