Patients who carry MRSA may have increased risk for infection, mortality

Patients with a history of MRSA – as well as those with newly-acquired MRSA – should be targeted for intervention.

Issue: August 2008

Patients with methicillin-resistant Staphylococcus aureus who have been known carriers for at least one year may be at an increased risk for mortality and morbidity, according to the results of a new study jointly conducted by researchers at Harvard University and the University of California Irvine.

Susan Huang, MD, from the division of infectious diseases at the University of California Irvine Medical Center, said the results indicate that patients with a history of MRSA – as well as those with newly-acquired MRSA – should be targeted for intervention.

The study was conducted as a single-center retrospective cohort study and was designed to evaluate the risk for subsequent MRSA infection and mortality among patients who had harbored MRSA for at least one year. Two hundred eighty-one patients who met this criteria were identified as “prevalent carriers” of MRSA and were included in the study.

The results were published in Clinical Infectious Diseases.

Patients’ risks

Sixty-five (23%) of the patients developed 96 discrete and unrelated MRSA infections during the one-year period following their identification as prevalent carriers. According to Huang, the most common infections among these patients were pneumonia, soft-tissue infection and central venous catheter infection.

Thirty-eight MRSA infections occurred during new hospitalizations; 32 of these infections were the reason for admission.

MRSA was associated with 14 deaths; six of these deaths were deemed “attributable to MRSA.”

According to Huang, the results indicated that patients who harbored MRSA for less than two years and those who had MRSA colonization at the time of their identification as a prevalent carrier were more likely to experience subsequent infection with MRSA.

Huang told Infectious Disease News that although the results indicated an increased mortality risk for patients who harbored MRSA, more information is needed before researchers can predict which other factors may increase mortality risk. “In this study, mortality due to MRSA existed and is worrisome,” she said. “Nevertheless, the numbers were not high enough to assess predictors of death. We did assess predictors of infection among long-term carriers and did not find any specific health factors that increased risk. However, in prior studies of infection, wounds, diabetes, and hemodialysis have been found to be risk factors for MRSA disease.”

Advice for physicians

Huang said that since the findings were based on a population-based study, the results are not able to inform a specific individual patient’s risk. “Nevertheless, physicians should know that the risk for morbidity is quite high among the chronically and critically ill and they should at minimum weigh the risk and benefits of decolonization therapy among that patient group,” she said. “These decisions must be made at the individual physician level since there are no guidelines on decolonization and active research is ongoing.”

Huang added that doctors should urge patients with MRSA to be vigilant about protecting themselves to prevent further complications. “General good hygiene, hand washing and vigilance to any incurred cuts or wounds – even if seemingly trivial – is a good idea,” Huang said. “Those who have recurrent MRSA infection should consult with their physician for other instructions and options, including decolonization.” – by Jay Lewis

For more information:

Datta R, Huang S. Risk of infection and death due to methicillin-resistant Staphylococcus aureus in long-term carriers. Clin Infect Dis. 2008;47:176-181.