P-681. Evaluation of Clinical Characteristics and Antimicrobial Stewardship Interventions in Mycoplasma pneumoniae Infections at a Community Teaching Hospital

Abstract Background Patients admitted with community-acquired pneumonia (CAP) are empirically treated with broad-spectrum antibiotics due to challenges identifying causative organisms. Mycoplasma pneumoniae is a common atypical pathogen but has historically been difficult to detect. Implementation of rapid molecular diagnostics at our institution improved detection of M. pneumoniae, supporting more targeted interventions by the Antimicrobial Stewardship Program (ASP). A recent rise in M. pneumoniae cases presented an opportunity to assess clinical characteristics, management, and stewardship impact. Methods We performed a retrospective review of patients admitted to our institution from June 2024 – March 2025 with M. pneumoniae identified by PCR, including the Respiratory Pathogen Panel (RPP) and the Pneumonia Panel (PN). Data collected included demographics, comorbidities, imaging, co-infections, antimicrobial therapy, ASP interventions, and outcomes. Results 55 patients were reviewed (median age 46 years, 60% female), with most diagnoses occurring in fall months (September–November). Dyspnea and cough were the most common complaints. Pneumonia was diagnosed in 76% of cases and 19% of those were admitted to the ICU. Potential co-pathogens were observed in 44%, including bacterial (14%), viral (16%), and mixed (13%) cases. Median length of stay was 3 days; mortality was 5.5%. Most patients received azithromycin (47%) or doxycycline (45%). The ASP provided 53 interventions across 29 patients, including 7 in which atypical coverage was initiated. Median procalcitonin and WBC were 0.13 and 10, respectively. Additional results in Tables 1–3. Conclusion A marked rise in M. pneumoniae cases was observed over the review timeframe, consistent with known cyclical trends and potentially influenced by reduced public health mitigation measures following the COVID-19 pandemic. Most infections occurred in younger female patients with typical clinical findings and were managed on general medical floors with short stays. Rapid diagnostic testing facilitated early identification and enabled ASP-led optimization of antimicrobial use. These observations highlight the importance of ongoing surveillance of atypical pathogens and the role of stewardship in improving targeted therapy. Disclosures Thomas M. File, Jr., MD, MSc, MACP, FIDSA, Merck: Advisor/Consultant|MicroGenDx: Advisor/Consultant|Paratek: Advisor/Consultant|Shionogi: Advisor/Consultant|Shionogi: Honoraria|ThermoFisher: Advisor/Consultant|ThermoFisher: Honoraria