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Editor,—Several Campylobacterspp are a frequent cause of gastroenteritis in children, particularly those younger than 2 years in developing countries.1 Recent articles have reported the emergence of campylobacter isolates resistant to quinolones, which are commonly used for the treatment of this infection.2 We have observed the emergence of Campylobacter spp resistant to nalidixic acid, a commonly used quinolone. We propose that due consideration be given to the research and development of allicin, the primary antimicrobial component in garlic (Allium sativum) as an alternative form of enteral treatment in cases of campylobacter infection that fail to respond to conventional antibiotic regimens. Allicin, a naturally occurring antibiotic, has been shown in vitro to have a broad spectrum of activity against Gram positive and Gram negative bacteria, yeasts,3 Candida spp,Cryptococcus neoformans, andHelicobacter pylori.4
The antibacterial effect of an aqueous garlic extract was investigated against 38 clinical isolates of campylobacter from children presenting with diarrhoeal infections, and 32 isolates ofH pylori from adults with peptic ulcers. The campylobacter strains tested wereC jejuni subjejuni (n = 20),C fetus (n = 5),C coli (n = 4),C upsaliensis (n = 3),C jejuni sub doylei(n = 2), and one strain of each of the following:C hyeintestinalis, C ureolyticus, C mucosalis, and C helveticus.
An aqueous garlic extract was prepared according to a modified method of Fromtling and Bulmer.5 Cloves of garlic were dehusked, crushed, and homogenised. Distilled water (100 ml) was added to each 50 g of garlic pulp. The aqueous mixture was mixed for one hour and allowed to stand for a further two hours at 4°C. The resulting aqueous supernatant was decanted to remove the larger tissue particle. The supernatant was centrifuged for 15 minutes to remove smaller particles and then passed through a 0.45 μm acetate membrane filter followed by storage at 4°C for up to seven days before in vitro testing.
The Nathan agar well diffusion assay6 was used to test the susceptibility of the 70 clinical isolates of campylobacter and H pylori to allicin in the aqueous garlic extract at a concentration of 0.5 g/ml. Blood agar plates were inoculated with the different strains and a well (6 mm diameter) made in the centre of each plate. The well was filled with 100 μl of the aqueous extract and incubated at 37°C in an H2 increased atmosphere for 48 hours. Plates were examined, re-incubated, and examined frequently for an additional four days.
The 70 clinical isolates were all susceptible to allicin as seen by zones of inhibition (range 16–32 mm in diameter, mean 21 mm) (table1). Subcultures from the zones of inhibition produced no growth after 48 hours, suggesting that the mode of action of allicin against campylobacter is bactericidal.
These results suggest that allicin should be investigated as a possible enteral treatment for gastroenteritis involving antibiotic resistant campylobacter strains and as a possible cure forH pylori infections.