Use of rapid polymerase chain reaction-based diagnostic tests for methicillin-resistant Staphylococcus aureus (MRSA) significantly reduced the use of vancomycin and linezolid in patients who were mechanically ventilated with suspected pneumonia at risk for MRSA, according to a study published in CHEST.

This prospective, unblinded randomized clinical trial ( Identifier: NCT02660554) was designed to determine if rapid diagnostic testing for MRSA in bronchoalveolar lavage could safely decrease the use of vancomycin and/or linezolid for patients with suspected MRSA pneumonia. Rapid diagnostic testing was compared with care as usual, and the primary outcome was the duration of vancomycin or linezolid administration. Secondary end points concerned safety, including the need for additional anti-MRSA treatment within 28 days, hospital length of stay, and in-hospital mortality. Patients (N=45) were randomly assigned to antibiotic management based on rapid diagnostic testing (n=22) or to usual care (n=23).

Duration of antibiotic administration was significantly reduced in the rapid diagnostic testing group (32 hours [IQR, 22-48] vs 72 hours [IQR, 50-113]; P <.001). Lower rates of complications and length of hospital stay were observed in the rapid diagnostic testing group, with 13.6% hospital mortality compared with 39.1% in the usual care group (95% CI, –3.3% to 50.3%; P =.06). The standardized mortality ratio was 0.48 for the rapid diagnostic testing group and 1.18 for the usual care group.

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Despite limitations such as the bronchoalveolar lavage samples coming from a critically ill cohort at a single treatment center with a relatively low prevalence of culture-positive MRSA pneumonia, study investigators concluded that tests for MRSA “resulted in significant reductions in use of anti-MRSA agents… Stopping or avoiding anti-MRSA antibiotic use based on [rapid polymerase chain reaction] results not only had no adverse effects, but was actually associated with trends in lower adverse events, hospital length of stay, and in-hospital mortality. Early safe discontinuation of anti-MRSA antibiotics based on rapid diagnostic testing can play an important role in antibiotic stewardship.”

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Disclosures: Richard G. Wunderink declares an affiliation with bioMerieux and Curetis.


Paonessa JR, Shah RD, Pickens CI, et al. Rapid detection of methicillin-resistant Staphylococcus aureus in bronchoalveolar lavage: a pilot randomized controlled trial [published online February 15, 2019]. CHEST. doi:10.1016/j.chest.2019.02.007