Abstract Background M. pneumoniae infections declined during the SARS-COV-2 pandemic and resurged in 2023. This study aimed to characterize contemporary clinical characteristics and macrolide- resistance of M.pneumoniae infections from 2023-2024 in a Maryland-based hospital system. Table 1:Characteristics and diagnostic results of patients with acute respiratory infection/pneumoniaAbbreviations: IQR: Interquartile Range, CRP: C-reactive proteinTable 2:Clinical outcomes of patients with acute respiratory infection/pneumoniaAbbreviations: ED: Emergency Department, ICU: Intensive Care Unit, IQR: Interquartile Range Methods We conducted a retrospective cohort study of patients of all ages with M.pneumoniae infection presenting to 5 hospitals in the Johns Hopkins Health System in Maryland from 2023-2024. We reviewed the Electronic Health Record (EHR) for patients with positive Respiratory Pathogen Panel (RPP), IgM test result, or with M.pneumoniae ICD-10 codes and documented external test result. Patients lacking consistent clinical symptoms or with alternative diagnosis were excluded. For resistance testing, M.pneumoniae DNA was extracted and amplified from RPP swabs. Library preparation was performed with nanopore sequencing and binary alignment maps were analyzed using Integrative Genomics Viewer 2.19.1. Results We identified 431 patients, 377 (87.5 %) by RPP and 54 (12.5%) by IgM. In total, 373 (86.5 %) patients had signs of acute respiratory infection (Table 1). Of those, 25.7% were 5 years, 56.6% were 5-18 years, and 17.7 % were adults. Most commonly, patients had cough, fever, and congestion, and 85% had abnormal Chest X-Ray (CXR) findings. Regarding outcomes (Table 2), 44.8% patients were hospitalized, 30.5% required respiratory support, and 9.4% had Intensive Care Unit (ICU) admission. We identified 58 patients with extrapulmonary manifestations with a median age of 10 years, 65.6% had dermatologic and 24.1% had central nervous system manifestations. We tested 134 (35.9%) RPPs for macrolide resistance testing, of which 35 (26.1%) had genetic polymorphism: 18 in A2063G, 4 in A2064G, and 13 in both genes. Conclusion In this cohort, roughly one quarter of infections were in children 5 years which is atypical for M.pneumoniae infections and the majority of patients had acute lung findings. Of tested specimens, 26% had polymorphism in macrolide-resistance genes. Next, we will assess clinical outcomes among those with detected macrolide resistance. These findings may inform future empiric treatment for M. pneumoniae infections. Disclosures Heba Mostafa, MD, PhD, D(ABMM), Hologic, Qiagen, Diasorin: Grant/Research Support|Qiagen, Diasorin, Roche: Honoraria|Seegene: Advisor/Consultant
Marimuthu et al. (Thu,) studied this question.