Pilot Study on the Action of Thymus vulgaris Essential Oil in Treating the Most Common Bacterial Contaminants and Salmonella enterica subsp. enterica Serovar Derby in Poultry Litter.

The indiscriminate use of antimicrobials in poultry farms is linked to the increase in multi-resistant bacteria. Accordingly, based on the antimicrobial properties of Thyme Essential Oil (TEO), the present study evaluated the effects of TEO on the reduction of common microbial contaminants and Salmonella on poultry litter. A litter bulk sample was collected in a broiler farm and qualitative/quantitative investigations identified Escherichia coli and Mammaliicoccus lentus. The experimental contamination with Salmonella Derby wild strain was also performed. All pathogens showed phenotypic and genotypic resistance to different classes of antibiotics. The litter, split in different units, was treated with aqueous solutions of TEO at different concentrations (5% to 1.25%), demonstrating its effectiveness in reducing the total number of bacteria. The strongest antibacterial action was observed at the lowest concentration against Enterobacteriaceae, with a growth reduction compared to the positive control of 73.3% and 77.8% against E. coli and Salmonella Derby, respectively, while towards M. lentus the reduction was 50%. Our data confirm the antimicrobial activity of TEO and suggest its possible application for the treatment of poultry litter as an effective and natural approach for the prevention of diseases caused by the most common bacteria that colonize poultry farms, counteracting the onset of antibiotic resistance.

Virucidal and antiviral effects of Thymus vulgaris essential oil on feline coronavirus.

Feline infectious peritonitis (FIP) is a fatal systemic disease of felids caused by a Coronavirus (CoV) (FIPV). In spite of its clinical relevance and impact on feline health, currently the therapeutic possibilities for treatment of FIP in cats are limited. The emergence of the pandemic Severe Respiratory Syndrome (SARS) coronavirus (CoV) type 2 (SARS-CoV-2), etiological agent of the 2019 Coronavirus Disease (COVID-19), able to infect a broad spectrum of animal species including cats, triggered the interest for the development of novel molecules with antiviral activity for treatment of CoV infections in humans and animals. Essential oils (EOs) have raised significant attention for their antiviral properties integrating and, in some cases, replacing conventional drugs. Thymus vulgaris EO (TEO) has been previously shown to be effective against several RNA viruses including CoVs. In the present study the antiviral efficacy of TEO against FIPV was evaluated in vitro. TEO at 27 µg/ml was able to inhibit virus replication with a significant reduction of 2 log10 TCID50/50 µl. Moreover, virucidal activity was tested using TEO at 27 and 270 µg/ml, over the cytotoxic threshold, determining a reduction of viral titre as high as 3.25 log10 TCID50/50 µl up to 1 h of time contact. These results open several perspectives in terms of future applications and therapeutic possibilities for coronaviruses considering that FIPV infection in cats could be a potential model for the study of antivirals against CoVs.