title: Rapid PCR/ESI-MS-based molecular genotyping of Staphylococcus aureus from nasal swabs of emergency department patients.
abstract: BACKGROUND
  A limitation of both culture-based and molecular methods of screening for staphylococcal infection is that current tests determine only the presence or absence of colonization with no information on the colonizing strain type. A technique that couples polymerase chain reaction to mass spectrometry (PCR/ESI-MS) has recently been developed and an assay validated to identify and genotype S. aureus and coagulase-negative staphylococci (CoNS).
  
  
  METHODS
  This study was conducted to determine the rates, risk factors, and molecular genotypes of colonizing Staphylococcus aureus in adult patients presenting to an inner-city academic emergency department. Participants completed a structured questionnaire to assess hospital and community risks for infection with methicillin-resistant S. aureus (MRSA). Nasal swabs were analyzed by PCR/ESI-MS to identify and genotype S. aureus and CoNS.
  
  
  RESULTS
  Of 200 patients evaluated, 59 were colonized with S. aureus; 27 of these were methicillin-resistant strains. Twenty-four of the 59 S. aureus carriers were co-colonized with a CoNS and 140 of the 200 patients were colonized exclusively with CoNS. The molecular genotypes of the 59 S. aureus strains were diverse; 21 unique molecular genotypes belonging to seven major clonal complexes were identified. Eighty-five of 200 patients carried strains with high-level mupirocin resistance. Of these eighty-five participants, 4 were colonized exclusively with S. aureus, 16 were co-colonized with S. aureus and CoNS, and 65 were colonized exclusively with CoNS.
  
  
  CONCLUSIONS
  The prevalence of S. aureus and methicillin-resistant S. aureus colonization in a random sample of patients seeking care in Emergency Department was 29.5% and 13.5%, respectively. A substantial fraction of the S. aureus-colonized patients were co-colonized with CoNS and high-level mupirocin-resistant CoNS. Determining the molecular genotype of S. aureus during intake screening may prove valuable in the future if certain molecular genotypes become associated with increased infection risk.
authors.affiliation: Department of Community Health and Prevention, Drexel University School of Public Health, Philadelphia, PA, USA. ak955@drexel.edu.
authors.forename: Aleksandar
authors.initials: A
authors.lastname: Kecojevic
authors.forename: Ray
authors.initials: R
authors.lastname: Ranken
authors.forename: David J
authors.initials: DJ
authors.lastname: Ecker
authors.forename: Christian
authors.initials: C
authors.lastname: Massire
authors.forename: Rangarajan
authors.initials: R
authors.lastname: Sampath
authors.forename: Lawrence B
authors.initials: LB
authors.lastname: Blyn
authors.forename: Yu-Hsiang
authors.initials: YH
authors.lastname: Hsieh
authors.forename: Richard E
authors.initials: RE
authors.lastname: Rothman
authors.forename: Charlotte A
authors.initials: CA
authors.lastname: Gaydos
mesh_terms: D000293:Adolescent; D000328:Adult; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data; D005260:Female; D005838:Genotype; D060005:Genotyping Techniques; D006801:Humans; D008297:Male; D008396:Maryland / Q000453:epidemiology; D016106:Methicillin Resistance; D055624:Methicillin-Resistant Staphylococcus aureus / Q000302:isolation & purification; D008875:Middle Aged; D016712:Mupirocin; D009666:Nose / Q000382:microbiology; D016133:Polymerase Chain Reaction / Q000379:methods; D015995:Prevalence; D011446:Prospective Studies; D012307:Risk Factors; D021241:Spectrometry, Mass, Electrospray Ionization; D013203:Staphylococcal Infections / Q000175:diagnosis* / Q000453:epidemiology / Q000382:microbiology; D013211:Staphylococcus aureus / Q000235:genetics*; D055815:Young Adult
chemical_list: D016712:Mupirocin