title: A diversity of Antibiotic-resistant Staphylococcus spp. in a Public Transportation System.
abstract: OBJECTIVE
  Our goal was to determine the diversity and abundance of Staphylococcus bacteria on different components of a public transportation system in a mid-sized US city (Portland, Oregon) and to examine the level of drug resistance in these bacteria.
  
  
  METHODS
  We collected 70 samples from 2 cm × 4 cm sections from seven different areas on buses and trains in Portland, USA, taking 10 samples from each area. We isolated a subset of 14 suspected Staphylococcus spp. colonies based on phenotype, and constructed a phylogeny from16S rRNA sequences to assist in identification. We used the Kirbye-Bauer disk diffusion method to determine resistance levels to six common antibiotics.
  
  
  RESULTS
  We found a range of pathogenic Staphylococcus species. The mean bacterial colony counts were 97.1 on bus and train floors, 80.1 in cloth seats, 9.5 on handrails, 8.6 on seats and armrests at bus stops, 3.8 on the underside of seats, 2.2 on windows, and 1.8 on vinyl seats per 8 cm(2) sample area. These differences were significant (p < 0.001). Of the 14 isolates sequenced, 11 were staphylococci, and of these, five were resistant to penicillin and ampicillin, while only two displayed intermediate resistance to bacitracin. All 11 isolates were sensitive to trimethoprim-sulfamethoxazole, vancomycin, and tetracycline.
  
  
  CONCLUSIONS
  We found six different strains of Staphylococcus, and while there were varying levels of drug resistance, we did not find extensive levels of multidrug-resistant bacteria, and no S. aureus was found. We found floors and cloth seats to be areas on buses and trains that showed particularly high levels of bacteria.
authors.affiliation: Department of Biology, Portland State University, Portland, Oregon, USA. ; Department of Environmental Health Sciences, School of Public Health, UCLA, Los Angeles, California, USA.
authors.forename: Pamela J
authors.initials: PJ
authors.lastname: Yeh
authors.forename: Dawn M
authors.initials: DM
authors.lastname: Simon
authors.forename: Jess A
authors.initials: JA
authors.lastname: Millar
authors.forename: H Forrest
authors.initials: HF
authors.lastname: Alexander
authors.forename: Darleen
authors.initials: D
authors.lastname: Franklin
keywords: Staphylococcus; antibiotic resistance; community-acquired infections; environmental microbiology; methicillin-resistant Staphylococcus aureus; pathogen transmission; transportation