COMPARATIVE STUDY OF DISINFECTANT EFFICIENCY OF ETHANOL, BLEACH AND PHENOLICS AGAINST PSUDOMONAS AERUGINOSA AND STAPHYLOCOCCUS AUREUS
ABSTRACT
Ethanol, Bleach and Phenolics are three kinds of disinfectants which have been widely used in common laboratories. In this study, a compared experiment on these three disinfectants efficiency was conducted against Staphylococcus aureus and Pseudomonas aeruginosa using agar hole diffusion method. Different concentrations of bleach (1%, 2%, 3%, 4% and 5%) were used on both organisms. Also (50%, 60%, 70%, 85% and 95%) of ethanol as well as (5%, 10%, 20%, 25%, and 30%) Phenolics were used. Differences in concentrations tested was because, the original concentrations of the disinfectants differs. After 24 hours of incubation at 370C, the results showed that all the disinfectants inhibited the growth of the test organism in their concentrated forms. The diameter of zone of inhibitions were measured around each well by using a ruler in millimeters, using different concentrations, their efficacies varied. The results showed that 30% Phenolics had the best efficiency against both test organisms and 5% bleach had a better effect on Staphylococcus aureus than Pseudomonas aeruginosa, while ethanol showed least sensitivity. 70% concentration gave the highest effect on Staphylococcus aureus as compared with Pseudomonas aeruginosa.
1.INTRODUCTION
In the mid 1800s, the Hungarian physician Ignaz SEMMELIVEIS and English physician Joseph Lister used these thoughts to develop some of the first microbial control practice for medical procedures. These practices include hand washing with microbes killing chloride of lime and use of techniques of aseptic surgery to prevent microbial contamination of surgical wounds (Hamamah, 2004). Over the last century, scientists have continued to develop a variety of physical methods and chemical agents to control microbial growth. Control directed at destroying harmful microorganisms is called disinfection. It usually refers to the destruction of vegetative (non-endospore forming) pathogens example bacteria by using a disinfectant to treat an inert surface or substances (Bhatia and Icchpujani, 2008).
Bacteria are major causes of disease and even human death. A disinfectant is one of the diverse groups of chemicals which reduces the number of microorganisms present (normally on an inanimate object). There are various official definitions of the process of disinfection and disinfectants agents. It is defined as a chemical that inactivates vegetative microorganism but not necessarily high resistant spores (ISO, 2008). Cleaning and disinfection of surfaces are essential steps for maintaining the cleanliness of pharmaceutical industries, hospitals and environments (Rollins, 2000). Disinfectant as effective agents that kill or eliminates bacteria is widely used in various ways; especially in microbial laboratory. Disinfectant can be mainly divided into five agents; alkylating, sulfhydryl combining, oxidizing, dehydrating and permeable. The most commonly used disinfectants in laboratories are ethanol, bleach and Isol (Larson and Morton, 1991). Bleach also known as sodium hypochlorite is a broad spectrum disinfectant, non specific in their action, only action biological material that is present on any surface. They effects by oxidizing the cell of microorganism and attacking essential cell components including lipid, protein and DNA (Ho-Hyuk Jang et al, 2008). Ethanol, as a dehydrating agent, lies between the highly specific and broadly based categories. It is effective against actively growing bacteria and viruses with a lipid based outer surfaces, but are not effective against bacterial spores or viruses that prefer watery environment. They cause cell membrane damages, rapid denaturalization of proteins with subsequent metabolism interference an cell lyses (Larson and Morton, 1991). Another surface disinfectant is the compound that contain phenol group, a popular commercial brand of Isol, (a saponated brand of cresol) as a phenolics are intermediate level disinfectant derived from coal tar, that are effective on contaminated surfaces (Bittel and Hughes, 2003).