title: Detection and analysis of Staphylococcus aureus isolates found in ambulances in the Chicago metropolitan area.
abstract: BACKGROUND
  Given the frequency with which many different strains of Staphylococcus aureus are found in various prehospital settings, this study sought to characterize S aureus isolates taken from one such environment. The objectives were to determine the frequency of S aureus in front-line, advanced life support (ALS) ambulances throughout the Chicago metropolitan area, and to generate antibiograms (antibiotic resistance profiles) for each S aureus isolate using 8 clinically relevant antibiotics.
  
  
  METHODS
  Samples were obtained from 26 sites in 71 ambulances from 34 different Chicago-area municipalities. Selected colonies that demonstrated a growth pattern consistent with that of S aureus were subjected to a latex agglutination test specific for S aureus. Antibiograms and genetic analyses were performed on all latex agglutination test-positive isolates.
  
  
  RESULTS
  At least one S aureus isolate was found in approximately 69% of all ambulances in the study. Of all isolates detected, 77% showed resistance to at least one antibiotic, and 34% displayed resistance to 2 or more antibiotics. Some level of oxacillin resistance was found in 21% of isolates; however, only slightly more than half of these oxacillin-resistant isolates were found to carry the methicillin-resistant S aureus-specific SCCmec cassette. Some 12% of all isolates were ultimately determined to be methicillin-resistant S aureus, whereas the remaining 88% were methicillin-sensitive S aureus with varying antibiograms.
  
  
  CONCLUSIONS
  Antibiotic resistance appears to be prevalent in S aureus isolates detected in Chicago area ALS ambulances. Given the ease with which S aureus can survive on inanimate surfaces and exchange antibiotic resistance elements, a conscientious approach to the application of existing cleaning techniques, especially in key ambulance sites, is needed. Future work will include further characterizing isolates using multiple techniques, as well as follow-up studies with interested municipalities.
authors.affiliation: Department of Biology, Lewis University, Romeoville, IL, USA. ragoja@lewisu.edu
authors.forename: James V
authors.initials: JV
authors.lastname: Rago
authors.forename: Lieutenant Keith
authors.initials: LK
authors.lastname: Buhs
authors.forename: Viktorija
authors.initials: V
authors.lastname: Makarovaite
authors.forename: Esha
authors.initials: E
authors.lastname: Patel
authors.forename: Melissa
authors.initials: M
authors.lastname: Pomeroy
authors.forename: Christian
authors.initials: C
authors.lastname: Yasmine
mesh_terms: D000552:Ambulances; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002641:Chicago; D024881:Drug Resistance, Bacterial; D004783:Environmental Microbiology; D006801:Humans; D008826:Microbial Sensitivity Tests; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000302:isolation & purification*
chemical_list: D000900:Anti-Bacterial Agents