Introduction

Allium sativum belongs to the family Liliaceae, commonly known as garlic. Garlic is a well-known indigenous herbal medicine since ancient times and held a place of honor in Indian traditional ayurvedic medicine. Most of therapeutic effects are ascribed to specific oil and water-soluble organosulphur compounds, which are responsible for the typical odor and flavor of garlic (1). Fractionation and analysis of aqueous garlic extract have shown that the active ingredient is allicin, a low-molecular-weight compound whose biological activity is rapidly abolished by exposure to thiols (such as L-cysteine), heat, or alkali (2). Reuter et al. (1996) and Harris et al. (2001) reviewed the therapeutic effects of Garlic on the cardiovascular system, antibacterial, antiviral, antifungal, antiprotozoal, anticancer, antioxidant, immuno-modulatory, anti-inflammatory hypoglycemic and hormone like effects (3, 4). This study will focus only on antibacterial activity of A. sativum cloves and leaves.

E. coli and S. aureus are the most prevalent urinary tract pathogens capable to causing urinary tract infections (UTIs). There are several reports on the phenomenon of development of antibiotic resistance in human urinary tract (UT) pathogens i.e. E. coli, S. aureus, K. pneumoniae, P. aeruinosa, Enterococcus spp. (5, 6, 7). Among many therapeutic applications of garlic, there are few reports published on its use as a natural herbal antibiotic (8, 9, 10). In present study we have tested specifically the antibacterial activity of aqueous allicin from cloves and leaves of A. sativum against antibiotic resistant gram-negative and gram-positive UT bacteria.

Materials And Methods

Allicin assay discs

Test organisms

Antibacterial activity by disc diffusion method

Statistical analysis

Results And Discussion

Disc diffusion method was applied to confirm the resistance status of urinary tract pathogens against many antibiotics such as Polymyxin B, gentamycin, kanamycin, neomycin, tetracycline, chloramphenicol and ciprofloxacin. Resistance rate was determined as given in table 1.

Figure 1

In the study, most resistance bacterial isolates of E. coli, S. aureus, K. pneumoniae, P. aeruinosa, Enterococcus spp were used to check the antibacterial activity of A. sativum cloves and leaves samples, were collected from U.K. and U.P. Crude extracts of A. sativum cloves and leaves from U.K. and U.P. were tested for antibacterial activity against gram positive and negative UT bacteria and the extracts showed antibacterial activity higher in U.K. samples as compare to U.P. (data not shown). The further study was focused on U. K. samples. On the basis of several past reports, A. sativum was used as a traditional medicine and has exhibited wide range of biological activity (1, 3, 4) and antimicrobial activity of A. sativum is well recognized in relation to those organisms that were antibiotics resistant. In India, Sharma et al. (1977) conducted study, which reveals that crude garlic extracts exhibits greater antibiotic action against Bacillus anthracis (anthrax) than tetracycline, penicillin, streptomycin, erythromycin and other antibiotics (16).

The increasing resistance rate against many antibiotics in community has led to a demand for new herbal agent that may be used to decrease the spread of these bacteria. There are huge literatures on the antibacterial effects of fresh garlic juice, aqueous and alcoholic extracts, lyophilized powder, steam distilled oil and other commercial preparations of garlic. Garlic is active even against organisms that have become resistant to antibiotics (17). ^{In 2006, Adeniyi et al. have reported increasing multidrug resistance uropathogenic bacteria by plasmid profile (18). Allicin of garlic is well documented as an active ingredient in herbal medicine and has already been proved to have antimicobial efficacy against those microbes, which are already resistance against many antibiotics (19). Therefore, the present study was performed to purify and identify the allicin from cloves and leaves of A. sativum as natural source. Further it has already been established that natural drugs have few side effects as compare to allopathic drugs. Antibacterial activity of aqueous allicin was checked against antibiotic resistant gram-negative and gram-positive UT bacteria by disc diffusion method and results were summarized in table 2).}

All test isolates were found sensitive with aqueous allicin that was extracted from A. sativum leaves and cloves. A total five quantities i.e. 10, 20, 30, 40 and 50 µg/disc of allicin from both parts of A. sativum were used to determine maximum inhibitory quantity against antibiotics resistance urinary tract bacteria. Out of five quantities of allicin only 40µg/disc showed highest inhibition zone in case of A. sativum cloves i.e. 22.50 mm for E. coli, 18.50 mm for K. pneumoniae, 17.00 mm for Enterococcus spp., 19.50 mm for P. aeruginosa & 23.50 mm for S. aureus and in case of A. sativum leaves 16.00 mm for E. coli, 15.50 mm for K. pneumoniae, 11.50 mm for Enterococcus spp., 11.00 mm for P. aerguinosa & 16.50 mm for S. aureus.

Gram-positive bacteria showed significant higher sensitivity than gram-negative bacteria at the maximum inhibitory concentration of allicin. In 2006, Indu et al. previously have also reported that garlic extract possessed low level of antibacterial activity against gram negative bacteria due to major plant pathogens are gram negative having an effective permeability barrier such as outer membrane, MDR pumps etc (20). Among all gram-negative bacteria E. coli showed maximum zone of inhibition (22.50mm). This finding indicates the maximum inhibitory action of allicine was on E. coli and S. aureus. Results of quantitative efficacy were found similar as previously reported (21). Allicin from A. sativum cloves against test bacteria have higher activity (Statistically P<0.01) than A. sativum leaves in the study.

Results demonstrate that A. sativum remarkably sensitive agent against antibiotics resistant gram- negative and gram-positive UT bacteria. The results are in close agreement with observation of previous researchers (8, 9, 22, 23). A growing body of scientific evidence confirms that natural herbs and spices exhibit antibiotic properties that are equivalent (24) and may be superior to drugs (8, 19, 25).

Many investigations suggested that the herbal antibiotics might be used to treat the urinary tract infections. But the present study indicates the use of herbal antibiotics in the treatment of urinary tract infections that did not treat by antibiotics. Therefore A. sativum has considerable sensitivity against antibiotics resistant UT bacteria and may be used a substitute of antibiotics in near future.