Infection Control Today - 06/2004: Bioburden

Eradicating the Hidden Vectors

By Becki Jensen, CST, RCST, CRCST, FEL

Bioburden, as it is understood by infection control practitioners and other healthcare workers, is referred to as the number of microorganisms on a contaminated object; it is also called bioload. Bioload can be divided into two components:

  • Macroscopic: Visible to the naked eye.
  • Microscopic: Requires the use of a microscope to identify.

Macroscopic bio-burden can be identified as:

  • Blood-red cells
  • Pus or virulent material
  • Fat-lipids
  • Carbohydrate
  • Bone
  • Skin or other tissues

Microscopic bioburden can be identified as any bio-material that cannot be seen with the naked eye such as:

  • White blood cells
  • Bacteria
  • Viruses
  • Normally occurring microscopic flora
  • Vegetative or non-vegetative biofilm

Dealing with macroscopic bioload is easily accomplished because you are able to see it. Standard cleaning methods and solutions can be used to address each type by visual inspection to include:

  • Use of detergents, enzymatic cleaners and disinfectants
  • Use of sonic machines and washer sterilizers, washer decontaminators or high-level, device-specific machines (i.e., endoscope equipment)

By using one or more of these methods, one can be reasonably assured that the device will be rendered clean and safe to handle. Microscopic bioburden is an altogether different challenge. Because microscopic bioburden cannot be seen with the naked eye, there must be a set universal protocol in determining what is clean and what is contaminated. The universal way to look at it is this: when unsure of whether a device is clean or not, it is to be assumed that the device is dirty, and then processed according to universally accepted cleaning/decontamination/ disinfection practices as defined by such agencies as the Association for the Advancement of Medical Instrumentation (AAMI), Centers for Disease Control and Prevention (CDC) and/or the International Association of Healthcare Central Service Materials Management (IAHCSMM). There are many different virulent viruses, bacteria and other disease- causing microorganisms that can contaminate medical devices but are not seen, such as but not limited to:

  • Methicillin-resistant Staphylococcus aureus (MRSA)
  • Vancomycin-resistant enterococcus (VRE)
  • Human Immunodeficiency Virus (HIV)
  • Hepatitis B virus (HBV)
  • Droplet-forming organisms
  • CJD prion

All bioburden can be removed in much the same way (with the exception of CJD-prion), whether it be macro or micro. Close attention and committed practice of universal cleaning/decontamination processes can eradicate any concerns of cross contamination from person to person or patient to patient. Bioburden on medical devices, including instruments, equipment and furniture such as beds, tables, and surfaces of any kind, is an expected norm, as the potential vectors they are in the healthcare theatre and are dealt with accordingly. The term vectors of disease often brings to mind insects or rodents as the vehicle by which organisms causing disease can be transmitted. The word vector means a carrier of pathogenic microorganisms from one host to another. Whether one can assimilate the term vector to include people and inanimate objects, is not up for dispute. We are all aware of the obvious modes of bio-transmission from one object or person to another; this is why we address bioburden with such diligence and fervent commitment to the reduction and/or removal of all bioburden anywhere it may be found. But what if the vector or mode of transmission is not identified or recognized?

Many articles have been written on handwashing and its obvious importance everywhere in the healthcare delivery system. But handwashing is only one part of infection control. Infection control directives can be found in housekeeping, floor nursing, the OR, sterile processing, in ancillary departments like maintenance/ER, and even in the cafeteria.

Strictly controlled policies for each areas must be followed to prevent bioburden contamination from place to place, person to person or patient to patient.


This is an area that is frequently overlooked, and that can have serious consequences. For example, use of rags or mops from one area or another without replacement can be the vector to transmit micro or macro bio-material from one place to another. Reusing mop water and/or not cleaning the mop bucket from one area to another is another way bioburden can be transferred. Refilling spray bottles without cleaning the bottle first can be a mode of transmission; the containers used to refill secondary containers can be just as critical to the transmission of infectious agents and can become a viable living environment for bioburden. Using contaminated bottles of solution is a very real risk if not properly handled and identified.

Floor Nursing

Generally, all clinical floors are equipped with handwashing stations, gloves, or products that can be used to minimize microorganism transfer from surface to surface or patient to patient. Nurses and techs are rigorously trained in the importance of handwashing or the use of gloves and bacteriostatic products to prevent inadvertent cross contamination. For the most part, these principles of infection control are strictly followed, and if not, there are policies in place to address those who choose to ignore infection control protocols.

But what about the person cleaning a patient room (that may or may not be professionally trained) or changing the bed over which they may sneeze, cough or scratch their nose? Or how about the person who has just cleaned the bathroom and proceeds to clean the side table with the same rag that just wiped the toilet? Does it seem very unlikely that this would happen? Not at all, as this is a common occurrence. All staff members must be trained on the mode of transmission of bioburden, including all aspects of control, management and prevention.

OR/Sterile Processing

Obvious potential vectors in the OR are instruments and equipment. But what about OR beds that were not properly taken apart and cleaned, with new sheets being placed on them? Is anyone aware that mops are not routinely changed and water is used over and over between cases and OR rooms? There are facilities that use disposable mop heads and buckets to alleviate this problem.

There have been cited incidents where mop heads are changed but the water is not, or vice versa. Has anyone considered the potential cross contamination or transfer of bioload from one patient to the next via instruments that were rushed through the cleaning process or were not inspected and cleaned/decontaminated when received from outside the facility? Or what about cannulated items that were not properly cleaned and disinfected using prescribed manufacturer-recommended cleaning equipment or processes? Instead, workers have been known to barely flush fluid through the lumen before putting into a washer that will only reach the outside of the instrument.

Many times I have seen nurses attend to the patient in the OR, then proceed to do their paperwork while still wearing the same gloves with which they performed patient-care tasks. Not only is the chart now contaminated, but so are the desk, the phone, and whatever surface they touched; when the chart is picked up again, the contamination will follow a new route of transmission. This type of error can facilitate an ongoing cycle of contamination and transfer of micro bioburden.

I was sitting in an ED recently and noticed that the nurse behind the station sneezed into her disposable jacket, then proceeded to scratch her nose with the sleeve of the same jacket just before she took the blood pressure and temperature of her patient. Not once did she change her jacket, nor did she change her gloves, wash her hands or clean any surface that may have been contaminated by her 360-plus mile-per-hour sneeze (not to mention a droplet spread of an estimated three to five feet right to left). The implications of this scene are scary, more so because it is so common. I was able to stop the cycle by pointing out to this nurse what I considered to be obvious contamination.

Cafeteria/Ancillary Departments

Cafeteria staff wear hair nets, gloves and sometimes additional covering of the mouth. Although the right forms of inhibitory bio-transfer equipment are used, it is common to see many of the following scenarios in healthcare facilities:

  • Scratching of the head with gloves on, then serving food
  • Touching of the face with gloved hands, then serving food
  • Half wearing of hats and mask
  • Using the same rag on clean table surfaces that was used to clean chairs in the seating area; the rag is then put back into the detergent and further cleaning is done Handling money with gloves on and using the same gloves to serve food, or using gloved hands to wipe off tables and then the same gloved hands are used to put out condiments or silverware

These are just a few examples of how the mode of transmission or vector can be human beings or inanimate objects. It is clear that further training needs to be done on the subject of mode of transfer, and the understanding of bioburden relating to all areas of the healthcare environment. There are very good guidelines and protocols/recommendations from AAMI, AORN and nationally recognized food service professional organizations, as well as from the CDC and IAHCSMM, for the protection of patients and the public from contamination via bioburden. Education and a firm commitment to obtain and maintain the level of knowledge needed to stay in the war against infection is a must.

Perhaps the area that raises the most concern is sterile processing, because of the type of bioburden that is addressed there and the more critical threat to patients if protocol is not followed. Again and again, my colleagues and I have stressed certification and training in all areas of processing. It is time that professional training and certification be required, not suggested or recommended in our standards of universal practice. We must take a hard look at what we have to do to protect patients and staff, and come to grips with the fact we can no longer afford to depend on staff members who are not up to date on all infection-control protocols. We can no longer look upon any area and call it less important than another in the chain of infection.

Routine, recordable training in bioburden and infection pathways for all healthcare professionals degreed or not, and certified or not must be done so that we can be removed as the potential hidden vectors in the infection chain.

Becki Jenkins CST, RCST, CRCST, FEL, is president/CEO of Sterilization by Design, Inc. She is the winner of the 2003 AAMI Becton Dickinson Career Achievement Award and the 2002 Healthcare Heroes Award.

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