JAC Advance Access published online on November 11, 2008
Journal of Antimicrobial Chemotherapy, doi:10.1093/jac/dkn457
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Original research |
In vitro activity of an aqueous allicin extract and a novel allicin topical gel formulation against Lancefield group B streptococci
1 University of East London, Romford Rd, Stratford, London E15 4LZ, UK 2 Primal Health Research Centre, London NW3 2JR, UK 3 Allicin International, University House, Romford Rd, Stratford, London E15 4LZ, UK 4 Queen Elizabeth Hospital NHS Trust, Woolwich, London SE18 4QH, UK
Received 20 June 2008; returned 7 August 2008; revised 4 October 2008; accepted 7 October 2008
* Corresponding author. Tel: +44-20-8223-4162; Fax: +44-20-8223 4959; E-mail: r.cutler{at}uel.ac.uk
Background: Studies have shown the efficacy of intra-partum antibiotics in preventing early-onset group B streptococcal sepsis. This approach results in a high intra-partum antibiotic use. Worryingly, the same antibiotics used in prophylaxis are also first-line treatment for neonatal sepsis, and antibiotic exposure in the peri-natal period has been shown to be a risk factor for late-onset serious bacterial infections and allergic disease. Antibiotic exposure in the peri-natal period is becoming a major public health issue; alternative strategies are needed. Garlic has been traditionally used to treat vaginal infections. Allicin is the main antibacterial agent isolated from garlic.
Objectives: The aim of the study was to investigate the in vitro activity of a novel allicin extract in aqueous and gel formulation against 76 clinical isolates of Lancefield group B streptococci (GBS).
Methods: MICs and MBCs of allicin were determined for 76 GBS isolates by agar dilution and microtitre plate methods. Killing kinetics were determined for a selected 16 of the 76 strains. Agar diffusion tests were compared for allicin liquid and gel (500 mg/L).
Results and conclusions: MICs and MBCs of allicin liquid were 35 to 95 mg/L and 75 to 315 mg/L, respectively. Time/dose kill curves produced a 2–3 log reduction in cfu/mL within 3 h and no detectable growth at 8 and 24 h. A novel 500 mg/L allicin gel produced an average zone size of 23 ± 6 mm compared with 21 ± 6 mm for allicin in water. Aqueous allicin is bactericidal against GBS isolates and maintains activity in a novel gel formulation.
Key Words: EOGBS , neonatal infections , garlic