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Next-generation sequencing (NGS)-library preparation for whole-genome sequencing (WGS) starts with DNA fragmentation, and sonication is a physical approach used most often due to its simplicity and reproducibility. However, the commercially available Covaris instrument has a high price for both the device and consumables. Here, we describe our in-house method of DNA shearing by sonication with small (100–600 µm) glass beads and an ultrasonic bath. The fragmentation conditions were optimized for the bacterial WGS with ∼550-bp fragment size (the ultrasonic bath water temperature 5–10°C, glass beads 0.06 g, the fragmentation time 50 s) and for human DNA with ∼250 bp (fragmentation with the same parameters for 4 min). Fragmentation results were compared with the Covaris instrument for preparing several bacterial NGS libraries for Illumina NGS platforms by several characteristics. We obtained close mean fragment lengths (523–623 versus 480–646), similar mono- and dinucleotide specificity of shearing, and comparable indicators of read alignment and de novo assembly for both methods. Thus, the described method is a new fast, and effective DNA fragmentation approach that can be used in different WGS applications.

Foodborne disease is one of the major public health problems worldwide. The conventional methods used to detect foodborne pathogens require multiple incubation steps and take a long time to results. Thus, there is an urgent need for biosensors that can determine pathogens without special sample preparation. This paper outlines a method for discriminating E. coli contaminated meat since this bacterium has been implicated as one of the main causative agents of food illness. The method is based on the laser-induced fluorescence response of the Flavin group that is presented among E. coli bacteria’s metabolites. The fluorescence activity of metabolites produced by five E. coli strains was investigated. The list of analyzed strains contains ATCC 25922 E. coli, Enteropathogenic E. coli, Enteroinvasive E. coli, Enterotoxigenic E. coli, and Enteroaggregative E. coli. The preliminary results have allowed developing the statistical model using a part of the fluorescence spectra in the range of 520-560 nm when excited at 450 nm. The proposed model is aimed to differentiate contaminated and uncontaminated meat samples. It has been confirmed that the examined technique provides detection of a bacterial concentration of 106 CFU∙cm-2 in five hours after initial contamination at room temperature. The further improvement of the method by using fluorescent probes is discussed.

The aim of this study was to compare the prevalence of different virulence factor (VF) genes in extended-spectrum beta-lactamase (ESBL) producingEscherichia colistrains isolated from the Baltic Sea region. A total of 432 strains of phenotypically ESBL positiveE. coliwere collected from 20 institutions located in Estonia, Latvia, Lithuania, and the region of St. Petersburg in Russia from January to May 2012 and analyzed for phylogenetic group and prevalence of 23 VF genes. The strains were collected from clinical material (urine, blood, wound, and respiratory tract). Bacterial isolates were compared according to phylogenetic group, clinical material, and geographical origin. Most of the VF genes were concentrated within phylogenetic group B2 and/or D. When comparing strains isolated from different countries, it was found that strains originating from Estonia and Latvia belonged mainly to group B2 and strains from Lithuania and Russia mainly to groups B2 and D. The P-fimbrial adhesin genepapEFwas more prevalent in Russian strains, colicin genecvaCin Lithuanian strains, and capsular genekpsMTIIin Latvian strains; serum resistant genetraTwas less prevalent in Estonian strains. The regional differences of VF genes remained statistically significant after taking into account the phylogenetic distribution in the countries.

The spread of carbapenemase-producing Enterobacteriaceae is a global problem; however, no exact data on the epidemiology of carbapenemase in the Baltic countries and St. Petersburg area is available. We aimed to evaluate the epidemiology of carbapenemase-producingEscherichia coliandKlebsiella pneumoniaein the Baltic States and St. Petersburg, Russia, and to compare the different methods for carbapenemase detection. From January to May 2012, allK. pneumoniae n=1983andE. coli n=7774clinical isolates from 20 institutions in Estonia, Latvia, Lithuania, and St. Petersburg, Russia were screened for carbapenem susceptibility. The IMP, VIM, GIM, NDM, KPC, and OXA-48 genes were detected using real-time PCR and the ability to hydrolyze ertapenem was determined using MALDI-TOF MS. Seventy-seven strains were found to be carbapenem nonsusceptible. From these, 15K. pneumoniaestrains hydrolyzed ertapenem and carried theblaNDMgene. All of these strains carried integron 1 and most carried integron 3 as well as genes of the CTX-M-1 group. No carbapenemase-producingE. coliorK. pneumoniaestrains were found in Estonia, Latvia, or Lithuania; however, NDM-positiveK. pneumoniaewas present in the hospital in St. Petersburg, Russia. A MALDI-TOF MS-based assay is a suitable and cost-effective method for the initial confirmation of carbapenemase production.