Standard precautions: The bedrock of prevention
First line of defense against emerging infections
(Editor's note: With this issue, we begin a series of stories on the recently issued patient isolation guidelines by the Centers for Disease Control and Prevention. In this issue we take a look at some new additions to standard precautions. Look for coverage of the transmission-based precautions and other aspects of the guidelines in upcoming issues of Hospital Infection Control. The following story is based on an interview with Jane Siegel, MD, and a presentation by Michael Bell, MD, recently in San Jose at the annual conference of the Association for Professionals in Infection Control and Epidemiology.)
While it's easy to get caught up in exotic pathogens and novel transmission routes, the Centers for Disease Control and Prevention is re-emphasizing that standard precautions remains the bedrock of infection prevention in health care settings. The CDC's new patient isolation guidelines include some additions to standard precautions, but also reiterate the importance of longstanding recommendations such as safe needle practices.1 (See table.)
"Standard precautions in these new guidelines still remain the foundation of infection prevention for both patients and personnel," says Bell, a medical epidemiologist in the Centers for Disease Control and Prevention's division of healthcare quality promotion. "This involves constant use of gloves and hand hygiene as well as application of face protection and gowns if splashes are anticipated. This is for any contact with blood and moist body substances, mucous membranes or broken skin. In addition to standard precautions, the importance of adherence to appropriate glove use and correct hand hygiene procedures are reinforced in this guideline."
More than just snapping on gloves
But standard precautions are more than just snapping on a pair of gloves or decontaminating hands — although those elements are a critical part of it. Standard precautions are really the first line of defense in infection prevention, setting the stage for subsequent layers of contact, droplet or airborne isolation measures as needed.
"If people truly understood standard precautions the way they should be practiced, we would be much further along in preventing transmission of infections," says Siegel, lead author of the guidelines as a former member of the CDC's Healthcare Infection Control Practices Advisory Committee (HICPAC). "Those elements [in the table] are excellent principles and practices to be followed in all health care settings because we don't know who will be infected with what. When you don't know what a patient is infected with, you have to have a recognition that all body fluids except for sweat could be potentially infective."
The application of standard precautions during patient care is determined by the nature of the worker-patient interaction and the extent of anticipated blood, body fluid, or pathogen exposure, the guidelines state. For some interactions (e.g., performing venipuncture), only gloves may be needed. However, during other interactions (e.g., intubation), use of gloves, gown, and face shield or mask and goggles is necessary. Education and training on the principles and rationale for recommended practices are critical elements of standard precautions because they lead to appropriate decision making and promote adherence when health care workers are faced with new circumstances, the CDC explained. For example, standard precautions may be all that stands between the health care worker and an emerging infection until the pathogen and its transmission routes are identified.
In recent years, emerging infectious diseases such as severe acute respiratory syndrome (SARS) have tended to follow a similar pattern, Bell says. "We find that one person may become ill, and bring that back into a community with a small amplification there — sort of a point-source cluster," he says. "Once this starts to spread among human beings the end result is consistently that patients come to a health care facility where amplification is very efficient. And that amplification tends to occur in health care personnel. For that reason, we particularly underscore the importance of isolation precautions."
Your mother was right: Cover that cough
In that regard, standard precautions also include a new section on respiratory/cough etiquette, which came into widespread use in emergency departments and waiting areas during the 2003 outbreak of SARS. "That's the new component that gets the most attention right now because of pandemic planning," Bells says. "This includes recommendations for education both for personnel and for patients, patient behavior recommendations, cohorting as well as administrative polices and practices. [It includes] how to put up signage, and how to coordinate the movement of patients who come in with fever and cough so they are not sitting in a waiting area or a big, open emergency room possibly transmitting to other patients."
The CDC guidelines recommend basic "source control" measures such as covering the mouth/ nose with a tissue when coughing and prompt disposal of used tissues, or using surgical masks on the coughing person when tolerated and appropriate. Though some consider the evidence for the practice anecdotal, the CDC emphasizes that covering sneezes and coughs and placing masks on coughing patients are proven means of source containment that prevent infected people from dispersing respiratory secretions into the air. "A lot of people say that is very nice, but it's not evidence-based," Siegel says. "But in the background of the guideline we do present the evidence. There was evidence for the efficacy of masks to contain infectious respiratory secretions in 1918 [during the flu pandemic.]"
In addition, this latest version of standard precautions reemphasizes safe needle injection practices in light of outbreaks of HBV and HCV among patients in ambulatory care facilities. The four outbreaks cited by the CDC occurred in a private medical practice, a pain clinic, an endoscope clinic, and a hematology/oncology clinic. The primary breaches in infection control practice were reinsertion of used needles into a multiple-dose vial or solution container (e.g., saline bag), and use of a single needle/syringe to administer intravenous medication to multiple patients. The outbreaks could have been prevented by adherence to basic principles of aseptic technique for the preparation and administration of parenteral medications. Those include the use of a sterile, single-use, disposable needle and syringe for each injection given and prevention of contamination of injection equipment and medication, the CDC reported. Whenever possible, use of single-dose vials is preferred over multiple-dose vials, especially when medications will be administered to multiple patients. "Outbreaks related to unsafe injection practices indicate that some health care personnel are unaware of, do not understand, or do not adhere to basic principles of infection control and aseptic technique," the CDC concluded.
"The section about safe injection practices is especially important," Siegel says. "There is nothing new in that, but with the outbreaks of hepatitis B and C that have been described in recent years in ambulatory settings it's clear that people are not practicing safe needle injection practices. That is a part of standard precautions that needs to be re-emphasized."
Mask before lumbar puncture
Another new component of standard precautions calls for masking before performing lumbar puncture procedures due to the risk of provider-to-patient transmission of meningitis. In 2004, CDC investigated eight cases of post-myelography meningitis. Blood and/or cerebrospinal fluid of all eight cases yielded streptococcal species consistent with oropharyngeal flora and there were changes in the cerebral spinal fluid and clinical status indicative of bacterial meningitis. Equipment and products used during these procedures (e.g., contrast media) were excluded as probable sources of contamination. Procedural details available for seven cases determined that antiseptic skin preparations and sterile gloves had been used. However, none of the clinicians wore a face mask, giving rise to the speculation that droplet transmission of oralpharyngeal flora was the most likely explanation for these infections, the CDC reported.
"There was acknowledgement that several instances of infection transmission have been documented with oral flora being transmitted to the central nervous system of patients receiving, for example, spinal anesthesia," Bell says. "So, standard precautions now recommend that the person doing the procedure wear a simple surgical mask to prevent contamination of the procedure site."
- Siegel JD, Rhinehart E, Jackson M, et al. Centers for Disease Control and Prevention Healthcare Infection Control Practices Advisory Committee. Guideline for Isolation Precautions: Preventing Transmission of Infectious Agents in Healthcare Settings 2007. On the web at www.cdc.gov.