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Infection Control and the Emergency Department
Author: Jonathan M. Glauser, MD, Department of Emergency Medicine, Cleveland Clinic Foundation, Cleveland, OH.
Peer Reviewers: Ralph Riviello, MD, MS, FACEP, Associate Professor and Associate Program Director, Department of Emergency Medicine, Thomas Jefferson University, Philadelphia, PA; and John W. Hafner, Jr., MD, FACEP, Clinical Assistant Professor of Surgery, Department of Emergency Medicine, University of Illinois College of Medicine at Peoria, Director of Research, Emergency Medicine Residency, Attending Physician, OSF Saint Francis Hospital, Peoria.
This issue of Emergency Medicine Reports deals with infection control as it relates to the emergency department (ED). Several states now require infection control training for continued licensure, and it is hoped that this article may be useful to some in meeting that requirement. For the rest, knowledge of infection transmission and ways to prevent contamination are very important. The recent SARS epidemic led to significant morbidity and mortality primarily in emergency personnel who cared for patients, at least initially, with poor protection from the airborne infection.
Some of the measures discussed in this issue may seem simplistic. For example, the greatest weapon we have against the spread of many infections is simply washing hands. Of all healthcare workers, physicians are the least likely to wash their hands between patients or even after using the bathroom. In a surveillance project of healthcare professionals attending a professional conference, a surprisingly large number of individuals did not wash their hands after using the toilet. Ironically that meeting was the Interscience Conference on Antimicrobial Agents and Chemotherapy, one of the largest infectious disease meetings! In response to the failure of physicians and other healthcare workers to simply wash their hands before and after caring for patients, some hospitals have deployed hand washing "police" to monitor compliance.
Beyond handwashing is the real impact that diseases such as methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin resistant enterococci (VRE) have on our healthcare system. In older facilities, there are few private rooms, and isolation of patients with MRSA or VRE often contribute to the hospital bed shortage by taking up two beds. Whether isolation truly will decrease the incidence of MRSA or even slow the spread of the disease may never been known. Still, we will continue to isolate and take appropriate precautions to control infection in our EDs.
—Sandra M. Schneider, MD, FACEP, Editor
The recognition that infections might be transmitted by health care personnel within hospitals to susceptible patients is generally dated to the work of Semmelweis. He noted the association between the incidence of puerperal fever and lack of handwashing by physicians who also performed autopsies. The rate of infection was much lower among women who had their children delivered by non-physicians than those whose children were delivered by physicians. The Centers for Disease Control and Prevention (CDC) since 1970 have published isolation guidelines for use by hospitals. The AIDS epidemic and the growing concern regarding tuberculosis, both in the 1980s, have spurred further developments in shaping guidelines.1 The CDC estimates that there are at least two million health-care-associated infections each year,2 resulting in 90,000 deaths, and that at least one-third of deaths from hospital-acquired infections are preventable.3 In fact, infection control programs resulted largely from mandates of the Joint Commission for Accreditation of Hospitals (JCAHO) (now the Joint Commission) and the leadership of the CDC.
The majority of nosocomial infections are spread by contact. In virtually all cases, the primary mechanism for contact spread is via the hands of hospital personnel.4 Effective hand hygiene is felt to be the single most effective means of preventing their spread, and is at the heart of much of the work of Joint Commission.
Alcohol-based Hand Rubs
Alcohol-based hand rubs are recommended for general use by the CDC Hand Hygiene Guidelines.5 These products are considered more effective than soap and water in reducing bacterial counts on the hands of healthcare workers. A six-year observational study found a decrease in the nosocomial acquisition of methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) with a switch from handwashing to an alcohol-based hand rub.6 A study from Switzerland verified a similar decrease in nosocomial MRSA infections following a switch from handwashing to the use of an alcohol-based hand rub. In contrast to the decrease in infection rates for MRSA and VRE with the use of alcohol-based hand rubs, the incidence of Clostridium difficile (C. difficile) colitis was unchanged in that study.7 Since alcohol-based rubs do not seem to have an effect on spore-forming bacteria, hand-washing is still recommended after contact with patients with C. difficile infection. Use of an alcohol-based hand rub is also recommended before having direct contact with patients, after having contact with a patient's intact skin or bodily secretions, and before inserting indwelling urinary catheters or peripheral vascular catheters.5
Washing hands with plain soap and water or with an antimicrobial soap should be employed when hands are visibly soiled. One crossover study demonstrated a 27% decreased incidence of nosocomial infections in three adult intensive care units (ICUs) over eight months when a chlorhexidine soap was used versus a combination of 60% isopropyl alcohol and soap.8 Handwashing is recommended by the CDC after touching blood, bodily fluids, secretions, and contaminated items whether or not gloves are worn, and between patient contacts. It is recommended before eating and after using a restroom.9 (See Table 1.)
|Table 1. CDC Handwashing Recommendations|
|According to the CDC, handwashing is recommended:
• After touching blood, bodily fluids, secretions, and contaminated items, whether or not gloves are worn;
• Between patient contacts
• Before eating
• After using the restroom
Of all healthcare workers, physicians have been particularly resistant to these guidelines. One observational study of 2834 opportunities for handwashing evaluated compliance by healthcare personnel. Overall compliance was 48%, with the highest among nurses and lowest among physicians.10 In one study, compliance with hand rubs was higher than with handwashing, but physicians as a group were still poorly compliant.7
The category of standard precautions combines the features of body substance isolation policies and universal precautions. These aim to reduce the risk of transmission of infectious agents from patient to health care worker and vice versa. Standard precautions apply to all body fluids, secretions, and excretions except sweat. They entail:
CDC Isolation Guidelines
The 1996 CDC guidelines include three isolation categories based on three means of infection transmission: contact, respiratory droplets, and airborne spread. Each is defined in turn.
Direct contact includes touching, sexual contact, percutaneous or mucous membrane exposure, or exposure via infectious vector, such as an insect. Organisms spread in this fashion include C. difficile, scabies, drug-resistant organisms in wounds, sputum, or in the gastrointestinal tract, or herpes simplex virus via mucocutaneous contact.
Airborne spread depends upon aerosolization of small particles of an infectious agent that can spread over long distances in the air. The most common nosocomial organisms spread via this route include Mycobacterium tuberculosis, varicella-zoster virus, and measles. In theory, smallpox might qualify in this category as a potential bioterrorism agent.12
Respiratory droplets are large particles (> 5 µm in size) expelled during coughing, sneezing, or talking. One study indicated that respiratory droplets travel less than six feet from the source patient.13 Organisms spread in this fashion include Neisseria meningitidis, Hemophilus influenza type b, Bordetella pertussis, Mycoplasma pneumoniae, influenza virus, and rubella virus.
Droplet precautions are applied for patients known or suspected to be infected with micro-organisms transmitted by droplets larger than 5 µm. The patient should be placed in a private room or with patients infected with the same micro-organism. The door may remain open, but patients should be separated by at least 3 feet from other patients or visitors if no private room is available. A mask should be worn when working within 3 feet of the patient, and the patient should be masked if transport is necessary.14
The emergency department potentially has a critical role in limiting the spread of dangerous respiratory pathogens, including severe acute respiratory syndrome (SARS), avian influenza, influenza, and bioterrorism agents. Some of these respiratory pathogens may not be immediately identifiable. Threat of contagion exists for visitors as well as patients, healthcare workers, and in-patient populations. The population at risk includes the increasing number of immunocompromised patients who are status-post organ transplant, HIV-infected, or post-chemotherapy. However, one report indicated that 44% of SARS cases at the Prince of Wales Hospital in Hong Kong occurred in hospital workers who did not take special precautions during the SARS outbreak.15 Other reports confirm that healthcare workers account for 42% of SARS cases in Canada and 25% of cases in Hong Kong.16,17 The SARS epidemic, however, did demonstrate that isolation was helpful. In Vancouver, which instituted isolations early and intensely in the ED, there were only 5 cases of SARS (all but 1 imported). This is in contrast to Toronto where isolation was less intense and where there were 247 cases (3 imported) and 43 deaths.18 Clearly, hospital workers are at risk of contracting respiratory infections, and just as clearly emergency physicians and nurses must participate in any effective response to respiratory threats in hospitals.
Personal protective equipment includes gowns, gloves, masks, and respirators. These provide barrier protection, protecting from skin and mucous membrane exposures. The personal air-filtration systems approved by both the CDC and Occupation Safety and Health Administration (OSHA) are N95, 99, or 100 masks and powered air-purifying respirators. N95 masks have the ability to filter particles 1 µm in size with a filter leakage of less than or equal to 5%. N95 masks require individual fit-testing. Powered air-purifying respirators are more expensive and cumbersome, but fit uniformly.19
Apart from droplet precautions outlined earlier, engineering controls may be employed to provide passive protection for healthcare workers, visitors, and patients. These measures include isolation rooms, including negative pressure, filtration devices, and physical separation, such as closing doors or cohorting patients with identical infections.19
Negative pressure isolation systems prevent contaminated air from traveling to other areas of the hospital. In this way, infectious respiratory pathogens from single rooms or small units can be controlled. High efficiency particulate air (HEPA) filtration systems supplement negative-pressure systems. HEPA filters have been demonstrated to remove 99.97% of particles greater than or equal to 0.3 µm in diameter. They are available as portable units, but also can be installed in ventilation ducts. These can remove fungi and bacteria greater than 0.1 µm from the atmosphere, having been demonstrated to remove aspergillus spores (1.5-6 µm) to undetectable levels.20 Ultraviolet lights in addition allow killing of spores and active organisms.
Airborne precautions apply for patients with known or suspected infections with micro-organisms that remain suspended in the air and that can be widely dispersed by air currents within a room or over a long distance. Patients should be placed in a room with monitored negative air pressure in relation to the surrounding areas. There should be six to 12 air changes per hour, with discharge of air outdoors, or HEPA filtration of room air before recirculation. The door should be kept shut, or patients infected with the same micro-organism should be cohorted. Susceptible caregivers, including pregnant caregivers, should not enter the rooms of persons with known or suspected varicella or measles if other immune caregivers are available. Immune persons entering do not need to wear respiratory protection, but susceptible persons should wear respiratory protection with an N95 respirator if they enter the room.21
Even with the new vaccine, chicken pox (varicella) cases are frequently seen in the ED. Most of these cases require only confirmation of the disease by a physician or mid level provider and are generally in and other of the ED before negative pressure rooms can be set up. For these patients, airborne precautions should be instituted as rapidly as possible. Patients with possible infection should be identified at triage and care provided only by staff with immunity to varicella. Transport of the stable patient should be limited. After the patient departs, the room should be throughly cleaned and sanitized on all surfaces. Interventional airway procedures in the ED, including nebulized therapy and endotracheal intubation, increase risk of exposure to healthcare personnel. When these are essential for patient care, healthcare workers should use N95 respirators or powered air-purifying respirators, along with gowns and gloves. After completion of the procedure, personal protective equipment should be safely discarded to avoid contaminating the worker or the environment.22 The patient may require adequate sedation or paralysis to reduce the possibility of cough.23
Vaccination and Chemoprophylaxis
The CDC provides recommendations for influenza vaccination among healthcare workers.24 It has been demonstrated that vaccination of healthcare workers contributes to a decrease in patient mortality.25 There are no uniform recommendations for healthcare vaccination for other respiratory pathogens. Immunization against pneumococcus with either the 23-valent polysaccharide vaccine, currently recommended for adults over the age of 65, or with the 7-valent conjugated vaccine to children has been proposed to decrease mortality from influenza.26 This is not currently mandated by any authority.
The CDC provides specific recommendations for protection of EMS personnel during transport of suspected SARS patients. Although specific recommendations do not exist for each of the transmissible respiratory diseases, general principles apply to the transport of any patient with a suspected serious and contagious life-threatening respiratory infection:27,28
While ED personnel have routine access to N95 respirators (masks) and generally undergo FIT testing to assure they are protected, few programs in the country provide these materials or this testing to EMS personnel.
Specific Infectious Agents
Certain specific infectious agents have generated enough attention in recent months and years that they are worthy of individual discussion from the perspective of emergency medicine. These are addressed in turn.
Methicillin-resistant Staphylococcus aureus (MRSA). Staphylococci with a positive tube coagulase test are classified as S. aureus. This organism was uniformly sensitive to penicillin G until 1942. The prevalence of penicillin-resistant clinical isolates increased rapidly. In 1959 methicillin, the first of the semisynthetic "penicillin-resistant" antibiotics, was introduced, and others such as nafcillin, dicloxacillin, and oxacillin followed.30 Resistance to these anti-staphylococcal medications in a nosocomial outbreak was reported as an outbreak at Boston City Hospital in 1968, and coined MRSA.31 Methicillin resistance in S. aureus is defined as an oxacillin minimum inhibitory concentration (MIC) ≥ 4 mcg/mL.32
In 1975, the U.S. rate of isolation of MRSA in hospitals was 2-3%. By 1991, it had increased to 30%, and by 2000 MRSA had accounted for more than 50% of all nosocomial S. aureus infections. The most common mechanism for transmission is person to person, with the source being an individual with an asymptomatic nasal carriage state or with an open draining lesion.30 Skin lesions such as abrasions, eczema, puncture wounds, cosmetic shaving, or skin-to-skin contact in football players have been reported as well. Antibiotic use within the past 3 months, hospitalization within the past 12 months, and HIV infection should also be considered risk factors for MRSA carriage.32 Chronically indwelling lines, intravenous drug use, and prostheses have to be considered as sources. Large outbreaks of MRSA were first reported in the hospital setting, but in recent years there have been many more reports of MRSA emerging in the community, or community-acquired MRSA (CA-MRSA).33 CA-MRSA infections have become more frequent in otherwise active, healthy young persons.34
Currently, MRSA has become the primary bacteria of concern when assessing skin conditions such as pemphigus and other blistering disorders. The prevalence of MRSA was 59% overall of skin and soft-tissue infections of S. aureus reported from 11 different EDs in one recent report, making it the most common identifiable cause of skin and soft-tissue infections among emergency patients.35
MRSA can be screened within 2 hours with a polymerase chain reaction (PCA) test.36 Without rapid testing, patients with MRSA are isolated often for days. Where private rooms are not readily available, this practice may increase the pressure on hospital capacity and lead to boarding of patients in the ED or in the hallways. Once a patient is identified as MRSA, isolation is generally indicated, though patients with the same strain identified can be cohorted when necessary. There have been recent reports of severe cases of community-acquired pneumonia caused by MRSA. These cases often affect young, otherwise healthy individuals and can be rapidly fatal. MRSA should be especially suspected during influenza season, and in those patients with cavitary infiltrates. Risk factors include a history of MRSA skin infection or exposure to an MRSA-infected individual. Of the six patients who died, the median onset of respiratory symptoms until death was 3.5 days, and of the six for whom vaccination status was available, none had been immunized against influenza.37
Although much less common, vancomycin resistance is also a growing concern. This may be Vancomycin Intermediate Staph. aureus (VISA) or Vancomycin Resistant Staph. aureus (VRSA). VRSA is defined as an MIC ≥ 16 mcg/mL, and VISA as an MIC of 4-8 mcg/mL.38
Most nosocomial MRSA isolates remain sensitive to rifampin, vancomycin, and linezolid.30 For CA-MRSA, the empirical antibiotic therapy has been cited as trimethoprim-sulfamethoxazole and rifampin, the latter to reduce the likelihood of nasal carriage.32 Clindamycin, daptomycin, and tetracyclines in children older than 8 years of age are options.39 MRSA susceptibility to fluoroquinolones was only 60% in one recent report.35
Recommendations for hospital policies regarding infection control and MRSA have been formulated.35 Standard precautions, including the use of gowns and gloves when contact with wound drainageis anticipated. Contact precautions, which include the use of gowns and gloves for all contact with patients or their environment, have been recommended for patients in acute care facilities who are known to be infected or colonized with MRSA.40 Infection control strategies for MRSA include the following:
Vancomycin-resistant Enterococci (VRE). Since 1989, a rapid increase in the incidence and infection and colonization with VRE has been reported by hospitals, prompting recommendations published by the CDC in 1995.43 This posed particular concerns not only because of resistance to traditional drugs such as ampicillin and aminoglycosides, but also because of the potential that the vancomycin-resistant genes present in VRE could be transferred to other gram-positive organisms such as Staphylococcus aureus. Because enterococci can be found in normal gastrointestinal and female gastrointestinal tracts, historically most enterococcal infections have been attributed to endogenous sources within the individual patient. However, reports of outbreaks by VRE have indicated that transmission can occur through direct hand contact with personnel or via contaminated patient-care equipment. From 1989 to 1993, the reported percentage of nosocomial enterococcal infections resistant to vancomycin increased from 0.3% to 7.9%. The occurrence of VRE was associated with larger hospital size and with university affiliation.44 Patients at risk include those with severe underlying disease including immunosuppression, those with indwelling urinary or central venous catheters, and persons with history of prolonged hospital stay, especially with antimicrobial therapy.
Recommendations by the CDC's Hospital Infection Control Practices Advisory Committee (HICPAC) formulated recommendations for preventing and controlling the spread of vancomycin resistance.
Since vancomycin has been reported consistently as a risk factor for infection and colonization with VRE, the CDC has formulated the following guidelines for acceptable use of vancomycin:45
|Table 2. Guidelines for Use of Vancomycin|
|• Treatment of serious infections caused by beta-lactam-resistant gram-positive microorganisms.
• Treatment of infections caused by gram-positive organisms in patients with serious allergies to beta-lactams.
• Treatment of antibiotic-associated colitis unresponsive to metronidazole.
• Prophylaxis for endocarditis following high-risk procedures as recommended by the American Heart Association.
• Prophylaxis for major surgical procedures involving implantation of prosthetic materials or devices at institutions with high rates of MRSA infections.
Situations that arise in emergency care in which the use of vancomycin should be discouraged include:
Tuberculosis. Multiple factors have contributed to the resurgence of tuberculosis (TB) in the general population. These relate to the HIV epidemic; outbreaks of multi-drug resistant TB; increasing numbers of other immunosuppressed patients including those on steroids, on dialysis, and post-transplantation; and the presence of unrecognized pulmonary or laryngeal TB, notably among immigrant and homeless populations. Alcohol-dependent patients and injection drug users are also at risk. The ED treats all of these groups routinely.
Health care personnel should wear an N95 respirator when entering a room of a patient with known or suspected tuberculosis. If possible, a surgical mask should be placed on the patient, and movement and transport of the patient minimized. Patients should be educated about the purpose of such isolation, and encouraged to cover their nose and mouth when coughing or sneezing.21 Any patient with significant suspicion for active pulmonary or laryngeal TB should be placed in a negative pressure isolation room.20 Person-to-person transmission of TB occurs via transmission of airborne particles, or droplet nuclei, 1-5 µm in diameter. Airborne infection isolation rooms ideally should have >12 air exchanges per hour, but at least 6 exchanges, with incoming air HEPA filters. Air exhaust should be directed outside.19 If recirculation to general ventilation is unavoidable, HEPA filters should be installed in the exhaust ducts.20
It is important to note that the clinical and radiographic presentations of TB are often atypical in patients infected with HIV, especially when the CD4 count is < 200/ µL. These patients have a high incidence of extra-pulmonary TB and may have pulmonary disease with a normal chest x-ray.46
Particular procedures that place providers at increased risk of TB transmission have been shown to include: endotracheal intubation, bronchoscopy, sputum induction, and aerosol treatments.20 Multi-drug resistant TB was reported from the New York City Department of Health in 1996. The authors noted that 86% of patients infected with TB resistant to isoniazid, rifampin, ethambutol, and streptomycin were HIV-infected.47 This has implications for healthcare workers administering aerosol treatments in the ED, for example, with pentamidine.48
Discontinuation of TB isolation may be permitted, including release from a negative pressure isolation room, if all of the following conditions have been met: the patient is on effective therapy, is improving clinically, and three consecutive sputum samples collected on different days are smear-negative for acid-fast bacilli.20 Management of healthcare workers infected with TB is beyond the scope of this report.
Influenza. Influenza is a seasonal disease, with the vast majority of cases occurring during the winter months from November through March. While the avian strain A (H5N1) has received much publicity due to its high virulence and over 200 deaths worldwide,49 this discussion will focus on transmission of Influenza A and B in general. Influenza can be transmitted from person to person via direct contact with contaminated articles, by droplet (> 10 µm) transmission released by sneezing or coughing, resulting in contact with nasal, oral, or conjunctival mucosa of another person, or by airborne transmission leading to inhalation of small (< 5 µm) nuclei suspended in the air. Laboratory tests, some commercially available in the ED that provide confirmation of infection within 30 minutes include rapid antigen testing, polymerase chain reaction, immunofluorescence, serology from various respiratory specimens: nasopharyngeal swab, throat swab, nasal wash, nasal aspirate, sputum, bronchial wash. Sensitivity exceeds 70% and specificity is greater than 90% for these tests.19
The principal known preventive measure to decrease the likelihood of individuals contracting influenza and lessen the burden of a public health crisis from influenza is immunization. Data indicate the value of using the ED for influenza immunization; the number of patients at high risk, including the elderly and nursing home patients who have been un-immunized presenting for emergency care has been well-documented.50,51
The American College of Emergency Physicians has endorsed the following principles regarding the use of the emergency department in outbreaks of influenza:
Disease Reporting and Quarantine
The list of reportable diseases varies by state, and timeliness for reporting varies by disease. Cases of gonorrhea may be reported weekly, while smallpox must be reported immediately. Quarantine is authorized for SARS, cholera, diphtheria, plague, smallpox, yellow fever, tuberculosis, and viral hemorrhagic fever.19
Healthcare-associated bacterial infections are most commonly transmitted on the hands of healthcare workers. As a result, good hand hygiene is considered an essential measure for reducing the spread of pathogens. A number of approaches can be tried to eliminate bacterial carriage in patients. The efficacy of such treatments is controversial. The principal means for healthcare workers to decrease the spread of influenza is immunization.
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