Utilization of clove and cinnamon essential oils as an alternative to inhibit MDR and biofilm producing E. coli from raw chicken meat

The microbial contamination and spoilage found in chicken meat is responsible for food-borne illnesses and outbreaks leading to hospitalizations. E. coli is the most commonly reported microorganism. The dissemination of bacterial strain with biofilm-formation ability and resistance to antimicrobials at the end of the food chain is a global concern; as well. Eco-friendly and novel means like essential oils are required to break these vicious patterns and ensure the longevity of quality food products. The study aimed to probe the prevalence, pattern of antimicrobial resistance and the biofilm formation ability in E. coli isolated from chicken meat samples. It also explored the antimicrobial and anti-biofilm formation ability of clove and cinnamon essential oils. 150 chicken meat samples from different localities of Karachi, Pakistan were isolated and identified by selective culturing and conventional microbiological techniques. Following antibiogram analysis, antibacterial activity of clove and cinnamon essential oils was evaluated. Putative biofilm production ability was also explored using the test tube, microplate reader, and scanning electron microscopy. Finally, the molecular characterization of potentially strong biofilm producers was done along with exploration of the pathogenic gene (PapC). 49 chicken meat samples out of 150 were contaminated with E. coli. 90% (44 isolates) of E. coli were multidrug resistant. 59.2% (29 isolates) were biofilm producers (BPs). Out of 29 BPs, nine (31%) were strong biofilm producers (SBPs). No significant correlations were observed between antimicrobial resistance and biofilm producing ability of E. coli isolates (p value ≥ 0.05). 40% of SBPs were inhibited when subjected to both clove (MIC: 250 to 500 µL/mL) and cinnamon (MIC: 62.5 µL/mL) EOs. Activity of both neat CO and CinO had no significant difference (p value ≥ 0.05). The identity of 3 SBPs (Strains: AR11E, AR12E and AR22E) were further confirmed by molecular identification (16SrRNA) and SEM revealed potential degradation of the bacterial cells with a reduction in count when treated with CinO and CO. Only one strain (AR22E) was positive for the papC gene. The prevalence of E. coli and strong-biofilm producers in retail chicken meat was not very high; however, the majority of the isolates were multi-drug resistant. Therefore, it is important to keep a tab on the prevalence of these commensal and pathogenic microorganisms in retail chicken meat since they are an exposure site close to the consumer. The use of alternative means like essential oils in poultry, meat and meat-products is a good strategy since they have proven efficacy against pathogenic E. coli.