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Transmission based precautions

Standard precautions are adequate to break the chain of infection for many infectious diseases, such as Anthrax and HIV, but not for others.

Standard precautions are adequate to break the chain of infection for many infectious diseases, such as HIV, but not for others that are spread by different modes.

Transmission based precautions

Once a patient is confirmed or suspected to be infected with a pathogen, extra precautions are implemented. These are referred to as transmission based precautions (TBP). TBP are performed in conjunction with standard precautions. There are three sets of TBP depending on the mode of transmission of the infectious agent involved:

  • Contact
  • Droplet
  • Airborne

More than one set of TBP is required for diseases that have multiple routes of transmission such as chicken pox (varicella) (Contact and Airborne) or influenza (Contact and Droplet).

You may be wondering why there are only three sets of TBP when you learned earlier that there are five modes of transmission. This is because the necessary precautions for some modes of transmission are the same for others. To remind you, the five modes of transmission are:

  • Contact (direct and indirect)
  • Ingestion
  • Inoculation
  • Inhalation (droplet and airborne)
  • Trans-placental

As the trans-placental mode of transmission only poses a risk to the foetus and not to others, precautions are not strictly necessary. Ingestion and inoculation are essentially types of contact, so the necessary precautions are easily congregated into Contact TBP. Inhalation is subdivided into droplet and airborne, which require different precautions. This is because droplets can only travel limited distances compared with airborne particles. To summarise:

TBP Mode of transmission Example disease
Contact Direct/indirect contact
Droplet Inhalation (droplet) Whooping Cough
Airborne Inhalation (airborne) Measles

All three sets of TBP involve the continued implementation of standard precautions; however some aspects are performed with greater intensity. This refers mainly to environmental cleaning, hand hygiene and PPE. Mandatory PPE varies with the TBP set, as well as the nature and risk level of the planned procedure. PPE for Contact precautions focuses more on protecting the healthcare personnel’s hands and clothing, whilst PPE for Droplet and Airborne precautions focuses more on protecting their mucous membranes and airways, respectively. For example, gloves and gowns/aprons should always be worn for Contact precautions, but masks are not always necessary. Normal surgical masks are mandatory for Droplet precaution whilst for Airborne precautions, high-filtration respirators are recommended. Hand hygiene and PPE use is not exclusive to healthcare personnel; visitors must also adhere to these standards before seeing the patient.

Patient isolation

Apart from enhanced standard precautions, TBP also involves patient isolation, to protect others. Patients should be accomodated preferably into single rooms. This may not always be possible however, especially during outbreaks. The use of patient dedicated equipment and limiting the movement of the patient within and between facilities is also effective in limiting transmission.

Patients with Airborne precautions should be placed in a negative-pressure isolation room with air-filtering capabilities. The negative pressure limits diffusion of airborne infectious agents out of the room (Li et al., 2007). Isolation rooms should be accompanied by an anteroom: a room with the same relative air pressure where the healthcare personnel and visitor can perform hand hygiene and don/remove required PPE. Isolation can come at a cost however, as some patients can feel neglected or confused (Barratt, Shaban, & Moyle, 2011), while others enjoy the peace and quiet (Findik, Ozbas, Cavdar, Erkan, & Topcu, 2012).

The application of both standard precautions and TBP is essential in limiting HAIs. Preventing HAIs not only prevents excess expense, pain and death, but also the development of antimicrobial resistance.

Your Task

Have a look on your country’s government websites for official guidelines on preventing infectious diseases in healthcare settings. Can you find any? Share with the group. You can provide links.


Barratt, R.L, Shaban, R., & Moyle, W. (2011). Patient experience of source isolation: Lessons for clinical practice. Contemporary Nurse, 39(2), 180-93.

Findik, U.Y, Ozbas, A., Cavdar, I., Erkan, T., & Topcu, S.Y. (2012). Effects of the contact isolation application on anxiety and depression levels of the patients. International Journal of Nursing Practice, 18(4), 340-6.

Li, Y., Leung, G., Tang, J., Yang, X., Chao, C.Y., & Yuen, P.L. (2007). Role of ventilation in airborne transmission of infectious agents in the built environment: A multidisciplinary systematic review. Indoor Air, 17(1), 2–18.

© Griffith University
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