ABSTRACT
A total of 528 patients with nosocomial pneumonias were examined by bacteriological methods during 4 years. The data on the patients and on 2468 bacterial strains isolated from them were computer processed using original software "Hospital Infection". Special attention was paid to hospital strains of pneumonia agents of the same taxonomic position with identical markers of antibacterial resistance. Tendencies and seasonal fluctuations in the prevalence of hospital serovars were detected. Special bacteriological studies helped detect differences in the translocation capacity of different biological variants of the agents. Routine bacteriological studies and their adequate statistical computer processing yield information needed for epidemiological analysis of the development of nosocomial pneumonias in patients of clinical wards of different profile.