In certain situations the human body is a perfect environment for microorganisms to grow. Both harmless and harmful microorganisms are found on our skin, mucous membranes and other body orifices. Normal flora are microorganisms that live both on and/or in our body in a symbiotic and non-harmful relationship with us.
Every day we are constantly exposed to transient microorganisms. For example: when someone coughs on your hair when travelling on public transport. In this instance this transient flora will eventually be removed by washing, hand washing, being flushed out of our immune system or by urine and sweat secretions.
Pathogenic microorganisms are those that are harmful to humans and result in disease. These provide the most concern and therefore a back to basics approach to hand hygiene and respiratory management are appropriate ways to prevent infection. Occasionally microorganisms that are not normally considered pathogenic can cause infections when the body’s defence system is weak or damaged, and so called opportunistic for that reason.
The method of transmission for the current COVID-19 is currently thought to be via contact with respiratory droplets when a person infected with the virus coughs or sneezes. These droplets can then be inhaled by people in close proximity or land on surfaces where they are transferred via touching the surface and then touching the eyes, nose or mouth.
Risk of spread from person to person is thought to be low if no symptoms are present however some of those infected experience only a very mild cough and do not feel unwell. There is ongoing research that aims to establish the period of transmission for COVID-19.
In the dental practice we maintain a Standard Precautions approach and treat all patients as if they are a potential source of infection, irrespective of perceived risk. A good risk-based assessment is necessary for Coronavirus, just as it is for any other illness that a patient or staff member may present with.
Transmission of Coronavirus Disease (COVID-19)
A method of transmission is the way in which a pathogenic microorganism is able travel and spread from the host. In the dental environment this can include:
Contact - direct or indirect
This is direct or indirect contact with dry skin or contaminated surfaces. Direct contact is most likely to occur from working without gloves or direct contact with a patient such as shaking hands. Indirect contact can occur when there is insufficient cleaning of items and surfaces and poor hand hygiene. This relates to dental instruments or equipment but also includes general areas such as door handles and bench tops. Viruses and bacteria that can be spread in this way include MRSA, impetigo, herpes simplex, scabies, lice, chickenpox, and shingles.
Contact transmission can be minimised or eliminated with good Hand Hygiene protocols and techniques. Correct use of PPE including the type, how well the items are worn and how they are removed are important. Indirect contact can be controlled with implementation of appropriate cleaning products and procedures.
Airborne - aerosols
Aerosol contamination includes splatter (>50μm), droplet (≤50μm) and droplet nuclei (≤10μm). In the dental setting 90% of aerosol contaminants are incredibly small (<5μm). Aerosol contamination as a method of transmission means contact with mucosal membranes or broken skin from equipment or patients. Aerosols are particularly challenging due to their small particle size and that they can remain suspended in the air for long periods of time.
Performing dentistry generates significant airborne contamination from both highspeed handpieces and ultrasonic scalers. Unnecessary manual cleaning of instruments can also contribute to airborne contamination. Aerosols can also be generated by coughing and sneezing. The diseases that can be transmitted in this way include; meningitis, whooping cough, influenza, avian flu, swine flu, scarlet fever, rubella, and the common cold.
Aerosol transmission can be minimised using preprocedural rinsing and good control with high volume evacuation or isolation products. Patients and team members can be kept safe with the correct use of PPE, particularly good quality face masks when worn properly without gaps on the sides. Quarantine periods, Cough Etiquette and Respiratory Hygiene policies can be useful to manage patient and staff illness.
Coronavirus – Standard Precautions are the best defence.
Continue to read our blogs over the coming weeks to ensure you have up to date reminders about the appropriate methods of transmission in more detail.
Next week’s blog - Hand Hygiene.
In the meanwhile, remember and review!
*1 Carton of Level 3 Face Masks Complimentary On Every Purchase of Infection Prevention And Control Combi Pack