[Possible sources of aspergilla infection in a hematological hospital].

AIM

To investigate spread, species spectrum, quantity of aspergilla spores in the air of a hematological hospital.

MATERIAL AND METHODS

Air samples (250 I/min, PU-1B device) were collected in hematological departments monthly. Isolation and identification of mycelial fungi were made on Chapek medium. In detection of Aspergillus spp. culture in the biomaterial, additional samples of the air and wash-out from the surfaces were collected.

RESULTS

A 4-year mycological monitoring of the air has found that aspergilla constituted dominating micromycetes both by occurrence (45%) and amount (5.66%). The spectrum of Aspergillus spp. were represented by 17 species. Of them A. fumigatus, A. niger, A. flavus, A. terreus and A. nidulans comprised 31%. Aspergillus spp. concentrations in the wards with laminar ventilation was 1.8 CFU/m3, in plenum-air exhaustion ventilation--2.1 CFU/m3, exchange ventilation--12.2 CFU/m3. Increased amount (31%) and concentration (11.9 CFU/m3) of Aspergillus spp spores in the air occurred in autumn. A. fumigatus (44%), a. flavus (42%), A. niger (8%), A. versicolor (3%), Aspergillus spp (3%) were detected in 33 patients. The rate of detection of Aspergillus isolated from the patients was also the highest in autumn (34%). Aspergillus spores mean concentration in the wards of patients with invasive aspergillesis was 13.1 CFU/m3, in the nearby wards--12.4 CFU/m3. Morphologically identical strains Aspergillus spp. isolated from the patient and environment were obtained in 9 cases.

CONCLUSION

Minimal concentration of aspergilla spores was in the wards with laminar air flow furnished with plenum-air exhaustion ventilation. Annual correlation (for 4 years) of seasonal dynamics of the incidence of Aspergillus spp. from patients with invasive aspergillesis and number of spores in the air support suggestion that air is one of the sources of infection in immunocompromised patients. In spite of wide prevalence of Aspergillus spp. in hospital air, morphologically identical strains from the patient and environment are encountered rarely. There may be additional sources of infection and mechanisms of invasive aspergillesis onset in immunocompromised patients. Genotyping of morphologically identical strains was not made.