More to MRSA infection than just exposure to antibiotics

Nov 1 2004

Johns Hopkins researchers report potentially life-threatening hospital infections with bacteria resistant to the antibiotic methicillin can occur even if patients havent been treated with that drug. But, they add, these infections can be stopped with one of medicines oldest and most powerful antibacterial treatments: hand washing.

We know there is more to MRSA infection than just exposure to antibiotics, says infection control and antibiotic management expert Xiaoyan Song, M.D., M.S., a research associate at Hopkins. So the best way to avoid these infections is for doctors and nurses to wash their hands before they touch you, and for patients to tell their caregivers to wash their hands before they touch you.

Song led a look-back study of 2,279 patients admitted to Hopkins between 2000 and 2002. None of the patients had a history of methicillin-resistant Staphylococcus aureus (MRSA) infection, after hospital stays averaging 19 days, but 3.4 percent (77) patients acquired the infection anyway.

Compared to patients who remained MRSA-free at discharge, MRSA patients tended to have additional medical problems, such as chronic respiratory illness and/or liver or kidney disease. In addition, patients infected with MRSA were also more likely to be admitted to an intensive care unit or a medical ward, or to have been transferred from other health care facilities. The Hopkins researchers suspect that unclean hands among health care workers were the likely cause.

The Hopkins team discovered that there was no exclusive or clear association in their patient population between those given antibiotics and those who acquire S. aureus bacteria resistant to methicillin. MRSA infections can cause serious pneumonia or surgical wound infections, says Song.

Although patients infected with MRSA were up to 2.6 times more likely to have been treated with an antibiotic such as carbapenem or vancomycin, the researchers found that antibiotic treatment alone was not a risk factor for acquiring this organism.