Monika Ivanova

Waste Water Treatment Plants (WWTP) aim to reduce contamination in effluent water; however, studies indicate antimicrobial resistance genes (ARGs) persist post-treatment, potentially leading to their spread from human populated areas into the environment. This study evaluated the impact of a large WWTP serving 125,000 people on the Iskar River in Bulgaria, by characterizing the spatial and short-term temporal dynamics in bacterial community dynamics and resistance profiles of the surface water. Pairs of samples were collected biweekly on four dates from two different locations, one about 800 m after the WWTP effluents and the other 10 km downstream. Taxonomic classification revealed the dominance of Pseudomonodota and Bacteriodota, notably the genera Flavobacterium, Aquirufa, Acidovorax, Polynucleobacter, and Limnohabitans. The taxonomic structure corresponded with both lentic and lotic freshwater habitats, with Flavobacterium exhibiting a significant decrease over the study period. Principal Coordinate Analysis revealed statistically significant differences in bacterial community composition between samples collected on different dates. Differential abundance analysis identified notable enrichment of Polynucleobacter and Limnohabitans. There were shifts within the enriched or depleted bacterial taxa between early and late sampling dates. High relative abundance of the genes erm(B), erm(F), mph(E), msr(E) (macrolides); tet(C), tet(O), tet(W), tet(Q) and tet(X) (tetracyclines); sul1 and sul2 (sulphonamides); and cfxA3, cfxA6 (beta-lactams) were detected, with trends of increased presence in the latest sampling dates and in the location closer to the WWTP. Of note, genes conferring resistance to carbapenems blaOXA-58 and blaIMP-33-like were identified. Co-occurrence analysis of ARGs and mobile genetic elements on putative plasmids showed few instances, and the estimated human health risk score (0.19) according to MetaCompare2.0 was low. In total, 29 metagenome-assembled genomes were recovered, with only a few harbouring ARGs. This study enhances our understanding of freshwater microbial community dynamics and antibiotic resistance profiles, highlighting the need for continued ARGs monitoring.

Aims: We aimed to evaluate the prevalence of irritable bowel syndrome (IBS), functional dyspepsia (FD), and their overlap syndrome (OS) in the Bulgarian population and to assess the risk factors associated with these disorders. Methods: We sent an internet-based survey to Bulgarian adults. The survey collected data on socio- demographic, behavioral and lifestyle characteristics, and diagnostic questions following the Rome IV criteria to assess IBS, FD and their overlap occurrence. Results: Data was collected from 1,896 individuals (mean age = 35.5 years, 18-65, SD=11.7), 73.1% females. The prevalence of IBS was 20% (14% were with predominant constipation, 32% with predominant diarrhea, 52% had IBS with mixed bowel habits, and 2% unclassified IBS). Gender (p=0.005), age (p<0.001), marital status (p=0.009), occupation (p=0.001), alcohol consumption (p=0.013), sexual problems (p<0.001), FD (p<0.001), and milk intolerance (p<0.001) were significantly associated with IBS. Females (p=0.032; OR: 1.50), patients with FD (p<0.001; OR: 104.98), sexual problems (p= 0.001; ОR: 1.55 ), and milk intolerance (p<0.001; OR: 2.22) are at a higher risk of having IBS. The prevalence of FD was 12.7% (39% had postprandial distress syndrome, 33% epigastric pain syndrome, and 28% had the overlapping variant). Patients with IBS (p<0.001; OR: 127.88) and milk intolerance (p<0.001) were significantly associated with FD prevalence. The prevalence of OS was 11.7%. Gender (p=0.013), milk intolerance (p<0.001, OR: 1.65), urinary (p=0.035) and sexual problems (p<0.001, ОR: 1.80) were associated with OS prevalence. Conclusion: This is the first study to estimate the prevalence of IBS, FD, and their OS and assess the behavioral and demographic risk factors associated with these disorders in the Bulgarian population. Our results are valuable in filling in the epidemiological data gap regarding IBS, FD, and OS in Eastern Europe.