The first cluster of hemorrhagic fever with renal syndrome (HFRS) in Poland was identified in 2007 in the Subcarpathian region. The natural environment of this area is a key habitat for hantavirus vectors. The animal reservoir of existing human HFRS clusters was studied to assess the occurrence of viruses (including Tula virus, Puumala virus, and Dobrava-Belgrade virus) among rodents. We examined 70 suspected human cases with symptoms corresponding to the clinical picture of HFRS. Serological analysis (indirect immunofluorescence assay and immunoblot) confirmed the presence of anti-hantavirus antibodies in 18 patients, which were surveyed with regard to developed symptoms and presumed rodent contact. Seroepidemiological analysis of newly confirmed human cases was performed, putative areas of human exposure were studied, and 194 rodents were subsequently captured from identified areas. Internal organs (lungs, heart, spleen, bladder, and kidneys) were collected from 64 Apodemus flavicollis, 55 Apodemus agrarius, 40 Myodes glareolus, 21 Mus musculus, and 14 Microtus arvalis and tested for the presence of hantavirus RNA by reverse transcription and subsequent real-time PCR. Positive samples were also tested by indirect immunofluorescence. Animal reservoir surveillance enabled the first detection of Puumala virus and Dobrava-Belgrade virus among animals in Poland. Furthermore, some places where rodents were captured correlated with areas of residence of laboratory-confirmed human cases and likely detected virus species. Moreover, three species of hantaviruses coexisting in a relatively small area were identified.

The emergence of resistance in microorganisms on a global scale has made it necessary to search for new antimicrobial factors. Antimicrobial peptides (AMPs) seem to meet these expectations. AMPs are produced by bacteria, viruses, plants, and animals, and may be considered as a new class of drugs intended for the prophylaxis and treatment of both systemic and topical infections. The aim of this study is to review the results of studies on the use of peptides to combat infections in vivo. Antimicrobial peptides may be applied topically and systemically. Among the peptides used topically, a very important area for their application is ophthalmology. AMPs in ophthalmology may be used mainly for the protection of contact lenses from ocular pathogens. Many AMPs are in clinical trials for application in the therapy of local infections. There may be mentioned such preparations as: pexiganan (magainin analogue), MX-226 (based on indolicidin), NEUPREX (isolated from human BPI (bactericidal/permeability-increasing) protein), IB-367 (variant of porcine protegrin), P113 (based on histatin), daptomycin, polymyxins, as well as peptidomimetics. In the combat against systemic infections are used such peptides as: P113D (modified P113 peptide containing D-amino acids), colistin, peptoids, and peptides containing non-typical amino acids or non-peptide elements. AMPs are also used as antiprotozoal, antifungal, antitoxic and immunostimulatory agents. The limitations in the use of peptides in the treatment of infections, such as susceptibility to proteolysis, and resistance of microorganisms to the peptides, are also discussed. AMPs are a promising strategy in the fight against microbial infections.

Modern threats of bioterrorism force the need to develop methods for rapid and accurate identification of dangerous biological agents. Currently, there are many types of methods used in this field of studies that are based on immunological or genetic techniques, or constitute a combination of both methods (immuno-genetic). There are also methods that have been developed on the basis of physical and chemical properties of the analytes. Each group of these analytical assays can be further divided into conventional methods (e.g. simple antigen-antibody reactions, classical PCR, real-time PCR), and modern technologies (e.g. microarray technology, aptamers, phosphors, etc.). Nanodiagnostics constitute another group of methods that utilize the objects at a nanoscale (below 100 nm). There are also integrated and automated diagnostic systems, which combine different methods and allow simultaneous sampling, extraction of genetic material and detection and identification of the analyte using genetic, as well as immunological techniques.

In a few months, the SARS-CoV-2 virus caused a worldwide COVID-19 pandemic. In Poland, 6 million cases of the disease and 113,000 deaths from COVID-19 have been reported. Healthcare workers (HCWs) constitute one of the main COVID-19 risk groups. The Microblot-Array COVID-19 IgG assay was used to detect antibodies against three major SARS-CoV-2 antigens: nucleocapsid (NCP), RBD, and Spike 2 (S2). The aim of our study was to determine the seroprevalence and titer of anti-SARS-CoV-2 IgG antibodies—NCP, RBD, and S2—as markers of the humoral response in vaccinated and unvaccinated HCWs. The study included 203 persons who were divided into four groups: “COVID-19 Vaccinated”, “COVID-19 Unvaccinated”, “Non-COVID-19 Vaccinated”, and “Non-COVID-19 Unvaccinated”. The obtained results indicate that both seroprevalence and the antibody titer are the highest in the “COVID-19 Vaccinated” group. There is no so-called sterile vaccination, and after 6 months from the second dose of vaccine, most vaccinated people have a fairly high level of antibodies. We suggest that multiple vaccination and continuous testing are necessary. The Microblot-Array assay can distinguish between antibodies acquired after infection and/or vaccination.

Coxiella burnetii is the etiologic agent of Q fever. It may occur as two different morphological forms, a large cell variant (LCV) and a small cell variant (SCV). The SCV is characterized by unique resistance to physical and chemical factors and may survive in the environment for many months. The objective of this study was to examine environmental samples for the presence of C. burnetii using real-time PCR in areas where Q fever was previously reported and in randomly selected animal farms where Q fever was not reported. The samples were collected in the following provinces in Poland: Lublin, Subcarpathian and Masovian. Monitoring was performed with real-time PCR and serological methods. Of the 727 environmental samples, 33 (4.54%) contained the multi-copy insertion sequence IS1111, which is specific for C. burnetii. Subsequently, the presence of C. burnetii antibodies was determined using serological tests in selected herds in which positive genetic results were obtained. Serological analyses of 169 serum samples using CFT and ELISA were performed on Polish black-and-white Holstein-Friesian cows and one cow imported from Denmark. Using the CFT method, 11 samples were positive for phase I antibodies and six were positive for phase II antibodies. Moreover, in two cases, the presence of antibodies specific for both phase I and phase II antigens of C. burnetii was detected. However, of the 169 examined serum samples, 20 were positive by ELISA test, of which six were also positive by CFT. Additionally, multi spacer typing (MST) of isolated C. burnetii strains was performed. The MST results identified two new genotypes in Poland, ST3 and ST6. The results indicate that continued research regarding spread of this pathogen within a country is necessary.

A microfluidic device for studies on the germination of bacterial spores (e.g. Bacillus subtilis) based on non-specific interactions on the nanoscale is presented. A decrease in the population of spores during germination followed by the appearance of transition forms and an increase in the number of vegetative cells can be registered directly and simultaneously by using the microfluidic device, which is equipped with a conductive polymer layer (polyaniline) in the form of a nano-network. The lab-on-a-chip-type device, operating in a continuous flow regime, allows monitoring of germination of bacterial spores and analysis of the process in detail. The procedure is fast and accurate enough for quantitative real-time monitoring of the main steps of germination, including final transformation of the spores into vegetative cells. All of this is done without the use of biomarkers or any bio-specific materials, such as enzymes, antibodies and aptamers, and is simply based on an analysis of physicochemical interactions on the nanoscale level.

A micellar electrokinetic chromatography method has been developed for simultaneous determination of melatonin and its precursors and metabolites. A 20 mM borate buffer pH 9.5 with 50 mM SDS served as the electrolyte. Tryptophan, 5-methoxyindoleacetic acid, 6-hydroxymelatonin, melatonin, serotonin, and 5-methoxytryptamine were baseline separated in less than 13 min. The limits of detection for UV detection and fluorometric detection based on native fluorescence of analytes were at the sub-ppm level. The proposed method with UV detection was applied to melatonin content control in pharmaceutical tablets with a precision expressed as RSD (n = 7) = 1.6%. For biological samples extraction with chloroform and ethyl acetate was examined. With ethyl acetate and chloroform recoveries of 87.2% and 82.1% melatonin, respectively, were obtained from plasma samples. The recovery of melatonin from spiked urine samples was 80.0% for ethyl acetate and 82.5% for chloroform. Fluorometric detection provides about two-fold improvement over UV in the detection of melatonin and minor improvements for three other analytes, but is much poorer than UV for tryptophan and 6-hydroxymelatonin in applied conditions.

The SARS-CoV-2 virus caused a worldwide COVID-19 pandemic. So far, 6,120,834 confirmed cases of COVID-19 with 116,773 deaths have been reported in Poland. According to WHO, a total of 54,662,485 vaccine doses have been administered. New variants emerge that become dominant. The aim of this study was a comparison of antibody level after infection caused by Delta and Omicron variants. The study included 203 persons who underwent mild COVID-19 despite two doses of vaccine. The obtained results indicate that a significantly lower titer was observed in patients with the Omicron variant infection. Therefore, these patients may be at risk of reinfection with new strains of the Omicron variant. Due to the possibility of reinfection, booster vaccinations are necessary. Further epidemiological and clinical studies are necessary to develop new prevention strategies.