Corrections

The treatment of P. aeruginosa infection in patients with cystic fibrosis (CF) is problematic despite the aggressive antibiotic therapy.

P. aeruginosa explores numerous strategies that promote chronic pulmonary colonization.

One of them is the ability of P. aeruginosa to generate antibiotic resistant subpopulations within one clonal population upon antibiotic stress.

Aim To assess the efficacy of antibiotic therapy of P. aeruginosa infection in patients with CF and to study the phenotypic heterogeneity of genetically identical P. aeruginosa cells isolated simultaneously from the sputum. Method.

The sputum of 315 patients with CF were analyzed using microbiological diagnostic algorithm (Russia).

Results P. aeruginosa was isolated from 39% of patients with CF.

Microbiological monitoring showed that antibiotic therapy was effective in 58,8% of patients.

Chronic infection developed in 41,2% of patients.

In 81% of patients the chronic infection was caused by long-term persistence of the one clone.

The study of different colonies of P. aeruginosa isolated from sputum on a agar plate simultaneously showed phenotypic heterogeneity.

Despite genetic similarity they had different antibiotic susceptibility pattern.

Conclusion Upon antibiotic stress certain “lucky” cells within an isogenic culture can survive and generate subpopulations with increased resistance.

Phenotypic heterogeneity must therefore be considered as a factors that limit the efficacy of antibiotic therapy.

Thus treatment with antimicrobial combinations may be necessary in certain cases.