African Journal of Microbiology Research Vol. 6(21), pp. 4475-4480, 9 June, 2012 Available online at http://www.academicjournals.org/AJMR DOI: 10.5897/AJMR11.540 ISSN 1996-0808 ©2012 Academic Journals Full Length Research Paper Inhibitory effect of aqueous garlic (Allium sativum) extract against clinical isolates of Salmonella typhi Abdul Hannan 1 , Kanwal Rauf 1 , Muhammad Ikram Ullah 2 , Tahir Naeem 3 , Mehwish Raja 1 , Muhammad Usman Qamar 1 , Romeeza Tahir 4 and Mehwish Saba 1 1 Department of Microbiology, University of Health Sciences, Lahore-Pakistan. 2 Department of Biochemistry, University of Health Sciences, Lahore-Pakistan. 3 King Saud University Hospital Riyadh, Saudi Arabia. 4 Department of Immunology, University of Health Sciences, Lahore-Pakistan. Accepted 6 February, 2012 Typhoid Fever is a systemic disease which is more prevalent in under-developed countries. Drug resistance has been developed against antibiotics used for the treatment of typhoid. It is very important to set the basis of alternative medicines for management of typhoid. Garlic is one of the natural plants being used as spicy food and folk medicine. Various beneficial therapeutic effects of garlic have been documented including anti-microbial, hypolipodemic and anti-oxidant. The objective of present study was to explore anti-bacterial activity of aqueous garlic extract against Salmonella typhi. A total of 50 clinical isolates of S. typhi including 30 multi-drug resistant (MDR) and 20 antibiotic sensitive isolates were investigated to check the inhibitory effects of garlic extract; screening was done by agar well diffusion assay and minimal inhibitory concentration (MIC) was performed by agar dilution technique. MIC of garlic extract ranged from 18-22 mg/ml; showing the inhibitory activity of garlic extract against S. typhi isolates. It is worth describing that garlic might be utilized as anti-typhoid agent after determining its pharmacokinetics and pharmacodynamics. Key words: Antibacterial activity, garlic extract, Salmonella typhi, minimal inhibitory concentration (MIC), agar dilution. INTRODUCTION Typhoid fever still causes substantial illness and deaths in many parts of the world, especially in developing nations (Ochiai et al., 2005). According to a report published WHO bulletin in 2000, the estimated global incidence of typhoid fever was about 21.6 million and mortality rate was up to 216,000 per year. The highest incidence rate of typhoid fever (>100/100,000 cases/year) has been reported in south-central Asia and south-east Asia (Crump et al., 2004). In 2008, it was reported that the incidence of typhoid fever is 451/100,000 in Pakistan (Kothari et al., 2008). Multi drug resistant (MDR) Salmonella typhi showed resistance to all three first line drugs {Ampicillin (AMP), Chloramphenicol (C), and Trimethoprim-sulfamethoxazole *Corresponding author. E-mail: kanwal.rauf@gmail.com. Tel: +92334-4153248. (SXT)} (Ackers et al., 2000). MDR S. typhi emerged somewhere in the mid 1990s and are now reported in different regions of the world (Ward and Thelfall, 2001; Parry et al., 2002). Under these circumstances, third generation cephalosporin namely, ceftriaxone (CRO) appears to be the most reliable choice for MDR and nalidixic acid resistant isolates of S. typhi (NARST) (Bhutta, 2006). In 1999, high level resistance to CRO (MIC 64 mg/L) has been reported from Bangladesh (Parry et al., 2002; Saha et al., 1999). Recently extended spectrum beta lactamase (ESBL) production has been reported in S. typhi isolate isolated from the 54 year old Dutch man returned from Philippines (Naiemi et al., 2008). This continuous spread of MDR pathogens and cost- effectiveness of drug regimen has become a serious threat to public health and infection control practitioners. The multiple and repeated difficulties with antibiotics has prompted research to explore alternate agents.