Comparison of the effects of antibiotics and essential oils against Acinetobacter baumannii in planktonic and biofilm conditions

Salim, Jisa; Nariapara, Vikas; Adukwu, Emmanuel; Snook, Aislinn

Abstract

Background: Acinetobacter baumannii is a common nosocomial pathogen causing pneumonia, bacteraemia, wound and urinary tract infections. Due to improper and frequent antibiotic use A. baumannii has become multi-drug resistant, the World Health Organization has classified A. baumannii as a priority pathogen of which novel antibiotics are desperately needed. Research into natural antimicrobial compounds are essential in developing novel strategies to treat multidrug resistant infections.

Aims: To investigate the antibacterial and antibiofilm effects of antibiotics and the essential oils of thyme (Thymus vulgaris) and lemongrass (Cymbopogon flexuosus) against A. baumannii isolates.

Methods: Antimicrobial susceptibility tests were conducted using the disk and vapour diffusion methods. The minimum inhibitory concentration (MIC) and minimum biofilm inhibitory concentration (MBIC) method was performed using a 96-well plate method. Spot inoculation from the wells of the plate, onto nutrient agar, was used to determine the minimum bactericidal concentration (MBC). Time-kill assay was performed to determine the time for the test compound to achieve a 3-log kill of the bacteria.

Results and Conclusion: Both lemongrass and thyme essential oils were effective at inhibiting the growth of A. baumannii including the ATCC BAA-1710 strain which was found to be resistant to Ciprofloxacin. The MIC and MBC of the ATCC BAA-1710 strain was found to be 0.16% for lemongrass. At the concentration <0.2% (v/v) thyme EO inhibited the growth of A. baumannii and also inhibited the formation of biofilms for both wild type (NCTC 12156) and clinical strain (SM37212). Thyme and lemongrass EO are effective at inhibiting and eradicating in planktonic as well as biofilm forms of A. baumannii, suggesting potential use for it in as an antimicrobial agent. Due to the widespread antimicrobial resistance exhibited by A. baumannii, the need for novel antimicrobials to target these infections is necessary, EO’s show promising results, further research should be conducted due to their cytotoxic effects.

• Presentation Conference Type: Poster
• Conference Name: Annual Biomedical Research Conference for Minoritised Scientists
• Start Date: Nov 14, 2023
• End Date: Nov 18, 2023
• Deposit Date: Mar 10, 2024
• Public URL: https://uwe-repository.worktribe.com/output/11777694