Quantitative Culture of Bronchoalveolar Lavage Fluid for the Diagnosis of Bacterial Pneumonia at a Tertiary Care Centre

Abstract

Background: Pneumonia remains the leading cause of infectious disease mortality globally, necessitating early diagnosis and appropriate antimicrobial management. Bronchoalveolar lavage (BAL) has been established as a crucial diagnostic tool in both immunocompetent and immunocompromised patients, offering advantages over conventional sputum samples by reducing contamination and providing accurate antimicrobial susceptibility data.

Objectives: This study aimed to evaluate the diagnostic yield of quantitative BAL fluid culture in identifying bacterial pathogens responsible for pneumonia and to assess the antimicrobial susceptibility of these pathogens to guide effective treatment.

Methods: Conducted at the Department of Microbiology, Government Medical College, Maharashtra, the study included patients over 18 years undergoing BAL via fiberoptic bronchoscopy for pneumonia diagnosis from June 2018 to May 2019. Quantitative cultures were grown on Blood Agar, MacConkey Agar, and Chocolate Agar, with a positive culture defined at ≥ 10^4 CFU/mL. Pathogen identification and antibiotic susceptibility testing were performed using standard microbiological techniques.

Results: Of the 63 patients studied, 57.14% showed a positive quantitative BAL culture. Staphylococcus aureus was the most frequently isolated pathogen, followed by Pseudomonas aeruginosa, Klebsiella pneumoniae, and Escherichia coli. Notably, Methicillin-resistant Staphylococcus aureus (MRSA) constituted a significant portion of S. aureus cases. Gram-negative bacteria showed high resistance to standard antibiotics but were sensitive to Imipenem and Piperacillin-Tazobactam.

Conclusion: Quantitative BAL fluid culture is a valuable diagnostic method for effectively identifying and managing bacterial pneumonia. The procedure not only confirms the pathogen but also informs targeted antibiotic therapy, thereby minimizing the use of broad-spectrum antibiotics and reducing the emergence of resistant bacterial strains.