The hospital-wide attack rate for Clostridium difficile-associated diarrhea at our tertiary-care university hospital was 0.02 per 100 patient discharges (0.02%) in 1982, but 0.41% and 1.47% in 1986 and 1987, respectively, with a peak incidence of 2.25% in the fourth quarter of 1987. Hospital antibiotic usage patterns showed concurrent increased use of third-generation cephalosporins, and intravenous vancomycin and metronidazole. Thirty-seven cases selected for study were older than 37 control patients, more likely to have an underlying malignancy and less likely hospitalized on the obstetrics/gynecology service. Their mean duration of hospitalization prior to diagnosis was 21 days, versus a mean total length of stay of eight days for controls. All cases received antibiotics, compared to 24 of the controls. Cases were given more antibiotics for longer periods, and more often received clindamycin, third-generation cephalosporins, aminoglycosides and vancomycin. Gender, race, duration of hospitalization, prior surgery and antiulcer therapy were not significant by logistic regression analysis. Epidemiologic variables with significantly different adjusted odds ratios (95% confidence intervals) were age greater than 65 years (14.1, 1.4-141), intensive care unit residence (39.2, 2.2-713), gastrointestinal procedure (23.2, 2.1-255) and more than ten antibiotic days (summation of days of each antibiotic administered) (16.1, 2.2-117). Control measures included encouraging earlier isolation and treatment of suspected cases and formulary restriction of clindamycin, with use of metronidazole for therapy of anaerobic infections. By the second half of 1988, the attack rate had dropped progressively to 0.74%.

The Food and Drug Administration (FDA) healthcare personnel handwash procedure allows for the use of a non-neutralizing stripping fluid after washing with an antimicrobial handwash product. The antimicrobial in the handwash product can remain active up until the time of neutralization or plating. A modified healthcare personnel handwash procedure using a pigskin substrate and a 4% chlorhexidine gluconate handwash product was used to demonstrate the need for a neutralizer in the stripping fluid. When tests were run with and without neutralizers in the dilution blanks, but with adequate neutralizers in the stripping fluid, there were no significant differences (p>.05) between results obtained after five washes or after each wash. When tests were run with a non-neutralizing stripping fluid, significant differences were noticed in the first and the fifth wash (p<.05), and in the presence or absence of neutralizers in the dilution blanks (p<.05). The data generated indicate that in order to determine the true activity of an antimicrobial handwash product, an adequate neutralizer should be incorporated into the stripping fluid and not just the dilution media. They also suggest that neutralizer carry-over from the stripping fluid is not a valid concern.

To identify predictors of infection in catheters used for total parenteral nutrition (TPN), clinical and microbiological data were prospectively collected on 169 catheter systems (88 patients). Based on semiquantitative catheter cultures, infection was associated with a positive insertion site skin culture taken close to the time of catheter removal (relative risk [RR] = 4.50), especially one yielding 250 colonies of an organism other than coagulase-negative staphylococci. Infection was also associated with erythema at the insertion site greater than 4 mm in diameter (RR = 2.93). In a subset of 67 catheters for which blood cultures were obtained, infection was also associated with a positive peripheral venous blood culture (RR = 5.90) and a positive central venous blood culture obtained through the catheter (RR = 5.44). Based on a logistic regression model, periodic cultures of the insertion site should be useful in evaluating subsequent fever in stable patients with indwelling central venous catheters. Another source of fever is likely if inflammation is absent and there is either no colonization or there is colonization by less than 50 colonies of coagulase-negative staphylococci at the insertion site. Conversely, the catheter should be removed and cultured semi-quantitatively if the site is colonized by an organism other than coagulase-negative staphylococci. We suggest that blood culture results add little to the risk estimate in these situations.

In the prevention of nosocomial infection, it is important to understand its epidemiology and pathogenesis. Only then are we able to formulate appropriate preventive methods for the various types of infection. However, in recent years there has been growing recognition that the implementation of preventive measures is often only possible when behavioral change occurs. In fact, an appreciation of behavioral change principles is critical for infection control nurses (ICNs) because most preventable nosocomial infections are related to inappropriate patient care practices. Procedures for prevention are often simple (e.g., washing hands), but compliance can be extremely difficult to enforce in the hospital.

A clinicoepidemiologic study was undertaken to investigate an apparent increase in frequency of nosocomial invasive filamentous fungal disease (NIFFD) in adult patients with acute leukemia hospitalized during a period of hospital construction, and to determine if a relationship existed between the construction activity and the acquisition of NIFFD.

The first study goal, to determine the incidence of NIFFD before and during construction, was approached by calculation of incidence rates of NIFFD in patients with acute leukemia, comparing 1982 and 1983 (a baseline period free of construction) to 1986 (a year when construction activity was at its peak). The second study goal, to identify risk factors for the development of NIFFD, was accomplished by reviewing the autopsy records of all patients with underlying hematologic disorders accompanied by granulocytopenia who died in our hospital from 1982 through 1986. Patients with and without autopsy evidence of NIFFD were then compared by univariate and multivariate (logistic regression) analysis to identify potential risk factors for the acquisition of NIFFD.

The incidence of NIFFD in patients with acute leukemia hospitalized during the period of hospital construction was significantly increased when compared to a baseline period without construction (11 per 139 versus 4 per 333, p < .001). Review of all granulocytopenic patients autopsied over the five-year interval 1982 through 1986 revealed duration of granulocytopenia and hospitalization during construction to be risk factors for NIFFD by univariate analysis (p < .005). Logistic regression showed duration of granulocytopenia to be a highly significant independent risk factor (p < .01) and construction activity to be a probable independent risk factor (p = .09). The effect of construction on risk of NIFFD was most striking in those patients granulocytopenic for less than 40 days. The increased incidence of NIFFD occurred despite anticipation of this potential problem and compliance with published recommendations for infection control during periods of hospital construction.

Given the potentiating effect of construction activity on the occurrence of NIFFD in granulocytopenic patients and the suboptimal impact of standard recommended preventive measures, additional risk-reduction methods (i.e., surveillance culturing, prophylactic antifungal therapy, use of portable high efficiency particulate air filters) may be appropriate for patients expected to experience prolonged granulocytopenia (> 14 days) while hospitalized during periods of major construction activity involving excavation. Further studies will be necessary to define the roles of each of these modalities.

The impact of recently recommended hospital infection control guidelines on Canadian acute-care hospitals is unknown. A confidential cross-sectional mailed survey of all acute-care Canadian hospitals was conducted to determine rates of receipt and adoption of published guidelines for Universal Precautions (UP) or Body Substance Isolation (BSI), rationale for adoption and knowledge of costs and benefits. Five hundred and seventy-nine of 943 sites (61%) responded (exceeding 80% in urban centers); 94% among hospitals with at least 300 beds and 57% among those under 300 beds. Seventy-four percent of responders claimed adoption of UP (65%) or BSI (9%), staff protection being their primary motivation. Adoption of either UP or BSI was associated with size (p<.001), increasing progressively from 45% in the smallest group (~25 beds) to 64% in the largest (2500 beds). Many hospitals introduced modifications and some substituted names other than UP or BSI in adopting a new strategy. In practice, UP and BSI now mean different things in different hospitals, and the distinction between them has become blurred. Furthermore, only 5% claiming adoption of a new strategy adopted all of the fundamental policies expected under UP or BSI. Receipt of guidelines was also correlated with size: one-third of hospitals under 200 beds had not received key publications defining UP and BSI. Only 19% claiming adoption of a new strategy indicated knowledge of cost implications. These results suggest a need for closer collaboration among hospitals and government agencies in developing uniform infection control policies, and for systematic evaluation of the cost and effectiveness of new strategies. (Infect Control Hosp Epidemiol. 1990;11:465-472.)

Recent reports have emphasized an increase in both infection and colonization with methicillin-resistant Staphylococcus aureus (MRSA) in institutionalized older patients. We studied whether or not local treatment with mupirocinointment could eliminate nasal colonization with S aureus. A total of 102 patients in a Veterans Administration nursing home were screened for S aureus nasal colonization. Thirty-nine patients (38.2%) were colonized, 18 with methicillin-sensitive Saureus (MSSA) and 21 with MRSA. Almost half of all colonized patients were in the most dependent functional category and there was a significant association of MRSA colonization, but not MSSA colonization, with poor functional status. Colonized patients were treated with mupirocin ointment applied to the anterior nares twice daily for seven days. After treatment, MSSA persisted in only two patients and MRSA in only one patient; thus, nasal colonization was eliminated in 91.4% of colonized patients. At one month and two months follow-up, 11 patients became transiently recolonized and three became persistently recolonized with S aureus. Mupirocin was well tolerated with no side effects noted. Mupirocin ointment may be useful in controlling nasal colonization with S aureus in the nursing home setting.

A cluster of four group A (β-hemolytic Streptococcus postoperative wound infections was investigated at a community hospital. The serotypes of the Streptococcus isolated from all four cases, an asymptomatic anesthesiologist and one of his household members were M nontypable T28. During the outbreak period, December 1988, the infection rate among the 40 patients of the anesthesiologist was 7.5%. Among other patients not having contact with this healthcare worker, it was 0.09% (p = .0002 Fisher's exact test). This is only the second reported Group A β-hemolytic Streptococcus hospital outbreak in which the pathogen was traced to a member of a healthcare worker's household. Early outbreak detection and intervention limited the extent of the outbreak.

In 1980, the Public Health Service established an objective of immunizing 60% of high-risk persons with influenza vaccine annually by the year 1990. As no more than 32% of high-risk persons currently receive influenza vaccine each year, the Health Care Financing Administration (HCFA) has undertaken an influenza vaccination demonstration project for Medicare enrollees. Federally purchased vaccine is being distributed to physicians, health departments, hospitals, nursing homes and health maintenance organizations (HMOs). If the project is cost-effective, Congress has authorized HCFA reimbursement for influenza vaccination. Changing reimbursement policy alone, however, is unlikely to substantially improve influenza vaccine delivery; HCFA reimbursement for pneumococcal immunization since 1981 has not increased the use of pneumococcal vaccine. In contrast, federal purchase and distribution of vaccines to state and local health departments has helped maintain the remarkable success of childhood immunization programs. In addition, in Canada, provincial health departments purchase more than 80% of all influenza vaccine distributed, and from 1980 through 1988, per capita vaccine distribution increased 140%. These experiences suggest the need for an expanded policy goal for the influenza vaccination demonstration project that includes federal purchase and distribution of influenza vaccine. This approach, together with a change in reimbursement policy, offers greater promise for achieving our nation's objective for influenza vaccination.

Forty-three intubated and mechanically ventilated patients in five intensive care units (ICUs) of one hospital developed respiratory colonization or infection with Acinetobacter calcoaceticus subspecies anitratus over a 16-month interval. Neither the frequency nor rate of A anitratus isolation exceeded the hospital endemic norms. Single isolates from 34 of the patients were subtyped by plasmid DNA analysis, two biotyping systems and antimicrobial susceptibility to 24 drugs. Plasmid DNA fingerprints were distinct in 18 isolates (they differed from each other and all others), similar in two and identical or similar in ten. The latter group of isolates were recovered from patients in four ICUs. Reproducibility of biotyping was poor. Neither biotyping nor antimicrobial susceptibility were successful in identifying sameness among the group isolates nor differences among other isolates. We conclude that plasmid DNA fingerprinting should be used to assess the possibility of multiple patient transmissions of the same A anitratus strain in the absence of an obvious outbreak.

Hospital-acquired legionella pneumonia is emerging as a major problem; potable water distribution systems have been shown to be the primary reservoirs for the legionella organisms. As a result, disinfection measures have been developed to eradicate the organism from the hospital water supply. Each disinfection modality differs in its design and application such that choosing an appropriate cost-effective control measure requires careful analysis and planning.

We assess in comparative fashion the disinfection modalities of thermal eradication (“heat-and-flush”), instantaneous steam-heating system, chlorination, ultraviolet light irradiation, ozonation and metal ionization. The theoretical bases, the actual procedure or system, the logistics of implementation, the costs and personnel requirements and the advantages and disadvantages are presented for each modality. Criteria for selection of a method, the use of combinations of methods, parameters for installation, pitfalls in implementation and a plan for subsequent environmental surveillance are discussed in detail.

During the 1984–1985 influenza season, outbreaks of influenza A (H3N2) occurred in three Connecticut nursing homes. Influenza vaccination rates were 67% (96 out of 144), 35% (30 out of 85) and 69% (332 out of 483), respectively. The relative risk of illness for vaccinated compared to unvaccinated residents was 1.8 (95% confidence interval, 0.6, 5.9), 1.6 (95% confidence interval, 0.8, 3.0) and 1.1 (95% confidence interval, 0.8, 1.7) for each of the three nursing homes, respectively. In the third outbreak, 22 vaccinated residents without clinical illness had a geometric mean titer of hemagglutination-inhibition (HI) antibody of 20. Although low, this titer was significantly higher than that of nine unvaccinated residents without clinical illness (12, p<.05); only three (14%) vaccinated residents had HI titers of 340. These results suggest that levels of HI antibody in vaccinated residents were not protective at the time of the third outbreak, four to five months after vaccination. In general, the study of vaccine effectiveness in nursing homes is limited by sample size and statistical power. Despite these limits, the retrospective investigation of influenza outbreaks in nursing homes is often the only practical way to evaluate influenza vaccine effectiveness in the elderly on a yearly basis.

Consensus statements bearing on issues related to healthcare workers (HCWs) who are, or may be, infected by the human immunodeficiency virus (HIV) have been developed by the Centers for Disease Control (CDC), the American Medical Association (AMA), the American Academy of Pediatrics, the American Hospital Association (AHA), the American Academy of Orthopedic Surgeons, the American College of Obstetricians and Gynecologists8 and the British working groups. In general, these organizations conclude that few, if any, special procedures are required to accommodate an HIV-infected HCW. All except one oppose routine screening of HCWs for HIV infection; all except one oppose broad practice proscriptions for HIV-infected HCWs. Only one of these consensus statements focuses on the HIV-infected HCW. None address important related questions that confront hospitals and other healthcare institutions. These issues are difficult to resolve because: 1) there are insufficient data to establish a scientific basis for their solution; 2) the questions involve medicolegal, ethical or public relations issues that are beyond the usual scope of scientific consensus body recommendations; and/or 3) the situations occur infrequently. Nevertheless, in actual hospital practice, decisions about these questions, at least occasionally, must be made.

In the normal individual, about 100 billion polymorphonuclear leukocytes (neutrophils) enter the bloodstream daily from the bone marrow. About half of the intravascular neutrophils are adherent (marginated) to the endothelium of small vessels and the remainder are circulating. Without unusual disturbances, the half-life of the intravascular neutrophil is about six hours. Although the number of circulating neutrophils seems enormous, it represents only 5% of the total body content of these cells, the major portion residing in the bone marrow.

It is remarkable that quantitation ofpolymorphonuclear leukocytes in a drop of peripheral blood can be highly predictive of an individual's resistance and response to infectious diseases, especially those caused by bacteria. Neutrophil activity is complex and its role in host defense is dependent upon factors other than quantity. Nevertheless, when the absolute neutrophil count is maintained at values less than 1000/cu mm, increased susceptibility to infection occurs and is at a rate that is inversely proportional to the neutrophil count. When the count is decreased to values of 500 neutrophils/cu mm or less, the frequency of serious bacterial infection reaches a point where special attention must be directed to the patient at the earliest sign of infection.

Recent trends in medical care have resulted in increasing numbers of patients being cared for in the home health setting. The annual growth rate for home care is projected to be between 12% and 20%, at least through 1990. Many patients who would formerly have stayed in the hospital are now being discharged to home care. This trend has been prompted and driven by cost considerations, but other factors, such as new approaches to the care of dying patients, have also played a role. Many patients cared for at home may have communicable diseases, multiple invasive devices or an immunocompromising condition. The patient, family members and the home health professional (HHP) all may be at risk for developing or transmitting infection, although the actual risk has not been determined. Thus, there is a need for prevention and control of home-acquired infections.

Methicillin-resistant Staphylococcus aureus (MRSA) infections emerged as a problem in acute-care hospitals in this country in the 1970s. However, as is true of most nosocomial infections, long-term care facilities have not been exempt from those issues that plague acute-care hospitals, and, indeed, bring their own peculiar circumstances to bear on the problem. Infection and colonization with MRSA has been no exception and has evolved as a major infection control issue within long-term care facilities. Aside from an early report of MRSA cultured from patients in a nursing home in Seattle, Washington in 1969, data on MRSA in long-term care facilities have appeared only recently. In spite of the dearth of information, many long-term care facilities established policies relating to MRSA in the early to mid-1980s; often these policies were developed in hopes of excluding MRSA from their facility, and for many reasons often have not helped solve the problems associated with MRSA in long-term care facilities.

The cumulative risk of human immunodeficiency virus (HIV) infection over a healthcare career has rarely been estimated, but is more relevant to the description of an occupational hazard than the risk of seroconversion from a single exposure. We describe a model for assessing the individualized risk for HIV infection after multiple potential exposures over many years for surgeons and other operating room personnel, a high-risk group. For the average surgeon operating over a 30-year career on patients with an HIV seroprevalence of 0.01, the cumulative risk is estimated at 1%. The same surgeon operating on patients with a seroprevalence of 0.10 has an estimated cumulative risk of 10%. These risks may vary dramatically depending on the assumed rate of skin punctures during surgery. Healthcare workers need to be aware of the cumulative risk from multiple exposures to infectious blood and body fluids, to follow proposed suggestions for the reduction of percutaneous blood exposures and to assist in developing new technology to further reduce these risks. Failure to protect these professionals could result in the reduction of services for the approximately 1 to 1.5 million HIV-infected persons in the United States.

Achromobacter xylosoxidans is a nonfermenting, oxidase-positive, gram-negative rod that prefers aqueous environmental reservoirs. A variety of such sources have been implicated in epidemic and sporadic A xylosoxidans infections, including the deionized water of a hemodialysis system, a swimming pool chlorhexidine solutions, intravascular pressure transducers and distilled water. Nuclear medicine tracer material prepared at our institution was implicated in a 1978 outbreak that involved four hospitals. Fourteen patients developed proven or suspected A xylosoxidans bacteremia following intravenous injection with this tracer for lung, liver and bone scans. Contaminated non-bacteriostatic saline used as a diluent for the radioactive material was the likely source.

A xylosoxidans has been isolated from many different body sites, including the bloodstream, urinary tract, central nervous system, peritoneum, respiratory tract, biliary tree; bowel, eyes, ears, pharynx and surgical wounds. Many infected individuals have had compromised host defenses of varying types. Serious infections with this organism may be fatal, perhaps, in part, because of its resistance to multiple antibiotics.