Bronchial Bacterial Colonization in Patients with Lung Cancer

Introduction: Infections are a part of the natural course of lung cancer but few studies have looked at the clinical and microbiological documentation of infections in these patients. The aim of this study is to analyze the profile of potentially pathogenic bacteria that colonize the bronchial tree in patients with primary lung cancer. Material and Methods: The study was conducted from January 2006 to August 2007. It included 44 consecutive patients (34 males and 10 females) with primary lung cancer aged from 38 to 77 (mean age of 57.9 years). In all patients, bronchoalveolar lavage (BAL) was performed during bronchofiberoscopy. Obtained BAL fluid was subjected to microbiological examination. The number of bacteria present in 1 ml of fluid was estimated by quantitative culture. A diagnostic level was set on ≥ 10⁴ cfu/ml. Results: In 26 (59.1%) of 44 patients physiologic bacterial flora was found in the bronchial tree. In three cases (6.8%), potentially pathological bacteria were cultured but their number was < 10⁴ cfu/ml. In 15 (34.1%) cases, the colonization of potentially pathogenic bacteria was ≥ 10⁴ cfu/ml. Both Gram-positive and Gram-negative bacteria were isolated. The most frequently isolated bacterium in the first group was Streptococcus pneumoniae (n = 7), and in the second group Haemophilus influenzae (n = 3). Multibacterial colonization was found in five patients (11.4%). In four cases (9.1%), the bronchial tree was colonized simultaneously by two and in one case [2.3%] by three types of micro-organism. Multi-drug-resistant strains were not found in the examined materials but among Streptococcus pneumoniae the constitutive MLSB phenotype was observed. Conclusions: 1. Approximately 30% of patients with lung cancer had a respiratory tract colonized by micro-organisms whose number was higher than the assumed diagnostic level. 2. Among micro-organisms colonizing the lower respiratory tract, Gram-positive cocci such as Streptococcus pneumoniae and Staphylococcus aureus were dominant. 3. The analysis of antibiotic-resistance did not detect multi-drug-resistant micro-organisms but some strains of Streptococcus pneumoniae exhibited resistance to macrolide, lincosamide and streptogramin B.