[Microbial population of lower respiratory tract in children from different age groups with cystic fibrosis].

AIM: To study microflora of lower respiratory tract of children from different age groups with cystic fibrosis during follow-up for determination of its variability and possible sources of infectious complications. MATERIALS AND METHODS: One hundred forty-one medical histories of patients from different age groups with cystic fibrosis living in various regions of Russian Federation were analyzed. Eighty-four children with cystic fibrosis living in Moscow and Moscow region treated as outpatients and inpatients were prospectively followed. For identification and characterization of microorganisms, microbiological, molecular biological, and statistical methods were used. RESULTS: It was demonstrated that chronic pseudomonas, staphylococcal or mixed infection was already diagnosed in 25% of children aged 1-4 years, and identified in 80% of patients to the age of 18 years. In two-thirds of cases association of microorganisms was identified, and in hospitalized patients these associations were comprised by 3-5 microorganisms in 60% of cases. Aside from main agents in associations (Pseudomonas aeruginosa and Staphylococcus aureus), representatives of Gram-negative nonfermentative microorganisms (Burkholderia cepacia, Stenotrophomonas maltophilia, Acinetobacter baumanii) were often identified that possibly determined by tropism of these species to lung tissue. CONCLUSION: Chronic mixed infection is characteristic for patients with cystic fibrosis. Identification of possible mechanisms of lung infection in patients with cystic fibrosis will allow to develop evidence-based system of prevention of infectious complications in these patients.

[Biofilm formation by strains of Burkholderia cepacia complex in dependence of their phenotypic and genotypic characteristics].

Biofilm formation was studied in 54 strains of Burkholderia cepacia complex isolated in 7 Moscow hospitals. 80% of strains (biofilm groups I and II) had the capacity to biofilm formation and only 16.7% of strains (group III) were not capable to biofilm formation. Molecular genetic methods allowed to identify one of the epidemic markers (CBL, IS hybrid sequence, Burkholderia Cepacia Epidemic Strain Marker - BCESM) in 46.7, 23.3, and 33.3% of strains from group I, II, and III respectively. Gene cepR from the Quorum Sensing system was identified in three biofilm groups in nearly equal frequency (92.3, 96.2 and 100% for group I, II, and III respectively), whereas cepl gene was found more often in group I (76.9%) and II (65.4%). Strains from all three groups had protease and lipase activity and 13.3% of group I strains had chitinolytic activity. B. cepacia strains from group I produced hemolysin in 33.3% of cases, from group II--in 26.6%, and from group III--in 11.1% of cases. The majority of Moscow hospital strains of B. cepacia complex were identified as B. cenocepacia (genomovar III, group A). RAPD-PCR method enabled to differentiate isolated strains into several genotypic variants. 13.3% of strains from group I were susceptible to imipenem/ciprofloxacin, as well as 33.3% of isolates from group II and 44.4% of isolates from group III.

[Virulent properties of hospital strains of bacteria of the Burkholderia cepacia complex, isolated in hospitals of Moscow].

The results of the study of hospital strains of the B. cepacia complex, isolated in hospitals of Moscow, with the use of phenotypical and molecular-genetic methods are presented. The phenotypical methods made it possible to differentiate Russian strains and classify them with a group of genomovars (I, III, IV). As the result the epidemic importance of the strains with epidemic markers, having specific characteristics for every clinic, was determined. The detection of the collection of genes cepI and cepR in the strains made confirmed the epidemic importance of the stains which had, due to the regulatory "quorum sensing" (QS) system, the potential capacity for inducing infection and persisting in the patient's body. The presence of gene cepR in all strains and the absence of gene cepl in 33% of strains gave evidence to suggest that in some strains the activation of the production of pathogenicity factors required the presence of other bacteria having the fully developed QS system. Thus, the new complex approach with the use of phenotypical and molecular-genetic methods permits more precise identification of the source of hospital infection induced by the bacteria of the B. cepacia complex.