Bacterial adhesion can be controlled by different material surface properties, such as surface charge, on which we concentrate in our study. We use a silica surface on which poly(allylamine hydrochloride)/sodium poly(4-styrenesulfonate) (PAH/PSS) polyelectrolyte multilayers were formed. The corresponding surface roughness and hydrophobicity were determined by atomic force microscopy and tensiometry. The surface charge was examined by the zeta potential measurements of silica particles covered with polyelectrolyte multilayers, whereby ionic strength and polyelectrolyte concentrations significantly influenced the build-up process. For adhesion experiments, we used the bacterium Pseudomonas aeruginosa. The extent of adhered bacteria on the surface was determined by scanning electron microscopy. The results showed that the extent of adhered bacteria mostly depends on the type of terminating polyelectrolyte layer, since relatively low differences in surface roughness and hydrophobicity were obtained. In the case of polyelectrolyte multilayers terminating with a positively charged layer, bacterial adhesion was more pronounced than in the case when the polyelectrolyte layer was negatively charged.

The concentrations of microorganisms, aerosol black carbon and carbon dioxide (CO₂) in indoor and outdoor air of two kindergartens were investigated during four seasons. The highest mean concentrations of aerobic mesophilic microorganisms in indoor air were detected in spring. Cladosporium, Penicillium and Aspergillus were the most common fungi in all air samples. The concentrations of Staphylococci, Enterobacteria and CO₂ had a positive correlation with the number of persons in the rooms. The highest mean concentration of black carbon in indoor and outdoor air was obtained in winter. Concentrations of CO₂ exceeded 1000 ppm in 89.3% of the indoor air measurements. The reduction of the number of children in individual playrooms and more frequent ventilation are recommended for lowering the concentration of CO₂ and the number of microorganisms in the air, especially potential pathogen fungi. The renovation of buildings with installation of effective artificial ventilation is recommended as well. Abbreviations: CFU, Colony-Forming Unit; HPC, Heterotrophic Plate Count (Aerobic Mesophilic Microorganisms); YGC, Yeast Extract Glucose Chloramphenicol Agar; BC, Aerosol Black Carbon Particles; CO₂, Carbon Dioxide; PM, Particulate Matter

The aim of the study was to identify consumers’ food safety knowledge, practices, and hygiene status in the observed home kitchens. The results provide the starting point for evaluating progress or regression in this area compared to the past statewide study. Food safety knowledge was analyzed among 380 consumers with an online questionnaire. Additionally, 16 consumers were observed during their preparation of specified foods. The hygiene conditions in the kitchens were microbiologically examined using contact agar plates, while the cleaning adequacy was determined by measuring the ATP bioluminescence. A lack of knowledge on certain topics regarding food safety was established; the consumers aged from 36 to 55 in general and women demonstrated the highest level of knowledge. In some cases, the observed consumers did not take proper action when preparing the food. Increased total bacteria, coliform bacteria, and Escherichia coli counts were detected in 12.7% of the consumers’ kitchens observed here. Eighty-three (74.1%) out of 112 surfaces examined with either hygiene test sheets or ATP swabs met the standards and were adequately or acceptably cleaned. The kitchen surfaces exceeded the recommended limits for 25% of consumers. Statistical differences in RLU and TCC levels on surfaces between older and younger consumers were not observed, although all (25%) inadequately cleaned kitchens belonged to older consumers. The greatest emphasis has to be put on the cleaning of home kitchens and personal hygiene. Even though consumers have some knowledge on food safety, they often fail to put that knowledge into daily practice.

Bacterial adhesion is a complex process influenced by many factors, including hydrodynamic conditions. They affect the transfer of oxygen, nutrients, and bacterial cells in a water supply and cooling systems. The aim of this study was to identify hydrodynamic effects on bacterial adhesion to and detachment from stainless steel surfaces. For this purpose we observed the behaviour of bacterium L. pneumophila in no-flow and laminar and turbulent flow conditions simulated in a fluid flow chamber. The bacterial growth in no-flow and laminar flow conditions was almost identical in the first 24 h, while at 48 and 72 h of incubation, the laminar flow stimulated bacterial growth. In the second part of this study we found that laminar flow accelerated bacterial adhesion in the first 48 h, but after 72 h the amount of bacterial cells exposed to the flow dropped, probably due to detachment. In the third part we found that the turbulent flow detached more bacterial cells than the laminar, which indicates that the strength of shear forces determines the rate of bacterial removal.

This study was conducted to determine the bacterial colonization of some bacterial groups, including extended-spectrum β-lactamase (ESBLs) producers and methicillin-resistant Staphylococcus aureus (MRSA), on surfaces of the equipment and instruments in patient rooms and other workspaces in three different medical wards. The number of microorganisms on swabs was determined with the colony count method on selective microbiological mediums. The aerobic mesophylic microorganisms were found in 73.5 % out of 102 samples, with the average and maximum values of 2.6 × 10² and 4.6 × 10³ colony forming units (CFU) 100 cm^-2, respectively. Members of the family Enterobacteriaceae, coagulase positive staphylococci, coagulase-negative staphylococci, and enterococci were detected in 23.4, 31.4, 53.2, and 2.9 % of samples, respectively. The differences in bacterial counts on the surfaces of the psychiatric, oncology, and paediatric wards were statistically significant (P<0.001). About 40 % out of 19 isolates from the family Enterobacteriaceae showed multiple resistance to three or more different groups of tested antibiotics, while ESBL was confirmed for only one strain. Staphylococci isolates were mostly resistant to penicillin. MRSA was confirmed in 5.2 % of the tested S. aureus isolates. Greater attention should be paid to cleaning and the appropriate choice of disinfectants, especially in the psychiatric ward. Employees should be informed about the prevention of the spreading of nosocomial infections. Routine application of rapid methods for hygiene control of surfaces is highly recommended.