Emerging microorganisms in cystic fibrosis

Area of Science:

• Medical Microbiology
• Pulmonology
• Infectious Diseases

Background:

• Pseudomonas aeruginosa is a common isolate in cystic fibrosis (CF) lung infections.
• Emerging multiresistant organisms pose diagnostic and therapeutic challenges in CF patients.

Purpose of the Study:

• To identify bacterial isolates from CF patients during pulmonary exacerbations.
• To evaluate antibiotic susceptibility, focusing on Pseudomonas species and Achromobacter xylosoxidans.
• To assess the efficacy of ceftazidime and aminoglycoside combinations against multiresistant strains.

Main Methods:

• Isolation and identification of bacterial strains from 24 CF patients.
• Antibiotic sensitivity testing using minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) for nine antibiotics.
• Evaluation of synergistic activity of ceftazidime combined with aminoglycosides.

Main Results:

• Pseudomonas aeruginosa (67.6%) was the most frequent isolate, followed by Pseudomonas non-aeruginosa (15.5%) and Achromobacter xylosoxidans (16.9%).
• Achromobacter xylosoxidans demonstrated the least responsiveness to tested antibiotics.
• Ceftazidime exhibited the highest activity against both Achromobacter and Pseudomonas isolates.
• No synergistic effect was observed for 23 combinations of ceftazidime with aminoglycosides against multiresistant strains.

Conclusions:

• Achromobacter xylosoxidans represents a significant challenge in CF pulmonary infections due to its resistance patterns.
• Ceftazidime is a promising antibiotic for treating Pseudomonas and Achromobacter infections in CF.
• Combination therapy with ceftazidime and aminoglycosides does not appear to offer synergistic benefits for these multiresistant strains.