Hematophagous arthropods are important vectors for zoonotic pathogens. To date, a huge number of viruses have been identified in these arthropods, with a considerable proportion of them being human pathogens. However, the viromes of hematophagous arthropods are still largely unresearched. In this study, a number of arthropods were collected from Belgrade, Serbia including mosquitoes, ticks and bedbugs. The viromes of these arthropods were identified and characterized using Illumina MiSeq sequencing. In total, 21 viruses belonging to 11 families were characterized, with 11 of them representing novel species. These results may contribute to our knowledge of RNA viruses in arthropods and the discovery of novel human pathogens.

The aim of this prospective cohort study was to determine the prevalence of gut colonization with multidrug-resistant (MDR) bacteria, risk factors for colonization, infection risk, and outcomes among preterm neonates hospitalized at a tertiary-care center in Serbia. During the period from December 2017 to April 2018, 103 neonates were screened for rectal carriage at admission and on the seventh day of life. Characterization of MDR strains was done by conventional microbiology and molecular methods. Out of 61 (59.2%) colonized neonates, 12 (11.6%) were found colonized at admission, while 49 (47.6%) became colonized at the study site. Among a total of 72 MDR isolates, extended-spectrum beta-lactamase (ESBL)-producing enterobacteria prevailed (56/72, 77%), followed by Acinetobacter baumannii (14/72, 19%). The majority of ESBL-producing strains carried multiple genes (blaTEM/blaCTX-M-15 or blaTEM/blaSHV). Longer previous hospitalization and delivery by cesarean section were associated with MDR colonization, while mechanical ventilation was a risk factor for colonization at the study site. Infections due to MDR bacteria were more frequent among colonized than non-colonized neonates, but not significantly, and mortality was low (1%) in the studied neonates. These results indicate that hospitalized preterm neonates in Serbia are rapidly colonized with a diversity of MDR species and resistance phenotypes/genotypes.

The aim of this study was to estimate substitution rate and imprints of natural selection on parvovirus B19 genotype 1. Studied datasets included 137 near complete coding B19 genomes (positions 665 to 4851) for phylogenetic and substitution rate analysis and 146 and 214 partial genomes for selection analyses in open reading frames ORF1 and ORF2, respectively, collected 1973–2012 and including 9 newly sequenced isolates from Serbia. Phylogenetic clustering assigned majority of studied isolates to G1A. Nucleotide substitution rate for total coding DNA was 1.03 (0.6–1.27) x 10⁻⁴ substitutions/site/year, with higher values for analyzed genome partitions. In spite of the highest evolutionary rate, VP2 codons were found to be under purifying selection with rare episodic positive selection, whereas codons under diversifying selection were found in the unique part of VP1, known to contain B19 immune epitopes important in persistent infection. Analyses of overlapping gene regions identified nucleotide positions under opposite selective pressure in different ORFs, suggesting complex evolutionary mechanisms of nucleotide changes in B19 viral genomes.

Our aim was to investigate gut colonization with carbapenem-resistant Enterobacterales (CRE) in the population of preterm neonates at discharge from a tertiary care center in Serbia. The study included 350 randomly selected neonates/infants discharged in the period April 2018–May 2019. CRE colonization was present in 88/350 (25.1%) of patients. Klebsiella pneumoniae producing KPC and OXA-48 carbapenemase were detected in 45 and 42 subjects, respectively, while NDM producing Escherichia coli was identified in one patient only. All OXA-48 strains harbored bla_CTX-M-15, while both bla_TEM and bla_SHV were present in all but one KPC-producing strain. CRE isolates exhibited a multidrug resistance pattern with uniform fluoroquinolone resistance, universal susceptibility to colistin, and variable susceptibility to aminoglycosides. Administration of carbapenems was common (~50%) and it was strongly associated with colonization, as well as the combinational therapeutic regimens that included meropenem, contrary to ampicillin–sulbactam/colistin therapy and prolonged course of the initial therapy (ampicillin/amikacin ≥ 7 days). Other risk factors for CRE carriage were level of immaturity, admission to neonatal intensive care unit, prolonged hospitalization and invasive procedures. Although the rate of clinically and/or laboratory proven systemic infections was significantly higher among colonized patients, CRE infection was confirmed in one patient only (1.1%) that was colonized with NDM E. coli. Clonal relatedness of CRE isolates was high, with seven and eight clusters detected among KPC (N = 30) and OXA-48 (N = 37) producing strains, respectively. The follow up of the 31 KPC-colonized patients after discharge from hospital revealed common decolonization within one month (~68%). In conclusion, our results demonstrated a high rate of CRE colonization that is most likely related to carbapenem consumption and lack of screening as important infection prevention practice.