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Comparative molecular analysis of community- or hospital-acquired methicillin-resistant Staphylococcus aureus
Journal article   Open access   Peer reviewed

Comparative molecular analysis of community- or hospital-acquired methicillin-resistant Staphylococcus aureus

P D Fey, B Saïd-Salim, M E Rupp, S H Hinrichs, D J Boxrud, C C Davis, B N Kreiswirth and P M Schlievert
Antimicrobial agents and chemotherapy, Vol.47(1), pp.196-203
01/2003
DOI: 10.1128/aac.47.1.196-203.2003
PMCID: PMC149027
PMID: 12499191
url
https://doi.org/10.1128/aac.47.1.196-203.2003View
Published (Version of record) Open Access

Abstract

Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) is a growing public health concern that has been associated with pediatric fatalities. It is hypothesized that the evolution of CA-MRSA is a recent event due to the acquisition of mec DNA by previously methicillin-susceptible strains that circulated in the community. This study investigated the genetic relatedness between CA-MRSA, hospital-associated MRSA (HA-MRSA), and nonmenstrual toxic shock syndrome (nmTSS) isolates. Thirty-one of 32 CA-MRSA isolates were highly related as determined by pulsed-field gel electrophoresis and spa typing yet were distinguishable from 32 HA-MRSA strains. The 31 related CA-MRSA isolates produced either staphylococcal enterotoxin B (n = 5) or C (n = 26), and none made TSS toxin 1. All CA-MRSA isolates tested contained a type IV staphylococcal cassette chromosome mec (SCCmec) element. In comparison, none of the HA-MRSA isolates (n = 32) expressed the three superantigens. Antibiotic susceptibility patterns were different between the CA-MRSA and HA-MRSA isolates; CA-MRSA was typically resistant only to beta-lactam antibiotics. Six of twenty-one nmTSS isolates were indistinguishable or highly related to the CA-MRSA isolates. MnCop, an nmTSS isolate obtained in Alabama in 1986, was highly related to the CA-MRSA isolates except that it did not contain an SCCmec element. These data suggest that CA-MRSA strains may represent a new acquisition of SCCmec DNA in a previously susceptible genetic background that was capable of causing nmTSS. CA-MRSA poses a serious health risk not only because it is resistant to the antibiotics of choice for community-acquired staphylococcal infections but also because of its ability to cause nmTSS via superantigen production.
 Phenotype Community-Acquired Infections - genetics Staphylococcus aureus - genetics Methicillin Resistance - genetics Staphylococcus aureus - isolation & purification Humans Indians, North American - genetics Cross Infection - genetics Electrophoresis, Gel, Pulsed-Field Nebraska

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