Sputum Bacteriology in Chronic Obstructive Pulmonary Disease Exacerbation Patients

Abstract

Background: Chronic obstructive pulmonary disease (COPD) is a complex and heterogeneous respiratory condition characterized by persistent airflow limitation and associated with inflammatory responses in the lungs. COPD exacerbations can significantly impact patient health and often necessitate medical intervention. Understanding the bacterial etiology of these exacerbations can aid in optimizing treatment strategies.

Objective: The objective of this study was to determine the frequency of bacterial pathogens in the sputum of patients experiencing COPD exacerbations at a tertiary care hospital.

Methods: This cross-sectional study was conducted in the Department of Pulmonology at Pakistan Emirates Military Hospital, Rawalpindi, from December 12, 2023, to June 12, 2024. A total of 160 patients aged 18 to 60 years, admitted with acute exacerbation of COPD, were included using non-probability purposive sampling. Exclusion criteria were patients with lung malignancy, acute asthma exacerbations, bronchiectasis, or interstitial lung disease. Sputum samples were collected, and standard microbiological procedures were followed. Microscopy with Gram staining was performed, and specimens with more than 10 epithelial cells per low power field were cultured. Quantitative culture was conducted using blood agar and chocolate blood agar plates incubated in 5% CO2 at 35°C for 18–24 hours. Isolates with higher than 10^5 colony-forming units were reported as positive growth. Statistical analysis was performed using SPSS Version 25.

Results: The mean age of the patients was 37.89 ± 11.2 years, with 94 (58.8%) males and 66 (41.3%) females. The average duration of COPD was 4.87 ± 1.19 years. Among the participants, 89 (55.6%) were from urban areas, and 71 (44.4%) from rural areas. Educational status showed 33 (20.6%) illiterate, 111 (69.4%) with intermediate education, and 16 (10.0%) graduates. Comorbid conditions included diabetes mellitus in 37 (23.1%) patients, hypertension in 29 (18.1%), ischemic heart disease in 15 (9.4%), and smoking in 62 (38.8%). Sputum cultures revealed pathogens in 43 (26.9%) patients. Klebsiella pneumoniae was the most frequently identified bacterium (19 cases, 11.9%), followed by Staphylococcus aureus (10 cases, 6.3%), Pseudomonas aeruginosa (5 cases, 3.1%), Actinobacter (1 case, 0.6%), and Streptococcus pneumoniae (10 cases, 6.3%).

Conclusion: The study concluded that COPD exacerbation patients exhibited a variety of single pathogenic bacterial isolates, with Klebsiella pneumoniae and Streptococcus pneumoniae being the most common. Sputum culture is a valuable tool in identifying bacterial pathogens in COPD exacerbations, guiding appropriate antibiotic therapy.