Mateusz Ossowski

Staphylococcus aureus is a high-priority pathogen causing skin and soft tissue infections (SSTIs). The frequent resistance to anti-staphylococcal agents exhibited by this underscores the need for accurate diagnostics to guide effective therapy. Therefore, this study aimed to compare phenotypic and genotypic resistance in S. aureus isolates from nasal carriers and SSTIs and to elucidate gene-silencing mechanisms. In total, 355 S. aureus isolates (256 isolated from carriers and 79 from SSTIs) were studied for their phenotypic and genotypic resistance to β-lactams, macrolides, tetracyclines, aminoglycosides, and mupirocin. The silenced mupA gene (low prevalence: 0.6%; 2/335), linked to mupirocin resistance, was sequenced, and expression was assessed via reverse transcription qualitative PCR (RT-qPCR) in all mupA-positive isolates. SSTI isolates showed significantly higher resistance to erythromycin, gentamicin, and mupirocin, along with a higher prevalence of multidrug-resistant strains and ermC and tetM genes. Sequencing revealed multiple mutations in silent mupA, including a critical frameshift (c.372 delA) in a poly(A) tract that brings about premature truncation. RT-qPCR indicated upregulation of silent mupA variants and high variability in functional strains, suggesting that frameshift alone prevents resistance. These findings highlight silent resistance genes as key targets for advancing S. aureus surveillance and for combating emerging threats.

Reducing the environmental impact of animal production is a major challenge in the context of climate change and sustainable agriculture. Although rabbit farming is generally considered less resource-intensive than other livestock systems, it still contributes to emissions of ammonia (NH₃), hydrogen sulfide (H₂S), and methane (CH₄), which can negatively affect air quality and the climate. This study aimed to evaluate whether dietary supplementation with selected natural feed additives could mitigate gaseous emissions and lower the environmental footprint of rabbit production. An experimental feeding trial was conducted in which gaseous emissions from rabbit housing were monitored, and the gas composition of feces was analyzed. Emissions were quantified and expressed as carbon dioxide equivalents (CO₂e) to allow comparative assessment of environmental impact. The inclusion of natural feed additives significantly reduced the emission of gaseous pollutants compared with the control diet, resulting in a lower calculated environmental footprint of the production system. These findings indicate that targeted modification of rabbit diets using natural feed ingredients can be an effective strategy for reducing harmful gaseous emissions and enhancing the environmental sustainability of rabbit farming.

Introduction and objective: Milking wastewater (MW) is an under-recognised reservoir of antibiotic resistant bacteria (ARB) and antimicrobial resistance genes (ARGs). The aim of the study is to evaluate MW as a point source pollutant for the presence of ARB and ARGs, to develop a treatment...

The implementation of new technologies and best practices on factory farms is crucial for reducing the environmental pollution burden. This study aimed to evaluate the use of natural sorbents in the cows’ diet to reduce gaseous pollutants released on the farm and the content of faecal biogenic compounds. To this end, a mixture of natural sorbents (65% beechwood biochar, 25% aluminosilicate, and 10% glycerine) was added to cows’ feed. Pollutants released from all groups of cows were continually monitored on the farm during the experiment. Blood samples were also collected from the cows for haematological and biochemical analysis to determine the sorbents’ impact on their health. The average level of gaseous pollutants in the air on the farm were highest in the control group and lowest in the experimental groups. The levels of NH₃, CH₄, and H₂S were statistically significant at p < 0.05. The results demonstrated that the added sorbents effectively reduced gaseous pollutants without adversely affecting the health of cows. Natural additives in the cows’ diet, including sorbents, bind harmful substances such as NH₃ and CH₄, which are common gaseous by-products of digestion. This leads to improvements in animal welfare and the natural environment.

Understanding digestive functions and the role of microorganisms in the prevention of gastrointestinal and systemic diseases may be a strategy for preventing intestinal dysbiosis during critical periods of animal rearing, strengthening the immune system and reducing herd mortality. The aim of the study was to determine the effect of the addition of fermented rapeseed meal (FRSM) to the diet of rabbits on the composition of the bacterial microbiota of the caecal contents. The experiment was conducted using 40 35-day-old rabbits ( Oryctolagus cuniculus ) assigned to four groups of 10 animals each. Animals in the control group (group C) were fed a standard diet, while the experimental groups received 4% (group E1), 8% (group E2) or 12% (group E3) dried FRSM in place of the previously used soybean meal (SBM). After 120 days, six rabbits (three males and three females), of average size and intended for slaughter, were selected from each group. The contents of the caecum were collected from these animals for metagenomic analysis. The research demonstrated that the microbiome of the caecum of rabbits shows low diversity at higher phylogenetic levels, but is highly diverse at lower levels. The study showed no directly proportional relationship between the various groups of microorganisms inhabiting the digestive tract and the share of fermented rapeseed meal used in the diet. To the best of our knowledge, this is the first study to characterize the microbiome of rabbits fed diets with the inclusion of fermented feed components.

Parcel vending machines (PVMs) are receiving more recognition as an environmentally friendly last-mile delivery service. However, their high popularity creates the risk of microbial contamination of touchscreens and keypads resulting in the spread of pathogens in humans. The study aimed at assessing the degree of bacterial contamination of PVMs and characterizing the microbial population using mass spectrometry-based identification. In total, 64 PVMs located in 16 districts of city Lublin (Poland) were studied for the total number of aerobic bacteria (TNAB) using contact plates, whereas bacterial identification was conducted using the MALDI-TOF MS. Study revealed that the average TNAB for the analyzed districts ranged from 1 ± 0.4 CFU/cm² to 8.54 ± 10.77 CFU/cm². Statistical analysis showed a positive correlation between the TNAB and the population density (p = 0.0193), emphasizing the influence of human microbiota on the level of bacterial contamination. Among 140 reliably identified bacterial species (96.3%), the most prevalent were Bacillus spp. (52.8%) and Staphylococcus spp. (10.7%). Multiple opportunistic pathogens were detected, including B. cereus and Escherichia coli. This study indicates the need to develop procedures for disinfection or to implement modified materials for the PVMs touchscreens to limit the adhesion of potentially pathogenic microorganisms.

Many studies conducted on livestock point to fermented rapeseed meal (FRSM) as a component that provides adequate quality and quantity of protein. Additionally, it is a very good source of probiotics, prebiotics, enzymes, and antioxidants. A study was undertaken to assess the impact of a feed supplemented with FRSM fermented with Bacillus subtilis strain 87Y on production parameters, nutrient digestibility, and haematological and lipid indicators of the blood in growing rabbits. Forty New Zealand White rabbits (body weight 816,25 ± 24,98 g) aged 35 days were used in this study. The animals were divided into four groups, a control group (C) was fed a standard diet, while in the diet of three experimental groups, soybean meal (SBM) was replaced with FRSM at 4% (FR4 group), 8% (FR8 group), or 12% (FR12 group). Detailed analysis revealed that the contribution of FRSM in the rabbit feed, regardless of the amount, had a significant effect on body weight gain (BWG), as well as average daily gain (ADG), compared to the control group (C), (P = 0.017). All groups receiving FRSM had a significantly lower (P = 0.05) feed conversion ratio (FCR) compared to the control group. In rabbits fed a diet containing 8% FRSM, the blood haematological parameters, such as red blood cells (RBC), haematocrit (HCT), haemoglobin (HGB), and mean corpuscular volume (MCV), were significantly higher compared to the control group (P = 0.037). In addition, a significant reduction in the plasma levels of the low-density lipoprotein fraction (LDL-chol), the ratio of total cholesterol to high-density lipoprotein (CHOL/HDL), (P = 0.001), and triacylglycerols (TG), (P = 0.004) were observed in the experimental groups compared to the control group. Based on the encouraging outcomes, it is possible to recommend domestically produced FRSM as a viable substitute for genetically-modified (GM) SBM in rabbit feed.

Essential oils (EOs), being mixtures of various natural compounds, constitute an attractive source of novel antimicrobial agents. Along with multiple studies concerning their rich biological activity, there are different methods allowing to determine both antimicrobial activity in direct contact, as well as through the activity of vapours. Thyme constitutes one of the most common aromatic herbs used for pharmaceutical, cosmetic and culinary purposes. The aim of the study was to compare the antibacterial activity of liquid and vapour phases of Thymus vulgaris L. essential oil (TEO) against most common pathogenic Gram-positive (Staphylococcus aureus ATCC 25913, Enterococcus faecalis ATCC 29212, Bacillus cereus ATCC 10876) and Gram-negative (Escherichia coli ATCC 25922, Salmonella typhimurium ATCC 14028, Pseudomonas aeruginosa ATCC 27853) microorganisms. To determine TEO antibacterial properties, two methods were used: disc-diffusion assay so as to test activity in direct contact; disc-volatilization assay so as to determine activity in gaseous contact. Statistical analysis showed that Gram-positive bacteria were more sensitive to TEO vapours than Gram-negative (p=0.005), while in the case of disc-diffusion assay, no such differences were evident. Moreover, sensitivity towards TEO differed among Gram-positive bacteria in disc-diffusion (p=0.009) and disc-volatilization assay (p=0.001). Among Gram-negative rods, a statistically higher sensitivity regarding E. coli was noted when compared to S. typhimurium in both direct (p=0.011) and gaseous (p=0.006) TEO contact. No activity of TEO against P. aeruginosa was found. As thyme essential oil exhibited significant antimicrobial activity against Gram-positive bacteria in gaseous contact, this justifies its use as an addition to inhalation agents to prevent or support the treatment of upper respiratory tract infections. Further studies should therefore apply other methods for determining the antibacterial activity of TEO vapours to assess the exact minimal concentration inhibiting bacterial growth.