Dr. Jaffe presented an update on the risk of HIV infection to health care workers. He noted that information has come from three sources: 1) analysis of national AIDS surveillance data: 2) prospective studies of injuries and exposures of health care workers: and 3) anecdotal reports.

The national AIDS surveillance data indicate that 5% of reported AIDS cases occur in health care workers; health care workers represent 5.7% of the US workforce. By itself, this would suggest that employment as a health care worker is not associated with a disproportionately large risk of AIDS. The health care workers with AIDS have an age and sex distribution that is similar to that of all AIDS patients; the health care workers with AIDS are more likely to be white, however. The health care workers with AIDS are more likely to he homosexual/bisexual men (73%) than are all AIDS patients (62%); conversely, they are less likely to admit to intravenous drug use.

The world pandemic of acquired immunodeficiency syndrome (AIDS) caused by the human immunodeficiency virus (HIV) is now in its eighth year and may represent the most serious infectious disease threat to world health in modern history. We now have the capability to diagnose HIV infection very accurately by simple serologic means. However, there has been great reluctance in this country to use serologic testing on a wide scale as a weapon in the war against AIDS. It is hard to believe that when serologic testing first became available, there was controversy as to whether blood donors should be routinely screened.

It has been little more than four years since the human immunodeficiency virus (HIV) was definitively associated with acquired immunodeficiency syndrome (AIDS). Although a few holdouts still insist that the true cause of AIDS has not yet been found, an over whelming body of evidence indicates that a retrovirus is responsible. The human retroviruses can be classified into transforming retroviruses (HTLV-I and HTLV-II) and cytopathic retroviruses (HIV-I and HIV-Y). As their name suggests, the cytopathic viruses rapidly lyse cells, but it is now clear that they do not lyse all of the cell types that they infect. Many T4 helper cells, which have an abundance of CD4 receptors on their surface, are destroyed following infection. However, HIV does not kill other cell types, such as macrophages, so readily, but rather persists either productively or latently within them. In this fashion, the virus persists in the host generally for the life of the individual.

In the past few years, several hospital epidemiology programs in the United States have developed the capacity to monitor drug usage in hospitalized patients. This activity has been stimulated by a Joint Commission on the Accreditation of Healthcare Organizations (JCAHO) mandate to monitor antimicrobial agents and also by the emergence of technology for automated medical record linkage. There is a growing recognition that these methods to link computerized pharmacy records and discharge diagnoses can be used to identify “signals” for side effects and toxicities of all drugs and not only just for antimicrobial agents. In addition, clinical trials designed to detect occurrences of adverse experiences with commonly used antimicrobials have led some hospital epidemiologists to seek collaboration with experts in the methodologies for study of drug usage and drug effects, i.e., pharmacoepidemiologists.

The role of hospital epidemiology is expanding. Today's hospital epidemiologists are being asked for advice by hospital administrators for matters outside of infection control. The latter relate to the optimal use of drugs, the level of health care provided by the employee health services and a number of issues related to the distribution and determinants of health care in the institution, all of which fall under the umbrella of quality assurance (QA). There is no doubt about the national preoccupation for monitoring health care and health care providers.

In recent years we have all been distressed by reports in the popular press of inaccurate hospital mortality data. We have been concerned when quality assurance programs attempt to compare infection rates among surgeons without adjusting for the differences in underlying illnesses of their patients. A similar concern arises when infection rates are compared among hospitals. And university hospital administrators have been concerned by the inadequate reimbursement given to referral hospitals compared with community hospitals.

Congress has mandated that the Health Care Financing Administration (HCFA) adopt a severity adjuster for DRGs (Diagnosis Related Groups), the basis of Medicare's prospective payment system. A number of states are close to mandating the use of severity adjusters. These states include New Jersey, Colorado, Pennsylvania, Iowa and Washington. Finally, the Joint Commission on Accreditation of Healthcare Organizations (JCAHO) is developing severity-adjusted clinical indicators to assess the quality of care.

Dr. William Scheckler, when he was the president of the Society of Hospital Epidemiologists of America (SHEA), had the foresight to set up a task force so that SHEA could develop a position on the severity of illness indicators. The findings of the task force have been published previously in this journal (see volume 9, number 7, pp 309–316).

Health care workers are exposed to a vast array of health and safety hazards, unsurpassed by any other service industry and perhaps unequaled by industry in general. These hazards include exposure to biological agents, physical agents, stress, injury and chemical agents.

The hospital environment abounds with hazardous chemical agents. A hospital survey conducted by the National Institute for Occupational Safety and Health (NIOSH) found at least 135 chemicals recognized as carcinogens, teratogens, mutagens, or which have some combination of these effects in humans or animals. Another 179 chemicals found in hospitals are primary irritants of the skin or eyes. Although employee risks associated with chemicals have been neglected all too frequently, attention finally is being directed to assessing and reducing these risks. Among the toxic substances that present health hazards to health care providers are disinfecting and sterilizing compounds, chemotherapeutic agents and anesthetic gases.

The use of glycoprotein G (gG) from the herpes simplex virus has made possible an immunoprecipitation test that distinguishes prior infection with herpesvirus type 1 (HSV-I), herpesvirus type 2 (HSV-2) or both. The test is more sensitive than previously available tests. A national study employing this new immunologic test suggests great differences in prevalence of antibodies to each of these two viruses at different ages in different ethnic groups. For example, in the 20-to 25-year age group, about 5% of Caucasians have antibody to HSV-2, while the frequency of antibody to HSV-2 in blacks is about four times that high. This study also suggests a higher prevalence of HSV infection in the population of women of childbearing age than was previously estimated with less sensitive testing methods. Since HSV disease in newborns is closely related to the frequency of herpes simplex infection in the mother, estimates of the likelihood of nosocomial infection with HSV in newborns must take these new data into account. The specificity of the new test was not discussed.

Opportunistic fungal infections increasingly are becoming important causes of morbidity and mortality in the hospitalized patient. In addition to the well-known pathogenic fungi such as the Zygomycetes and Aspergillus spp, serious infections are being reported with increasing frequency due to Fusarium spp, dematiacious fungi and other usually “nonpathogenic” fungi. Recent data, however, suggest that Candida spp are emerging as one of the major nosocomial pathogens in both seriously ill immunocompetent and immunocompromised patients. Given the importance of Candida spp as opportunistic fungal pathogens, this summary will focus on newer clinical and epidemiologic observations of nosocomial candidiasis.

I have two major concerns about the immunocompromised host field in 1989. The first relates to the tremendous impact that acquired immunodeficiency syndrome (AIDS) has had on nosocomial infections and the management of hospitalized patients. It is a major consideration in screening patients for organ transplants. Concern about AIDS influences all aspects of blood transfusion therapy.

The second concern relates to the increasing demand for expensive technologically-oriented procedures involved in the management of immunocompromised hosts. I believe the demand for these approaches is irresistible and adds to the mounting problems that hospitals face in containing basic costs. Since there is a finite dollar available for medical expenses, 1 see these demands exacerbating the rationing of medical resources.

It is not difficult to predict the future of hospital epidemiology. It will become increasingly important. The need to prevent and control hospital-acquired infections and to protect the staff from communicable diseases will grow. Hospitals will continue to be filled with patients, life-prolonging technical advances will continue to be introduced, resistance will emerge to the new antimicrobial agents, the number of patients with acquired immunodeficiency syndrome (AIDS) will increase and the population will continue to age. Concomitant increases in costs and demands for accountability and for quality assurance will occur (Table 1).

The future for practitioners of hospital epidemiology is less assured. We will have to continue to convince hospital administrators that we are more than “bean counters” engaged mainly in surveillance. We must assure them that the benefits of our work justify the costs of maintaining effective infection control units and that we are dedicated to prevention and control.

Candidiasis is a well-recognized complication of immunosuppression, parenteral nutrition, surgery and broad spectrum antimicrobial chemotherapy. The majority of cases of candidiasis are caused by Candida albicans. Since the mid-1970's, however, Candida tropicalis has assumed an increasingly important pathogenic role, especially in granulocytopenic patients.

C tropicalis is a unicellar yeast organism that belongs to the genus Candida, the family Cryptococcaceae and the group Deuteromycetes (Fungi Imperfecti). C tropicalis grows well at 25°C and 37°C on blood and Sabouraud agars in an aerobic atmosphere, producing white, smooth colonies (Figure 1). It forms pellicle in broth. Microscopic examination shows round, oval or oblong noncapsulated budding cells (blasto-conidia), 2.5 μm X 3-14 μm in size. Singe cells, clusters or chains may be seen. C tropicalis forms hyphae and pseudohyphae, but not the germ tubes, unlike C albicans. (C tropicalis strains forming morphologically atypical germ tubes have been repotted, but are rare.) N 0 chlamydospores are produced on cornmeal agar. C tropicalis assimilates glucose, maltose, sucrose, galactose, cellobiose, xylose and trehalose, and ferments glucose, maltose, sucrose, galactose and trehalose. (Sucrose-negative variants have been described.”) Several commercially available biochemical panels are widely used for identifying C tropicalis.