In Vitro Bactericidal Effect of Garlic (Allium sativum) on Staphylococcus aureus

ABSTRACT
Staphylococcus aureus is a major human pathogen responsible for various infections, including skin infections, food poisoning, toxic shock syndrome, and hospital-acquired infections. The increasing prevalence of antibiotic-resistant S. aureus strains, such as methicillin-resistant S. aureus (MRSA), poses a significant challenge in clinical medicine. This study investigates the in vitro bactericidal effect of garlic (Allium sativum) on S. aureus isolated from wound infections.

Ten wound swab samples were collected from patients at ABU Teaching Hospital, Shika, and cultured on Mannitol Salt Agar for selective isolation of S. aureus. Five of the samples tested positive and were subjected to confirmatory identification before antimicrobial testing. Ethanolic extracts of garlic were used to determine the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) against the isolates. The results were interpreted based on inhibition zone measurements, indicating garlic's antibacterial potential.

The findings support the use of garlic as a natural antibacterial agent against S. aureus, highlighting its potential role in alternative medicine and antimicrobial therapy. Based on the results, recommendations include improved hygiene practices, mass drug administration, microbial resistance monitoring, health education, and further research on garlic's antibacterial properties. This study contributes to the search for alternative treatments in the face of rising antibiotic resistance.

1.1 INTRODUCTION

Over the past 20 years, there has been a lot of interest in the investigation of natural materials as sources of new antibacterial agents (Chehregani et al., 2017). Literature reports and ethno-botanical records suggest that plants are the sleeping giants of pharmaceutical industry and provide natural source of antimicrobial drugs that provides novel compounds that may be employed in controlling some infections globally (Chehregani et al., 2017). Different extracts from traditional medicinal plants were tested and some natural products were approved as new antibacterial drugs. However, there is still an urgent need to identify novel substances active against pathogens with higher resistance (Malika et al., 2014).

For several centuries, garlic has been known to possess dietary and medicinal properties (Ross et al., 2011). Garlic (Allium sativum) has come to be seen as an all rounded treatment for preventing wound infection, common cold, malaria, cough and lung tuberculosis, hypertension, sexually transmitted diseases, mental illness, kidney diseases, liver diseases, asthma, diabetes (Tessema et al., 2016) Allium is the largest and important representative genus of the Alliaceae family and comprises 450 species, widely distributed in the northern hemisphere (Lanzotti, 2016). These species are characterized by a specific flavour and are used for cooking (Tada et al., 2018).

Increased consumption of Allium vegetables decreases the risk of gastric cancer possibly because of the effect of garlic on Helicobacter pylori, as this organism is associated with gastric cancer (Cellini et al., 1996). In addition to their nutritional effects, the antibacterial and antifungal activities against the variety of Gram-negative and Gram positive were and continue to be extensively investigated (White et al., 2018) . Garlic (Allium sativum) has traditional dietary and medicinal applications as an anti-infective agent (Lawson et al., 2018).

Staphylococcus aureus is a Gram-positive spherically shaped bacterium, a member of the Bacillota, and is a usual member of the microbiota of the body, frequently found in the upper respiratory tract and on the skin. It is often positive for catalase and nitrate reduction and is a facultative anaerobe that can grow without the need for oxygen (Masalha et al., 2021). Although S. aureus usually acts as a commensal of the human microbiota, it can also become an opportunistic pathogen, being a common cause of skin infections including abscesses, respiratory infections such as sinusitis, and food poisoning. Pathogenic strains often promote infections by producing virulence factors such as potent protein toxins, and the expression of a cell-surface protein that binds and inactivates antibodies. S. aureus is one of the leading pathogens for deaths associated with antimicrobial resistance and the emergence of antibiotic-resistant strains, such as methicillin-resistant S. aureus (MRSA), is a worldwide problem in clinical medicine. Despite much research and development, no vaccine for S. aureus has been approved.

In vitro evidence of the antimicrobial activity of fresh and freeze dried garlic extracts against many bacteria (Shalaby et al., 2016), fungi (Adetumbi et al., 2016). And viruses (Weber et al., 2012) support these applications. Several studies have proved that garlic has antimicrobial effects (Noori et al., 2017). It inhibits the growth of both gram-negative and gram-positive bacteria, the same as molds and yeasts (Pai, 2012). Increased consumption of Allium vegetables decreases the risk of gastric cancer possibly because of the effect of garlic on Helicobacter pylori, as this organism is associated with gastric cancer (Cellini et al., 2016). This broad spectrum of activity has been attributed to the over 100 phytotherapeutic sulfur compounds present in varying concentrations in garlic. They include allicin and thiosulfinates, which are formed by crushing-induced metabolic action of the enzyme allicinase (a cysteine sulfoxide lyase) on the odorless amino acid allicin (Lawson et al., 2021). Variations in composition of garlic and genetic disparity among bacteria and fungi of the same or different species have been found responsible for the few inconsistencies in the antibacterial and antifungal properties of garlic extract, necessitating the need for local antimicrobial testing of garlic (Kinab et al., 2017).

Staphylococcus aureus is very important pathogen that causes a variety of diseases including skin infections. Gastro intestinal disease (staph) food poisoning, toxic shock syndrome and nosocomial infections acquired during hospitalization.

There is a growing medical problem due to increasing frequency of infection caused by penicillin resistant Staphylococci. Beta-lactamase producing strains of S. aureus that are resistant to penicillin first appeared in cinica specimens in early 1950s. Soon thereafter, multiple antibiotic resistance was detected in chemical isolates of S. aureus; these strains were resistant to macrolide antibiotic, amino glycoside, and tetracycline. Therefore there is need to investigate plants for possible solutions, including garlic.

Therapeutic use of garlic has been recognized as a potential medicinal value for thousands of years to different micro-organisms. For example, antifungal, antiviral, antibacterial anthelmintic, antiseptic and anti-inflammatory properties of garlic are well documented. Moreover, garlic extracts exhibited activity against both gram negative (E. coli, Salmonella species and Citrobacter Enterobacter, Pseudomon, Kilabsella) and gram positive (S. aureus, S. pneumonia Group A streptococcus and Bacillus anthrax) all of which are causes of morbidity worldwide. This study will focus on recent research on protective effects of garlic against Staphylococcus aureus. The information date generated from this research work will be used as a baseline date for possible intervention on drug resistance to antibiotics.

1.4.1 Aim of the study

The aim of this study is to determine the invitro bactericidal effect of Garlic on staphylococcus aureus.

i. To isolate and identify staphylococcus aureus from clinical samples.

ii. To test the susceptibility of staphylococcus aureus to other antibiotics.

iii. To determine the minimal bactericidal effect of Garlic on staphylococcus aureus.

This research will be restricted to testing and determine the bactericidal effect of Garlic on staphylococcus aureus obtain from clinical samples.