Mortality risks from methicillin-resistant staphylococcus aureus (MRSA) increase with age, nursing home residence, and organ impairment, according to a study in the July issue of Emerging Infectious Diseases.

Researchers retrospectively reviewed 699 episodes of MRSA infection in 603 patients at Mount Sinai Medical Center in New York City, including 65 patients who contracted MRSA at least twice between 2002 and 2007. Additional data came from frozen MRSA samples and hospital databases. Researchers then performed a multivariate analysis of risk-factors for all-cause death rates three months after patients contracted MRSA.

Reseachers found that vancomycin was used to treat 81% of MRSA cases, and 27% of MRSA infections resulted in death. They specifically noted that the following variables independently increased a patient's risk of death by MRSA infection by 7% to 15%:

• Cirrhosis;
• Renal insufficiency;
• Having lived in a nursing home before hospitalization; and
• Admission to the ICU.

Furthermore, patients that required vasopressors had an absolute increase in mortality risk by about 50%. Older age also increased risk of death.

However, consultation with an infection disease specialist reduced the risk of death by 11%.

"The adjusted risk difference enables clinicians to use a targeted approach, directed toward patients with the highest risk of death," says study co-author Mina Pastagia of Rockefeller University in New York. Pastagia hopes that the findings will help hospitals develop appropriate prognoses for patients with certain risk factors, and that more patients will consult an infectious disease specialist when appropriate.

Other findings include:

• Over 40% of MRSA patients had surgery within the previous three months;
• A central venous catheter caused 43% of infections;
• Sixty percent of cases were hospital-associated—meaning, patients contracted MRSA 48 after admission and had no health-care associated risks (Bankhead, MedPage Today, 6/13; Pastagia, Emerging Infectious Diseases, July 2012)