Nosocomial infections as one of the most important problems of healthcare system.

Healthcare-associated infections (HAI) are commonly defined as adverse events resulting from the provision of healthcare. The reduction of risk arising from the spread of pathogenic microorganisms in the hospital environment is a considerable challenge in the context of the proper functioning of the medical services sector. The financial costs of hospitals resulting from HAI are a serious problem for the Polish healthcare system. The spread of strains with a high level of drug resistance in individual hospitals is associated with the local epidemiological situation. In 2015-2017, there was a high increase in the number of infections caused by New Delhi strains. The highest increase due to this strain occurred in Mazowieckie and Podlasie provinces. The dynamics of infection caused by New Delhi strains throughout Poland in 2015-2016 indicated an increase of 278.7%. In 2017, the phenomenon of antibiotic abuse in all regions of Poland was 24% higher than the EU average. One of the reasons is the insufficient number of diagnostic tests ordered by both general practitioners and doctors representing hospital care. In 2016-2017, the average number of microbiological tests in diagnosing hospital infections performed annually within the entire territory of Poland was 50% lower than in European Union countries and the number recommended by WHO. Increased, and at the same time inappropriate antibiotic therapy led to a build-upof drug resistance among bacterial species of significant clinical importance. The current epidemiological situation imposes the necessity for constant HAI control and broadly understood rationalization of the guidelines of hospital antibiotic policy.