Characteristics of Microbial Factors of Healthcare-Associated Infections Including Multidrug-Resistant Pathogens and Antibiotic Consumption at the University Intensive Care Unit in Poland in the Years 2011-2018

Introduction: In recent years, an increase in healthcare-associated infections (HAIs) caused by resistant pathogens, which is a clinically troublesome trend, has been observed. The aim of the study was to analyze the microbial factors of HAIs and the drug resistance of microorganisms to selected antibiotics and their consumption. Material and Methods: The retrospective study included 3708 patients hospitalized in the intensive care unit (ICU) of the University Teaching Hospital in Wroclaw, who were diagnosed with 742 HAIs in the period from 1 January 2011 to 31 December 2018. The aim of the study was the analysis of microorganisms isolated in the respective clinical forms of HAIs, including the occurrence of alert pathogens, presence of multidrug-resistant (MDR) strains, and consumption of selected antibiotics. Findings: During the study period, 846 microorganisms were cultured in patients with HAIs, and among them, Acinetobacter baumannii MDR represented 31.8%; Klebsiella pneumoniae ESBLs, 11.3%; Pseudomonas aeruginosa MDR, 4.1% and MRSA, 2.2%; and Enterococcus spp. vancomycin-resistant enterococci (VRE), 1.3%. Among all the pathogens, Gram-negative bacteria (GNB) were dominant (71.6%). Gram-positive bacteria and fungi accounted for 21.6% and 7%, respectively. The total number of strains responsible for ventilator-associated pneumonia (VAP), urinary tract infection (UTI), and central line-associated blood stream infection (CLA-BSI) was as follows: 458 (54.1%), 274 (32.4%), and 114 (13.5%), respectively. Among the etiological factors of VAP, there was a prevalence of A. baumannii MDR (41.9%), as well as in the case of UTI (21.9%). With regards to CLA-BSI, MRCNS (29.8%) was the dominant pathogen. The alert pathogens accounted for 54.7% of all the analyzed strains. The MDR strains represented 72.6% and 9.7% among A. baumannii and P. aeruginosa, respectively. In the years 2011 vs. 2018, an increase in infections with MDR bacilli was observed, 34.6% vs. 61.0% (p = 0.0008), respectively, including A. baumannii MDR 16.54% vs. 34.56 % (p = 0.0009) and Enterobacterales ESBL+/AMPC 11.8% vs. 15.44 % (p = 0.3921). Resistance to methicillin was confirmed in 35.2% of S. aureus strains. Resistance to vancomycin was found among 30.9% of Enterococcus spp. The observed period was marked by an increase in the consumption of carbapenems: 197.7 vs. 235.9 defined daily dose (DDD)/1000 patients-days. Conclusions: Gram-negative bacteria were found to be dominant pathogens in healthcare-associated infections. The most frequently cultured pathogens were multidrug-resistant A. baumannii, K. pneumoniae ESBL(+), and P. aeruginosa. The study showed an increase in the incidence of alert pathogens and MDR bacilli, as well as the tendency of a growing resistance to antibiotics during the observed period. Microbiological analysis of HAIs and the consumption of antibiotics is the necessary element of the proper antibiotic policy in hospitals.