Bioburden and Biofilm: Know Your Enemy

Incision · · 8 min read

The OR found bioburden on the tray you sent up … they ended up having to delay the case.

These are words no Sterile Processing Manager wants to hear. The twin concepts of bioburden and biofilm can strike fear into even the most battle-hardened of techs. These are two of the strongest and most ruthless enemies facing the Sterile Processing Professional. Day in, day out, we do battle. Patient safety is at stake. Once again, the SPD stands firm, steadfast at the frontline of our defense. But to prevail, we need to study our enemies closely. We must test their strengths, exploit their weaknesses, and arm ourselves with the knowledge we need for victory…

Image created with Midjourney AI.

If you know your enemy and know yourself, you need not fear the result of a hundred battles.

– Sun Tzu, The Art of War

Enemy 1: Bioburden

Bioburden is something we fight every day in the SPD. It is a measure of overall threat: the number of biological microorganisms present on something after it has been used.

The total number of viable microorganisms in a sample (or total viable count) is usually expressed in terms of colony forming units (or CFUs); the higher the count, the higher the burden. Visible and invisible bioburden left over from surgery must be removed through decontamination or the instrument cannot be properly sterilized. This brings us to enemy number 2, the sworn adversary of decontamination: biofilm.

Enemy 2: Biofilm

When too much bioburden is left from the OR, or decontamination is delayed, a biofilm can develop. Biofilms are collections of microorganisms that form on a surface. They are held together by a slimy connective layer called a matrix. The term biofilm was actually first used in the 1960s to describe the layer that formed on a type of filter used in wastewater purification (think pond scum) [1].

Image from ARTIS Micropia Biofilm: A Community of Microbes, 2023.

A biofilm creates a protective environment that allows microbes to survive in numerous and extreme conditions. It shields them from some of the chemicals and processes we use in the SPD, making them extremely difficult to remove through decontamination. Evidence of biofilms can even be found in the fossil record stretching back billions of years [2]. They occur in nature, industry, and healthcare, from wastewater to agriculture, leg ulcers to urinary catheters to dental plaques. They are the most prevalent form of a natural ecosystem; in short, the biofilm is one formidable foe!

The Arch Nemesis: Surgical Site Infection

Surgical site infection, or SSI, can probably be considered (to squeeze the last few drops out of this metaphor) the nemesis of the SPD … the ultimate villain to our SP superhero. It is the pathological endpoint of bioburden and biofilm: the dreaded consequence of instrument contamination. SSIs occur in 2–5% of all patients undergoing inpatient surgery in the United States. Of those infected, around 3% will die as a consequence [3].

In addition to this very human price, SSIs cost the US an estimated $3.3 billion annually, extending average hospital stay by 9.7 days, and increasing the cost of hospitalization by more than $20,000 per admission. Troublingly, up to 60% of SSIs are thought to be preventable [4].

Image created with Midjourney AI.

Outbreaks of SSIs have been directly related to contaminated instruments being used in the OR [5, 6]. These have resulted in patient deaths, avoidable illness, severe federal penalties and multimillion-dollar lawsuits. This all goes some way to explain why the bioburden detected in the tray at the start was enough to cancel the surgery…

Our Enemies Are Changing

To make matters worse, the microbes in a biofilm are much more difficult to kill than those outside a biofilm. This has caused a 10–1000-fold increase in the antibiotic resistance of biofilm microbes compared with non-biofilm microbes. Of all human infections, 60–80% are now linked to biofilm formation [7].

In surgery, biofilms can attach to the surface of things like catheters, stents and implants. An infected knee implant, for example, can only be treated by removing the prosthesis itself in order to remove the surface that the biofilm is attached to. This is bad news for the patient, who will need multiple surgeries and prolonged antibiotic therapy to recover.

Image from Schoenmakers, JWA. et al. [8].

But the SPD Is Always One Step Ahead

Now we know our enemies. We see their strengths but we understand their weaknesses. So how do we plan our attack?

Given how hard these things can be to remove and treat, first, we must take every step possible to stop them from forming at all. Here, attack is the best form of defense. Surgical instruments should be cleaned as soon as possible after use to reduce the window of opportunity for biofilm to form. Manufacturers’ IFUs must be available and meticulously followed to stop contamination dead in its tracks.

Visual inspection is essential; however, most microorganisms will still not be seen. So we need to test. Fortunately, several tests can now be used to verify that cleaning standards are met. These include protein tests and adenosine triphosphate (ATP) bioluminescence tests, both of which look for organic material (such as blood and proteins) that might suggest biofilm formation [9].

With the latest weapons added to our arsenal, and our strategies mapped out and perfected, the full force of the SPD can be unleashed against our biological enemies. Bad news for bioburden and biofilm … at the end of the day, they never really stood a chance.

Image from Tenor

Here at Incision, we’re dedicated to writing blogs that inspire conversation, bring teams closer together and educate in a dynamic way. When we learn together we grow together, so join the conversation!

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  1. Flemming HC, Baveye P, Neu TR, Stoodley P, Szewzyk U, Wingender J, Wuertz S. Who put the film in biofilm? The migration of a term from wastewater engineering to medicine and beyond. NPJ Biofilms Microbiomes. 2021 Jan 27;7(1):10. Link
  2. Hall-Stoodley L, Costerton JW, Stoodley P. Bacterial biofilms: from the natural environment to infectious diseases. Nat Rev Microbiol. 2004 Feb;2(2):95-108. Link
  3. Berríos-Torres SI, Umscheid CA, Bratzler DW. et al. Healthcare Infection Control Practices Advisory Committee. Centers for Disease Control and Prevention Guideline for the Prevention of Surgical Site Infection, 2017. JAMA Surg. 2017 Aug 1;152(8):784-791. Link
  4. Ban KA, Minei JP, Laronga C, Harbrecht BG, Jensen EH, Fry DE, Itani KM, Dellinger EP, Ko CY, Duane TM. American College of Surgeons and Surgical Infection Society: Surgical Site Infection Guidelines, 2016 Update. J Am Coll Surg. 2017 Jan;224(1):59-74. Link
  5. Seaman J. At least one death, “hundreds of severe infections” linked to Porter Hospital’s use of contaminated surgical instruments, lawsuit alleges. The Denver Post. Published Jun 16, 2019. Accessed Oct 10, 2023. Link
  6. Bouffard K. DMC says $1.2M spent to fix dirty instrument problems. The Detroit News. Published March 30, 2017. Updated Mar 31, 2017. Accessed Oct 10, 2023. Link
  7. Sharma S, Mohler J, Mahajan SD, Schwartz SA, Bruggemann L, Aalinkeel R. Microbial Biofilm: A Review on Formation, Infection, Antibiotic Resistance, Control Measures, and Innovative Treatment. Microorganisms. 2023 Jun 19;11(6):1614. Link
  8. Schoenmakers, JWA., Heuker, M, López-Álvarez, M, et al. Image-guided in situ detection of bacterial biofilms in a human prosthetic knee infection model: a feasibility study for clinical diagnosis of prosthetic joint infections. 2021. Eur J Nucl Med Mol Imaging 48: 757–767 Link
  9. Klacik, S. CRCST Self-Study Lesson Plan. Lesson No. CRCST 136 (Technical Continuing Education). 2013. Accessed Oct 10, 2023. Link

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