Antibiotic Susceptibility and Biofilm Formation of Bacterial Isolates Derived from Pediatric Patients with Cystic Fibrosis from Tehran, Iran.

Cystic fibrosis (CF) is a genetic disease with a high rate of morbidity and mortality. Children with CF commonly suffer from recurrent and persistent pulmonary tract infections caused by diverse bacterial pathogens. This study aimed to investigate the prevalence, antimicrobial susceptibility, and biofilm formation of bacterial isolates in pediatric patients with CF. The study population of this cross-sectional study included 8,908 children suspected to have CF by clinical manifestations from March 2015 to August 2017 who were referred to the Tehran Pediatric Central Hospital, Iran. The tests carried out for each participant included screening sweat test, sputum culture, antibiotic susceptibility test using Kirby-Bauer disk diffusion method, and biofilm formation in microtiter plates method. Based onclinical examination and screening sweat test, 183 (2.05 %( out of 8,908 children, were positive for CF. The mean age of children was estimated at 2.93 years, and the majority of them were male (n=103, 56.2%). No gender-specific difference was observed in CF disease in this study (P>0.05). In addition, the results of sputum culture showed that 153 (83.6%) microorganisms (bacteria and fungi) were collected from CF patients. Normal flora was isolated in 30 (16.4%) patients and more than one bacterial species were isolated in 7.2% of patients. The obtained results indicated that Pseudomonas aeruginosa was the most prevalent isolated bacteria followed by Staphylococcus aureus, and Klebsiella pneumoniae. Based on the antibiotic susceptibility test results, P. aeruginosa and piperacillin/tazobactam had the highest (11.7%) and the lowest (2.3%) resistance rate against gentamicin, respectively. However, all K. pneumoniae isolates were resistant to Cefotaxime. Among S. aureus isolates, 83.4% and 16.6% were methicillin-susceptible Staphylococcus aureus and Methicillin-resistant Staphylococcus aureus respectively. Concerning biofilm formation, 76%, 67%, and 72.5% of P. aeruginosa, S. aureus, and K. pneumoniae isolates were biofilm producers, respectively. Based on the study results, P. aeruginosa was the dominant pathogen in pediatric patients with CF from Tehran, Iran, and most of the pathogens were biofilm producers. No severe antibiotic resistance was observed in the isolates; however, the anti-microbial resistance profile should be carefully checked in CF patients on a regular basis.