Molecular and clinical characteristics of clonal complex 59 methicillin-resistant Staphylococcus aureus infections in Mainland China

PLoS One. 2013 Aug 7;8(8):e70602. doi: 10.1371/journal.pone.0070602. eCollection 2013.

Abstract

Detailed molecular analyses of Clonal Complex 59 (CC59) methicillin-resistant Staphylococcus aureus (MRSA) isolates from children in seven major cities across Mainland China were examined. A total of 110 CC59 isolates from invasive and non-invasive diseases were analyzed by multilocus sequence typing (MLST), Staphylococcus cassette chromosome mec (SCCmec) typing, staphylococcal protein A (spa) typing and pulsed-field gel electrophoresis (PFGE). Antibiotics susceptibilities, carriage of plasmids and 42 virulence genes and the expression of virulence factors were examined. ST59 (101/110, 91.8%) was the predominant sequence type (ST), while single locus variants (SLVs) belonging to ST338 (8/110, 7.3%) and ST375 (1/110, 0.9%) were obtained. Three SCCmec types were found, namely type III (2.7%), type IV (74.5%) and type V (22.7%). Seven spa types including t437, which accounted for 87.3%, were determined. Thirteen PFGE types were obtained. PFGE types A and B were the major types totally accounting for 81.8%. The dominant clone was ST59-t437-IVa (65.5%), followed by ST59-t437-V (14.5%). The positive rate of luks-PV and lukF-PV PVL encoding (pvl) gene was 55.5%. Plasmids were detected in 83.6% (92/110) of the strains. The plasmid size ranging from 23.4 kb to 50 kb was most prevalent which accounted for 83.7% (77/92). A significantly lower expression of hla was found in ST59-t437-IVa compared with ST59-t437-V. Among the 110 cases, 61.8% of the patients were less than 1 year old. A total of 90 cases (81.8%) were community-associated (CA) infections whereas 20 cases (18.2%) were hospital-associated (HA) infections. Out of the 110 patients, 36.4% (40/110) were diagnosed with invasive infectious diseases in which ST59-t437-IVa accounted for 67.5% (27/40). In brief, ST59-t437-IVa was proved as the dominant clone in CC59 MRSA strains. The carriage rate of pvl gene was high. CC59 MRSA could result in CA and HA infections. The majortiy of MRSA infection children were in young age.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Child
  • China / epidemiology
  • DNA, Bacterial / analysis
  • DNA, Bacterial / genetics
  • Drug Resistance, Microbial / genetics
  • Electrophoresis, Gel, Pulsed-Field
  • Gene Expression Regulation, Bacterial
  • Genes, Bacterial / genetics
  • Humans
  • Methicillin-Resistant Staphylococcus aureus / classification
  • Methicillin-Resistant Staphylococcus aureus / genetics*
  • Methicillin-Resistant Staphylococcus aureus / pathogenicity*
  • Microbial Sensitivity Tests
  • Multilocus Sequence Typing / methods*
  • Plasmids / genetics
  • Prevalence
  • Prospective Studies
  • Reverse Transcriptase Polymerase Chain Reaction
  • Species Specificity
  • Staphylococcal Infections / epidemiology
  • Staphylococcal Infections / microbiology*
  • Virulence / genetics
  • Virulence Factors / genetics

Substances

  • DNA, Bacterial
  • Virulence Factors

Grants and funding

The current study was supported by the National Natural Science Foundation of China and the Research Grants Council of Hong Kong Joint Research Scheme (no. 81061160509) and the National Natural Science Foundation of China (no. 81171648). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.