Infections caused by multidrug-resistant strains of microorganisms are extremely difficult to treat with conventional antimicrobial agents (AMP). Garlic is a sufficiently potent phytopreparation which can protect the macro-organism against various infectious diseases caused by bacteria, viruses and fungi. However, to date, little is known about the potential of fresh garlic extract to improve the susceptibility of multiresistant isolates of microorganisms to antibiotics.

In a study in China, the antimicrobial activity of garlic extract, as well as the combination of antibiotics with garlic extract on strains resistant to methicillin Staphylococcus aureus (MRSA ), Pseudomonas aeruginosa and Candida albicans, and the interactions between antibiotics and garlic extract have also been studied.

Clinical strains were obtained from samples of clinical material taken from patients at the Xi'an Jiaotong University Research Center. In total, the study tested 30 strains of each microorganism (MRSA, P. aeruginosa, C. albicans). The S strains were used as control strains to determine the quality of the disc diffusion method in accordance with the CLSI protocol. aureus ATCC®25923, C. albicans ATCC®90028 and P. aeruginosa ATCC®27853. The microorganisms tested (n = 93) were divided into 4 groups: controls (deionized water, fresh garlic extract, antibiotic, antibiotic + garlic extract). Antibacterial activity was assessed by measuring the diameter of growth inhibition zones in accordance with existing standards from the Clinical and Laboratory Standards Institute (CLSI), formerly known as the National Committee for Clinical Laboratory Standards (NCCLS).

The fresh garlic extract showed clear inhibitory activity against C. albicans and MRSA, while suppressing activity against Pseudomonas aeruginosa was negligible. In addition, garlic extract has shown an improvement in the antimicrobial activity of AMP against resistant strains of microorganisms. Synergy of garlic extract with fluconazole and itraconazole compared to C. albicans manifested in larger areas of growth inhibition compared to the use of fluconazole and itraconazole alone (P less than 0.01). Similar results were obtained by comparing generation III cephalosporins with and without garlic extract compared to P. aeruginosa (P less than 0.01).

Thus, this study demonstrated that the addition of garlic extract can improve the sensitivity of the pathogens studied to a number of antimicrobial agents.