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 β-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.

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.

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.

Listeriosis is one of the most serious foodborne diseases under surveillance, with an overall mortality rate in the EU currently being high at 18.1%. Therefore, this study aims to investigate Listeria monocytogenes strains isolated from clinical and food samples for susceptibility to antimicrobials, presence of virulence factors, and genetic diversity. Species were identified using the MALDI-TOF, resistance to 11 antibiotics was determined according to EUCAST guidelines, and multiplex PCR was used for serotyping and detecting virulence genes. Strains were genotyped using the PFGE method. Clinical strains showed full sensitivity to all tested antibiotics. In total, 33.3% of strains from food products were found to be resistant to ciprofloxacin and 4.2% to tetracycline. Most of the tested isolates (79.2%) belonged to serotype 1/2a-3a, and the rest (20.8%) belonged to serotype 4ab-4b,4d-4e. Five virulence genes (prfA, hlyA, plcB, inlA, and lmo2672) were detected in all strains studied. The llsX gene was the least common, in 37.5% of clinical strains and 18.75% of strains isolated from food products. Among the analyzed strains, 13 strains displayed unique PFGE profiles. The other 11 strains belong to 3 clusters of pulsotypes: cluster 1 (2 strains), cluster 2 (6 strains), and cluster 3 (2 strains). The percentage of hospitalizations and deaths of Polish patients with listeriosis indicates the seriousness of this disease, especially in an aging society, while the molecular testing of clinical strains has been rarely performed, which makes it difficult to determine the source of infection.

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 effec-tiveness 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 re-sistance 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 has shown 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 re-sistance by A. baumannii.

Background: The gut microbiome has been increasingly recognized for its potential role in schizophrenia through gut-brain interactions involving immune, neural, and metabolic pathways. This pilot study evaluated the impact of fecal microbiota transplantation (FMT) on the abundance and variability of selected fungal and archaeal species in the gut microbiota in the rat model of schizophrenia. Methods: Sprague-Dawley rats using as a prenatal methylazoxymethanol acetate (MAM-E17) model of schizophrenia underwent FMT or placebo. Fecal DNA was extracted and analyzed via quantitative Real-Time PCR (qPCR) to quantify selected fungi (Candida tropicalis , Malassezia spp., Cryptococcus neoformans ) and archaea ( Methanobrevibacter smithii , Methanosphaera stadtmanae ) before and after intervention Results: A slightly higher prevalence of C. tropicalis was noted in MAM-exposed rats compared to healthy controls (19% vs. 10%). Post-FMT, C. tropicalis colonization increased to nearly 100% across all groups, irrespective of transplantation source, indicating natural microbiome maturation rather than FMT effect. Malassezia spp. were commonly present before treatment, with their abundance significantly declining after both FMT and placebo administration, suggesting procedural impacts rather than specific FMT effects. C. neoformans and methanogenic archaea were absent. Conclusions: Overall, the results suggest that FMT has limited impact on gut fungal populations, possibly due to the developmental stage of microbiome maturation or procedural interventions. The absence of archaea underscores the complexity of the microbiome’s role in neurodevelopmental disorders, highlighting the necessity for continued research into microbial influences on schizophrenia pathophysiology.