Comprehensively updating an infection control guideline that is two decades old, the Centers for Disease Control and Prevention (CDC) currently is immersed in an immense draft and review process that will include an “out of the box” rethinking of occupational exposures.
Originally published in 1998, the CDC recommendations for infection control in healthcare personnel are undergoing a systematic update that will provide recommendations for occupational exposures with more than 20 pathogens that can be acquired in healthcare settings.
One of the difficulties is defining an unprotected exposure to a given pathogen that does not underestimate the risk nor overstate it, says David Kuhar, MD, of the CDC’s division of healthcare quality promotion. “If you ‘under-identify,’ transmissions can happen,” he says. “If you ‘over-identify,’ that can lead to work restrictions and post-exposure prophylaxis for people who don’t need them.”
Emphasizing that this is a somewhat theoretical framework designed to generate discussion and feedback, Kuhar recently presented the following seven occupational exposure definitions to the CDC’s Healthcare Infection Control Practices Advisory Committee (HICPAC):
• Percutaneous Injury Exposure: A percutaneous injury (e.g., needlestick) with inoculation of potentially infectious body fluids that may include blood, tissue, secretions, or others;
• Mucous Membrane Contact Exposure: Mucous membrane contact with potentially infectious body fluids that may include blood, tissue, secretions, or others;
• Non-intact Skin Contact Exposure: Contact of exposed skin that is chapped, abraded, afflicted with dermatitis, or otherwise compromised with potentially infectious body fluids that may include blood, tissue, secretions, or others;
• Intact Skin Contact Exposure: Unprotected direct contact with an infectious source person or their environment;
• Face-to-Face Exposure: Unprotected, close, face-to-face contact with an infectious source person;
• Close Proximity Exposure: Unprotected contact within 6 feet of an infectious source person;
• Long-distance Exposure: Unprotected contact with infectious particles suspended in the air at a distance greater than 6 feet from the source.
Caveats and Questions
There is a wealth of contingencies in this approach, including pathogen-specific factors that may vary by the duration of some exposures. Likewise, potentially infectious body fluids can differ among pathogens.
Options for post-exposure prophylaxis will vary, and work restrictions also are largely dependent on the source of exposure. To reiterate, the one consistency in all of the definitions is they are regarded as “unprotected exposures, with ‘unprotected’ encompassing whether or not they were wearing, or not appropriately using, recommended personal protective equipment,” he says.
We continued our interview with Kuhar with the following questions.
HIC: What is the underlying concept of these definitions of occupational exposures?
Kuhar: The idea is to have a consistent way to try to approach this between pathogens. Some of them are very different from one another, but we want to try to take a consistent and understandable approach.
We will also provide examples where we can for guideline users. The challenges in doing this are many. We have very limited science on how some of these are transmitted from person to person. So, achieving some consistency amid the limitations is challenging.
HIC: You used the term “strawman” in referring to these exposure groups, emphasizing that this is an early iteration of a theoretical model.
Kuhar: Yes, we just wanted to put forward a draft of a set of definitions that cover the spectrum of infectious exposures in healthcare. We wanted to see if [HICPAC] thought this was an adequate way to do it. We wanted to put something out that covered the whole spectrum — to give the committee something to react to. But we were clear that we are not married to this if people thought we should take a different approach. In truth, we are still testing it.
Our plan now is to apply it to several different pathogens that we intend to cover in the guidelines, such as measles, tuberculosis, Staph aureus, and others that are transmitted in different ways in healthcare settings to see how well this kind of categorization fits and how well it describes exposures.
HIC: What kind of feedback are you getting on this approach?
Kuhar: Overall, the feedback was very positive. I got the sense that having some consistency and clarity in describing exposures is very much wanted, not just by the HICPAC committee but by the liaison [members] as well.
Some of the considerations are that we need to be careful about how accurate we are in our descriptions. We received some feedback of the need for examples of procedures and interactions when providing care for patients, which may vary for diseases that are transmitted. The at-risk interactions that involve providing care for a patient may be different even between diseases that are transmitted similarly. So our examples are probably going to have to be pathogen-specific.
HIC: Is this concept of “long distance” exposure another way to look at airborne transmission?
Kuhar: The idea was to capture exposures to contaminated air at distances greater than six feet from the source -— things that we often think of as airborne transmission relevant to TB, measles, and varicella.
For a number of reasons, we didn’t call it airborne transmission, as that may come with some preconceptions that are not quite accurate. We have to give some careful thought to the names of these categories. We were struggling with sensible names for some of them, and that one in particular.
HIC: How are these exposure definitions different from what has been in previous CDC guidelines?
Kuhar: The ones that are subtly different are the ones that are describing exposures to a person. Sharps injuries, touching people — those are fairly well recognized kinds of exposures and consistent with how we previously thought about it. However, distance from an infectious source is something that there has been previous questions about, something where there has been a lot of variability in exposure definitions over the years.
For example, for diseases where you recommend droplet precautions, not everything is considered an exposure within six feet, which is a typical droplet distance. Really, intense face-to-face contact is needed. Six feet away for a brief period of time wouldn’t be considered an exposure. We are hoping that we can tease out those differences to provide clarity, but not lose specificity and accuracy in how we describe these. We don’t want to over-identify or under-identify potential exposures.
HIC: Where do the guidelines stand and what are you looking at in terms of a timeline?
Kuhar: We are doing two major sections. One is the infrastructure for occupational health services for infection prevention.
The second is the individual pathogens, where we are talking about the epidemiology and control of roughly 20 to 25 pathogens that are transmitted in healthcare settings among healthcare personnel.
Section one is that entire infrastructure, which is done. The second section is going to come out as pieces on individual pathogens.
We are not going to hold that whole section [for publication]. Section one we developed all together; section two we are going to publish in smaller pieces.
So, we will put out a measles, mumps, and rubella section, for example, and keep adding individual pathogens until we get them done.
HIC: When will the first section on occupational health program infrastructure be published for public comment?
Kuhar: The draft is in CDC clearance. I anticipate getting it through in the next six weeks. After that, it will go in the Federal Register for public comment.
It will then come back to HICPAC to review the public comments and update the guideline as needed. Then it will go back through CDC clearance.
I think from start to finish we are talking about roughly a year to [final] publication of that section.