Curtis Donskey and colleagues from the Cleveland Veterans Affairs Medical Center, Ohio, US, collected stool samples from inpatients and analysed these for S. aureus. The researchers also took samples from the patients' nostrils, armpits and groins, as well as surrounding surfaces such as bed rails and bedside tables using a moist cotton swab. To determine whether these bacteria would be transferred to the researchers' hands they bravely touched each of the skin and environmental sites with one hand previously disinfected with an alcohol hand rub. Handprints in agar jelly before and after testing were used to determine the presence of bacterial transfer.
The study's most important finding was that patients harbouring S. aureus in both their intestines and noses were significantly more likely than those with this bacterium in their nostrils alone to have positive skin cultures. There was also a statistically non-significant trend toward contaminating surrounding surfaces and bacterial transfer to the investigator's hands.
Cultures from environmental surfaces yielded an average of 12.7 colonies with a range of 1 to 80, while cultures from armpits and groins yielded colonies of bacteria "too numerous to count." Hand cultures after contact with environmental and skin surfaces yielded an average of 15.3 colonies with a range of 1 to 80. Most of the patients colonized with S. aureus had the MRSA (Methicillin-resistant Staphylococcus aureus) strain, which is unaffected by treatment with certain antibiotics.
"Because staphylococci on skin may contaminate devices or wounds and be acquired on hands, our data provide support for the hypothesis that colonization of the intestinal tract may facilitate S. aureus infections and nosocomial transmission," Donskey says.