Cathryn Louise Murphy RN, PhD, CIC
Susan A. Resnik RN, Dip IC, CIC
Julie Louise Gerberding MD, MPH
In 1958, the American Hospital Association first recommended that United States hospitals have formal programs to monitor and prevent infections. Early hospital infection control programs dealt primarily with the management and control of staphylococcal outbreaks in nurseries and among surgical patients, and these efforts emphasized teaching the principles of asepsis to clinical staff, monitoring cases of infection, and providing advice on the reprocessing of used equipment and instruments. Since that time, hospital epidemiology has grown in breadth and scope and is recognized as an important component of healthcare quality promotion. In recent years, changes in the healthcare delivery system and increased utilization of non-hospital-based healthcare services have created conditions conducive to the acquisition and spread of infections in long-term care facilities, outpatient clinics, dialysis centers, and the home care environment. Hence, the domain of infection control programs has expanded beyond the hospital to include these settings. The primary goals of a modern infection control program now include the following:
Principal stakeholders who have been responsible for developing clinical guidelines and supporting the development of programs to achieve these goals include the Centers for Disease Control and Prevention (CDC), the Association for Professionals in Infection Control and Epidemiology, and the Society for Healthcare Epidemiology of America.
This chapter provides healthcare providers with basic information that will enable them to prevent additional transmission of infectious agents in the healthcare setting and to respond appropriately in the event of inadvertent exposure to infectious agents prevalent in the health care environment.
ROLE OF THE INFECTION CONTROL PRACTITIONER
In the United States, early studies demonstrated that an effective infection control program with at least one trained infection control practitioner per 250 occupied hospital beds led to lower infection rates than programs with a lower ratio of expert infection control staff to patients. Most infection control practitioners are nurses, although in some settings physicians, epidemiologists, microbiologists, medical technologists, or specific administrators may coordinate the infection control program. Ideally, the infection control practitioner has experience and knowledge in adult education techniques, epidemiology, patient isolation strategies, and basic patient care. In addition, knowledge of antimicrobial agents, infectious diseases, microbiology, and basic principles of asepsis, sterilization, and disinfection is essential. The infection control practitioner often consults with other staff members on these issues and regularly assesses patient outcomes to evaluate the effectiveness of infection control recommendations. Additionally, the practitioner intervenes when data or direct observation suggests that variation from recommended practice is jeopardizing patient safety, recovery, or well being.
The specific functions performed by the infection control practitioner vary according to the type and size of the facility as well as the acuity of the patient population. However, regardless of these factors, the practitioner usually is responsible for implementing and evaluating effective prevention and control activities. Additionally, the infection control practitioner ensures that staffers are aware of relevant regulatory and legislative mandates and are equipped to comply with them.
The principal goals for infection control and prevention programs in extended-care and nonhospital settings are identical to those for acute-care settings. These goals are to protect patients, healthcare workers, and visitors and to do so in a manner that is timely, evidence based, and cost effective. Surveillance, development of local policies, intervention to prevent infections, and provision of education and training to the staff provide mechanisms for these goals to be met.
ROLE OF THE HEALTHCARE EPIDEMIOLOGIST
Ideally, the infection control practitioner works in collaboration with a healthcare epidemiologist. Typically, the epidemiologist is a physician trained in infectious diseases, internal medicine, or pediatrics who has special skills or experience in utilizing the basic tools of epidemiologic investigation. This individual usually is employed by the facility or serves as a paid consultant to the facility's infection control service.
The epidemiologist complements the infection control practitioner by providing additional clinical insight into specific problems. In addition, the epidemiologist is often better able to persuade administration and fellow clinicians to support and comply with the recommendations and directives of the infection control program. In some facilities, including nonhospital settings, the size of facility, available resources, or both may dictate the level of involvement of consultants—outside experts in infectious diseases, infection control, and epidemiology—in coordination of the infection control program.
THE INFECTION CONTROL COMMITTEE
In hospitals, the infection control practitioner and the epidemiologist usually interact with a hospital-based infection control committee (ICC). The ICC includes members with specific areas of expertise and interest, including hospital administration, infectious diseases, surgery, microbiology, pharmacy, occupational health, reprocessing, and other related fields. A primary function of the ICC is to develop and implement infection control policies and procedures. The multidisciplinary nature of the ICC ensures that the specific interests and needs of individual clinical and administrative units within the hospital are represented and addressed in infection control decisions and recommendations. Increasingly, nonhospital facilities also rely on multidisciplinary committees to oversee the infection control program.
INFECTION CONTROL POLICIES & PROCEDURES
ICCs routinely develop local policy positions that address specific clinical issues. These policy positions are often available in a locally focused infection control manual, a useful document that usually includes relevant state or federal standards and regulations. The following sections summarize basic infection control recommendations for common clinical issues. Clinicians should seek additional detail from the infection control manual within their respective facilities. Assisting other staff to comply with appropriate accreditation and regulatory requirements is a key role of the infection control program staff.
The Joint Commission on Accreditation of Healthcare Organizations (JCAHO) stipulates that the goal of hospital infection control is to identify and reduce the risk of infection acquisition and transmission among patients and healthcare providers. Hospitals participating in the JCAHO accreditation process must demonstrate their efforts to achieve this goal. These efforts involve compliance with six specific infection control standards. The standards address staffing and management systems, monitoring and reporting of infections, intervention in outbreaks, and other preventive actions. The JCAHO also accredits infection control components of ambulatory and long-term-care facilities as well as pathology and clinical laboratory services.
The Health Care Financing Administration (HCFA) is a federal agency that, in addition to providing healthcare insurance, surveys and certifies nonhospital healthcare facilities. Facilities surveyed by HCFA are expected to comply with predetermined infection control standards. Similarly, the National Committee for Quality Assurance administers an accreditation program and combines the results with data from a set of standardized performance measures to provide information to healthcare purchasers and consumers on comparative performance of managed-healthcare plans. Finally, several state and federal agencies promulgate regulatory directives that have direct implications for infection control programs. Generally, the infection control team ensures that staffers understand and comply with such requirements.
INFECTION MONITORING & PREVENTION
One of the most important activities of the infection control team is to monitor healthcare-associated infections and related events within the facility. Routine monitoring potentially provides valuable data that can be used to establish the endemic infection or event rate, identify the need for targeted prevention interventions, and assess the effectiveness of specific interventions. The quality and usefulness of data are improved if the system uses methods that are standardized and based on sound epidemiological principles. If a facility intends to compare its data with those collected by others, it is critical that the data be collected in a standard manner and that adjustment be made for relevant intrinsic (eg, severity of illness) and extrinsic (eg, use of central venous catheters) risk factors in the patient population.
The CDC's National Nosocomial Infections Surveillance (NNIS) system is a comprehensive system for standardized monitoring of healthcare-associated infections. By 2000, more than 300 hospitals were contributing data to the NNIS system about surgical-site infections, central venous catheter infections, ventilator-associated pneumonia, and other serious infections among intensive care patients. These data are used to develop risk-adjusted benchmarks that are widely disseminated and that serve as a reference for comparing and monitoring infection rates in comparable hospitals.
The NNIS system recently identified significant reductions of reported infection rates over the past decade. The reasons for these improvements are not entirely known, but activities characterizing hospitals that have reported improvements are presented in Figure 5-1. This model, which is based on the continuous-quality-improvement paradigm, involves initial measurement of infection rates, using standardized case definitions. The second stage involves comparison of data with an aggregate data set such as the benchmarks periodically published by CDC. In the next stage, the comparative data are interpreted locally to identify needed targeted interventions. Multidisciplinary teams of local experts and stakeholders are assembled to help develop and implement these interventions. Finally, follow-up progress is measured and disseminated to local stakeholders to motivate and document ongoing improvements. By default, completion of this final stage actually initiates the first stage of the next continuous-quality-improvement cycle.
Figure 5-1. Activities characterizing hospitals that have reported significant reductions of infection rates over the past decade.
Similar strategies have been successful in improving use of antimicrobial agents and limiting resistance to them in some intensive care units. A national system for standardized monitoring of occupational exposures and infections among healthcare personnel (CDC's National Surveillance System for Healthcare Workers) is in the early stages of development. As interest in patient safety and reporting of adverse events increases, it is likely that similar systems for monitoring and motivating improvements will be adopted in other healthcare settings to address infectious diseases and other patient safety issues.
CDC currently advocates a two-tiered approach for infection control and isolation systems. The first tier includes “standard precautions.” Standard precautions are precautions recommended for the delivery of care to all patients regardless of their diagnosis or presumed infection status. Standard precautions apply to the following:
Standard precautions are designed to limit healthcare exposure to blood or other body substances and include elements such as routine hand hygiene and use of appropriate protective apparel, eg, masks, eye protection, and gloves when needed to prevent direct contact.
The second tier in the infection control and isolation system recommended by CDC encompasses “transmission-based precautions,” which are specifically designed for the management of patients known or suspected to be infected with pathogens whose transmission can be limited by the adoption of additional precautions beyond those included as standard precautions. The three defined types of transmission-based precautions are the following:
The essential components of each individual type of precaution are summarized in Table 5-1.
PREVENTING ANTIMICROBIAL-AGENT-RESISTANT INFECTIONS
The expanding use of broad-spectrum agents in more severely ill patients (eg, critically ill patients in intensive care) and those housed in settings with a high potential for person-to-person transmission (eg, long-term-care facilities) has resulted in emergence and spread of multidrug-resistant pathogens. By 2000, at least 70% of hospital-acquired pathogens were resistant to one or more antimicrobial agents commonly used for treatment. These resistant pathogens adversely affect the outcome of care for many patients and add to the expense of treatment.
Antimicrobial-agent-resistant pathogens emerge and spread through several convergent mechanisms. First, pathogens develop or acquire the genetic traits responsible for resistance. Then they are introduced into healthcare settings via patients, visitors, or healthcare personnel or via contaminated materials. Antimicrobial therapy selects for strains that express the resistance mechanism, which in turn increases their capacity to spread to other patients or personnel.
Previous studies have demonstrated a relationship between the emergence of resistant organisms and inappropriate or extended use of antimicrobial agents, noncompliance with hand hygiene and other infection control precautions, and indiscriminate use in food animals of products containing antimicrobial agents.
Clinicians can act to prevent the emergence and spread of multidrug-resistant infections in all healthcare settings. Professional societies, healthcare organizations, healthcare purchasers, and federal agencies have mounted efforts to promote judicious antimicrobial use. CDC has developed a series of 12-step programs to prevent infections in various patient settings. These programs emphasize four key strategies: infection prevention (eg, through immunization and decreased use of invasive devices in other procedures); effective pathogen-directed antimicrobial treatment to eradicate infection when present; judicious antimicrobial use; and prevention of person-to-person spread (eg, through effective hand hygiene and patient isolation practices) (Table 5-2). Effective strategies for improving antimicrobial-agent prescription practices are outlined in Table 5-3. Of these, providing individual clinicians or groups with feedback on prescription practices and real-time decision support via computerized pharmaceutical-ordering systems holds the most promise for effecting meaningful improvements.
Hand hygiene is a critical component of programs to prevent transmission of healthcare-associated infections. When hands or other skin surfaces are contaminated with blood or other body substances, they should be cleaned as soon as practicable. The requirements for hand hygiene apply regardless of whether gloves are worn.
There are three key methods for healthcare personnel to maintain hand hygiene: hand washing, hand antisepsis, and surgical scrubbing. The appropriate method depends on the degree of soiling of the hands, the available equipment and supplies, the nature of the intended work that will be undertaken immediately following hand hygiene, and the susceptibility of the patient with whom the healthcare provider will be in contact.
Hand washing typically involves the use of running water and plain soap to remove soil and transient skin flora. Hand antisepsis is preferred when contact with pathogens is highly likely and when patients are highly susceptible to infection. Removal or destruction of transient flora occurs when personnel perform hand antisepsis using an antimicrobial soap or hand rub. Some commonly used agents for hand antisepsis include products that contain alcohols (eg, n-propanol, isopropanol, and ethanol in appropriate concentrations), chlorhexidine gluconate, iodine or iodophors, para-chloro-meta-xylenol, and triclosan. The optimal duration of either hand washing or hand antisepsis is not clearly defined, but most experts suggest that hand washing for 15–30 s is sufficient. Manufacturers' instructions should be followed for determining the duration of hand contact with antiseptics.
Table 5-1. Summary of the essential elements of recommended isolation precautions.1
Table 5-2. Twelve steps to prevent antimicrobial resistance in hospitalized adults.
Table 5-3. Effective strategies to promote judicious antimicrobial use.
The most aggressive form of hand hygiene is the surgical scrub. The surgical scrub is undertaken to remove or destroy transient flora and to reduce the resident flora so that surgical wounds will not be contaminated even if gloves are torn. If an antimicrobial soap or detergent is used, personnel should use a brush and an action that involves friction for a minimum of 2 min. Care must be taken to include nail beds, wrists, and all surfaces of the hand.
Clinician compliance with hand hygiene recommendations is universally poor. Accordingly, hand hygiene should be encouraged whenever there is any doubt about the need to do so. Hand-washing facilities should be easily accessible and supplied with clean, running water and either soap or an antiseptic hand-washing agent. When clean, running water is inaccessible, waterless antiseptic agents such as alcohol-based hand rubs or foam products may provide acceptable alternatives.
Asepsis refers to the absence of microorganisms that are capable of causing disease. Healthcare workers routinely use the following methods to provide healthcare aseptically:
Clinicians should first use an antiseptic solution to prepare a patient's skin for insertion of invasive devices or for other invasive procedures that breach the skin. The goals are to prevent translocation of flora into the wound and egress of flora from adjacent tissue into the wound. When a maximum and immediate antiseptic effect of relatively short duration is required, alcohols are preferred. When a more prolonged duration of antiseptic activity is relevant (eg, during intravenous-catheter insertion), a product containing 2% aqueous chlorhexidine may be superior to plain alcohols or povidone-iodine. For preoperative surgical cutaneous disinfection, an alcohol-based preparation of iodine or povidone-iodine solution is preferred.
The intended use of an item or piece of equipment and manufacturer's instructions dictate its appropriate method of reprocessing, ie, whether cleaning, disinfection, or sterilization is in order. Intact skin provides an effective barrier to most microorganisms; thus, items touching only intact skin require only routine cleaning unless contaminated by blood or other body fluids. Instruments or equipment coming into contact with mucous membranes or nonsterile tissue (other than intact skin) must, before use, be cleaned and then disinfected with a suitable disinfectant. Those instruments or pieces of equipment used to enter or capable of entering tissue that would be sterile under normal circumstances or to enter the vascular system of a patient must be thoroughly cleaned and then sterilized before use.
Proper cleaning to remove organic debris is essential before any disinfection or sterilization procedure. Relevant manufacturer's instructions for equipment, instruments, disinfectants, sterilants, sterilizers, and processors should be followed during reprocessing. Sterilized items should be handled and stored in a manner that ensures the integrity of packing material and prevents contamination of contents from any source. If an item is suspected of being nonsterile or its sterility cannot be guaranteed, the item should not be used.
OCCUPATIONAL HEALTH ISSUES
A core component of any healthcare infection control program is a system that ensures that clinical and nonclinical healthcare personnel can perform their work in an environment where the risk of acquiring or transmitting infection is as low as possible. Provision of education, training, personal protective gear, safety equipment, appropriate patient placement, and protection through immunization or vaccination are strategies routinely used to minimize the risk of transmission of infectious disease from or to healthcare personnel. In 1998, CDC developed a new guideline for infection prevention in healthcare personnel (see Bolyard 1998). This guideline outlines the requirements for an effective occupational health program in healthcare settings and provides specific recommendations for prevention and management of occupational infectious diseases.
INFECTIOUS CONDITIONS OF CONCERN
Blood-borne pathogens are an important concern in healthcare settings. Most attention has been focused on hepatitis B virus (HBV), hepatitis C virus (HCV), and HIV, but any infectious pathogen in the blood can probably be transmitted under some circumstances. HBV is the most highly transmissible of these agents, but vaccination programs have dramatically reduced the proportion of healthcare personnel at risk. For HIV, the best estimate of the average risk associated with punctures by a needle or similar “sharp” contaminated with blood from an HIV-infected patient is still approximately 0.32%. Risk is highest when the exposure involves blood from a patient with preterminal AIDS, the injury is deep, or it is inflicted by a visibly blood-contaminated device that has been used in an artery or vein. Fewer data are available to determine the HCV transmission risk, but current data suggest that approximately 1.9% of HCV-contaminated-needle injuries result in infection.
CDC's standard precautions (above) include measures to prevent exposure to blood and other body fluids, which will in turn prevent transmission of blood-borne occupational infections. The single most important prevention strategy is to eliminate or at least prevent, to the extent technologically possible, injuries caused by needles and other sharps. Reducing the number of needle punctures and injections used for patient treatment is an important and sometimes overlooked component of this effort. Proper training and supervision are also important. Facilities that use trained phlebotomists or other skilled staff to obtain blood samples and insert catheters are often rewarded with fewer injuries and exposures. Technologic improvements in the design of needles and related devices also contribute to safety efforts, provided that their implementation is accompanied by comprehensive training in their safe use and disposal.
Management of an occupational exposure to blood or another body fluid should include the following:
Detailed guidelines for postexposure care, including HBV, HCV, and HIV prophylaxis, have been prepared by CDC and are periodically updated. These documents can be found on the World Wide Web at http://www.cdc.gov/ncidod/hip/Guide/guide.htm.
Tuberculosis infection can be acquired and transmitted in healthcare settings. Patients, healthcare personnel, and even visitors have been sources of spread to others. Outbreaks of drug-resistant infection in New York City in the early 1990s, with high attack rates observed among exposed healthcare and prison personnel, illustrate the tremendous morbidity this infection can still cause. Employee health programs in settings where exposure to tuberculosis can reasonably be expected are now charged with the responsibility for conducting surveillance (skin testing) and postexposure follow-up. Current CDC guidelines for preventing tuberculosis transmission in healthcare facilities can be found at http://www.cdc.gov/ncidod/hip/Guide/tb_excerpt.htm.
Tuberculosis prevention in healthcare settings relies first and foremost on prompt recognition and isolation of suspected cases. Precautions against airborne infectious agents include appropriate air containment, filtration, and exchange to prevent tuberculosis transmission. Appropriate respiratory protection may provide an additional measure of safety, but it cannot substitute for proper ventilation. Patients suspected of having tuberculosis should be placed in a room that meets the precautionary specifications for such airborne pathogens, including monitored negative air pressure in relation to the surrounding area, 6–12 air changes per hour, and appropriate discharge of air outdoors or monitored high-efficiency filtration of room air before the air is circulated to other areas in the hospital.
If these steps are not feasible in the short run, then patients should at least be advised to don a surgical mask to reduce dissemination of droplets that may desiccate to form infectious aerosols. Healthcare personnel and others sharing air with patients who are known or suspected to have active tuberculosis should use a properly fitted respirator (eg, the N95 respirator—a half-mask filtering face piece respirator rated at least 95% efficient by the National Institute for Occupational Safety and Health [see National Institute for Occupational Safety and Health 1987]). High-risk procedures, eg, bronchoscopy and other cough-inducing procedures, should be performed in isolation rooms with suitable ventilation, by personnel using appropriate respiratory protection.
CDC recommends periodic tuberculin skin tests (TST) for healthcare workers who have the potential for exposure to Mycobacterium tuberculosis. Results are used in the clinical management of healthcare workers and in the assessment of the adequacy of infection control measures in healthcare facilities. CDC recommends that the periodicity of routine TSTs be based on an assessment of the risk of transmission of M tuberculosis in that particular setting. This includes a profile of TB in the community, the number of infectious TB patients admitted to the area or ward, or the estimated number of infectious TB patients to whom healthcare workers in an occupational group may be exposed, and the results of analysis of healthcare workers' TST conversions, where applicable, and possible person-to person transmission of M tuberculosis. Epidemiologic investigations to evaluate the possibility of nosocomial transmission should be conducted when TST conversions are noted. Finally, TST programs should be evaluated periodically to ensure that healthcare workers who should be included are being tested at the appropriate intervals.
The CDC's Advisory Committee on Immunization Practices (ACIP) strongly recommends that healthcare personnel with direct patient contact be immunized against HBV, influenza, measles, mumps, and rubella. Depending on the nature of their work, susceptibility, and risk, individual staff may benefit from immunization against hepatitis A virus, meningococcal disease, pertussis, typhoid, and smallpox. Specific recommendations regarding preimmunization screening, dose schedule, indications, precautions, contraindications, and other considerations are contained in the relevant CDC guideline, which is based on the recommendations of the U.S. Public Health Service's Advisory Committee on Immunization Practices that is available at http://www.cdc.gov/epo/mmwr/preview/mmwrhtml/00050577.htm.
Personnel performing work that involves contact with blood or other body fluids containing blood are at greatest risk of acquiring occupational HBV infection. This group should routinely be vaccinated against HBV. Persons vaccinated due to occupational risk do not require prevaccination serologic screening although serologic testing should be undertaken 1–2 months postvaccination to establish and record the serologic response.
Influenza is also gaining appreciation as an important occupational infection. Healthcare personnel are at risk for acquiring and transmitting this pathogen across the entire spectrum of care delivery sites. Despite widespread recognition that immunization of healthcare personnel saves time lost from work, money, and probably lives, most healthcare personnel still do not receive the yearly vaccination. With the growing concern about another global influenza pandemic, emergence of new influenza strains, and advent of new antiviral treatments, influenza detection and prevention are growing components of infection prevention in healthcare settings.
The U.S. Public Health Service's Advisory Committee on Immunization Practices recommends that all healthcare personnel should be immune to varicella. Accordingly, it is prudent to ensure that all healthcare workers are screened for varicella immunity within 2 weeks of commencing duties. Healthcare personnel are considered immune if they have either a positive history of varicella-zoster virus (VZV) infection or proof of varicella immunization. Cases of nosocomial transmission of VZV have been reported, and patients, visitors, and staff have been implicated as sources of infection. Healthcare worker exposure to VZV is considered to have occurred when a susceptible healthcare worker not wearing respiratory protection enters a confined space occupied by a person with active varicella or zoster. A person is also infectious in the 48 h before the appearance of varicella, and contact during this time may also lead to infection in susceptible persons. Airborne precautions should be used in the care of patients with varicella or zoster. Following exposure, healthcare personnel should be assessed and a decision made regarding administration of varicella-zoster immune globulin (VZIG). Exposed susceptible healthcare workers should cease work for 8–21 days. Healthcare personnel with varicella are considered fit for duty when they are well enough to return and only when all lesions have dried and crusted, which is most often after 5 days.
NEW & EMERGING AGENTS
Infectious diseases continue to emerge, threatening the health and well being of both patients and healthcare providers. Legionnaires' disease, Lyme disease, AIDS, and the development of drug-resistant strains of tuberculosis, certain pneumonias, and Staphylococcus aureus demonstrate the seriousness of emergent infectious diseases. Vigilant compliance with recommended infection control measures and judicious prescribing and dispensing of antimicrobial agents offer two opportunities for healthcare workers to limit the emergence of further infectious disease. Timely identification and reporting of cases of notifiable disease assists in the accurate estimation of the magnitude of the infectious disease problem and in the development of additional preventative and treatment measures.
Arias KM: Infection Control Tool Kit Series: Assessing and Developing an Infection Control Program in the Acute Care Setting. Association for Professionals in Infection Control and Epidemiology Inc., 2000.
Beltrami EM et al: Risk and management of blood-borne infections in health care workers. Clin Microbiol Rev 2000;13:385.
Bolyard EA et al: Guideline for infection control in healthcare personnel, 1998. Hospital Infection Control Practices Advisory Committee. Infect Control Hosp Epidemiol 1998;19:407. Erratum. Infect Control Hosp Epidemiol 1998;19:493.
Cardo DM et al: A case-control study of HIV seroconversion in health care workers after percutaneous exposure. Centers for Disease Control and Prevention Needlestick Surveillance Group. N Engl J Med 1997;337:1485.
Centers for Disease Control and Prevention: Monitoring hospital-acquired infections to promote patient safety–United States, 1990–1999. Morb Mortal Wkly Rep 2000;49:149.
Centers for Disease Control and Prevention: Immunization of health-care workers. Morb Mortal Wkly Rep 1997;46(RR–18).
Fridkin SK et al: Surveillance of antimicrobial use and an timicrobial resistance in United States hospitals: project ICARE phase 2. Project Intensive Care Antimicrobial Resistance Epidemiology (ICARE) hospitals. Clin Infect Dis 1999;29:245.
Friedman C et al: Requirements for infrastructure and essential activities of infection control and epidemiology in out-of-hospital settings: a consensus panel report. Association for Professionals in Infection Control and Epidemiology and Society for Healthcare Epidemiology of America. Infect Control Hosp Epidemiol 1999;20:695.
Graham M: Frequency and duration of handwashing in an intensive care unit. Am J Infect Control 1990;18:77.
Haley RW et al: The efficacy of infection surveillance and control programs in preventing nosocomial infections in US hospitals. Am J Epidemiol 1985;121:182.
Jennings J, Manian F (editors): APIC Handbook of Infection Control. Association for Professionals in Infection Control and Epidemiology, 1999.
Larson EL: APIC guideline for handwashing and hand antisepsis in health care settings. Am J Infect Control 1995;23:251.
Maki DG, Ringer M, Alvarado CJ: Prospective randomised trial of povidone-iodine, alcohol, and chlorhexidine for prevention of infection associated with central venous and arterial catheters. Lancet 1991;338:339.
National Center for Infectious Diseases: Preventing Emerging Infectious Diseases: A Strategy for the 21st Century. Centers for Disease Control and Prevention, 1998.
National Institute for Occupational Safety and Health: NIOSH Respirator Decision Logic. DHHS publication (NIOSH)87-108. U.S. Public Health Service, 1987.
Scheckler WE et al: Requirements for infrastructure and essential activities of infection control and epidemiology in hospitals: a consensus panel report. Society for Healthcare Epidemiology of America. Infect Control Hosp Epidemiol 1998;19:114.
Weber DJ, Rutala WA: Varicella immunization of health care workers. In Panlilio AL, Cardo DM: Bailliere's Clinical Infectious Diseases: International Practice and Research: Prevention Strategies for Health Care Workers. Bailliere Tindall, 1999.