Antimicrobial susceptibility of cinnamon and red and common thyme essential oils and their main constituent compounds against Streptococcus suis. (26th October 2021)

• Record Type: Journal Article
• Authors: de Aguiar, F.C.; Solarte, A.L.; Gómez‐Gascón, L.; Galán‐Relaño, A.; Luque, I.; Tarradas, C.; Rodríguez‐Ortega, M.J.; Huerta, B.
• Is Part Of: Letters in applied microbiology. Volume 74:Number 1(2022)
• Page Start: 63
• Page End: 72
• Publication Date: 2021-10-26
• Subjects: essential oils -- minimum bactericidal concentration (MBC) -- minimum inhibitory concentration (MIC) -- Streptococcus suis -- time‐kill curve -- zoonosis; Microbiology -- Periodicals; 660.62
• DOI: 10.1111/lam.13582
• Languages: English
• ISSNs: 0266-8254

Abstract

Abstract: Streptococcus suis is an emerging zoonotic pathogen causing different diseases, in both humans and pigs. Generally, the control of this pathogen is based on antimicrobial therapy, but the development of bacterial resistance has led one to look for new options. In this sense, the essential oils (EOs) constitute a promising alternative. The activity of cinnamon, common thyme and red thyme EOs and their main active compounds (cinnamaldehyde and thymol) against S. suis isolates from pigs ( n = 50) and humans ( n = 6) was determined by the broth microdilution method. MIC50–90, MBC50–90 and the bactericidal index (BI) (minimal bactericidal concentration (MBC)/minimal inhibitory concentration (MIC)) were calculated. Also, the time‐kill curve of each product against the S. suis P1/7 European reference strain was determined. No differences in the MIC or MBC values were observed between all the tested products, which suggest a homogeneous behaviour of S. suis, independently of their origin, organ of isolation or resistance profile. All the products showed a concentration‐dependent and time‐dependent killing activity and achieved the virtual eradication of S. suis at supra‐inhibitory concentrations within the first 5 min of exposure, except cinnamaldehyde that showed only bacteriostatic effect. It suggests that these products could be utilized as antimicrobials in veterinary medicine for the control of this zoonotic pathogen. Abstract : Significance and Impact of the Study : The growing emergence of cases of antimicrobial resistance in Streptococcus suis to many classes of antimicrobial agents represents a global issue in recent years. In response to this intractable problem, we investigated some alternatives to the use of conventional antimicrobials. The antibacterial activity of cinnamon, common thyme and red thyme essentials oils and their main active compounds (cinnamaldehyde and thymol) was analysed. All the tested products show an antimicrobial activity, suggesting that these products, although further studies are needed, may be suitable as a novel therapeutic approach to S. suis infection.