Microbiology Research

Antimicrobial resistance (AMR) is accelerating and driven by antimicrobial use. Hospital consumption and resistance data remain scarce in Serbia. This retrospective study assessed the prevalence of infectious agents among hospitalized patients (2019–2022), distribution and AMR rates of Escherichia coli and Klebsiella pneumoniae, antimicrobial consumption, and associations between AMR and antibiotic use (Spearman’s correlation). All bacterial isolates were included for species-frequency analyses. For AMR and specimen distribution, repeat isolates of E. coli and K. pneumoniae per patient were excluded. Among 10,780 isolates, E. coli remained most frequent (24.7% in 2019; 24.3% in 2022), whereas K. pneumoniae increased from 7.7% to 16.9% (p < 0.001). E. coli resistance to cephalosporins, fluoroquinolones, and piperacillin/tazobactam increased significantly from 2019 to 2022 (p < 0.05). K. pneumoniae resistance increased to most agents (p < 0.001), with meropenem resistance rising from 11.7% to 52.0%. Multidrug resistance rose from 27.3% to 35.4% for E. coli (2020–2022; p = 0.006) and from 62.4% to 82.9% for K. pneumoniae (2019–2022; p < 0.001). Total hospital antibiotic consumption nearly doubled from 57 to 111.8 Defined Daily Doses per 100 bed days (2019–2021) and decreased to 52.0 (2022). Temporal concurrence of increased antimicrobial use during COVID-19 and escalating resistance underscores the need for strengthened surveillance and stewardship.

The search for antagonistic microorganisms as alternatives to chemical pesticides is an urgent priority in sustainable agriculture. Previously, we isolated several bacterial isolates from spruce plants, and one of them, identified as Bacillus atrophaeus R7PjV2-12, showed strong antagonistic properties against plant pathogens such as Magnaporthe oryzae, Fusarium avenaceum, and Erwinia billingiae. Given its strong fungicidal properties, we decided to sequence the complete genome of this bacterium to determine how it can inhibit fungal growth. The whole genome size of B. atrophaeus R7PjV2-12 was 4,127,644 bp with 4032 open reading frames. B. atrophaeus R7PjV2-12 genome possessed clusters of secondary metabolites with a complete set of genes with 100% similarity representing clusters of biosynthesis of bacillin, bacillibactin, subtilosin A, and fungicin, which indicates the studied strain’s ability to synthesize these substances. Thus, this paper has shown and discussed the potential importance of B. atrophaeus R7PjV2-12 for biocontrol of pathogenic microorganisms in agriculture.

Thuja arborvitae are widely grown in North America and East Asia for their ornamental value, and their leaf oil extracts have been used to treat bacterial infections. This study aimed to identify antibacterial compounds from Thuja leaves. The methanol extract of Thuja leaves exhibited strong antibacterial activity against Gram-positive (Staphylococcus aureus and Streptococcus mutans) and Gram-negative (Acinetobacter baumannii, Pseudomonas aeruginosa) bacteria. The major compounds in the active fractions were isolated and identified as apigenin-7-di-p-coumarylglucoside and eicosapentaenoic acid. The identified compounds showed potent antibacterial activity against the four tested microorganisms with IC50 values of 10 to 50 µg/mL. More importantly, these compounds showed potent inhibitory activity (IC50: 10 μg/mL) against the multidrug-resistant bacterial strain Acinetobacter baumannii. Two antibacterial compounds are now being reported for the first time in Thuja arborvitae, and they may have potential for the treatment of bacterial infections.