Investigation of role of anaerobic bacteria in cystic fibrosis patients

Abstract

Repetitive pulmonary infections are the main cause of morbidity and mortality in cystic fibrosis (CF) patients. In recent years, non-culture dependent metagenomic studies showed complex dynamics of the pulmonary environment of CF patients and pointed out the importance of anaerobic bacteria. Molecular-based studies indicate that anaerobic bacteria can be found more than aerobic or facultative anaerobic bacteria in CF lung environment. However, limited number of studies are far away to clarify the importance of anaerobic bacteria in CF pulmonary disease. The aim of this study was to evaluate the role of anaerobic bacteria in CF patients admitted to Hacettepe University, Pediatric Respiratory Diseases Department, by using quantitative culture method for both aerobic and anaerobic bacteria. Anaerobic bacteria were identified by conventional and semi-automated methods. Antibiotic susceptibilities were performed by agar dilution method. Seventy-seven anaerobic bacteria were isolated from 35 (81.4%) of 43 patients. The total count of anaerobes and facultative bacteria (mean 16 x 106), was higher than aerobes and facultative bacteria (mean 14.1 x 106). If anaerobe culture were not performed merely 63.65% of all species could be obtained. In patients whose samples yielded intermediate or high numbers of PMNLs, significantly more obligate anaerobic bacteria were isolated (p= 0.046). Patients older than 18 years were colonized with higher number of anaerobic bacteria. Susceptibilities of 72 isolates out of 77, against ampicillin, sulbactam-ampicillin, piperacillin, piperacillin-tazobactam, moxifloxacin, metronidazole, imipenem, and clindamycin were also evaluated. Clindamycin was found to be the least effective antibiotic among all. None of the isolates was resistant to imipenem. This is the first study to show the role and importance of anaerobic bacteria in CF patients in our country. The resistance rates in anaerobic bacteria isolated from CF patients is concerning. Therefore, intermittent anaerobic culture and follow-up of resistance rates will be helpful in the follow-up of these patients.