Increased Mortality Seen With Empirical Anti-MRSA Treatment for Pneumonia

By Will Boggs MD

February 22, 2020

NEW YORK (Reuters Health) - Empirical anti-MRSA treatment is associated with an increased risk of 30-day mortality in patients hospitalized for pneumonia, compared with standard antibiotic therapy, according to a retrospective study.

"What we were most surprised about was that we were unable to establish benefit of early empiric anti-MRSA antibiotics for any group of patients, even those with risk factors for MRSA infection that are traditionally felt to warrant therapy," said Dr. Barbara Ellen Jones of Veterans Affairs Salt Lake City Health Care System and the University of Utah, also in Salt Lake City.

"To me, this calls into question whether our current risk approaches and microbiologic tests are adequate to confidently determine which patients with pneumonia should be treated with early empiric anti-MRSA therapy," told Reuters Health by email.

Timely empirical antibiotic therapy against the most likely pathogens is a cornerstone of pneumonia care, but causative pathogens are rarely identified, leaving the choice of empirical antibiotic therapy uncertain.

Fewer than 5% of hospitalized patients with pneumonia have resistant organisms (like MRSA) detected, but more than a third receive broad-spectrum antibiotics.

Dr. Jones and colleagues used data from the VA health care system to evaluate 30-day risk of death in patients hospitalized for pneumonia who were receiving empirical anti-MRSA therapy plus standard antibiotics versus those receiving standard antibiotics alone.

Among more than 88,000 hospitalizations for pneumonia, empirical anti-MRSA therapy was administered to 38% of patients. Patients receiving empirical anti-MRSA therapy had a greater comorbidity burden, more risk factors for MRSA, greater illness severity and worse outcomes, compared with patients receiving standard therapy alone.

The 30-day all-cause mortality was higher among patients treated with anti-MRSA therapy without (18%) or with standard antibiotics (16%) than among patients treated with standard antibiotics alone (6%), the researchers report in JAMA Internal Medicine.

Compared with standard therapy alone, empirical anti-MRSA treatment plus standard therapy was associated with 40% higher 30-day mortality and empirical anti-MRSA treatment with non-standard antibiotics was associated with 50% higher 30-day mortality in propensity score-weighted analyses.

In subgroup analyses, anti-MRSA therapy was associated with higher 30-day mortality in patients admitted to ICU, those who were at high clinical risk for MRSA, and those in whom MRSA surveillance was PCR-positive. Only among patients who were MRSA culture-positive was there no significant difference in mortality between anti-MRSA and standard empiric therapy.

Use of empirical anti-MRSA therapy was associated with a 40% higher risk of kidney injury, a 60% higher risk of C. difficile infection, a 60% higher risk of vancomycin-resistant Enterococcus species and a 50% higher risk of secondary gram-negative rod detection.

"I think it's important to keep in mind that even though our study did not demonstrate a clear benefit of early anti-MRSA therapy in pneumonia using our current risk approaches, this does not mean that empiric anti-MRSA treatment is inappropriate for everyone," Dr. Jones said. "Instead, I think it suggests that there is just not currently a clear algorithm that can be followed consistently to determine who warrants early therapy - the empiric antibiotic decision must be made one patient at a time."

"If a clinician is highly concerned about MRSA for a specific patient, then early MRSA therapy may be very appropriate for that individual," she said. "On the other hand, for many patients, I hope our study helps clinicians feel more comfortable questioning whether their patients really need anti-MRSA therapy upfront, or whether it may be safe to treat first with standard antibiotics and observe their test results and clinical response."

Dr. Michael Klompas of Brigham and Women's Hospital and Harvard Medical School, in Boston, who wrote an editorial related to this report, told Reuters Health by email, "We need randomized trials comparing empiric management with versus without MRSA coverage to settle the question of whether unnecessary MRSA coverage is harmful or not."

He advised, "Exercise caution both in making the diagnosis of pneumonia and choosing empiric antibiotics. A large fraction of patients treated for pneumonia most likely do not have pneumonia. And just as there is harm in withholding antibiotics from patients with severe infections, there is a strong possibility that giving antibiotics to uninfected patients or unnecessarily broad antibiotics to infected patients also confers harm."

SOURCE: and JAMA Internal Medicine, online February 17, 2020.