When patients are hospitalized with COVID-19, clinicians are often concerned about bacterial co-infections, among which is methicillin-resistant Staphylococcus aureus (MRSA) . Obtaining respiratory cultures can be difficult due to lack of sputum or concern for aerosolizing the virus. As a result, many physicians prescribe Vancomycin with other antibiotics to COVID-19 patients in case they are co-infected with MRSA—a practice that may lead to antibiotic resistant organisms or even kidney injury.

In a study published online on August 26 in Infection Control & Hospital Epidemiology involving more than 4,000 patients admitted to Montefiore Medical Center, Chitra Punjabi, M.D., Liise-anne Pirofski, M.D., and colleagues determined the prevalence of MRSA co-infection in COVID-19 patients and the diagnostic usefulness of the MRSA Nares (nasal) PCR test, which is conveniently obtained with nasal swabs and therefore avoids the risk of aerosolization. The MRSA nasal test’s accuracy was assessed by comparing its results with results from respiratory cultures obtained from the same COVID-19 patients.

MRSA was found to be an uncommon respiratory co-pathogen in COVID-19 patients. In addition, the MRSA Nares PCR test performed well at diagnosing MRSA infection and produced no false-negative results. The findings suggest that administering Vancomycin for the possible presence of MRSA is not indicated for COVID-19 patients and that obtaining a negative nares test for MRSA could help to stop the use of this antibiotic.

Dr. Punjabi is an assistant professor of medicine at Einstein and an attending physician at Montefiore. Dr. Pirofski is chief of infectious diseases at Montefiore and Einstein, professor of medicine, and of microbiology & immunology at Einstein. She is also a Selma and Dr. Jacques Mitrani Professor in Biomedical Research at Einstein.