Written by Clay Smith
Empiric anti-MRSA antibiotics were not associated with improved mortality in hospitalized patients with pneumonia. In fact, this evidence suggests they might actually do worse.
Why does this matter?
Antibiotics have downside risks, such as kidney injury or secondary infections. In the recent IDSA/ATS community acquired pneumonia guidelines, HCAP was abandoned. Broader spectrum therapy was not found to improve outcomes, per these guidelines. Does empiric anti-MRSA therapy help or hurt?
This was a retrospective multicenter study over 6 years across the Veteran’s Health Administration hospitals, with 88,605 patients hospitalized for pneumonia included. For the primary outcome, patients who received empiric anti-MRSA antibiotics in addition to standard antibiotic therapy (i.e. beta-lactam + macrolide) were propensity matched with those who did not. They found, after adjustment, that the risk of mortality was greater in those who received anti-MRSA treatment than those who did not; adjusted risk ratio, aRR 1.4 (95%CI, 1.3-1.5). They also found an increase in secondary outcomes of kidney injury and secondary infections, such as C. difficile colitis and vancomycin-resistant Enterococcus. Even in the subgroup of patients with risk factors for MRSA*, empiric anti-MRSA therapy suggested higher mortality compared to standard CAP therapy; aRR 1.2 (95%CI 1.1-1.4). There was also no mortality benefit to anti-MRSA antibiotics in patients sick enough to go to the ICU; aRR 1.3 (95%CI 1.2-1.5). Even if propensity matching may not account for all possible confounding – namely, sicker patients got vancomycin and also had higher mortality – this gives me pause to empirically start anti-MRSA drugs in most pneumonia patients.
*Risk for MRSA was defined as: “history of MRSA infection or colonization in the past year or at least 2 of the following: previous hospitalization, nursing home residence, and previous intravenous antibiotic therapy”
Empirical Anti-MRSA vs Standard Antibiotic Therapy and Risk of 30-Day Mortality in Patients Hospitalized for Pneumonia. JAMA Intern Med. 2020 Feb 17. doi: 10.1001/jamainternmed.2019.7495. [Epub ahead of print]
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