colonization of streptococcus pneumoniae in pneumonia patients with lung cancer

Background: lung cancer is the mostcommoncancer and the leading cause of cancer deaths. streptococcus pneumoniae is the most common pathogen found among lung cancer patients that has shown increased resistance towards various antibiotics. reports on bacterial colonization especially s. pneumoniae colonization in patients with lung cancer are scarce. objectives: the study aimed to determine the prevalence and antibiotic resistance of s. pneumoniae isolated from lung cancer patients with pneumonia infection not undergoing any surgical procedure. methods: bronchoalveolar lavage (bal) and blood samples for blood culture and pcr were collected from 152 lung cancer patients with pneumonia. blood culture and bal specimens were cultured to isolate s. pneumoniae and antibiotic resistance was determined by minimum inhibitory concentration assay. results: of the 152 blood samples, 85 (55.9%) samples from blood culture method and 97 (63.8%) samples from bal specimens were positive for bacterial growth. streptococcus pneumoniae was the predominant organism isolated from both blood culture (45.9%) and bal (46.4%) specimens. forty-seven (30.9%) samples were found to be positive for s. pneumoniae by pcr. the detection of s. pneumoniae in 60 patients by at least one of the 3 detection methods indicates that these patients harbored s. pneumoniae infection. fifteen (9.9%) patients died due to the severity of pneumonia, rapid progression of lung cancer, multiple therapeutic failures, and unknown etiology. all our isolates were susceptible to penicillin; however, 48.7% and 60% of the isolates respectively from blood culture and bal specimens were found to be resistant to erythromycin. conclusions: streptococcus pneumoniae was the predominant organism colonized in lung cancer patients diagnosed to have pneumonia and showed higher resistance towards erythromycin. our results emphasize the need for a continuous monitoring of s. pneumoniae colonization and resistance patterns, which needs to be considered during treatment of lung cancer patients with pneumonia.