Objective: to study the features of the formation of antibacterial resistance of the causative agents of pyo-inflammatory lung diseases. Material and methods. The microbiological landscape of 59 patients with severe forms of pneumonia, the ability of the isolates to form biofilms, and the presence of the resistance genes to carbapenems and cephalosporins have been studied. Results. 73 isolates were isolated by the microbiological method. K. pneumoniae was the most common (64.4%). The microflora was not detected in 5 cases. The use of the PCR diagnostics made it possible to identify the associations of microorganisms in all the cases. P. aeruginosa was the one which formed the biofilm most intensively. The most common resistance genes were OXA-48 (63.1 %), CTX-M (35.9 %), and NDM (25 %). Conclusion. K. pneumoniae having the OXA-48 resistance gene was the most common pathogen in the patients with severe forms of pneumonia in the Resuscitation and Intensive Care Ward of Vitebsk Regional Clinical Hospital. The majority of the isolates possessed a moderate or high ability to form the biofilm with its maximum weight in P. aeruginosa 136.5 [23; 75.1] µg/well. The detection of antibiotic resistance genes by the method of the PCR diagnostics will make it possible to adjust the choice of drugs.