AbstractIntroductionGold nanoparticles are known for its antimicrobial and immune response eliciting properties. It has been using for centuries in prevention of infectious diseases by increasing the immunity of the host.ObjectiveThe role of antibacterial therapy is the gold standard in all the established guidelines for prevention, mitigation, treatment and control of the known bacterial species which are harmful to human health. In this study we determined the antibacterial effectiveness of high dose of amoxicillin/potassium clavulnate and Gold nanoparticles(AuNPs) sourced from different pharmaceutical companies.MethodologyAfter obtaining the informed written consent from the subject, culture swabs were obtained from the Fournier’s gangrene. The collected sample is made to grow on blood agar and MacConkey agar in ambient temperature of 370 Celsius over 24 hours. The growth is observed and confirmed as Klebsiella pneumonia a Gram-negative, non-motile, encapsulated, lactose-fermenting, facultative anaerobic, rod-shaped bacterium. Appearing as a mucoid lactose fermenter on MacConkey agar.Klebsiella pneumonia is isolated and inoculated on Mueller-Hinton Agar. The agar well diffusion method is carried out with 4 well containing AuNPs I , AuNPs II , amoxicillin/potassium clavulnate and blank respectively. The results are observed after 24 hours and 48 hours of inoculation.ResultsThe Agar well diffusion method containing AuNPs I , AuNPs II , amoxicillin/potassium clavulnate and blank respectively after 24 hours showed higher Zone of Inhibition for amoxicillin/potassium clavulnate rather than AuNPs I & II and no Zone of inhibition around the blank well. The Zone of Inhibition observed after 48 hours of inoculation is 23 mm for amoxicillin/potassium clavulnate, 18 mm for AuNPs I and 15 mm for AuNPs II. No Zone of inhibition is observed around blank even after 48 hours.Discussion and ConclusionThe rate of diffusion of Gold nanoparticles in the particular agar is not known and due to heavy metal of gold and its insolubility property in water makes it difficult for liquid preparation. The zone of inhibition(ZOI), minimum inhibition concentration(MIC) of the gold nanoparticles are not well established. The accuracy of the agar well diffusion method for evaluation of antimicrobial property of gold nanoparticles is not yet standardized. Keeping all these limitations of this study we present our data about antimicrobial activity of gold nanoparticles against Klebsiella pneumonia is minimum as compared to amoxicillin/potassium clavulnate. The further studies can be carried with functionalized AuNPs in the prevention of antimicrobial resistance.KeywordsGold nanoparticles(AuNPs), Agar well diffusion method, Zone of inhibition(ZoI), amoxicillin/potassium clavulnate and Klebsiella pneumonia .1. INTRODUCTIONAntibiotic resistance is a major threat to global health. Resistant bacterial infections are currently resulting in over 1.2 million deaths every year1 and are projected to reach 10 million casualties annually by 2050. This crisis is due to the continuous emergence and spread of antibiotic-resistance genes across important human pathogens and the limited introduction of new, broad-acting, clinically useful antimicrobials since the 1970s2. Alongside genetic resistance, alternative bacterial lifestyles during infection, such as persistence3 and growth in biofilms4, also contribute to patient mortality due to ineffective antibiotic treatment. As such, it has become essential to not only boost our currently insufficient preclinical and clinical antimicrobial development pipelines5 but to also safeguard the longevity of our approved antibiotics. Both feats heavily rely on our ability to evaluate the efficacy of antimicrobial agents against bacteria, which underpins the identification of antibiotic-resistant strains in the clinic and enables testing of novel antibiotic or antibiotic-adjuvant candidates.A wide variety of medicinal products which originate from natural compounds and which are widely used to target and treat various appear diseases. The extraction of these complicated chemical molecules from plants, animals, microorganisms and minerals are common natural sources via several extraction processes, these compounds work as an initiator of future sinker molecules. Gold is inert and universally recognized as biocompatible. Until the recent past, it was only known as the metal. With the arrival of nanotechnology and the discovery of nanoparticles and the exploration of the physico-chemical properties of gold make it a supreme material for progress fields6,7. A nanoparticle is defined as a tiny particle with a size ranging between 1 and 100 nm.Agar well diffusion method is widely used to evaluate the antimicrobial activity of plants or microbial extracts 8,9. Similarly to the procedure used in disk-diffusion method, the agar plate surface is inoculated by spreading a volume of the microbial inoculum over the entire agar surface. Then, a hole with a diameter of 6 to 8 mm is punched aseptically.Zone of inhibition (ZOI), also known as a zone of clearing or a halo assay, refers to the clear zone surrounding an antimicrobial agent. These ZOIs result from a complete absence of bacteria on, or within a confluent bacterial lawn.The antimicrobial activity of the agent is screened against a test organism which is used to create a confluent lawn of bacterial growth on an agar plate. The ZOI is measured in mm after 24 to 48 hours of incubation.A primary function of the immune system is to protect the host from pathogenic microbial infections. Innate immune mechanisms dominate during the early phase of the antimicrobial immune response. As the innate response sometimes does not clear the infecting microbe, T lymphocytes and neutralizing antibodies may often be required for its complete elimination. The innate response is nonetheless indispensable for host survival since it prevents such microbes from spreading in an uncontrolled manner and thereby provides the host with the “grace period” of 3–4 d required for the activation of an efficient adaptive immune response.2. MATERIAL AND METHODSThe amoxicillin/potassium clavulanate is obtained from Karnataka antibiotic and pharmaceuticals limited plot no 14, II Phase, Peenya, Bengaluru 560058. AuNPs I is obtained from Shree Dhootapapeshwar Limited, 135, Nanubhai Desai Rd., Khetwadi, Mumbai – 400 004. AuNPs II is obtained from Nanoshel United kingdom through its subsaidiary located in Punjab, India.Composition of Blood AgarBlood agar, like most other nutritional media, has one or more protein sources, salt, and beef extract for vitamins and minerals. Besides these components, 5% defibrinated mammalian blood is also added to the medium. The blood agar base is commercially sold by various vendors, or it can also be prepared in the laboratory if the necessary ingredients are available. The exact composition of the blood agar base is given below: