Most point-of-care tests (POCT) use swabs for sampling and/or for applying a sample on the test. A variety of swabs differing in tip materials is commercially available. Different tip materials have different chemical and physical characteristics which might influence the specimen collection and release. We investigated properties of various types of swabs used in clinical diagnostics with focusing on two kinds of analytes, DNA and proteins, which are most often used targets in POCT. As the model samples we used diphtheria toxoid NIBSC 69/017 for investigating recovery of protein analytes such as antigens and bacterial strains of Escherichia coli ATCC 25922, diphtheria toxin-producing Corynebacterium diphtheriae NCTC 10648, and the clinical isolate nontoxigenic C. diphtheriae 5820/15 for investigating the recovery of nucleic acids. We investigated four types of swabs most commonly used in clinical diagnostics in terms of absorption capacity and efficiency of release of nucleic acids and proteins. Volume uptake was measured in milligrams. For DNA release various washing out buffers were used and the amount of released DNA was measured spectrophotometrically. The amount of protein released from the swabs were examined using the Lowry assay. We observed statistically significant differences (p < 0.05) in the mean weights of absorbed liquid, in the DNA recovery and protein recovery by the four variety of swab examined. However, the efficiency of DNA and protein release was not correlated to the absorbed volume of a sample, but rather to the properties of swabs. The swab composition and structure can have a significant impact on the collection and release efficiency of a sample. Therefore, validation of POCT in relation to the used swabs for sampling is really important. The use of inappropriate swabs could lead to false negative or misleading analysis results.

A Klebsiella pneumoniae epidemic strain that coproduced carbapenemase KPC-2 (K. pneumoniae carbapenemase 2) and 16S rRNA methylase ArmA has emerged in Poland. Four nonduplicate isolates from patients in a hospital in Warsaw, Poland, were found to carry the bla _KPC-2 and armA genes on ca. 50-kb and 90-kb plasmids, respectively. Tn4401 with a 100-bp deletion in the variable region was detected in all the isolates. XbaI pulsed-field gel electrophoresis (PFGE) revealed 93.2% similarity of the isolates. All the isolates were resistant to carbapenems and 4,6-disubstituted 2-deoxystreptamines.

The presented study is focused on the development of repetitive, fast and versatile “on-off” signaling electrochemical genosensor for detection of pagA gene of Bacillus anthracis. Such a sensor will be further used in the portable devices dedicated to molecular diagnostic. The DNA molecular beacon probe was immobilized onto gold electrodes in its folded state through the alkanethiol linker at the 5’-end, while the 3’-end was labeled with methylene blue redox molecule. Initial optimization was conducted for HPLC purified cDNA. Nonetheless application of such prepared biosensor for unpurified PCR product required further investigations. As the sensor response was significantly dependent on the stem-loop architecture, the three different hairpin probes were analyzed. The detected sequence was interior to amplicon, identical as in case of cDNA. The developed “on-off” genosensor allows for detection, in 5 minute, the pagA gene sequence at the level of 5.7 nM with 22.9–86.0 nM linear detection range also in the great excess of other DNA presented in the sample. Both LOD and linear range were significantly improved in case of longer assay time. The biosensor proved its applicability also in detection of pagA gene of Bacillus anthracis in PCR samples amplified with reduced number of cycles.