Infection Control Today - 06/2004: Bioburden


Eradicating the Hidden Vectors

By BeckiJensen, CST, RCST, CRCST, FEL

Bioburden, as it is understood byinfection control practitioners and other healthcare workers, is referred to asthe number of microorganisms on a contaminated object; it is also calledbioload. 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-materialthat 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 accomplishedbecause you are able to see it. Standard cleaning methods and solutions can beused 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 reasonablyassured 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 aset universal protocol in determining what is clean and what is contaminated. The universal way to look at it is this: when unsure ofwhether 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 theAdvancement of Medical Instrumentation (AAMI), Centers for Disease Control andPrevention (CDC) and/or the International Association of Healthcare CentralService Materials Management (IAHCSMM). There are many different virulent viruses, bacteria and otherdisease- causing microorganisms that can contaminate medical devices but are notseen, 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 theexception of CJD-prion), whether it be macro or micro. Close attention andcommitted practice of universal cleaning/decontamination processes can eradicateany concerns of cross contamination from person to person or patient to patient.Bioburden on medical devices, including instruments, equipment and furnituresuch as beds, tables, and surfaces of any kind, is an expected norm, as thepotential vectors they are in the healthcare theatre and are dealt withaccordingly. The term vectors of disease often brings to mind insects or rodents as the vehicle bywhich organisms causing disease can be transmitted. The word vector means acarrier of pathogenic microorganisms from one host to another. Whether onecan assimilate the term vector to include people and inanimate objects, is notup for dispute. We are all aware of the obvious modes of bio-transmission fromone object or person to another; this is why we address bioburden with suchdiligence and fervent commitment to the reduction and/or removal of allbioburden anywhere it may be found. But what if the vector or mode oftransmission is not identified or recognized?

Many articles have been written on handwashing and its obviousimportance everywhere in the healthcare delivery system. But handwashing is onlyone part of infection control. Infection control directives can be found inhousekeeping, floor nursing, the OR, sterile processing, in ancillarydepartments like maintenance/ER, and even in the cafeteria.

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


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

Floor Nursing

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

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

OR/Sterile Processing

Obvious potential vectors in the OR are instruments andequipment. But what about OR beds that were not properly taken apart andcleaned, with new sheets being placed on them? Is anyone aware that mops are notroutinely 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 thisproblem.

There have been cited incidents where mop heads are changedbut the water is not, or vice versa. Has anyone considered the potential crosscontamination or transfer of bioload from one patient to the next viainstruments that were rushed through the cleaning process or were not inspectedand cleaned/decontaminated when received from outside the facility? Or whatabout cannulated items that were not properly cleaned and disinfected usingprescribed manufacturer-recommended cleaning equipment or processes? Instead,workers have been known to barely flush fluid through the lumen before puttinginto 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 withwhich 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 thechart is picked up again, the contamination will follow a new route oftransmission. This type of error can facilitate an ongoing cycle ofcontamination and transfer of micro bioburden.

I was sitting in an ED recently and noticed that the nursebehind the station sneezed into her disposable jacket, then proceeded to scratchher nose with the sleeve of the same jacket just before she took the bloodpressure and temperature of her patient. Not once did she change her jacket, nordid she change her gloves, wash her hands or clean any surface that may havebeen contaminated by her 360-plus mile-per-hour sneeze (not to mention a dropletspread of an estimated three to five feet right to left). The implications ofthis scene are scary, more so because it is so common. I was able to stop thecycle by pointing out to this nurse what I considered to be obviouscontamination.

Cafeteria/Ancillary Departments

Cafeteria staff wear hair nets, gloves and sometimesadditional covering of the mouth. Although the right forms of inhibitory bio-transfer equipmentare used, it is common to see many of the following scenarios in healthcarefacilities:

  • 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 transmissionor vector can be human beings or inanimate objects. It is clear that furthertraining needs to be done on the subject of mode of transfer, and theunderstanding of bioburden relating to all areas of the healthcare environment.There are very good guidelines and protocols/recommendations from AAMI, AORN andnationally recognized food service professional organizations, as well as fromthe CDC and IAHCSMM, for the protection of patients and the public fromcontamination via bioburden. Education and a firm commitment to obtain and maintain thelevel of knowledge needed to stay in the war against infection is a must.

Perhaps the area that raises the most concern is sterileprocessing, because of the type of bioburden that is addressed there and themore critical threat to patients if protocol is not followed. Again and again, my colleagues and I have stressedcertification and training in all areas of processing. It is time thatprofessional training and certification be required, not suggested orrecommended in our standards of universal practice. We must take a hard look atwhat we have to do to protect patients and staff, and come to grips with thefact we can no longer afford to depend on staff members who are not up to dateon all infection-control protocols. We can no longer look upon any area and call it less importantthan another in the chain of infection.

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

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

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