Community-acquired Pneumonia in Bangladeshi Children Under Five: Pathogen Prevalence, Resistance Trends, and Diagnostic Biomarkers

Background: Community-acquired pneumonia (CAP) is a leading cause of childhood mortality, with diverse etiologies. This study aimed to generate region-specific data to inform treatment and vaccination strategies for childhood CAP. Methods: We enrolled 226 CAP cases and 201 controls (<5 years) at Dhaka Medical College & Hospital (March 2022–April 2023) in Dhaka, Bangladesh. Blood and nasopharyngeal swabs were collected for pathogen detection. Bacterial isolates were tested for antibiotic susceptibility, pneumococcal isolates were serotyped, and inflammatory markers (C-reactive protein, procalcitonin) were measured. Results: No bacteremic cases of CAP were identified. Streptococcus pneumoniae [odds ratio (OR) = 2.26, 95% confidence interval (CI): 1.5–3.4], respiratory syncytial virus (OR = 6.16, 95% CI: 2.54–14.9), SARS-CoV-2, and influenza A/B were significantly associated with CAP, with SARS-CoV-2 and influenza A/B detected only in cases. Co-identification of pathogenic bacteria and viruses occurred in 14% (33/226) of cases. Over 90% of pneumococcal isolates were non-pneumococcal conjugate vaccine-10 serotypes, and serotype 19A was predominant (19%, 19/101 in cases and 6%, 3/53 in controls). Multidrug resistance was frequent in S. pneumoniae (40%, 71/178) and Haemophilus influenzae (38%, 20/52); 86% of pneumococci were macrolide nonsusceptible. Among Staphylococcus aureus , 76% (31/41) were methicillin-resistant. C-reactive protein and procalcitonin were elevated in severe CAP cases; however, no definitive cutoff threshold distinguished bacterial from viral causes. Conclusions: Our findings highlight the current epidemiology of childhood CAP in Dhaka, Bangladesh, identifying high antimicrobial resistance and predominance of non-pneumococcal conjugate vaccine-10 serotypes. These results underscore the need for continued pneumococcal surveillance to guide vaccine and treatment strategies and strengthened approaches for addressing antimicrobial resistance.