Antimicrobial Properties Of Chlorine And Alcohol Disinfectants

Project and Seminar Material for Microbiology

Project and Seminar Material for Microbiology


This study was carried out on the antimicrobial properties of chlorine and alcohol disinfectants. Disinfectant solutions were pre-pared according to manufacturers’ instructions and tested against Staphylococcus aureus ATCC 29213,Pseudomonas aeruginosa ATCC 27853,Streptococcus mutans NCTC1044,Candida albicans ATCC 90028, Bacillus subtilis ATCC15244 spores, Mycobacterium tuberculosis ATCC 25177, My-cobacteriumavium subsp. avium ATCC 25291 and Hepatitis B virus using the Standard quantitative suspension test. The shelf-lives of the disinfectants were also determined.

The results showed that both disinfectants killed all the test organisms within 30 seconds. B. subtilis spores were killed in 2 and 2.5 minutes by chlorine dioxide and sodium dichloroisocya-nurate respectively. When diluted solutions of these disinfectants were stored in screw cap bottles, they retained their activity for at least 30 days. The study concluded that Chlorine dioxide and sodium dichloroiso-cyanurate containing disinfectants can be used in the dentalsettings for surfaces and heat sensitive instruments. However, chlorine dioxide is advantageous because it is non-corrosive and the effective concentration is lower than that recommended for sodium dichloroisocyanurate.

Chapter One


1.1 Background of the study

Antiseptics and disinfectants are used extensively in hospitals and other health care settings for a variety of topical and hard-surface applications. In particular, they are an essential part of infection control practices and aid in the prevention of nosocomial infections. Mounting concerns over the potential for microbial contamination and infection risks in the food and general consumer markets have also led to increased use of antiseptics and disinfectants by the general public (Harold, et al., 1969). A wide variety of active chemical agents (or “biocides”) are found in these products, many of which have been used for hundreds of years for antisepsis, disinfection, and preservation. Despite this, less is known about the mode of action of these active agents than about antibiotics. In general, biocides have a broader spectrum of activity than antibiotics, and, while antibiotics tend to have specific intracellular targets, biocides may have multiple targets. The widespread use of antiseptic and disinfectant products has prompted some speculation on the development of microbial resistance, in particular cross resistance to antibiotics (Cookson, 1991).

Chlorinated compounds are often used in dental clinics and laboratory environment due to their broad spectrum of antimicrobial activity, low toxicity, low cost and efficacy in biofilms.1 However, they corrode metals and are inactivated by organic matter at high concentrations. A slow-release chlorine compound, sodium dichloroisocyanurateis used in healthcare settings; however, it too is corrosive. Slow-release chlorine dioxide disinfectants have been developed containing corrosion inhibitors which are extensively used in the industrial settings (Dye, and Mead, 1972).

The use of chlorine dioxide containing products in dentistry has been explored. Studies have shown that in mouthrinses it is effective for the management of chronic atrophic candidiasis, denture stomatitis, and the control of plaque accumulation, periodontal pathogens and oral malodor.2-5 The efficacy of sodium dichloroisocyanurate for disinfection of radiographic films and irreversible hydrocolloid impression material has also been established (Bates, 1977). none of the above studies have tested the efficacy of these disinfectants against Mycobacteria and Hepatitis B virus. In addition, anti-hepatitis B virus activity of chlorine dioxide has not been established.

1.2 Statement of the problem

Chlorination of bacteria by active chlorine compounds with the aim of killing them occurs both in a variety of disinfection processes and, in vivo, in the myeloperoxidase-hypochlorite system that operates within phagolysosomes of human leuco-cytes.8–10 Investigations on the main long-lived oxidant produced by granulocytes and monocytes, N-chlorotaurine (NCT),11,12 revealed new insights in the consequences of the chlorination of pathogens.

Incubation for a sublethal time of 1min in 1% NCT solution caused a lag of regrowth (postantibiotic effect) of bacteria and a loss of virulence of highly encapsulated staphylococci and streptococci, demonstrated in the mouse peritonitis model.13,14 In addition, bacteria chlorinated by the myeloperoxidase system lost their ability to induce nitric oxide and tumour necrosis factor-a in macrophages.

These findings prompted us to establish methods of detection and quantification of chlorination of bacterial surfaces and to perform the first systematic examination of chlorine covers on Gram-positive and -negative bacteria and Candida albicans.

1.3 Objectives of the study

The main objective of the study is to assess the antimicrobial properties of chlorine and alcohol disinfectants.
This study compares the antimicrobial effect of a chlorine dioxide and a chlorine generating disinfectant on the contaminants commonly present on dental instruments and in the dental surgery.

1.4 Significance / Justifications of the study

This study will help to add to the existing knowledge in this area of research. It will be of significance in the health sector as it will reduce the effects and spread of bacteria on man. It will provide insightful information on individuals in order to educate them on the properties of chlorine and alcohol disinfectants.

This study will also help the educational sector, as it could be used as a source material to carryout further research related to this study.

Chapter Five


In conclusion this study has shown that a non-corrosive slow release chlorine dioxide and chlorine releasing sodium dichloroisocyanurate disinfectants are microbiocidal after 30 seconds exposure and sporicidal after two to three minutes in the presence of organic material. Both the disinfectant solutions were effective for 27 to 37 days if stored in screw cap bottles.

They have the potential to be used in the dental setting as a surface disinfectant and a sterilant for semicritical heat sensitive instruments.

Chlorine dioxide has an additional advantage because it is non-corrosive and the effective concentration is much lower than that required for sodium dichloroisocyanurate.

Clinical Significance

Chlorine dioxide has a broad-spectrum antimicrobial property and therefore it can be used in the dental settings for surfaces and heat sensitive instruments as a sterilant.

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