2046. Local validation of methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa prevalence in a community hospital: A cross-sectional retrospective cohort study
Authors: Nava Guillermo Rodriguez , Nava Guillermo Rodriguez , Egoryan Goar , Kishmiryan Armen 
Published: December 2022

Abstract

Background
Current 2019 management guidelines for community-acquired pneumonia (CAP) recommend against using the category healthcare-associated pneumonia (HCAP) as a basis for selecting extended-spectrum therapy and recommend using site-specific prevalence data. This study aimed to identify the most common pathogens in patients admitted with the diagnosis of HCAP in our community hospital.

Methods
This cross-sectional retrospective cohort study included 560 adult patients admitted to our community hospital located in Evanston, Illinois, between January 1, 2017, and December 31, 2021, with the diagnosis of HCAP (ICD-10-CM code J18.9). We performed regression analyses to compare the prevalence and determine odds ratios (OR) with 95% CIs to compare percentages between our local data and previously reported US HCAP and CAP populations.

Results
Among 560 patients with an admitting diagnosis of HCAP in 5 years, 117 (20.9%) patients had a respiratory pathogen isolate. Of those, 58 (49.6%) were bacterial isolates, 51 (43.6%) were viral, 5 (4.3%) were viral and bacterial coinfections, and 3 (2.6%) were bacterial and fungal coinfections (Figure 1). Methicillin-resistant Staphylococcus aureus (MRSA) was identified in 12 (2.1%) patients, and Pseudomonas aeruginosa was identified in 9 (1.6%) patients, corresponding to 10.3% and 7.7% of patients with an identified respiratory pathogen, respectively. Other common pathogens were influenza virus, Enterobacterales (3 extended-spectrum beta-lactamase and one carbapenem-resistant), Streptococcus pneumoniae, and respiratory syncytial virus (Table 1). Compared to a large US public database of culture-positive HCAP (Kollef et al.), patients from our community hospital had a decreased risk for MRSA (vs. 262/988 [26.5%]: OR 0.23 (95% CI, 0.12 – 0.46; p &lt; .001) and P. aeruginosa (vs. 250/998 [25.3%]: OR 0.25 (95% CI, 0.12 – 0.49; p &lt; .001) among the culture-positive patients. These rates were also significantly lower than overall US CAP populations (Table 2).Figure 1.Isolated organisms in patients with healthcare-associated pneumonia in a community hospital in Evanston, Illinois.Table 1.Other common isolates among patients admitted with the diagnosis of HCAP in our community hospital.Abbreviations: HCAP, healthcare-associated pneumonia, MSSA, methicillin-susceptible Staphylococcus aureus; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.Table 2.Prevalence of positive testing for methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa in our community hospital vs. the overall United States community.
1. Aliberti S, Reyes LF, Faverio P, et al. Global initiative for meticillin-resistant Staphylococcus aureus pneumonia (GLIMP): an international, observational cohort study. Lancet Infect Dis. 2016 Dec;16(12):1364-1376. doi: 10.1016/S1473-3099(16)30267-5.
2. Restrepo MI, Babu BL, Reyes LF, et al. Burden and risk factors for Pseudomonas aeruginosa community-acquired pneumonia: a multinational point prevalence study of hospitalised patients. Eur Respir J. 2018 Aug 9;52(2):1701190. doi: 10.1183/13993003.01190-2017.
Abbreviations: CI, confidence intervals; MRSA, methicillin-resistant Staphylococcus aureus; OR, odds ratios.

Conclusion
The prevalence of MRSA and P. aeruginosa pneumonia in patients categorized as HCAP was low in our community hospital, and the rates were significantly lower than previously reported US rates. Extended-spectrum therapy in our institution should be individualized and not generalized.

Disclosures
All Authors: No reported disclosures.