Antibacterial Activity of Origanum majorana and Curcuma longa Extracts against Multiple Drug-resistant Pathogenic E. coli and Methicillin-resistant Staphylococcus aureus Isolates Recovered from Meat Products

The presence of antimicrobial-resistant foodborne pathogens in our food can threaten our life. Thus, great attention was paid to find a potentially effective, safe, and natural antimicrobial agent. Therefore, this study carried out this study to in-vitro investigate the potential use of Origanum majorana and Curcuma longa as natural antimicrobial food additives to control multidrug-resistant foodborne pathogens isolated from minced beef and beef burger samples. Herein, we examined 100 raw meat product samples, i.e., 50 each of fresh minced beef and frozen beef burger samples, randomly collected from butcher’s shops in Egypt, for the presence of pathogenic E. coli and S. aureus. Pathogenic E. coli was detected in 36 % of examined minced beef samples, while we failed to isolate it from beef burger. On the other hand, coagulase-positive S. aureus was found in 26 and 10 % of minced beef and beef burger samples, respectively. The multiple-drug resistant (MDR) isolates of E. coli and S. aureus were identified using 11 and 6 commercial antimicrobial discs, respectively. MDR isolates were selected for molecular identification based on virulence and anti-microbial resistance genes. Molecularly, eaeA gene was detected in 100% of identified pathogenic E. coli strains, while stx1 was detected in one strain only. Whereas mecA and coa were detected in 100% of coagulase-positive S. aureus isolates, The antimicrobial effectiveness of Origanum majorana (OM) and Curcuma longa (CL) ethanolic extracts against isolated MDR pathogens were evaluated. OM and CL were potentially effective against MDR coagulase-positive S. aureus with variable inhibition zones ranged from 2mm to25mm. While they did not inhibit pathogenic E. coli strains (O158, O157, O114, O142, O44, O86, O25). Extracts of OM and CL were proved to be potentially effective against MDR coagulase-positive S. aureus, and can be used as a natural alternative food preservative to control S. aureus growth in food in place of chemical antimicrobial agents.