Standard and Transmission-Based Precautions

* Dr. Harte is a colonel, U.S. Air Force Dental Corps, and the chief military consultant, United States Air Force Surgeon General for Dental Infection Control, United States Air Force Dental Evaluation and Consultation Service, Great Lakes, Ill. Address reprint requests to Dr. Harte at United States Air Force Dental Evaluation and Consultation Service, 310C B St., Building 1H, Great Lakes, Ill. 60088

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Abstract

Background

Standard Precautions are the foundation of all infection control programs and include infection control practices that apply to all patients and situations regardless of whether the infection status is suspected, confirmed or unknown.

Methods

The author reviewed Standard Precautions, including two new elements introduced by the Centers for Disease Control and Prevention in 2007: safe injection practices and respiratory hygiene and cough etiquette. Standard Precautions sometimes are referred to as the first tier of precautions because for some diseases and circumstances, transmission cannot be interrupted completely with Standard Precautions alone and it is necessary to use second-tier Transmission-Based Precautions. The author reviewed the three categories of Transmission-Based Precautions—Airborne, Droplet and Contact—with an emphasis on their use in dental health care outpatient settings.

Conclusions and Clinical Implications

Dental health care personnel (DHCP) should update their infection control programs to ensure that safe injection practices and respiratory hygiene and cough etiquette measures are used routinely. In addition, with the emergence of new pathogens, re-emergence of variant organisms and more patients seeking care in ambulatory care facilities, DHCP need to be aware of additional measures to take when treating patients in their offices who are actively infected with certain organisms to protect fully other patients, their staff members and themselves.

Key Words: Infection control, Standard Precautions, Transmission-Based Precautions, Contact Precautions, Droplet Precautions, Airborne Precautions

ABBREVIATION KEY: AIIR:, Airborne infection isolation room; BSI:, Body Substance Isolation; CDC:, Centers for Disease Control and Prevention; DHCP:, Dental health care personnel; HBV:, Hepatitis B virus; HCP:, Health care personnel; HCV:, Hepatitis C virus; HIV:, Human immunodeficiency virus; MDROs:, Multidrug–resistant organisms; MRSA:, Methicillin-resistant Staphylococcus aureus; NIOSH:, National Institute for Occupational Safety and Health; OSHA:, Occupational Safety and Health Administration; PPE:, Personal protective equipment; SARS:, Severe acute respiratory syndrome; TB:, Tuberculosis

In 1996, the Centers for Disease Control and Prevention (CDC) introduced Standard Precautions, which combined and expanded on the elements of Universal Precautions to create a standard of care designed to protect all health care personnel (HCP) from pathogens that can be spread by blood or any other body fluid, excretion or secretion. Standard Precautions also include three subsets of precautions, known as “Transmission-Based Precautions,” that are based on the routes of disease transmission for a smaller number of patients who are known or suspected to be infected or colonized with highly transmissible or epidemiologically important pathogens. Transmission-Based Precautions are designed to reduce the risk of airborne, droplet and contact transmission and always are used in addition to Standard Precautions. Since the publication of the Guidelines for Infection Control in Dental Health-Care Settings—2003, 1 the CDC has published updated isolation guidelines, which have introduced new elements of Standard Precautions and provided more detailed information about Transmission-Based Precautions.

In this article, I review Standard Precautions, including the new elements applicable to dentistry, and the importance and relevance of Transmission-Based Precautions in dental settings.

STANDARD PRECAUTIONS

Overview

Because patients with blood-borne infections can be asymptomatic or unaware that they are infected, in 1985 the Centers for Disease Control (now the Centers for Disease Control and Prevention) introduced the concept that all blood and body fluids that might be contaminated with blood should be treated as infectious. 2 Infection control precautions were introduced largely because of the human immunodeficiency virus (HIV) epidemic and were updated and revised across the years. They eventually became known as Universal Precautions and were designed to prevent transmission of HIV, hepatitis B virus (HBV), hepatitis C virus (HCV) and other blood-borne diseases.3, 4 The Occupational Safety and Health Administration (OSHA) based its blood-borne pathogens standard on the concept of Universal Precautions. 5

Many fluids, secretions and excretions from patients not covered under Universal Precautions are colonized with organisms (that often are resistant to antimicrobial therapy) before any symptoms of illness become apparent, and they are potential sources of hospital- and community-acquired infections. Therefore, infection control personnel at the Harborview Medical Center, Seattle, and the University of San Diego introduced Body Substance Isolation (BSI) guidelines in 1987. These guidelines concentrate on isolating all moist and potentially infectious body substances (blood, feces, urine, sputum, saliva, wound drainage and other body fluids) primarily by wearing gloves. 6 Although these guidelines were accepted, there was some confusion regarding which body fluids or substances required HCP to use precautions under Universal Precautions and BSI. Also, it was becoming necessary to address droplet transmission and emerging multidrug–resistant organisms (MDROs) such as Clostridium difficile and vancomycin-resistant enterococci; direct or indirect contact transmission of some infectious microorganisms from dry skin or environmental sources (for example, C. difficile and vancomycin-resistant enterococci); and airborne transmission of infections across long distances by floating droplet nuclei. CDC expanded the concept of Universal Precautions in 1996 and began using the term “Standard Precautions,” which was introduced in the Guideline for Isolation Precautions in Hospitals. 7

Standard Precautions combined and expanded the elements of Universal Precautions and BSI into a standard of care designed to protect HCP and patients from pathogens that can be spread by blood or any other body fluid, excretion or secretion ( Table 1 ).1, 8 Standard Precautions apply to contact with blood; all body fluids, secretions and excretions (except sweat), regardless of whether they contain blood; nonintact skin; and mucous membranes. While the term “Universal Precautions” still is used in OSHA's blood-borne pathogens standard and other documents, no operational difference exists in clinical dental practice between Universal Precautions and Standard Precautions, because even when blood is not visible, saliva has been considered a potentially infectious material in dentistry. 1

TABLE 1

Elements of Standard Precautions. *

* For a complete discussion of the elements of Standard Precautions, refer to Kohn and colleagues 1 and Siegel and colleagues. 8

Standard Precautions are the foundation of a comprehensive infection control program and include a group of infection control practices that apply to all patients, regardless of suspected or confirmed infection status, in any setting in which health care is delivered, including dental settings. Although Standard Precautions apply to all patient encounters, the application of Standard Precautions during patient care is determined by the task being performed and the type of exposure to blood, body fluid or pathogens that is anticipated. In other words, infection control procedures are determined according to the procedure, not the patient. In OSHA terminology, they are performance-based standards because they are applied to the level necessary to provide exposure protection relative to the procedure performed and the given circumstances. For example, only gloves may be needed when obtaining dental radiographs, whereas protective eyewear and clothing, gloves and masks are necessary when placing restorations.

Update

In 2007, CDC updated and expanded the 1996 Guideline for Isolation Precautions in Hospitals 7 with the 2007 Guideline for Isolation Precautions: Preventing Transmission of Infectious Agents in Health Care Settings. 8 The 2007 isolation guideline introduced several new elements of Standard Precautions. The new additions—safe injection practices and respiratory hygiene and cough etiquette—focus on protection of patients, as well as that of HCP.

In 2006, CDC also published a comprehensive review and recommendations for prevention of transmission of MDROs. 9 Like the 2007 isolation guideline, this guideline addresses a variety of health care settings, not only hospitals. Even though this document is a separate publication, it is considered a part of CDC's 2007 isolation guidelines.

Safe injection practices

Across the years, the results of various infectious disease outbreak investigations indicated that reuse of syringes or the use of single-dose medication vials or bags of saline solutions for multiple patients caused numerous transmissions of HBV and HCV. These findings led to increased attention to aseptic technique during the handling of parenteral medications.8, 10 The conclusions of the investigations stated that these transmissions could have been prevented if HCP had adhered to basic principles of aseptic technique for the preparation and administration of parenteral medications. Safe handling of parenteral medications, including dental local anesthetics, and fluid infusion systems is required to prevent health care–associated infections among patients. These recommendations were included in the special considerations section of the Guidelines for Infection Control in Dental Health-Care Settings—2003 1 (Box ). Although these safe injection practices and associated recommendations are not new, they are considered elements of Standard Precautions.

BOX

Summary of Centers for Disease Control and Prevention's Recommendations for Aseptic Technique for Parenteral Medications.**Source: Kohn and colleagues.1(pp31,32,46)

Do not administer medication from a syringe to multiple patients, even if the needle on the syringe is changed.

If multidose vials are used, cleanse the access diaphragm with 70 percent alcohol before inserting a device into the vial, use a sterile device to access a multiple-dose vial and avoid touching the access diaphragm. Both the needle and syringe used to access the multidose vial should be sterile. Do not reuse a syringe even if the needle is changed.

Keep multidose vials away from the immediate patient treatment area to prevent inadvertent contamination by spray or spatter.

Use fluid infusion and administration sets (that is, intravenous bags, tubing and connections) for one patient only and dispose of them appropriately.

Respiratory hygiene and cough etiquette

The recommendation for respiratory hygiene and cough etiquette grew out of observations during the 2003 outbreaks of severe acute respiratory syndrome (SARS), in which failure to implement simple source-control measures with patients, visitors and HCP with respiratory symptoms may have contributed to SARS coronavirus transmission. Respiratory hygiene and cough etiquette are a combination of infection control measures designed to minimize the transmission of respiratory pathogens via droplet or airborne routes in health care settings. These measures apply not only to SARS, but also to any respiratory illness—such as influenza, respiratory syncytial virus and whooping cough—and are targeted at all patients with symptoms of respiratory infection and their accompanying family members or friends. These infection control measures begin at the point of the patient's initial encounter with a health care setting, such as the reception area in the dental office. The primary components of respiratory hygiene and cough etiquette are as follows:

offering a surgical mask to people who are coughing to decrease contamination of the surrounding environment;

turning the head away from others and maintaining spatial separation, ideally more than three feet, when coughing. 8

Respiratory hygiene and cough etiquette measures are considered a component of Standard Precautions and should be practiced routinely in dental settings. Posters that promote these measures are available, at no charge, from CDC's Web site ( Figure ). These posters can be downloaded, printed and placed in waiting areas or at reception desks to increase awareness of the importance of respiratory hygiene and cough etiquette. Dental office staff members should ensure that tissues, receptacles for used tissue disposal and hand hygiene agents (for example, alcohol-based hand-rub dispensers or soap and disposable towels if sinks are available) are available to patients, visitors and staff members so they can comply with respiratory hygiene and cough etiquette.

Centers for Disease Control and Prevention posters with tips to prevent the spread of germs from coughing and a notice for patients to report influenza symptoms, emphasizing covering coughs and sneezes and hand hygiene. These posters are available at “www.cdc.gov/flu/protect/covercough.htm” and “www.cdc.gov/ncidod/dhqp/pdf/Infdis/RespiratoryPoster.pdf”, respectively.

TRANSMISSION-BASED PRECAUTIONS

In some circumstances, patients have a documented infection or are suspected of having an infection with specified highly transmissible pathogens for which Standard Precautions cannot interrupt completely airborne or droplet transmission or transmission by contact with dry skin or contaminated surfaces. A second tier of precautions, referred to as Transmission-Based Precautions, is necessary to prevent the potential spread of these diseases. There are three categories of Transmission-Based Precautions: Airborne, Droplet and Contact.7, 8 More than one Transmission-Based Precaution category may apply at a time because some diseases are transmitted via multiple routes, and Transmission-Based Precautions sometimes are recommended for use on an empiric, temporary basis until a diagnosis can be made. When used alone or in combination, Transmission-Based Precautions always should be used in addition to Standard Precautions.

CDC's 2007 isolation guideline addresses the changing patterns of health care delivery, as well as those of emerging and evolving pathogens such as SARS and community-associated methicillin-resistant Staphylococcus aureus (MRSA). 8 A primary difference in this guideline from previous CDC isolation precautions is the inclusion of recommendations for a broader spectrum of health care delivery settings than found in the previous guidelines for hospitals only. Specifically, CDC makes recommendations for ambulatory care settings that include dental offices. Challenges may exist when adapting Transmission-Based Precautions to dental offices rather than to inpatient facilities. For example, dental office staff members may not be able to identify patients with infections immediately, patients frequently remain in common waiting areas for prolonged periods and treatment rooms may be turned around quickly with limited cleaning. 8

Transmission-Based Precautions were mentioned in CDC's 2003 infection control guidelines for dental health care settings, 1 but not to any great extent. The same is true for dental infection control textbooks and journal articles; the main focus generally is on Standard Precautions. This may be because patients usually do not seek routine dental outpatient care when they are acutely ill with diseases that require Transmission-Based Precautions. 1 Nonetheless, a general understanding of precautions for diseases transmitted via all routes is important, because some dental health care personnel (DHCP) are hospital based or work part time in hospital settings, patients infected with these diseases might seek urgent treatment at outpatient dental offices, and DHCP might become infected with these diseases. 1 Also, recently, several diseases requiring precautions beyond Standard Precautions (for example, MRSA or 2009 H1N1 influenza) have received extensive media coverage, and some dental professionals have inquired why there were not specific infection control recommendations to cover these conditions in ambulatory care dental settings.

The purpose of infection control procedures is to interrupt the spread of diseases. Therefore, applying Standard Precautions and, if indicated, the additional measures of Transmission-Based Precautions, is essential in preventing disease transmission.

Categories

The names of the three categories of Transmission-Based Precautions—Airborne, Droplet and Contact—mirror their modes of disease transmission. Some diseases have multiple routes of transmission and require using more than one Transmission-Based Precautions category. 8 In Table 2 , 8 . 9 I present examples of diseases requiring Transmission-Based Precautions in addition to Standard Precautions. I also present recommendations for duration of the precautions because, unlike Standard Precautions that are used for every patient, Transmission-Based Precautions typically remain in effect only while there is risk of the infectious agent being transmitted or for the duration of the illness. 8 DHCP will notice that, in some instances primarily with Contact and Droplet Precautions, the recommended precautions do not differ much from the infection control practices they normally use. For example, DHCP routinely wear gloves, protective eyewear, masks and gowns because they frequently are exposed to blood and blood-contaminated saliva during dental procedures, and OSHA requires them to wear personal protective equipment (PPE). On the other hand, nurses or physicians may not always wear a complete ensemble of PPE for all patient interactions.

TABLE 2

Select conditions and diseases requiring Transmission-Based Precautions. * †