By Gary Evans, Medical Writer

The CDC is seeking a balanced approach to new infection control guidelines for healthcare workers, trying to avoid overkill without sacrificing the necessary protections for a broad range of pathogens.

“If you underidentify, transmissions can happen,” says David Kuhar, MD, medical officer in the Division of Healthcare Quality Promotion at the CDC. “If you overidentify, that can lead to work restrictions and post-exposure prophylaxis for people who don’t need them.”

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.

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 his or her environment;

• Face-to-Face Exposure: Unprotected, close, face-to-face;

• Close Proximity Exposure: Unprotected contact within six feet of an infectious source person;

• Long-distance Exposure: Unprotected contact with infectious particles suspended in the air at a distance greater than six feet from the source.

There is a wealth of contingencies in this approach, including pathogen-specific factors that may vary by the duration of some exposures, Kuhar explains. 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.

“The idea is to have a consistent way to try to approach this between pathogens,” he adds. “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.”

There is limited science on how some of the occupational pathogens are transmitted, meaning achieving some consistency will be challenging. The term “strawman” was used in describing the exposure groups to HICPAC, emphasizing that this is an early iteration of a theoretical model.

“We just wanted to put forward a draft of a set of definitions that cover the spectrum of infectious exposures in healthcare,” Kuhar says. “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.”

Kuhar and colleagues will apply these definitions to a range of pathogens and see if the system is workable.

“Our plan is to apply this 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,” he says.

Overall, the feedback has been positive, as there is some consensus on the need for consistency and clarity in describing exposures, he says.

“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,” he says. “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.”

A novel addition is the concept of long-distance exposure as another way to look at airborne transmission.

“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 and measles,” he says. “For a number of reasons, we didn’t call it airborne transmission, as that may come with some preconceptions that are not quite accurate.”

How are the exposure definitions different from what has been in previous CDC guidelines?

“The ones that are subtly different are the ones that are describing exposures to a person,” he says. “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.”

The CDC is planning to draft the guideline in two major sections, one of which will be the infrastructure for occupational health services for infection prevention.

“The second section 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,” Kuhar says.

The draft of section one has been completed and is in CDC clearance. After that, it will be published 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,” he says. “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.”