Samta Shukla¹*, Shrikant Kol¹, Atul Kumar Tiwari² and CB Shukla³

¹Faculty, Centre for Biotechnology and Microbiology Studies, A.P.S. University, Rewa, Madhya Pradesh, India
²Associate Professor, Department of Environmental Biology, A.P.S. University, Rewa, Madhya Pradesh, India
³Ex Professor and Head, Department of Microbiology, S.S. Medical College, Rewa, Madhya Pradesh, India

*Corresponding Author: Samta Shukla, Faculty, Centre for Biotechnology and Microbiology Studies, A.P.S. University, Rewa, Madhya Pradesh, India.

Received: September 09, 2026; Published: October 05, 2026

Abstract

Background: Community-acquired pneumonia (CAP) remains a leading cause of infectious hospitalization worldwide. Although Streptococcus pneumoniae predominates globally, etiological patterns vary across Europe, Asia, and the United States. This study provides an expanded retrospective evaluation of microbiological etiology, diagnostic yield, seasonal variation, and mortality predictors among 1901 hospitalized adults, integrating global comparative epidemiology.

Methods: Retrospective cohort analysis of adults with radiographically confirmed CAP. Microbiological testing included blood cultures, sputum cultures, urinary antigen assays, and viral PCR. Multivariate logistic regression identified predictors of specific pathogens and mortality.

Results: Pathogen identification occurred in 25.7% of cases. Streptococcus pneumoniae (45.7%) remained predominant, followed by Haemophilus influenzae (19.8%), gram-negative bacilli (10%), influenza virus (9%), and Legionella pneumophila (7.6%). Dementia, COPD and advanced age independently predicted gram-negative infection, while active smoking predicted Legionella infection. Pseudomonas aeruginosa was independently associated with mortality (OR 13.02, 95% CI 2.94 - 57.7).

Conclusion: CAP etiology demonstrates substantial clinical and geographic heterogeneity. Risk-adapted empiric therapy and comprehensive diagnostic strategies are essential to improve outcomes.

Keywords: Community-Acquired Pneumonia (CAP); Streptococcus pneumoniae; Adult Community-Acquired Pneumonia; Legionella pneumophila; Pseudomonas aeruginosa

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Citation

Citation: Samta Shukla., et al. “Microbiological Etiology, Clinical Patterns, and Diagnostic Yield in Adult Community-Acquired Pneumonia: A Retrospective Study". Acta Scientific Microbiology 9.10 (2026): 16-24.

Copyright

Copyright: © 2026 Samta Shukla., et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.