Transmission based precautions

Understanding the difference between Standard Precautions and Transmission based precautions and how they interact and overlap is vital in understanding recommendations for safe compliant practice. 


Standard Precautions are the primary strategy to reduce the transmission of infectious agents with all patients, at every interaction to stop infectious agents spreading via contact, droplet or air.
Standard precautions consist of:
  • hand hygiene, as consistent with the 5 moments for hand hygiene
  • the use of appropriate personal protective equipment
  • the safe use and disposal of sharps
  • routine environmental cleaning
  • reprocessing of reusable medical equipment and instruments
  • respiratory hygiene and cough etiquette
  • aseptic technique
  • waste management
  • appropriate handling of linen.
Standard precautions should be used in the handling of blood (including dried blood); all other body substances, secretions and excretions (excluding sweat), regardless of whether they contain visible blood; non-intact skin; and mucous membranes.


Transmission based precautions are implemented where standard precautions alone may be insufficient to prevent further infection. Transmission based precautions are applied in addition to standard precautions to target infective agents based on their mode of transmission.
When undertaking transmission based precautions, the patient should not be kept waiting in the waiting area. A streamlined process for entry in, and exit out of the facility, reduces the risk of environmental contamination. Medical history and other details should be completed prior to the patient entering the practice, e.g. over the telephone.
During dental treatment under Transmission based precautions, the dental assistant does not leave the room during the procedure. An additional staff member should be available to serve as a “runner” if the clinician needs items that are outside the operatory.


Contact precautions prevent direct transmission (via blood or body fluids coming into contact with mucous membranes or broken skin) or indirect transmission (via contaminated hands, clothing, surfaces or devices). Infectious agents that require contact precautions include methicillin-resistant Staphylococcus aureus (MRSA) and Clostridium difficile.
Contact precautions include: patient isolation, placement of PPE prior to entering the patient room, removal of PPE without causing environmental contamination, strict adherence to hand hygiene procedures, limited patient movement within the healthcare facility, greater stringency for decontamination of impressions and laboratory work, environmental cleaning of the patient setting using a TGA registered disinfectant following the manufacturer’s instructions.
Droplet precautions are required where large infected respiratory droplets from coughing, sneezing or talking are directly transmitted via contact with mucosa (eyes, nose or mouth) or indirectly via hands or from contaminated surfaces within 1 metre. Infectious agents that require droplet precautions include seasonal viral influenza.
Droplet precautions require barrier use, surgical mask, patient placement and surface decontamination. These precautions include (1) the patient is seen as the last patient of the day; (2) ensuring that staff providing treatment have been immunised against the currently circulating influenza strains; (3) use of a pre-procedural mouth rinse; (4) use of a rubber dam for restorative procedures; (5) minimising the use of aerosol-generating techniques; and (6) applying two complete cycles of cleaning for environmental surfaces. In general, there will be few situations encountered where the patient has a significant dental emergency and where the use of analgesics and other measures will not allow a delay until the patient is no longer infectious.
Airborne precautions are required where health care workers and patients are at risk of inhaling small infective particles. Airborne precautions, such as wearing P2 (N95) surgical respirators, are designed to reduce the likelihood of transmission of microorganisms that remain infectious over time and distance when suspended in the air. These agents may be inhaled by susceptible individuals who have not had face-to-face contact with (or been in the same room as) the infectious individual. Infectious agents for which airborne precautions are indicated include measles, chickenpox (varicella), and Mycobacterium tuberculosis, as well as novel respiratory pathogens such as H5N1 (avian) influenza, H7N9 influence, and coronavirus infections.
The implementation of airborne precautions requires a negative pressure room, and this aspect makes airborne precautions not suitable for use in a typical office-based practice setting. For effective airborne precautions, a P2 (N95) surgical respirator is required, that forms an airtight seal with the face. A P2/N95 respirator should be fit-tested to ensure that a correct mask is selected which enables an air-tight fit, and then fit-checked by the clinician at the time of use. They cannot be used with facial hair, as this prevents the formation of an air-tight seal between the respirator and the facial skin of the HCW.
A powerpoint from Qld Health describing how to fit-check a P2/N95 respirator is available at

1. Donning Sequence

Don PPE in the following sequence:
  • Hand hygiene (ABHR)
  • Impervious gown
  • Mask – surgical or P2 respirator
  • Protective eyewear – goggles with side protection
  • Gloves

2. Doffing Sequence

  • Remove gloves, being careful not to touch outside of gloves
  • Hand hygiene (ABHR)
  • Remove protective eyewear (Place on paper towel. They will be cleaned later)
  • Remove gown, roll inside out and place in a rubbish bag,
  • Remove mask, by touching ties or elastics only, and place in a rubbish bag. Tie the bag closed. 
  • Hand hygiene


Table 14. Australian Guidelines for the Prevention and Control of Infection in Healthcare. (2019)


Table 14. Australian Guidelines for the Prevention and Control of Infection in Healthcare.(2019)

3. Clean up procedure

Place a rubbish bag for disposal of all disposable items utilised for patient care including PPE in the operatory in a convenient location, prior to commencing treatment.
Dentist – removes all sharps, then removes PPE as per Doffing procedure (placing this into designated rubbish bag) and then leave the room.
Dental Assistant - BEFORE removing PPE and after the patient has been escorted back out to the reception area by the runner:
  • Remove instruments from bracket tray and place them in a suitable carrier for later transport to the instrument processing area. At this stage leave the tip on the triplex syringe.
  • Purge all the dental unit waterlines (for 30 seconds) by running these directly into the high-velocity suction.
  • Take the bag off the headrest and invert this, so it can be used for collecting waste
  • Remove the triplex syringe.
  • Remove all disposable items such as gauze, cotton rolls, bibs, disposable suction tips, barriers and any other consumables, and place these into the headrest bag which then goes into the normal rubbish bag.   
  • Remove PPE as per Doffing procedures and place in a rubbish bag, then perform hand hygiene.  
  • Remove enough disposable towels with suitable TGA approved disinfectant action (e.g. Caviwipes) from their container to clean all surfaces and chairs twice.
  • Wipe all surfaces, starting from high to low and from clean to contaminated, changing the wipes for each section and depositing used wipes into the designated rubbish bag. A suggested cleaning sequence for the environmental clean is:
  • dental operating light, chair (upholstery where the patient sits)
  • Handpiece lines on the bracket table, bracket tray
  • Suction lines on the DA side and spittoon
  • Base of the dental chair
Perform hand hygiene, CHANGE GLOVES and wipe down
  • DA stool and dentist’s stool  
  • All benches
Perform hand hygiene again, CHANGE GLOVES again and perform the second wiping down sequence, allowing surfaces to completely dry naturally before resetting.
Doff PPE as per the procedure outlined above, and seal off the rubbish bag.

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