Molecular and microbiological diagnosis of Adenovirus and MDR Gram-negative pneumonia in Babylon, Iraq

Background: Adenovirus is a well-known viral pathogen implicated in respiratory tract infections that may advance to severe pneumonia. In contrast, Acinetobacter baumannii is a multidrug-resistant (MDR) opportunistic bacterium often associated with hospital- or war-related pneumonia, particularly in immunocompromised patients. Its extensive resistance mechanisms and ability to form biofilms pose major challenges in treatment. Objective: This study aimed to detect and quantify pneumonia cases caused by adenovirus and A. baumannii, assess their virulence profiles, and investigate the molecular markers related to pathogenicity and resistance. Methods: Ninety clinical specimens (blood and pharyngeal swabs) were collected from patients admitted to hospitals in Babylon, Iraq, between September and December 2024. Sixty-five patients diagnosed with pneumonia and 25 healthy controls were enrolled. Adenovirus was detected and quantified using quantitative real-time PCR (qRT-PCR) targeting the hexon gene, with JTVX as a reference gene. Samples with viral loads exceeding 30 copies were considered positive. Rapid antigen detection using latex chromatography was also performed. A. baumannii was isolated from 20 samples (30%) and identified through culture, biochemical assays, and PCR targeting the blaOXA-51 and intI-1 genes. Antibiotic susceptibility was assessed via disk diffusion. Results: Adenovirus was detected in 75% of pneumonia patients by qRT-PCR, showing significantly elevated viral loads (mean 34,219.99) compared to controls (mean 18.4, p < 0.001). Rapid tests detected adenovirus in 60% of cases. Among the bacterial isolates, 85% carried blaOXA-51 and 15% harbored intI-1, with universal resistance to cefotaxime and amikacin. Hexon gene expression correlated with viral load and disease severity, suggesting its utility as a molecular marker for adenoviral pneumonia. Conclusion: MDR A. baumannii exhibits greater virulence and treatment resistance than adenoviral pneumonia. These findings underscore the need for molecular diagnostics and highlight the urgency of developing effective therapies against resistant bacterial infections.