PREVENTING INFECTION IN THE HOSPITAL
Nurses specializing in infection control are responsible for agency-wide policy development and program direction. Infection risk is significantly increased as patient care equipment becomes more complex and as more devices that disrupt naturally protective anatomic barriers are used. Staff nurses play an important role in risk reduction by paying careful attention to hand hygiene, by ensuring careful administration of prescribed antibiotics, and by following procedures to reduce the risks associated with patient care devices.
Each year, an estimated 2 million patients in the United States acquire nosocomial infections while hospitalized. Approximately 240,000 additional residents of long-term care facilities become infected each year. With the anticipated growth of the elderly population, this number may increase to approximately 750,000 by 2005 ( Jarvis, 2001).
The CDC estimates that approximately one third of all noso-comial infections could be prevented with effective infection con-trol programs. An effective program includes the following components: a program of surveillance for nosocomial infections and vigorous control efforts, at least one infection control practi-tioner for every 250 hospital beds, a trained hospital epidemiol-ogist, and feedback to surgeons about individual surgical site infections. Unfortunately, many hospitals have not introduced all four required aspects, and only an estimated 9% of expected infections are prevented (Scheckler et al., 1998).
Clostridium difficile is a spore-forming bacterium with significantnosocomial potential. Infection is usually preceded by antibiotics that disrupt normal intestinal flora and allow the antibiotic-resistant C. difficile spores to proliferate within the intestine.
The organism causes pathology by releasing toxins into the lumen of the bowel. In pseudomembranous colitis, the most ex-treme form of C. difficile infection, debris from the injured lumen of the bowel and from white blood cells accumulate in the form of pseudomembranes or studded areas of the colon. The destruc-tion of such a large anatomic area can produce profound sepsis.
Because antibiotics are used so extensively in the hospital setting, most hospitalized patients are at risk for infection with C. difficile. The nosocomial potential is increased because thespore is relatively resistant to disinfectants and can be spread on the hands of health care providers after contact with equipment that has previously been contaminated with C. difficile. Control is best achieved by intensifying cleaning, using Contact Precautions for infected patients, and stressing glove use and hand hygiene for all care workers.
Methicillin-resistant S. aureus (MRSA) is a common nosoco-mial infection in hospitals and extended care facilities. MRSA refers to S. aureus organisms that are resistant to methicillin or its comparable pharmaceutical agents, oxacillin and nafcillin. Because of the pathogenicity of S. aureus, there has been concern about antibiotic resistance since the discovery of penicillin in the 1940s. Soon after penicillin was introduced, S. aureus became all but universally penicillin resistant. Fortunately, alternative therapies in the form of cephalosporins and, more importantly, synthetic
penicillin solutions such as methicillin were introduced. It was not until the late 1970s that S. aureus showed resistance to methi-cillin. At that time, the prevalence of the organism was originally linked epidemiologically to the IV/injecting drug use community. Since the late 1960s, however, MRSA has become increasingly more prevalent, and transmission within hospitals and nursing homes has been well documented.
Linezolid and vancomycin are the preferred alternative treat-ments for serious MRSA infection. However, there is concern that MRSA will eventually also become resistant to these med-ications because they are used so commonly. For the first time, in April 2002, a patient in Michigan was diagnosed with an S. aureus infection that was fully resistant to vancomycin (ie, vancomycin-resistant S. aureus [VRSA]). The CDC and other professionalorganizations have focused preventive efforts against the threat of transmission of this strain and the development of similar strains in other patients. The threat of the growth of VRSA is considered a public health catastrophe because many patients with S. aureus infections are likely to have a poor outcome (CDC, 2002b).
Health care providers often transmit MRSA to patients because S. aureus easily colonizes skin. Because colonization is seldom rec-ognized, the health care provider must assume that every patient contact offers the possibility of MRSA exposure. Although there is no evidence that MRSA is more virulent than other strains of staphylococci, the colonized patient faces the likelihood of infec-tion with MRSA when invasive procedures, such as intravenous therapy, respiratory therapy, or surgery, are performed. The patient colonized with MRSA also serves as a reservoir of resistant organ-isms to be transmitted to others. MRSA acquired in the hospital may persist as normal flora in the patient in the future.
Enterococcus is a gram-positive bacterium that is part of the nor-mal flora of the gastrointestinal tract. It can produce significant disease when allowed to infect blood, wounds, or urine. Entero-coccus is the second most frequently isolated source of nosocomialinfection in the United States.
Enterococcus has several traits that make it an ideal nosocomialorganism. The host carries an abundance of the organism even in a noninfected state; the organism is bile resistant and can with-stand harsh anatomic sites, such as the intestine; Enterococcus has the potential for resistance to many antibiotics, so that therapeutic agents reducing local bacterial competition may leave it to repli-cate freely; and the organism endures well on the hands of health care providers and on environmental objects.
As a relatively resistant organism at baseline, therapy for En-terococcus has been essentially limited to penicillin formulations(eg, ampicillin) or vancomycin in combination with an amino-glycoside (eg, gentamicin). In the 1980s, resistance to all of these agents was first reported. Between 1994 and 1999, the CDC recorded a more than 40% increase in the percentage of cases of vancomycin-resistant Enterococcus (VRE) infections in inten-sive care unit patients (CDC, 2001c).
This rapidly growing problem has serious implications. Be-cause many strains of VRE are resistant to all other antimicrobial therapies, clinicians are left without effective therapy for what was once seen as a relatively common infection. VRE infections may serve as a reservoir of genes coded for vancomycin resistance that may be transferred to the even more prevalent and virulent S. aureus. The first case of a patient infected with VRSA, illustratesthis concern, as that patient was infected with VRE and VRSA.
The gene that commonly causes resistance in VRE was found in both organisms, which strongly suggested genetic transfer be-tween species (CDC, 2002b).
Reducing the risk of nosocomial bloodstream infections requires preventive activities (in addition to Standard and Transmission-Based Precautions, which are discussed later). If a nosocomial bloodstream infection occurs, early diagnosis is important to pre-vent complications, such as endocarditis and brain abscess. Mortality rates may be as high as 25% for infection with some or-ganisms. The estimated cost attributed to catheter-related blood-stream infections is $3,700 to $29,000 per case (Mermel, 2000).
Bacteremia is defined as laboratory-proven presence of bacte-ria in the bloodstream. Fungemia is a bloodstream infection caused by a fungal organism. Any vascular access device (VAD) can serve as the source for a bloodstream infection. Contamination can occur from the patient’s own flora traversing the exterior of a catheter or by contamination of internal tubing during manip-ulation. The intravenous fluid itself can become contaminated and serve as a source of infection. Most hospitalized patients receive VADs, and increasingly, long-term central catheters are used to provide intravenous therapy to outpatients in a clinic or home setting. In all instances, the nurse must use appropriate care to re-duce the risk of bacteremia and to be alert for signs of bacteremia. Chart 70-1 identifies conditions that suggest the presence of noso-comial VAD-related bacteremia or fungemia.
During the insertion of all VADs, there must be strict attention to aseptic technique. Those inserting VADs must vigorously wash their hands before insertion. Those inserting central catheters should use surgical technique, including sterile gloves, sterile gowns with long sleeves, masks, and a large drape over the patient. The preferred solution to disinfect the insertion site is chlorhexidine gluconate, which first became available as a skin preparation solution in the United States in 2001. Alternative so-lutions are povidone iodine or alcohol. Triple-antibiotic oint-ment should not be used on the insertion site because it has been shown to lead to increased colonization with Candida species (Mermel, 2000).
There is no apparent difference in risk or benefit when com-paring the use of transparent polyurethane dressings or gauze dressings. However, if blood is oozing from the catheter insertion site, a gauze dressing should be used. The most important aspects for either material are that the dressing should be applied using aseptic technique and that the dressing should be sealed along its entire perimeter (Mermel, 2000).
Guide wires should not be used routinely when replacing central venous catheters. However, they may be used if there is no evi-dence of infection and insertion risk is unacceptably high, as when the patient has a coagulopathy or is obese.
Infusion sets and stopcock caps should be changed no more fre-quently than every 4 days, unless an infusion set is used for the delivery of blood or lipid solutions. Infusion sets and tubing for blood, blood products, or lipid emulsions should be changed within 24 hours of initiating the infusion. Blood infusions should finish within 4 hours of hanging the blood; lipid solutions should be completed within 24 hours of hanging. There are no guide-lines for the appropriate intervals for the hang time of other so-lutions. Injection ports should be cleaned with 70% alcohol or an iodophor before accessing the system (Mermel, 2000).
Nurses have an important role in the prevention of blood-stream infections as they assess patients for evidence of infection, make daily VAD site inspections, and monitor the interval of line changes. Signs of sepsis in patients with indwelling vascular lines should be promptly assessed and treated.
Isolation precautions are guidelines created to prevent transmission of microorganisms in hospitals. In 1997, the Hospital Infection Control Practices Advisory Committee (HICPAC), along with the CDC, implemented two tiers of isolation precautions. The first tier, called Standard Precautions, was designed for the care of all patients in the hospital and is the primary strategy for preventing nosoco-mial infections. The second tier, called Transmission-Based Pre-cautions, was designed for care of patients with known or suspected infectious diseases spread by airborne, droplet, or contact routes.
The tenets of Standard Precautions are that all patients are col-onized or infected with microorganisms, whether or not there are signs or symptoms, and that a uniform level of caution should be used in the care of all patients. The elements of Standard Pre-cautions include hand hygiene, use of gloves and other barriers (eg, mask, eye protection, face shield, gown), handling of patient care equipment and linen, environmental control, prevention of injury from sharps devices, and patient placement. Hand hygiene, glove use, needlestick prevention, and avoidance of splash or spray of body fluids are discussed in the following sections.
The most frequent cause of infection outbreaksin health care institutions is transmission by the hands of health care workers. Hands should be washed or decontaminated fre-quently during patient care. Table 70-3 describes the recom-mended situations for hand hygiene.
When hands are visibly dirty or contaminated with biologic material from patient care, hands should be washed with soap and water. In intensive care units and other locations in which viru-lent or resistant organisms are likely to be present, antimicrobial agents (eg, chlorhexidine gluconate, iodophors, chloroxylenol, triclosan) may be used. Effective hand washing requires at least 15 seconds of vigorous scrubbing with special attention to the areaaround nail beds and between fingers, where there is high bacte-rial burden. Hands should be thoroughly rinsed after this washing.
If hands are not visibly soiled, health care providers are strongly encouraged to use alcohol-based, waterless antiseptic agents for routine hand decontamination. These solutions are superior to soap or antimicrobial handwashing agents in their speed of action and effectiveness against bacteria and viruses. Because they are formulated with emollients, they are usually better tolerated than other agents, and because they can be used without sinks and towels, health care workers have been found to be more compli-ant with their use. Nurses working in home health care or other settings where they are relatively mobile should carry pocket-sized containers of alcohol-based solutions (Zaragoza et al., 1999).
Normal skin flora usually consist of coagulase-negative staphy-lococci or diphtheroids. In the health care setting, employees may temporarily carry bacteria (ie, transient flora) such as S. aureus,Pseudomonas aeruginosa, and other organisms with strong patho-genic potential. Generally, transient flora are superficially at-tached and are shed with hand hygiene and skin regeneration.
Hand washing or disinfection reduces the amount of benign normal flora and transient bacteria and decreases the risk of trans-fer to other patients. All health care settings should have programs to evaluate compliance with hand disinfection by all who care for patients.
Nurses should not wear artificial fingernails or extenders when providing patient care. These items have been epidemiologically linked to several significant outbreaks of infections. Natural nails should be kept less than 0.25-inch (0.6-cm) long, and nail polish should be removed when chipped, because it can support in-creased bacterial growth (CDC, 2002a).
Gloves provide an effective barrier for hands from themicroflora associated with patient care. Gloves should be worn when a health care worker has contact with any patient’s secretions or excretions and must be discarded after each patient care con-tact. Because hospital organisms colonizing health care workers’ hands can proliferate in the warm, moist environment provided by gloves, hands must be thoroughly washed with soap after gloves are removed. As patient advocates, nurses have an important role in promoting hand washing and glove use by other hospital work-ers, such as laboratory personnel, technicians, and others who have contact with patients.
Latex gloves are often preferred over vinyl gloves because of greater comfort and fit and because some studies indicate that they afford greater protection from exposure. Their increased use in recent years, however, has been accompanied by increased re-ports of allergic reactions to latex among health care workers. Re-actions range from local skin irritation to more severe reactions, including generalized dermatitis, conjunctivitis, asthma, angio-edema, and anaphylaxis.
The nurse who experiences irritation or allergic reaction asso-ciated with exposure to latex should report symptoms to an occu-pational health specialist or private physician. Suggested methods for reducing the incidence of such reactions include use of vinyl gloves, powder-free gloves, or “low-protein” latex gloves.
The most important aspect of reducingthe risk of bloodborne infection is avoidance of percutaneous in-jury. Extreme care is essential in all situations in which needles, scalpels, and other sharp objects are handled. Used needles should not be recapped. Instead, they are placed directly into puncture-resistant containers in the vicinity of their use. If a situation dictates that a needle must be recapped, the nurse must use a me-chanical device to hold the cap or use a one-handed approach to decrease the likelihood of skin puncture. Since 2001, OSHA has required nurses to use needleless devices and other instruments designed to prevent injury from sharps when appropriate (Occu-pational Safety and Health Administration [OSHA], 2001).
When the health careprovider is involved in an activity in which body fluids may be sprayed or splashed, appropriate barriers must be used. If a splash to the face may occur, goggles and facemask are warranted. If the health care worker is handling material that may soil clothing or is involved in a procedure in which clothing may be splashed with biologic material, a cover gown should be worn.
Some microbes are so contagious or epidemiologically significant that precautions in addition to the Standard Precautions should be used when such organisms are recognized. The CDC recom-mends a second tier of precautions, called Transmission-Based Precautions. The additional safety measures are called Airborne, Droplet, and Contact Precautions (Garner, 1996).
Airborne Precautions are required for patients with presumedor proven pulmonary TB or chickenpox. Airborne Precautions are also advised if, as a victim of bioterrorism, a patient is sus-pected of having smallpox. When hospitalized, patients should be put in rooms with negative air pressure; the door should remain closed, and health care providers should wear an N-95 respirator (ie, protective mask) at all times while in the patient’s room.
Droplet Precautions are used for organisms that can be trans-mitted by close, face-to-face contact, such as influenza or menin-gococcal meningitis. While taking care of a patient requiring
Droplet Precautions, the nurse should wear a facemask, but be-cause the risk of transmission is limited to close contact, the door may remain open. The CDC advises that negative-pressure rooms should be used in hospitals if available.
Contact Precautions are used for organisms that are spread byskin-to-skin contact, such as antibiotic-resistant organisms or C. difficile. Contact Precautions are designed to emphasize cau-tious technique for organisms that have serious epidemiologic consequences or those easily transmitted by contact between health care worker and patient. The principles of transmission control used in the Standard Precautions are accentuated. When possible, the patient requiring contact isolation is placed in a pri-vate room to facilitate hand hygiene and protection of garments from environmental contamination. Masks are not needed, and doors do not need to be closed (Chart 70-2).
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