When is an Infection Not an Infection?

All skin has a certain resident level of bacteria and fungi known as microflora. This may be a difficult concept for patients familiar with advertisements for cleaners that ‘remove all germs’, but this resident microflora is an essential part of the body’s protection against pathogenic organisms. The presence of this low-level, non-replicating microbial presence is known, somewhat misleadingly given its important role, as contamination. The term contamination tends to cover a bacterial count of up to 103 microbes per gram of tissue.

Colonization & Signs of Infection

The term colonization describes the presence of microflora that replicate to form colonies but that do not adversely affect the individual. The tipping point at which the increasing number of bacteria becomes a bioburden which does adversely affect the host is known as critical colonization. A critical colonization can usually be detected from a plateau in wound healing or a decline in wound status. The term infection describes the situation in which microorganisms multiply and invade viable body tissues. Infection can usually be identified quite readily through a decline in wound status, and the presence of the five classic signs of infection:

  • rubor
  • calor
  • tumor
  • dolor
  •  functio laesa

However, it is worth remembering that some wound infections can be ‘silent’, putting them at risk of going undetected, sometimes for a considerable time.

Bioburden & Effect on Patients

Infection, therefore, should not be considered a discrete phenomenon, but rather the end of a continuum of increasing bioburden. Attempts have been made to define the precise bacterial load required to constitute an infection, but this is misleading as different bacterial strains have a different virulence and different individuals have a different level of resistance. The best way to think of wound infection, therefore, is not in terms of microbial load, but in terms of its clinical effect on the patient. This issue will be covered in future articles.

All wound specialists need a detailed understanding of wound infection, and of the development of wound infection. To refresh your knowledge of wound infection, and to bring your skills up to date with current best practice, consider becoming wound certified. Studying for wound certification is the perfect opportunity to renew your skills and knowledge and to demonstrate your commitment to wound management.

Learn More With Our Wound Care Education Options

Interested in learning more about wound care certification? Browse through our wound care certification courses for information on our comprehensive range of education options to suit healthcare professionals across the full spectrum of qualifications and experience.


  1. Kingsley A. The wound infection continuum and its application to clinical practice. Ostomy Wound Manage. 2003 Jul;49(7A Suppl):1-7.
  2. Myers BA. Wound management principles and practice. 2nd ed. Upper Saddle River, NJ: Pearson; 2008.
  3. Sibbald RG, Woo KRN, Ayello EA. Increased Bacterial Burden and Infection: The Story of NERDS and STONES. Advances in Skin & Wound Care. 2006; 19(8):447-


  1. Thank you for your query. Detailed information about the University of Texas staging system may be viewed here. However, please note that this staging model is only used to classify diabetic foot ulcers. Please also see the NPUAP pressure ulcer staging system, which may be viewed at the NPUAP website, http://npuap.org/.

    The National Guideline Clearinghouse (NGC) is a public resource for evidence-based clinical practice guidelines. You will be able to find guidelines on a variety of wounds by visiting their website at: http://guidelines.gov/.

    As you are aware, it is important to note that the assessment and staging of a wound is only one part of the treatment plan. It is essential to consider the entire patient, including history, medications, and nutritional status prior to implementing a treatment plan.

    I hope that this information is helpful. Good luck with your BSN studies.

  2. Hey Linda, the staging can change depending on what layer you have debrided into.  If you are into muscle or bone it’s a level 4.  On charting you can always up stage a wound, say from 3 to 4.  You can never down stage a wound say from level 4 to 3. 


    Mike Pizzolatto, RN CWCA

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