Bacterial etiology and multidrug resistance patterns in hospital-acquired pneumonia: predominance of Gram-negative pathogens

M. Jubayer Abedin Mallik; Manal Mizanur Rahman; Mohammed Atiqur Rahman; Rajashish Chakrabortty; Samprity Islam; Faysal Ahmed; Rani Bilkis; Shamim Ahmed

doi:10.18203/2320-6012.ijrms20263490

Authors

M. Jubayer Abedin Mallik Department of Respiratory Medicine, Bangladesh Medical University, Dhaka, Bangladesh
Manal Mizanur Rahman Department of Respiratory Medicine, Bangladesh Medical University, Dhaka, Bangladesh
Mohammed Atiqur Rahman Department of Respiratory Medicine, Bangladesh Medical University, Dhaka, Bangladesh
Rajashish Chakrabortty Department of Respiratory Medicine, Bangladesh Medical University, Dhaka, Bangladesh
Samprity Islam Department of Respiratory Medicine, Bangladesh Medical University, Dhaka, Bangladesh
Faysal Ahmed Department of Respiratory Medicine, Bangladesh Medical University, Dhaka, Bangladesh
Rani Bilkis Department of Respiratory Medicine, Bangladesh Medical University, Dhaka, Bangladesh
Shamim Ahmed Department of Respiratory Medicine, Bangladesh Medical University, Dhaka, Bangladesh

DOI:

https://doi.org/10.18203/2320-6012.ijrms20263490

Keywords:

Antibiotic susceptibility, Gram-negative bacilli, Hospital-acquired pneumonia, Multidrug resistance

Abstract

Background: Hospital-acquired pneumonia (HAP) is a major nosocomial infection and is increasingly complicated by multidrug-resistant (MDR) pathogens. Center-specific data on bacterial etiology and susceptibility patterns are essential to optimize empiric therapy and antimicrobial stewardship. Objective was to determine bacterial etiology and MDR burden in HAP, and to describe organism-specific antibiotic susceptibility patterns, emphasizing Gram-negative predominance.

Methods: This cross-sectional study enrolled 100 adult inpatients with HAP (onset ≥48 hours after admission) in the department of respiratory medicine, Bangladesh Medical University, Dhaka, over 12 months, from August 2024 to August 2025. Sputum, induced sputum, or bronchoalveolar lavage specimens were cultured following quality screening, and antimicrobial susceptibility testing was performed by disc diffusion. Results were summarized using frequencies and percentages; MDR was defined as non-susceptibility to at least one agent in three or more antimicrobial classes.

Results: Bacterial growth was obtained in 78.0% of cases, with single-organism isolation in 68.0% and polymicrobial growth in 10.0%. A total of 89 isolates were recovered, predominantly Gram-negative (93.3%). Leading pathogens were Klebsiella spp. (33.7%), Pseudomonas aeruginosa (31.5%), and Acinetobacter spp. (24.7%). Overall MDR prevalence was 87.8%. Cephalosporin susceptibility was low among major Gram-negative organisms, while carbapenem susceptibility was moderate; colistin susceptibility varied across species.

Conclusions: HAP in this cohort was dominated by MDR Gram-negative pathogens with limited susceptibility to commonly used antibiotics, supporting the need for local antibiograms and stewardship-guided empiric therapy.

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