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Cleaning is the single-most-important step in making a medical device safe for handling. It is also extremely important as a preparatory step before any subsequent disinfection or sterilization process. This article addresses the rationale for cleaning of medical equipment or devices before any further processing and includes examples of infectious complications associated with inadequate cleaning. In addition, discussion is presented concerning the relationship between cleaning and any subsequent processing before patient use. Guidance relative to the use of various cleaning agents is also provided. Additional emphasis on the necessity of following manufacturer's recommendations on cleaning agents and procedures is noted.

The diversity of potentially infectious agents that frequent the health care environment continues to increase. As a result, healthcare workers are at some degree of risk, for exposure to, and infection by, a variety of infectious diseases or conditions. This article is devoted to the epidemiology of major infectious diseases and conditions known to be transmitted in health care settings. In addition, the relative risk of occupational exposure to and infection by these diseases is also discussed as are general preventive measures associated with Standard and Transmission-based Precautions.

This article is the third of a series devoted to the epidemiology of selected infectious diseases known to be transmitted in health care settings. Part 1 (Home Care Provider 1998;3:251-2) consisted of a brief review of general preventive measures associated with standard and transmission-based precautions. Part 2 (Home Care Provider 1998;3:304-5) included a discussion of specific viral illnesses associated with blood-borne transmission. This article will address cytomegalovirus (CMV) and herpes infections along with influenza and meningitis.

The Association for Professionals in Infection Control and Epidemiology, Inc (APIC) is a multidisciplinary, voluntary, international organization of professionals who practice infection control and the application of epidemiology in all health settings. APIC is an international leader in prevention and control of infection transmission.

The Association for Professionals in Infection Control and Epidemiology, Inc. (APIC) is a multidisciplinary organization of more than 11,000 health care professionals who practice infection control and epidemiology within a variety of health care settings. As an authority in infection control, APIC endorses the Advisory Committee on Immunization Practices (ACIP) recommendations that are published by the Centers for Disease Control and Prevention Morbidity and Mortality Weekly Report. APIC supports the immunization initiative of the Healthy People 2000: National Health Promotion and Disease Prevention Objectives, which contains a national strategy for significantly improving the health of the nation, including preventing infectious diseases through immunization.

The Association for Professionals in Infection Control and Epidemiology, Inc (APIC), is a multidisciplinary, voluntary, international organization of professionals who practice infection control and the application of epidemiology in all health settings. APIC is an international leader in prevention and control of infection transmission.

This article is the second of a series devoted to the epidemiology of selected infectious diseases known to be transmitted in health care settings. In subsequent issues, the relative risk of occupational exposure to and infection with these diseases will be discussed. Part 1 (October 1998 Home Care Provider) consisted of a brief review of general preventive measures associated with standard and transmission-based precautions. This article will address specific viral illnesses associated with blood-borne transmission.

The variety of potentially infectious agents that frequent the health care environment is indeed large. As a result, health care workers are at some degree of risk for exposure to a variety of infectious diseases. However, as healthy individuals, we can protect ourselves quite successfully by following the guidelines that govern personal hygiene and immunization and adhering to accepted infection control standards of patient care, disinfection, antisepsis, and disease isolation. A clear understanding of the mechanisms of disease transmission is also important in this regard.

Home health agencies are responsible for implementing measures to prevent further transmission of infection, which occasionally requires the exclusion of health care personnel from work or direct patient contact. Decisions on work restrictions should be based on the mode of transmission and the specific epidemiology of the disease or condition in question.

Early detection and treatment are of paramount importance in our efforts to bring tuberculosis (TB) under control. In this context, screening high-risk populations for active TB and TB infection is crucial. Most individuals who become infected with Mycobacterium tuberculosis do not develop overt disease.

For more than 150 years, we have known that medical and surgical devices may serve as vehicles for the transmission of infectious agents to a susceptible host. During that time, our knowledge and experience involving microbial inactivation through disinfection have become quite sophisticated. As a result, infectious complications associated with patient care are now the exception rather than the rule.

Gram-negative bacilli (GNB), enterococci, and staphylococci are common members of the human microflora and are often the cause of infectious complications in the elderly, the severely ill, and the immunocompromised patient. In addition, patients with invasive devices (e.g., trachs, feeding tubes, catheters), open wounds, and those whose normal microbial flora have been altered by antimicrobial therapy are also at risk for infection with these microorganisms. Urinary tract infection, bacteremia, and infected wounds are the principal anatomic sites involved.

Influenza virus infections regularly increase serious morbidity and mortality in the United States. From 1972 to 1985, between 10,000 and 40,000 deaths were attributed to influenza each year. More than 90% of these deaths were individuals 65 years or older.

Epidemic jaundice, known today as viral hepatitis, was described by Hippocrates nearly 2500 years ago. Yet only in the past 20 years or so have the main viruses that cause hepatitis been elucidated. During this short interval, the main modes of transmission and effective methods of prevention also have been described.

Scabies-a small word that can, and often does, impart great anxiety and apprehension among health care workers (HCWs). Yet the epidemiology associated with this human parasitic infestation is well understood, as are the mechanisms for both its treatment and control.

Nearly 150 years ago, Louis Pasteur introduced the world to the science of microbiology and to the fact that our environment contains microbes capable of causing disease. Subsequent to these discoveries, a pandemic of health care-related staphylococcal infections nearly a century later led to the recognition of hospital-associated (nosocomial) infection. Clearly such infections (nosohusial) now also afflict nursing home residents and patients who receive home health care.

As inhabitants of the planet Earth, we live in a veritable sea of microorganisms. Virtually every aspect of our environment is heavily populated with different forms of microbial life. From the air we breathe to the food we eat, our daily existence is in the direct presence of literally billions of microorganisms.

We have constructed an image-stabilization system that measures wave-front tilt over a telescope aperture that is due to atmospheric turbulence. This system uses small features on the Sun as point sources. The wave-front tilt power spectral density has been measured with this system out to more than 500 Hz. The spectra show three distinct asymptotic slopes that do not, in general, agree with theoretical predictions based on the Kolmogorov model.

Serum lysozyme and hemolytic complement (CH100) levels were measured in dogs with experimental Bacteroides peritonitis. The CH100 levels showed little change in surviving animals. Nonsurvivors showed a moderate decrease in complement levels shortly after contamination. Both surviving and nonsurviving animals showed a slight initial decrease in lysozyme levels shortly after contamination. In surviving dogs this was followed by an increase to normal levels. In nonsurvivors, levels continued to increase, reaching a threefold magnification just prior to death. As a result of antibiotic therapy, CH100 levels exhibited no major changes; however, dogs deprived of antibiotic showed noticeable and persistent increases in lysozyme levels while treated animals showed only a mild elevation in lysozyme levels. The changes in the level of serum lysozyme may be a good indicator of antibiotic efficacy and approaching death from Bacteroides peritonitis.

Calves were sensitized to tuberculin and histoplasmin. The delayed-type hypersensitivity skin response to these antigens was produced and the diameter of induration measured. Repeated skin tests prior to filtration demonstrated that the amount of induration produced by these skin tests was closely reproducible. Histoplasmin or tuberculin-coated columns were then introduced into a closed circuit extracorporeal thoracic duct circulation. A significant (P is less than 0.01) reduction or ablation of the delayed-type hypersensitivity response was obtained to the antigen used to coat the column. In contrast, no significant reduction occurred in the skin test response to the other antigen. Repeated skin tests to both antigens after the cessation of filtration showed a gradual rise toward prefiltration levels in the skin test to the filtered antigen. The results of these experiments indicate that a selective population of T lymphocytes can be removed from an in vivo system. The removal of these cells can selectively reduce a delayed-type hypersensitivity skin test response to a particular antigen. These results are consistent with the hypothesis that a type of in vivo selective immunosuppression can be produced by antigen-coated columns when they are placed in an extracorporeal thoracic duct lymph circulation system.

Removal of recirculating lymphocytes from the lymph of calves by extracorporeal thoracic duct filtration results in a state of immunounresponsiveness. Accompanying this is histological evidence of lymphocyte depletion from the lymph organs and structures of the body. Lymph nodes, spleen, hemolymph nodes, Peyer's patches, and thymus appear depleted of the recirculating small lymphocyte. We find this closed model of lymphocyte depletion effective and free of seyere problems with infections and physiological alterations as experienced in mechanical removal, extracorporeal irradiation, and open thoracic duct fistulas.

An increase in susceptibility to infection in an untoward effect common to nearly all immunosuppressive agents. The present investigation was designed to examine potential causes of this decreased resistance to disease. Rats were treated with low dosages of cyclophosphamide, and the effect of such therapy on the in vitro phagocytic capabilities of polymorphonuclear leukocytes was examined. Intracellular destruction of phagocytized bacteria was not significantly altered as a result of treatment. However, the ingestion of Staphylococcus aureus was significantly impaired in the presence of serum from treated animals. Enzymatic analyses for various hydrolytic enzymes associated with reticuloendothelial tissue were also undertaken. Decreased levels of acid phosphatase within alveolar tissue was the only significant change noted as a result of treatment. The reduced phagocytic powers and enzyme levels observed in this investigation offer a partial explanation for the increased susceptibility to disease after treatment with cyclophosphamide.

The effect of experimental long-term azathioprine administration on pre-existing in vitro and in vivo manifestations of delayed hypersensitivity was examined. Adult ewes were administered 3 mg/kg/day azathioprine for periods of up to 28 days. Neither phytohemagglutinin (PHA)-induced nor tuberculin-induced lymphocyte transformation was affected. Similarly, pre-existing skin test positivity to tuberculin showed no observable change following drug therapy. These results agree with the majority of those involving clinical situations and indicate that immunosuppression with azathiprine cannot be effectively monitored by either the lymphocyte transformation response to PHA or by changes in the in vivo or in vitro manifestations of pre-existing delayed cutaneous hypersensitivity.

To establish the credibility of the hospital infection control program at a major southeastern medical university hospital, the incidence rates of nosocomial infections were analyzed statistically following the implementation of an extensive infection control program. Continuous hospital-wide surveillance included documentation of all detected nosocomial infections by both site and service. Chi-square analysis of the incidence of infection during the years 1977 to 1979 revealed significant decreases in several distinct areas. The overall incidence rate of infection steadily declined from 100.8/1000 admissions in 1977 to 59.9/1000 in 1979. Decreases in the incidence of urinary tract, respiratory tract, and surgical wound infections were primarily involved. Analysis of incidence rates by service revealed that general surgery was responsible for much of the observed decrease. In contrast, none of the intensive care units exhibited a significant decline in morbidity rates over the 3-year period. It is concluded that involvement of infection control personnel at all levels of patient care as a part of a sophisticated hospital infection control program can result in a significant reduction in the incidence of nosocomial infections.

The effect of adult thymectomy on the thoracic duct lymphocyte population of yearling calves has been investigated. Four to 6 weeks after thymectomy animals showed significantly reduced thoracic duct lymphocyte concentrations when compared to non-thymectomized controls. In addition, phytohaemagglutinin responsiveness of thoracic duct lymphocytes, measured by (3H) thymidine uptake, was significantly decreased following adult thymectomy. However, this decreased response to PHA was not accompanied by a change in spontaneous isotope incorporation. It is concluded that adult thymectomy in the bovine probably leads to a reduction in the number of PHA responsive T cells in the thoracic duct lymph.

A large animal model for the induction of experimental allergic encephalomyelitis to study the immunological disease parameters through closed-circuit extracorporeal thoracic duct filtration was successfully produced in two different strains of sheep. This study demonstrates the advantages of using a well-defined antigen to obtain both rapid onset of disease and a higher percentage of animals succumbing to the illness.

Effects of cyclophosphamide immunosuppressive therapy upon reticuloendothelial function in the rat have been studied. Numerous side effects including leukopenia, hematuria, diarrhea, hemorrhagic cystitis, and petechial hemorrhage in the lungs and the small bowel were observed. Studies utilizing (32)P-labeled bacteria revealed no change in the ability of the liver, spleen, lungs, or kidneys to ingest Pseudomonas aeruginosa. Utilization of labeled Staphylococcus aureus revealed an impairment of splenic uptake in animals receiving the maximal dose of 100 mg/kg. However, the liver, lungs, and kidneys were not affected. Although no generalized defect in the ingestive powers of these organs was observed, the ability of the lungs and kidneys from treated animals to kill ingested bacteria was significantly impaired. Regardless of the bacterium employed, the lungs and kidneys revealed a decrease in bactericidal ability with increasing drug dosages. Neither the liver nor the spleen from treated animals exhibited any decrease in bactericidal effect. Possible causes of this reduction in the bactericidal ability of alveolar and renal tissue following immunosuppression with cyclophosphamide are discussed.