Predictive value of methicillin-resistant staphylococcus aureus nasal swab in patients with COVID-19 pneumonia and secondary bacterial pneumonia.

Objective: To determine the performance measures of admission methicillin-resistant Staphylococcus aureus (MRSA) nasal swabs for MRSA bacterial pneumonia in patients co-infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

Methods: The study included patients admitted with SARS-CoV-2-positive nasopharyngeal specimens, MRSA nasal screens, and bacterial cultures to assess secondary MRSA pneumonia.

Results: 293 patients and 662 microbiological cultures evaluated. Overall, the specificity (91.8% [95% CI 88.6% to 95%]) and negative predictive value (NPV 97.4% [95% CI 95.4% - 99.3%]) of MRSA nasal swabs was high. However, the sensitivity (46.2%; 95% CI 19.1% to 73.3%) and positive predictive value (PPV 20.7%; 95% CI 59.5 - 35.4%) were low. Those patients in the MRSA nasal swab negative group had a shorter median duration of linezolid therapy.

Conclusions: SARS-CoV-2 infection doesn't reduce the specificity or negative predictive value of MRSA nasal swabs for secondary MRSA pneumonia.