Distribution and Characteristics of Bacteria Isolated from Cystic Fibrosis Patients with Pulmonary Exacerbation.

Background: Cystic fibrosis (CF) is an inherited recessive disorder characterized by recurrent and persistent pulmonary infections, resulting in lung function deterioration and early mortality.

Methods: A cross-sectional study was conducted on the bacterial profile and antibiotic resistance pattern of 103 respiratory specimens from CF patients with signs of pulmonary exacerbation. Antibiotic susceptibility testing and biofilm formation of Staphylococcus aureus and Pseudomonas aeruginosa isolates were performed by the Kirby-Bauer disc diffusion method and microtiter plate assay, respectively. Molecular typing of S. aureus and P. aeruginosa isolates was carried out by spa typing and repetitive extragenic palindromic element PCR.

Results: In a total of 129 isolates, the most prevalent organisms were S. aureus (55.3%) and P. aeruginosa (41.7%). Other less prevalent bacterial isolates include coagulase-negative staphylococci, Escherichia coli, klebsiella spp., Enterobacter spp., and Achromobacter xylosoxidans. The highest rate of resistance for S. aureus was observed to azithromycin and erythromycin (80%), ciprofloxacin (52.3%), clindamycin (44.6%) and tetracycline (43%). Twenty percent of S. aureus isolates were methicillin-resistant S. aureus (MRSA) and 47.6% were MDR S. aureus. For P. aeruginosa isolates the highest resistance was to cefepime (38.3%) and levofloxacin (33.3%) and 20% showed MDR phenotype.

Conclusion: Our study demonstrated a significant decline in the prevalence of P. aeruginosa infections in comparison to previous studies. We found S. aureus to be more prevalent in younger patients, whereas mucoid P. aeruginosa showed a shift in prevalence toward older ages. Molecular typing methods showed great diversity between isolates.