No abstract

Background The 2019 American Thoracic Society and Infectious Diseases Society of America Community-Acquired Pneumonia (CAP) guidelines concluded that the major risk factors for methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa (PsA) include prior isolation of these organisms and previous hospitalization with IV antibiotic use within 90 days. However, the guidelines recognized that results may vary by region and recommended local validation of risk factors. The primary objective of this study was to determine which potential risk factors are associated with MRSA and Pseudomonas aeruginosa in CAP in our institution. This study also evaluated appropriateness of antibiotics used for empiric CAP therapy. Methods This was a single-center, retrospective cohort study performed in an urban academic medical center in Cleveland, OH. Adults hospitalized for CAP who had a respiratory culture performed between January 2016 and September 2020 were included. Patients were randomized in a 1:1:1 ratio into MRSA, PsA, and non-resistant CAP (NR-CAP) groups. Patients with bacterial co-infections or resistant pathogens other than MRSA or PsA were excluded. Results The study included 111 patients with 37 patients in each group. The median age was 61 years (IQR 52-70), and 58.6% of patients were male. There were no independent risk factors for MRSA (Table 1). Independent risk factors for PsA included prior isolation and enteral feeding (Table 2). MRSA risk factors as defined by the 2019 CAP guidelines were found in 48.6% of patients with MRSA CAP (Figure 1). Guideline-defined PsA risk factors were found in 56.8% of patients with PsA CAP (Figure 2). In NR-CAP, 62.2% received empiric MRSA coverage while only 27% had a guideline-defined risk factor; PsA coverage was administered in 78.4% of NR-CAP patients, but risk factors were found in only 24.3% of this cohort. MRSA and P. aeruginosa Risk Factor Analyses Empiric MRSA and P. aeruginosa Coverage and Guideline-Defined Risk Factors Conclusion Our findings were consistent with the risk factors identified in the 2019 CAP guidelines, but additional risk factors may be present in our patient population. Empiric coverage for MRSA and PsA was disproportionately high relative to the rate of recovery. This study encourages local validation of risk factors; however, further analyses are needed to determine the impact on empiric therapy. Disclosures All Authors: No reported disclosures