Antibacterial Activity of Aqueous Garlic Extract on Beta-Lactamase Producing Acinetobacter Isolates From Skin and Soft Tissue Infections

Abstract

Objective: The present study evaluates the antibacterial effect of aqueous garlic extract (AGE) on beta-lactamase-producing Acinetobacter strains isolated from skin and soft tissue infections (SSTIs). Methods:A total of 41 non-duplicate strains of Acinetobacter isolated from SSTIs specimens were tested for their antibiotic susceptibility pattern by Kirby-Bauer disk diffusion method. Ceftazidime-resistant Acinetobacter strains were screened for beta-lactamase production by phenotypic confirmatory disc diffusion test and E-test. Antibacterial activity of AGE was examined by the disc diffusion method, and the minimum inhibitory concentration (MIC) of AGE and cefotaxime was determined by the agar dilution technique. The combined activity of AGE and cefotaxime was evaluated by calculating the fractional inhibitory concentration index by the checkerboard method.Results: A total of 21 Acinetobacter strains were confirmed to be beta-lactamase producers, out of which, 6 were metallo-beta-lactamase producers, 3 were Ambler Class C, and 12 were multiple beta-lactamase producers. AGE exhibited a significant antibacterial activity as the observed zones of inhibition ranged from 18 to 31 mm against the test strains. The MIC of AGE was in the range of 0.5-2% (2.5-10 mg/ml) with a mean of 0.86% (4.28 mg/ml). About 11 test strains showed synergism, 5 strains exhibited additive and indifferent effect, each. By high-performance liquid chromatography analysis, the concentration of allicin was found to be 0.20, expressed as percentage w/w. Conclusion:It can be stated that AGE might have therapeutic value against beta-lactamase-producing Acinetobacter isolates from SSTIs.

Evaluation of synergism between Cefotaxime and Allium sativum against Extended-spectrum beta-lactamase and Ambler class C co-producers

“…However, a study by Guoliang et al (2015) reports a synergistic association between AGE and Cefotaxime against non-beta-lactamase producing Pseudomonas aeruginosa, Candida albicans, and Methicillinresistant Staphylococcus aureus. Previous study carried out by Shah et al (2016) also reported synergistic activity between Cefotaxime and AGE against Acinetobacter strains which coproduce ESBL and AmpC.…”

“…E-test ESBL and AmpC detection Ezy MIC TM strip (EM081, HiMedia, Mumbai, India) along with pure ESBL detection strips (EM079 Hi-Media, Mumbai, India) were used in the study. The strains were confirmed as ESBL and AmpC beta-lactamase coproducer in reference with the application sheet provided by the manufacturer (CLSI, 2012;Shah et al, 2016). The confirmed ESBL and AmpC co-producers were considered as the test strains in the study.…”

“…Fresh garlic bulbs (A. sativum) were purchased from the local market and its aqueous extract was prepared by the method described by Shah et al (2016). To estimate the dry weight of the extract, method of Eja et al (2007) was performed and the concentration was determined to be 500 mg/ml.…”

“…If the minimum FIC index was found to be >0.5 and ≤1, the effect of the combination was termed as an additive interaction. If the minimum FIC index was >1 and ≤2, the effect of the combination was recorded as indifference (Nakamura, 2000;Shah et al, 2016).…”