HealthDay News — The majority of advanced-life support (ALS) ambulances in the Chicago area are contaminated with antibiotic-resistant strains of Staphylococcus aureus, study data published in the American Journal of Infection Control indicate.

S. aureus was identified in approximately 69% of ALS ambulances, and 77% of isolates were resistant to at least one antibiotic, James V. Rago, PhD, from Lewis University in Romeoville, Ill., and colleagues found.

“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,” the researchers wrote.

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They investigated the frequency of S. aureus in front-line ALS ambulances using samples obtained from 26 sites in 71 ambulances from 34 Chicago-area municipalities. Antibiotic resistance profiles to eight clinically relevant antibiotics were determined for each isolate.

Resistance to two or more antibiotics was identified in 34% of S. aureus isolates. Resistance to oxacillin was most common, at 21%, and just more than half of these isolates carried the methicillin-resistant S. aureus (MRSA)-specific SCCmec cassette, believed to play a role in the bacteria’s virulence. A total of 12% of isolates were identified as MRSA.

“Future work will include further characterizing isolates using multiple techniques, as well as follow-up studies with interested municipalities,” the researchers wrote.

Rago JV et al. Am J Infect Control. 2012;40(3):201-205.