24 Oct, 2018
Keeping Surfaces Microbe Free
Who is Schulke & Mayr?
For over 125 years, Schulke & Mayr philosophy has been centred around one concept: hygiene. Schulke & Mayr products and services protect people and materials against infections and contamination. In so doing, Schulke & Mayr have learnt that the prevention of infections is considerably easier than fighting them.
In this informal CPD article, Dr Tim Sandle compares the advantages of alcohol and non-alcohol wipes. Dr Tim Sandle is a site Microbiologist at Bio Products Laboratory and a visiting tutor with the School of Pharmacy and Pharmaceutical Sciences, University of Manchester.
Taking Control of Your Surroundings
Infection control is an important part of dental practice, particularly in ensuring that surfaces are clean and maintained in a hygienic state, helping you to take control of your surroundings. Hygiene in this context refers to the elimination of potentially athogenic micro-organisms, including the bacteria that cause tuberculosis and MRSA infections. In order to achieve satisfactory disinfection, a good quality disinfectant is required. An ideal disinfectant should have a high inactivating capacity for a wide range of viruses, such as HIV and hepatitis, as well as being effective against bacteria, including tuberculosis. It should be safe to use and suitable for frequent application. Disinfectants are typically supplied as pre-saturated wipes, which may be alcohol-based, or non-alcohol based. This article considers the key requirements for a surface disinfectant and examines the comparative advantages of alcohol and non-alcohol wipes.
Disinfection and Hygiene
It is the responsibility of everyone working in the practice to ensure that surfaces are clean and disinfected. The process of wiping down surfaces between patients should be an integral part of good practice, helping to disinfect surfaces. The General Dental Council (GDC) recognises the importance of the disinfection of surfaces by making it a compulsory subject for Continuing Professional Development (CPD) for dentists and dental care professionals (DCPs).
Effective Disinfectants Types
Disinfection is the process of using a chemical with proven anti-bacterial, anti-virucidal and anti-fungal characteristics to kill or to inactivate micro-organisms. The effectiveness of disinfectants depends on the types required for micro-organisms. International standards are in place to assess disinfectants in relation to their ability to kill set numbers of micro-organisms (termed ‘biocide efficiency’), where a population of micro-organisms is reduced to a level that should not be harmful to patient health; and to eliminate a wide range of different types of micro-organisms (the spectrum of activity). Standards for disinfection applied to surfaces are distinct from those that apply to the decontamination of dental instruments.
To achieve good disinfection of a surface, there is a choice of different formats and different types of disinfectants. Wipes pre-saturated with the disinfectant of choice are usually the preferred format in a busy dental practice as they are convenient to use, disposable and require less storage space than sprays. Wipes have the added advantage of containing the correct amount of disinfectant. In relation to different types of effective disinfectants, there are two main types available for wiping hard, non-porous surfaces: those that are alcohol based and those which are non-alcohol based, with the latter group generally being types of quaternary ammonium compounds (‘quats’).
Selecting Effective Disinfectants
There are a number of factors that need to be considered when selecting the most appropriate type of disinfectant for surface cleaning. These are:
The disinfectant should be in a user-friendly format, ideally in the form of a wipe. Wipes avoid the need to mix and prepare solutions. They also require less stringent health and safety measures to be adopted (the main requirement is for the user to wear gloves).
It is important that the disinfectants are safe for staff to use, are compatible with the surfaces to which they are applied (in that they do not cause pitting or rusting), and that they can easily be disposed of without harming the environment.
Spectrum of Activity
When choosing a suitable disinfectant the bactericidal, virucidal and fungicidal properties should be carefully studied, as these are essential requirements for an effective disinfectant. A product that has all these properties will give the best possible spectrum of protection. When deciding between alcohol and non-alcohol based disinfectants, it is the alcohol-based types that have the widest spectrum of activity. In recent years there has been a considerable concern with the bacteria that cause MRSA (certain types of Staphylococcus aureus that are antibiotic resistant) and those that cause tuberculosis (Mycobacterium tuberculosis). With tuberculosis, reports suggest that cases in the UK have increased in the past 15 years and the incidence in the UK is above the European average, together with a parallel increase in multi-drug resistant types of the bacterium. In cases of tuberculosis, infection occurs through inhalation of the bacterium which then travels to the alveoli of the lungs. Most people who carry the bacterium do not show any symptoms (latent tuberculosis); however, the condition can be serious for people with weak immune systems. Although the disease is rare, dentists need to be aware of the possible occurrence of oral lesions of tuberculosis and consider them in the differential diagnosis of suspicious oral ulcers. However, in many cases symptoms are not apparent, therefore good disinfection practices should be in force in-between patients. To successfully disinfect surfaces, the format and spectrum of activity should always be reviewed.
One concern is that Mycobacteria have a tough, waxy cell wall that helps to prevent disinfectant entry. With the two common types of disinfectants used to disinfect surfaces, quats are generally regarded as ineffective against the tuberculosis bacterium. There is some evidence that tinctures of quats can inhibit the growth of M. tuberculosis, but not completely kill it. The effectiveness of inhibiting TB bacteria reduces in the presence of protein residues and the bacteria-killing properties of quat-based disinfectants are weakened when the disinfectants are combined with hard water or materials such as cotton or gauze pads. In contrast, alcohols are effective against mycobacteria, with 70 percent alcohol solutions the most effective against these types of microorganisms. Aside from the hardiest spore-forming bacteria, alcohols possess the widest disinfectant kill ranges of the commercially available disinfectants.
Another important consideration is with viruses. Quat-based disinfectants are generally virucidal against what are termed ‘enveloped’ viruses, such as HIV and hepatitis B. However, these chemicals are not virucidal against the ‘non-enveloped’ viruses, such as poliovirus, rhinoviruses (which cause the common cold) and hepatitis A. In contrast, alcohol-based disinfectants, especially those with high ethanol content, can efficiently destroy viruses of all types. One study determined that the optimal virucidal spectrum was with a concentration alcohol mixture (80 per cent ethanol and five per cent isopropanol) for the elimination of all relevant bloodborne viruses
Ease of use
The disinfectants used in a busy dental practice must be in a format that can be applied quickly. They must also have a short ‘contact time’. This is the time in which the disinfectant remains in contact with the surface in order to kill microorganisms. Both quats and alcohols have fairly rapid contact times, requiring less than one-minute contact time.
Importance of Cleaning to Disinfect Surfaces
Surfaces may contain protein residues, such as blood and pus from the patient. To successfully disinfect surfaces, it is important that the disinfection process effectively removes any protein present and allows the disinfectant to work. Alcohols can, in some circumstances, bind proteins to stainless steel instruments. However, this effect has only been demonstrated after a prolonged contact time of over 10 minutes – a period of time that is far in excess of the wiping process required to disinfect surfaces in the practice. Very few dental practices have surfaces that are composed of stainless steel. In practice, alcohols are as effective as quats on surfaces containing protein residues, when a double-wiping procedure is adopted. The first rub of the surfaces with the alcohol wipe removes the protein. The second rub with an alcohol wipe brings the alcohol disinfectant into contact with any remaining micro-organisms, allowing the disinfectant to penetrate through the microbial cell wall and to destroy the microbe by denaturing its cellular proteins.
The dental health-care setting is an environment where the disease in micro-organism transmissions can easily occur. Prevention of cross-infection is, therefore, a crucial aspect of good dental practice and dental professionals need to adopt effective basic routines. This includes the process to disinfect surfaces; especially in between patient visits particularly for the elimination of pathogenic microorganisms, like TB or MRSA bacteria. Given the array of different disinfectant types and formats, the article has considered the optimum criteria for a disinfectant. This assessment has concluded that alcohol wipes offer the best solution for staff and patients. While quats may act quickly on heavily soiled surfaces, a double-wipe with a saturated alcohol wipe ensures that a broader range of pathogens, including TB, are removed, thereby offering better protection of the patient from infection and a more hygienic dental practice.