- Volume 7, Issue 4, 2025

Antibiotic resistance is a major public health problem. The search for new therapeutic alternatives is becoming urgent. Essential oils are a promising alternative. This study aimed to evaluate the antibacterial activities of essential oils from selected plants on multidrug-resistant zoonotic strains isolated from dogs. Essential oils from dried Thymus vulgaris leaves, Cinnamomum verum bark and Cuminum cyminum seeds were extracted and tested on five multidrug-resistant Escherichia coli and four Staphylococcus aureus isolated from dogs in southern Benin. The study showed that T. vulgaris essential oil was bacteriostatic, with an MIC equal to 2.5 µl ml−1 and a minimum bactericidal concentration (MBC) of 17 µl ml−1 for E. coli strains and 11.25 µl ml−1 for S. aureus strains. Regarding C. verum essential oil, its bacteriostatic power was characterized by an MIC of 1.25 µl ml−1 for the isolates tested and an average MBC of 11.50 µl ml−1 for E. coli and 12.19 µl ml−1 for S. aureus. On the other hand, C. cyminum essential oil was ineffective on the strains investigated. Additionally, T. vulgaris essential oil contained predominantly thymol (36.57%), p-cymene (30.51%) and carvacrol (7.62%), whilst C. verum essential oil contained cinnamaldehyde (88.76%). This study reveals the antibacterial activity of T. vulgaris dry leaf and C. verum bark essential oils on multi-resistant E. coli and S. aureus isolated from dogs. These two essential oils may be alternative candidates for combating antibiotic-resistant E. coli and S. aureus infections.

Mobile linezolid-resistance genes (optrA, poxtA and cfr) that confer resistance to linezolid and florfenicol have been detected globally in various sources. Linezolid is a last-resort antimicrobial used in human clinical settings, and florfenicol is commonly used in veterinary clinical settings. The present study sought to evaluate the potential of florfenicol in veterinary use to select for linezolid-resistant bacteria. The growth and fitness of linezolid-resistant bacteria harbouring mobile linezolid-resistance genes were assessed in the presence and absence of florfenicol using Enterococcus faecalis and Enterococcus faecium, respectively. The bacterial strains harboured wild and cloning plasmids carrying mobile linezolid-resistance genes, which reduced their susceptibility to linezolid and florfenicol. The acquisition of plasmids carrying mobile linezolid-resistance genes improved bacterial growth in the presence of florfenicol and conferred fitness costs in its absence. Florfenicol imposes a selection pressure on bacteria harbouring plasmids carrying mobile linezolid-resistance genes. Hence, the appropriate use of florfenicol in veterinary clinical settings is important to control the dissemination of mobile linezolid-resistance genes and to ensure the sustained effectiveness of linezolid against multidrug-resistant bacteria, including vancomycin-resistant enterococci in human clinical settings.

Cutibacterium acnes is a bacterial skin commensal that is often isolated during routine testing of blood products like platelet concentrates (PCs). Due to the slow-growing nature of this bacterium in culture media, C. acnes contaminated PCs are often transfused into vulnerable patients before retrieval of these units can be initiated. This study aimed at obtaining the whole-genome sequence of six C. acnes isolates derived from contaminated PCs, comparing and assessing their genetic backgrounds. Furthermore, the whole genomes of the PC isolates were compared to clinical isolates obtained from different sites and types of infection. The results indicate that these PC isolates assessed belong to four phylotypes, namely IA, IB, II and III. Whole-genome comparisons identified differences in the virulence profiles of the isolates and provide a foundation for future studies aimed at evaluating the risk to transfusion patients by determining whether the expression of virulence factors is impacted in the PC storage environment.

Aerobic ammonia oxidation is crucial to the nitrogen cycle and is only known to be performed by a small number of bacterial lineages [ammonia-oxidizing bacteria (AOB)] and a single lineage of archaea belonging to the Nitrososphaeria class of Thermoproteota [ammonia-oxidizing Archaea (AOA)]. Most cultivated AOA originate from marine or soil environments, but this may capture only a limited subset of the full diversity of this clade. Here, we describe several genomes of AOA from metagenomic sequencing of a hot spring microbial mat, representing several poorly characterized basal lineages that may be important for understanding the early evolution of archaeal ammonia oxidation. These genomes include a novel genus most closely related to Nitrososphaera as well as novel species belonging to the genera Nitrosotenuis, Nitrososphaera and Nitrosotalea. Furthermore, the distributions and phylogenetic relationships of key metabolic genes support a history of vertical inheritance of ammonia oxidation and carbon fixation from the last common ancestor of crown group AOA.