MRSA Treatment: Can Shorter Drug Combinations Be Safer?

Why does the pandemic's resistance setback matter for antibiotic treatment?

The CDC's COVID-19 and antimicrobial resistance reporting describes how disrupted infection prevention, staffing shortages and antibiotic prescribing complicated hospital care. Its update covering 2021–2022 reported a combined 20% increase in six types of resistant bacterial infections beginning in hospitals during the pandemic compared with the preceding period. These are historical surveillance findings, rather than a measurement of infection rates today. [CDC surveillance update](https://www.cdc.gov/antimicrobial-resistance/data-research/threats/update-2022.html)

The pattern was not identical for every organism: by 2022, MRSA was the exception among those six, with rates no longer above the pre-pandemic baseline. Nevertheless, treating resistant infections remains a clinical challenge. The practical implication is that preventing transmission and improving prescribing must accompany drug development; simply exposing patients to additional antibiotics does not establish that their treatment is better. [CDC pandemic assessment](https://www.cdc.gov/antimicrobial-resistance/data-research/threats/covid-19.html)

What did CAMERA2 find about combining antibiotics for MRSA?

CAMERA2, published in JAMA in 2020, randomized 352 adults with MRSA bloodstream infections to standard therapy with vancomycin or daptomycin, with or without seven days of flucloxacillin, cloxacillin or cefazolin. Almost all participants received vancomycin. The main outcome combined death, persistent bloodstream infection, relapse and treatment failure. It occurred in 35% of the combination group and 39% of the standard-treatment group, without a statistically significant difference. [CAMERA2 trial](https://jamanetwork.com/journals/jama/fullarticle/2760737)

Although fewer combination recipients still had positive blood cultures on day five, kidney injury occurred in 23% versus 6% among evaluable participants not receiving dialysis at baseline. Recruitment stopped early over safety concerns. The study illustrates why faster bacterial clearance must be weighed against organ injury and patient outcomes; it also leaves uncertainty because enrollment ended before the planned sample was reached. [Trial results](https://jamanetwork.com/journals/jama/fullarticle/2760737)

Could shorter combination treatment preserve benefits with less kidney harm?

A post hoc CAMERA2 analysis published online in April 2026 examined beta-lactam exposure before and after randomization. Early exposure, during treatment before enrollment, was associated with faster bloodstream clearance without a statistically clear increase in kidney injury. Longer exposure patterns showed stronger associations with kidney injury. [Duration analysis](https://www.sciencedirect.com/science/article/pii/S1198743X26001904)

These exposure groups were reconstructed after the trial rather than randomly assigned as competing duration strategies. Differences between patients could therefore influence the results, and the kidney-risk estimate for early exposure was imprecise. The findings support testing shorter combinations prospectively; they do not establish a prescribing protocol or justify shortening the entire course of MRSA treatment. [Study methods and conclusions](https://www.sciencedirect.com/science/article/pii/S1198743X26001904)