1. Introduction

Infection is defined to be the invasion of a host’s body by disease-causing agents such as viruses, prions, bacteria, parasites and fungi (Garner et al, 1988). For infection to occur, each link of the chain of infection has to be present and be in sequential order. The chain of infection is defined to be: Infectious Agent > Reservoir > Portal of Exit > Mode of Transportation > Portal of Entry > Susceptible Host (Truman, 2001). In the United States alone , more than 46.5 million surgical procedures and even more invasive medical procedures are performed each year (CDC, 1996). Each procedure involves contact by a medical device or surgical instrument with a patient’s tissue. A high risk of all medical procedures, regardless of nature, is the introduction of pathogens that can lead to infection. Failure to disinfect or sterilize all items and procedures carries not only the risk associated with the breach of host barriers but also transmission of environmental pathogens. Infections caused by bacterias like Methicillin Resistant Staphylococcus aureus and Escherichia coli O157:H7 are very serious and very lethal. Therefore, it is imperative to stop the transmission of such infections. Our research is an analysis of the best disinfectant commonly used in the medical sector against S.aureus and E.coli (lists of all disinfectants agents below).

The motivation for using sterile diffusion disks for the purpose of the experiment is derived from the Kirby-Bauer method (Hudziki, 2009). This method was then adapted into our experiments by using diffusion disks in place of antibiotics disks. The principle of the Kirby-Bauer method is still retained in the end, although the way the agent is delivered is different.

We also studied the structures of the disinfectants used to formulate a well-thought hypothesis. Hydrogen Peroxide, we noted, will undergo homolytic cleavage, which results in a highly-reactive oxygen species with a oxidation state of -1, capable of strong disinfection properties. Sodium hypochlorite, will decompose into sodium chloride and sodium chlorate, with an oxidation state of +5 (Kotz et al, 1996). Chlorhexidine Gluconate, on the other hand, binds with the negatively charged phosphate groups of the cell wall of a bacteria, which affects the cell osmotic equilibrium, causing lysis. Chloroxylenol, disrupts cell membrane potential, which starves bacterial cells from adenosine triphosphate (University of Hertfordshire, 2013). The other alcohol based disinfectants denature the bacterial proteins, resulting in death due to a wide range of factors.

Based on the above, the team has hypothesised that Chlorhexidine Gluconate is the most effective disinfectant, due to its mechanism of action and long track-record in the medical sector.

No comments:

Post a Comment