Detection of methicillin-resistant and methicillin-susceptible Staphylococcus aureus colonization of healthy military personnel by traditional culture, PCR, and mass spectrometry

Ashley G. Shaw, Todd J. Vento, Katrin Mende, Rachael E. Kreft, Garth D. Ehrlich, Joseph C. Wenke, Tracy Spirk, Michael L. Landrum, Wendy Zera, Kristelle A. Cheatle, Charles Guymon, Tatjana P. Calvano, Elizabeth A. Rini, Charla C. Tully, Miriam L. Beckius, Clinton K. Murray

Research output: Contribution to journalArticlepeer-review

14 Scopus citations

Abstract

Background: Methicillin-resistant (MRSA) and methicillin-susceptible (MSSA) Staphylococcus aureus colonization is associated with increased rates of infection. Rapid and reliable detection methods are needed to identify colonization of nares and extra-nare sites, particularly given recent reports of oropharynx-only colonization. Detection methods for MRSA/MSSA colonization include culture, PCR, and novel methods such as PCR/electrospray ionization time-of-flight mass spectrometry (ESI-TOF-MS). Methods: We evaluated 101 healthy military members for S. aureus colonization in the nares, oropharynx, axilla, and groin, using CHROMagar S. aureus medium and Xpert SA Nasal Complete PCR for MRSA/MSSA detection. The same subjects were screened in the nares, oropharynx, and groin using PCR/ESI-TOF-MS. Results: By culture, 3 subjects were MRSA-colonized (all oropharynx) and 34 subjects were MSSA-colonized (all 4 sites). PCR detected oropharyngeal MRSA in 2 subjects, which correlated with culture findings. By PCR, 47 subjects were MSSA-colonized (all 4 sites); however, 43 axillary samples were invalid, 39 of which were associated with deodorant/anti-perspirant use (93%, p < 0.01). By PCR/ESI-TOF-MS, 4 subjects were MRSA-colonized, 2 in the nares and 2 in the oropharynx; however, neither of these correlated with positive MRSA cultures. Twenty-eight subjects had MSSA by PCR/ESI-TOF-MS, and 41 were found to have possible MRSA (S. aureus with mecA and coagulase-negative Staphylococcus (CoNS)). Conclusion: The overall 3% MRSA colonization rate is consistent with historical reports, but the oropharynx-only colonization supports more recent findings. In addition, the use of deodorant/anti-perspirant invalidated axillary PCR samples, limiting its utility. Defining MRSA positivity by PCR/ESI-TOF-MS is complicated by co-colonization of S. aureus with CoNS, which can also carry mecA.

Original languageEnglish (US)
Pages (from-to)752-759
Number of pages8
JournalScandinavian Journal of Infectious Diseases
Volume45
Issue number10
DOIs
StatePublished - Oct 2013
Externally publishedYes

Keywords

  • Electrospray-ionization
  • Ibis T5000
  • MRSA
  • MSSA
  • Mass spectrometry
  • Microbiology
  • PCR
  • Time-of-flight

ASJC Scopus subject areas

  • Immunology and Microbiology(all)
  • Microbiology (medical)
  • Infectious Diseases

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