Extensive Drug Resistance of Strong Biofilm-Producing Acinetobacter baumannii Strains Isolated from Infections and Colonization Hospitalized Patients in Southern Poland.

Acinetobacter baumannii (AB) is a bacterium that causes infections, particularly in immunocompromised patients. Treatment is challenging due to biofilm formation by AB strains, which hinders antibiotic effectiveness and promotes drug resistance. The aim of our study was to analyze the biofilm-producing capacity of AB isolates from various forms of infections in relation to biofilm-related genes and their drug resistance. We tested one hundred isolates for biofilm formation using the crystal violet microplate method. Drug resistance analyses were performed based on EUCAST and CLSI guidelines, and biofilm genes were detected using PCR. All tested strains were found to form biofilms, with 50% being ICU strains and 72% classified as strong biofilm producers. Among these, 87% were extensively drug-resistant (XDR) and 2% were extra-extensively drug-resistant (E-XDR). The most common gene set was bap, bfmS, csuE, and ompA, found in 57% of all isolates. Our research shows that, regardless of the form of infection, biofilm-forming strains can be expected among AB isolates. The emergence of E-XDR and XDR strains among non-ICU infections highlights the necessity for the rational use of antibiotics to stop or limit the further acquisition of drug resistance by A. baumannii.

Evaluation of the Efficacy of UV-C Radiation in Eliminating Microorganisms of Special Epidemiological Importance from Touch Surfaces under Laboratory Conditions and in the Hospital Environment.

INTRODUCTION: Healthcare-associated infections in the post-pandemic era are as important as they were before COVID-19. The dominant route of transmission of microorganisms in health care units is the contact route, for which hand hygiene is of cardinal importance, but also effective disinfection of touch surfaces. Traditional disinfection based on chemical compounds is sensitive to human errors. Therefore, a valuable supplement to it can be contactless disinfection methods, including the use of UV-C. The aim of the study was to assess the effectiveness of UV-C radiation in eliminating selected, most important pathogens of particular epidemic importance from surfaces made of various materials: stainless steel, plastic and glass, most often found in hospital conditions. MATERIAL AND METHOD: In laboratory conditions, the study was conducted using bacterial strains of great epidemiological importance and Candida auris. In hospital wards, samples were taken before and after disinfection for comparisons of the composition and quantity of bacteria. In laboratory conditions, carriers made of steel, plastic and glass were contaminated with a bacterial suspension with a density of approx. 0.5 McFarland, and then the density of persistent microorganisms was assessed after 10 min of UV-C irradiation. RESULTS: The high effectiveness of UV-C radiation in eliminating bacteria contaminating touch surfaces in hospital wards and in laboratory conditions has been confirmed. The elimination efficiency in laboratory conditions was slightly lower (statistically insignificant) on the plastic surface, which is probably related to subtle differences in the thickness of the contaminating layer. Hydrophobic properties and the smallest suspension diameter were confirmed for the tested plastic carriers. CONCLUSIONS: UV-C disinfection is a desirable element to support traditional, chemical methods of disinfection in hospital conditions, effective against multidrug-resistant bacteria and C. auris.

Bacterial Pathogens in the Food Industry: Antibiotic Resistance and Virulence Factors of Salmonella enterica Strains Isolated from Food Chain Links.

Salmonella is one of the most important foodborne pathogens. Fifty-three strains of Salmonella deposited in the Culture Collection of Industrial Microorganisms-Microbiological Resources Center (IAFB) were identified using molecular and proteomic analyses. Moreover, the genetic similarity of the tested strains was determined using the PFGE method. Main virulence genes were identified, and phenotypical antibiotic susceptibility profiles and prevalence of resistance genes were analyzed. Subsequently, the occurrence of the main mechanisms of ß-lactam resistance was determined. Virulence genes, invA, fimA, and stn were identified in all tested strains. Phenotypic tests, including 28 antibiotics, showed that 50.9% of the strains were MDR. The tet genes associated with tetracyclines resistance were the most frequently identified genes. Concerning the genes associated with ESBL-producing Salmonella, no resistance to the TEM and CTX-M type was identified, and only two strains (KKP 1597 and KKP 1610) showed resistance to SHV. No strains exhibited AmpC-type resistance but for six Salmonella strains, the efflux-related resistance of PSE-1 was presented. The high number of resistant strains in combination with multiple ARGs in Salmonella indicates the possible overuse of antibiotics. Our results showed that it is necessary to monitor antimicrobial resistance profiles in all food chain links constantly and to implement a policy of proper antibiotic stewardship to contain or at least significantly limit the further acquisition of antibiotic resistance among Salmonella strains.