Background
Microbial colonization of pleural drains during the postoperative period may be regarded as an important factor in infection development. The aim of this paper was to determine the frequency and risk factors associated with microbial colonization of pleural drains in patients with non-small-cell lung cancer (NSCLC) who underwent surgical resection.
Material and Method
A total of 72 pleural drain fluids obtained from 36 patients with NSCLC were microbiologically examined.
Results
Microbial colonization of pleural drain fluid was noted in 30/36 patients (83.34%). Aerobic and anaerobic bacteria were found in 13 (36.11%) and 7 (19.44%) patients, respectively, and mixed microflora were cultured from 9 (25%). Non-fermentative gram-negative rods and coagulase-negative staphylococci were mainly isolated. Univariate analysis revealed that FEV1% >65 and FEV1/FVC were significantly related to drain colonization by bacteria in general, FEV1/FVC to colonization by aerobic bacteria, and hospitalization >5 days before surgery to colonization by anaerobic bacteria. According to multivariate analysis, application of antibiotic prophylaxis other than cefuroxime or ceftriaxone and FEV1% >65 were the independent factors related to drain colonization by bacteria in general; antibiotic prophylaxis other than cefuroxime or ceftraixone alone and hospitalization >5 days before surgery to colonization by anaerobic bacteria; and a higher rate of FEV1/FVC, no chemotherapy before surgery, and postsurgical complications after surgery to colonization by aerobic bacteria.
Conclusions
Patients with resectable lung cancer showed a high rate of pleural drain colonization, mainly by opportunistic pathogens, even in the absence of clinical signs of infection.

Keywords: Pleural Cavity - microbiology, Multivariate Analysis, Lung Neoplasms - surgery, Drainage - adverse effects, Colony Count, Microbial, Carcinoma, Non-Small-Cell Lung - surgery, Bacteria, Aerobic - isolation & purification, Bacteria - isolation & purification, Risk Factors