Bronchial Bacterial Colonization in Patients with Lung Cancer

Abstract Background The first step in bacterial respiratory tract infection is bacterial colonization of the lower respiratory tract. The lower respiratory tract is sterile in contrast to the gastrointestinal tract. This sterility is maintained through a variety of mechanisms that counteract bacterial adherence and virulence factors and once overwhelmed bacterial colonization and infection occurs. The clinical course of lung cancer is often complicated by lung infections proved in 84% of cases. Objective to evaluate the prevalence and nature of bronchial bacterial colonization in patient with primary lung cancer at time of diagnosis. Methods This prospective cross-sectional study was performed on a total of 69 consecutive patients with suspected lung cancer during study duration from December 2022 to June 2023 referred to our bronchoscopy unit at chest department-Ain Shams University for diagnostic bronchoscopy. Results In 26 (52%) of 50 patients no bacterial growth was found in the bronchial tree. In four cases (8%), potentially pathological bacteria were cultured but their number was < 104 cfu/ml. In 20 (40%) cases, the colonization of potentially pathogenic bacteria was ≥ 104 cfu/ml. most common organisms were Gram-negative. The most frequently was pseudomonas (n = 15), and in the second group klebsiella (n = 5). In three cases (61%) the bronchial tree was colonized simultaneously by two types of micro-organism. Conclusion The current study found that 48% of patients with lung cancer are colonized by potentially pathogenic bacteria during their initial bronchoscopy work up. The dominant organisms colonizing the lower respiratory tract were gram negative bacteria and in which 40% of bronchial bacterial colonization had a cut-off level ≥104 CFU/ml. Oldest and COPD patients have higher risk of colonization. However, additional studies are suggested to further examine the clinical impact of bronchial colonization on lung cancer patients outcomes as regards infection rate and survival.