Reengineering and infection control programs: commentary and a case study

Transformation of the health care system has been an ongoing process for generations, but many changes in the past 2 decades have focused on reducing costs in concert with rapidly changing technologies and demands for high quality care. Many cost-containment efforts in the 1990s are characterized by attempts to apply the business model for "reengineering the corporation" to health care systems. This commentary reviews principles of reengineering and how strategies to reduce costs through market forces, competition, and downsizing can result in substantial problems for bureaucratic organizations unaccustomed to rapid change and innovation. A case study drawn from experiences of a large metropolitan academic health care system is presented, with specific focus on lessons that will be helpful to infection control professionals (ICPs) confronted with similar situations.

Infection control in ambulatory care

This article provides a structured review of the English literature focusing on areas that theoretically pose the greatest risk for nosocomial infections in ambulatory care. The review describes variations in methods of surveillance and a general paucity of studies that provide reliable estimates of the risk for infections in the ambulatory environment.

Managed care and the infectious diseases specialist

There is growing demand to contain health care costs and to reassess the value of medical services. The traditional hospital, academic, and research roles of the infectious disease (ID) specialist are threatened, yet there is an increasing need for expertise because of growing antimicrobial resistance and emerging pathogens. Opportunities exist to develop and expand services for the care of patients infected with human immunodeficiency virus and in infection control, epidemiology, outcomes research, outpatient intravenous therapy, and resource management. It is important for ID physicians to appreciate the principles involved in managed care and the areas in which ID services can be valuable. To be effective, physicians need to know about tools such as practice guidelines, physician profiling, outcomes monitoring, computerized information management, risk sharing, networking, and marketing, as well as related legal issues. With a positive attitude toward learning, application, and leadership, ID physicians can redefine their role and expand their services through managed care.

Designing surveillance for noninfectious outcomes of medical care

We present basic information that a hospital epidemiologist needs when designing a surveillance system for noninfectious adverse outcomes of care. Specific topics reflect key characteristics of such a surveillance system: the purpose, rationale, priorities, definitions, data collection tools, data collection, analysis and reporting, and validation.

Profiling physician practice: a potential for misuse

Profiling physician practice is not unfamiliar to hospital epidemiologists. Surgeon-specific postoperative wound infection rates have been used to monitor and improve the quality of surgical outcomes. However, concerns for small sample sizes, validity of methods for risk adjustment, and reliability of data collection methods along with other methodologic concerns have resulted in mixed opinions regarding physician profiling as a tool for improving quality of care. In light of pressures for healthcare reform and skepticism regarding physicians' decision making, it is unlikely that methodologic concerns will dissuade regulators and managers from expanding scrutiny of physician practice.

The clinical microbiology laboratory as an aid in infection control. The application of molecular techniques in epidemiologic studies of methicillin-resistant Staphylococcus aureus

A microbiologic surveillance study was performed in order to estimate the point prevalence, source, and nosocomial acquisition of methicillin-resistant Staphylococcus aureus (MRSA) within the Iowa City Veterans Affairs Medical Center (IC VAMC). Immediately following the microbiologic surveillance study, a cluster of nosocomial MRSA infections was detected by routine infection control surveillance. An epidemiologic investigation was conducted and all isolates of MRSA detected during the microbiologic surveillance study and the subsequent cluster of nosocomial infections were characterized by restriction endonuclease analysis of plasmid DNA (REAP). REAP subtyping defined a total of ten distinct subtypes from 24 patients infected or colonized with MRSA. The documentation of a single subtype of MRSA (subtype A2) in nine patients from the surgical service, eight of which were hospitalized in the surgical intensive care unit, provided convincing evidence of a breakdown of infection control practices in that unit. REAP subtyping was a highly discriminating means of identifying different subtypes among the various isolates of MRSA and was useful in directing infection control efforts to specific problem areas within the hospital. Molecular typing methods, such as REAP, when used appropriately in conjunction with careful epidemiologic investigation provide an effective approach to the investigation and control of the spread of MRSA within the hospital.

Late-onset congenital syphilis. A retrospective look at University of Iowa Hospital admissions

A retrospective review of 766,742 hospital admissions was performed between 1966 and 1986 at the University of Iowa Hospital for the diagnosis of congenital syphilis. Although 88 individuals were identified with this diagnosis, adequate treatment was documented in only 33 (38%). Thirty-nine of the 88 individuals identified were initially seen for visual complaints by the ophthalmology department. We recommend that all physicians increase their index of suspicion for this disease, and institute appropriate therapy and follow-up if late congenital syphilis is diagnosed.

Cardiovascular surgery prophylaxis. A randomized, controlled comparison of cefazolin and cefuroxime

A prospective double-blind trial was performed at a tertiary care center to evaluate perioperative cephalosporin prophylaxis in cardiac operations. Patients were randomized to receive either cefazolin (n = 104) or cefuroxime (n = 109), the preoperative dose being given within 1 hour before the initial incision. Drugs were continued for 48 hours (cefazolin, 1 gm intravenously every 8 hours; cefuroxime, 1.5 gm intravenously every 12 hours). Postoperative infections were assessed by trained nurse clinicians, and data were analyzed by the intention-to-treat principle. Sternal wound infections or mediastinitis occurred in one of 104 patients treated with cefazolin and 10 of 109 treated with cefuroxime (p = 0.01). Deep sternal wounds (including mediastinitis and sternal osteomyelitis) occurred in none of the cefazolin-treated patients and five cefuroxime-treated patients (p = 0.06). Although overall nosocomial infection rates were similar (16.3 versus 19.3 per 100), wound infection occurred somewhat more frequently with streptococci (groups B and D) in patients receiving cefazolin (four versus zero, p = 0.110); conversely staphylococcal infections were more frequent in the cefuroxime group (seven versus one, p = 0.066). Mean and median postoperative stay was 1 day shorter in the cefazolin group. In contrast to findings of a previous report, our data indicate that cefazolin prevented more sternal wound infections than cefuroxime, a finding that supports prophylaxis with a first-generation cephalosporin.

The epidemiology of cytomegalovirus infection among patients with burns

To determine the epidemiology of cytomegalovirus (CMV) infections among patients with burns, we prospectively studied 120 burn patients admitted to the University of Iowa Burn Center over a two-and-one-half year period. At the time of their admission, 44% of the patients had serologic evidence of prior CMV infection. Among 44 seropositive patients, 23 (52%) had four-fold or greater rises in CMV antibody titers. These patients had more severe burns (mean body surface area burn [BSAB] 26.8%) than those who did not exhibit titer rises (mean BSAB 16.2%, p = .04). Among 43 seronegative patients observed for at least 65 days after discharge from the center, eight (18.6%) seroconverted. Patients who seroconverted had longer hospital stays (p = .03), trends toward more severe burns (p = .08) and a younger age (p = .15) than patients who remained seronegative. Despite frequent serologic evidence of CMV infection, CMV did not contribute, either directly or indirectly, to the morbidity or mortality of burns in these patients.

The application of molecular and immunologic techniques to study the epidemiology of Legionella pneumophila serogroup 1

We applied monoclonal antibody typing and restriction endonuclease analysis of plasmid DNA to study 28 clinical and 35 environmental (potable water) isolates of Legionella pneumophila serogroup 1 from three hospitals in Iowa between 1981 and 1986. Monoclonal antibody typing employed a panel of seven antibodies and delineated eight different subtypes. Plasmids were present in 57% of the isolates including 12 of 28 (43%) clinical and 25 of 35 (69%) potable water isolates. The plasmids ranged in size from 28 to 98 kilobase pairs and comprised eight distinct subtypes by restriction endonuclease analysis with Eco RI. Combination of monoclonal antibody and restriction endonuclease subtyping (composite subtyping) revealed 19 different composite subtypes of Legionella pneumophila serogroup 1. The most common composite subtype, 09:04, comprised 29% (18 of 63) of the isolates and was only found in clinical and potable water samples from a single pavilion in hospital A during an outbreak of Legionella pneumophila serogroup 1 pneumonia. Aside from this cluster the diversity of composite subtypes of Legionella pneumophila serogroup 1 observed in clinical and potable water sources over the 5-year period was striking. The combination of monoclonal antibody and restriction endonuclease typing resulted in improved strain delineation and a more useful use of epidemiologic markers for Legionella pneumophila serogroup 1.

Use of cellular hydrophobicity, slime production, and species identification markers for the clinical significance of coagulase-negative staphylococcal isolates

Determining the clinical relevance of coagulase-negative staphylococci isolated from cultures of clinical specimens remains a common dilemma. One hundred eighteen strains of coagulase-negative staphylococci isolated from patients with and without indwelling foreign bodies were characterized with regard to cell-surface hydrophobicity, slime production, and species to determine the predictive value of these phenotypic markers in distinguishing clinically significant from insignificant isolates. The single test with the highest positive predictive value was hydrophobicity (79%). Hydrophobicity and speciation had the greatest combined predictive value of any two tests (89%), and this increased to only 90% when determination of slime production was added. These tests provide additional clinical information when coagulase-negative staphylococci are isolated in culture.

Botryomycosis of the oral cavity

Botryomycosis is a bacterial infection characterized histologically by granules containing bacteria. Usually there is surrounding granulomatous inflammation with occasional extension into muscle or bone. While there are several hypotheses regarding the pathogenesis of botryomycosis, the exact mechanism is unclear. Botryomycosis has been associated with a variety of aerobic and anaerobic bacteria, usually endogenous flora and low virulence organisms. Oral lesions appear to be uncommon despite continuous exposure to endogenous oral flora. Treatment should include surgical excision and antibiotic therapy.

Nosocomial infections in critical care units: causation and prevention

Nosocomial infections reflect a dynamic interaction between host, agent, and environment. In the compromised host, the microbes most frequently associated with nosocomial infections in the ICU are bacteria that normally reside in or on body surfaces or in the environment. Infections occur when the host, compromised by the underlying disease, is exposed to a variety of diagnostic and therapeutic interventions that disrupt normal physical and chemical barriers and allow direct access to the internal milieu of the host. Efforts to prevent nosocomial infections in critical care units must take into consideration the interplay of all of these factors to be successful.

Organization and operation of the hospital-infection-control program of the University of Iowa Hospitals and Clinics

The University of Iowa Hospitals and Clinics is located in the center of the United States in Eastern Iowa, has 1,000 hospital beds, and is the largest university owned teaching hospital in the country. Over 35,000 patients are admitted each year. The infection control efforts began in 1969 and were broadened in 1976 with the establishment and implementation of the Program of Epidemiology directed by W.J. Hierholzer, Jr., M.D., hospital epidemiologist. Hospital-wide surveillance is routinely performed by three and a half full-time equivalent LPN practitioners who assess problems and evaluate data essential to realistic identification of nosocomial infection rates, implementation of controls and evaluation of control measures. Nosocomial infection surveillance, utilizing modified CDC criteria, has been performed since July 1976. Ward rounds are made by staff, utilizing nursing care and medication Kardex's, microbiology, hematology and X-ray reports. Importantly, the surveillance system is being validated by concurrent prospective surveys to determine the sensitivity and specificity of reporting data. Outbreaks/epidemics of infections, such as Legionella pneumonia, diarrhea of unknown species, and wounds, as well as burns from manufactured changes in cautery grounds, have been identified and controlled before they have become major epidemics. Surveillance has identified one epidemic per 10,000 patients admitted.(ABSTRACT TRUNCATED AT 250 WORDS)

Implications of acquired oxacillin resistance in the management and control of Staphylococcus aureus infections

Refinements in testing for resistance to penicillinase-resistant penicillins (PRP) in Staphylococcus aureus have resulted in confusion in classifying isolates as PRP susceptible or resistant. Specifically, a group of organisms has been identified that produce large amounts of beta-lactamase and appear borderline resistant. These organisms have been called "occult resistant" or "acquired oxacillin-resistant" S. aureus (AORSA). A retrospective study was conducted to evaluate the implication of this in vitro phenomenon in managing patients with AORSA infections. Among 134 patients with S. aureus infections, 89 were infected with oxacillin-susceptible S. aureus (OSSA), 26 with AORSA, and 19 with oxacillin-resistant S. aureus (ORSA). There were no significant differences in outcomes when OSSA and AORSA infections were treated with PRP (chi 2MH = .990; P = .32). These results do not suppor the contention that AORSA infections should be managed differently from OSSA infections. Identifying AORSA may not be helpful in guiding antimicrobial therapy or predicting the outcome of infections with AORSA.

Cost of nosocomial infection: relative contributions of laboratory, antibiotic, and per diem costs in serious Staphylococcus aureus infections

This study reports an analysis of the relative importance of laboratory antibiotic, and per diem costs of caring for 58 patients with serious Staphylococcus aureus nosocomial infections. Laboratory costs accounted for 2%, antibiotics for 21%, and per diem costs for 77% of total infection-related costs. Only 45% of patients were hospitalized for additional days specifically because of infection, but these patients stayed an average of 18 extra days. Nosocomial infections with S. aureus resistant to penicillinase-resistant penicillins (PRP) were more frequently associated with additional infection-related days of hospitalization than were PRP-susceptible infections. The cost of PRP-resistant infections was also significantly greater than PRP-susceptible infections, primarily because of the costs of additional days of hospitalization. Rational strategies to control costs of nosocomial infection should focus on two approaches: (1) prevention and (2) reduction of acute hospital days attributable to infections.

Legionnaires' disease associated with a hospital water system. A five-year progress report on continuous hyperchlorination

In 1981, sixteen cases of nosocomial legionellosis occurred among 456 patients admitted to a new hematology-oncology unit (35 per 1000 admissions). Monoclonal antibody typing and restriction endonuclease plasmid analysis identified a unique strain (09,04) of Legionella pneumophila serogroup 1 isolated from both patients and water outlets. Continuous hyperchlorination of the hot and cold water began in January 1982, and chlorine levels of 3 to 5 mg/L have been maintained most recently. Water samples have been consistently negative for Legionella for more than five years. Four sporadic cases of nosocomial legionellosis have occurred in the hematology-oncology unit during the same period (one per 1000 admissions) associated with a different strain of L pneumophila serogroup 1 (09,00). The environmental reservoir(s) of L pneumophila serogroup 1 in these cases has not been identified. Levels of trihalomethanes (potential carcinogens) were high (greater than 100 micrograms/L) when chlorine levels of hot water exceeded 4 mg/L. Some corrosion damage to the water distribution system has occurred: the average number of leaks per month increased steadily from zero in 1982 to 5.2 in 1986. The chlorinator installation costs were +75,800, and annual operation expenses were +12,500. Continuous hyperchlorination is a promising but still experimental technique for control of nosocomial legionellosis. In our experience, epidemic disease has been controlled, but sporadic cases have continued to occur.

Nosocomial aseptic meningitis associated with administration of OKT3

An outbreak of nosocomial aseptic meningitis involving four renal allograft recipients on the transplant service occurred in July 1986, shortly after the release of the murine monoclonal antibody OKT3 for therapy for acute allograft rejection. No bacteria, fungi, or viruses were isolated from cultures of the cerebrospinal fluid of the four patients. All four had acute allograft rejection treated with OKT3 and developed signs and/or symptoms of meningitis within 72 hours of receiving the drug. To identify potential risk factors, the four patients with aseptic meningitis were compared with 12 patients on the renal transplant service in July 1986 who did not have signs or symptoms of meningitis. The development of aseptic meningitis was strongly associated with administration of OKT3. Because of this association, prospective surveillance of meningitis in patients receiving OKT3 was instituted. From November 1986 to May 1987, three (14%) of 21 patients treated with OKT3 developed aseptic meningitis. The clinical course of aseptic meningitis associated with OKT3 appears to be benign and self-limited. Nonetheless, this observation warrants continued surveillance of OKT3 therapy.

Development of the quantitative micro-test for slime production by coagulase-negative staphylococci

The macro-test for slime production by coagulase-negative staphylococci was adapted to a spectrophotometric micro-test assay to obtain more objective and quantitative information on slime production. A total of 135 isolates of coagulase-negative staphylococci (70 macro-test-positive and 65 macro-test-negative) were tested by both methods. The quantitative micro-test optical density readings were (mean +/- SD) 1.176 +/- 0.294 and 0.130 +/- 0.095 for the macro-test-positive and -negative groups, respectively. The micro-test was reproducible and demonstrated quantitative differences in slime production among the different species of coagulase-negative staphylococci. Aside from Staphylococcus epidermidis, the majority of the coagulase-negative staphylococci had very low optical density readings, indicating little or no slime production under the conditions employed in this assay. This test allows one to study the relative production of slime by different strains and species of coagulase-negative staphylococci, and may be useful in studying the effects of different conditions, such as antibiotic exposure, on slime production.

Evaluation of laboratory methods for the classification of oxacillin-resistant and oxacillin-susceptible Staphylococcus aureus

The purpose of this study was to examine the efficacy of the oxacillin disk diffusion test and the methicillin and oxacillin agar screen tests as predictors of oxacillin resistance as defined by the reference broth microdilution method. A total of 444 clinical isolates of Staphylococcus aureus collected from individual patients over a four-year period were tested by (1) the oxacillin disk diffusion test, with particular attention to the presence of fine growth of a resistant subpopulation within the zone of inhibition (Ox Grow interpretive criteria); (2) the agar screen method using agar plates with 4% NaCl and either 6 mg/L oxacillin or 10 mg/L methicillin; and (3) the oxacillin and methicillin broth microdilution test methods with 2% NaCl supplementation. Overall, 62 (14%) isolates were resistant and 382 (86%) isolates were susceptible to oxacillin with the use of the reference broth microdilution system. The results indicate that the disk diffusion test with the use of the Ox Grow criteria had a high sensitivity (94%) and negative predictive value (98%) but a low specificity (67%) and positive predictive value (32%) when compared with the reference broth dilution test. Similarly, the agar screen tests had a high sensitivity (95-97%) and negative predictive values (99%) but low specificity (64-74%) and positive predictive values (30-37%). These data indicate that the agar screen tests and the oxacillin disk test with the use of the Ox Grow interpretive criteria may be useful as screening tests for detecting resistance to the penicillinase-resistant penicillins but that all resistant isolates should be confirmed by the reference broth dilution method because of the large number of false-resistant screening test results.

Cytomegalovirus infection in burn patients

We studied the seroepidemiology of cytomegalovirus (CMV) infection in 59 patients with thermal injuries. Among the 31 patients who were initially CMV seronegative, seven (22.5%) seroconverted. Patients who seroconverted had longer hospital stays (mean, 27 +/- 23.9 days v 14.9 +/- 8.8 days in seronegative patients [P = 0.03]) and they received more blood products (mean, 10.7 +/- 17.9 units v 1.8 +/- 2.8 units [P = 0.02]) than patients who remained seronegative. Among 18 patients who were initially seropositive for CMV, 10 (56%) had a fourfold or greater rise in CMV antibodies, evidence of CMV reactivation. Patients who had reactivated CMV infection tended to be younger, to have a larger burn area, and to have a longer hospital stay. No patient who experienced CMV infection, whether primary or reactivated, had serious complications attributable to CMV.

Variation from standards in Staphylococcus aureus susceptibility testing

In an effort to assess the degree of methodologic variation and adherence to current guidelines for detection of methicillin-resistant Staphylococcus aureus (MRSA), the authors surveyed the susceptibility testing practices of all 162 microbiology laboratories in the Veterans Administration (VA) system. Completed questionnaires were returned by 136 (84%) of the laboratories. Overall, 96 (71%) laboratories used disk diffusion testing, 54 (40%) used manual broth dilution, and 36 (26%) used an automated method. The percentage of MRSA detected ranged from 0 to 52%, with a mean of 10%. In general, fewer than 60% of laboratories followed the current susceptibility testing guidelines for key methodologic variables such as inoculum preparation, duration of incubation, and medium supplementation. Failure to adhere to these guidelines may result in suboptimal detection of MRSA.

Use of the appropriateness evaluation protocol for estimating the incremental costs associated with nosocomial infections

Existing methods for estimating additional days of hospital stay due to nosocomial infections (NI) have a number of documented limitations. An alternative method described in this paper uses the Appropriateness Evaluation Protocol (AEP) to determine whether each day of acute inpatient care is appropriate based on the need for care of the NI, original cause of hospitalization (OC), or combined NI-OC requirements. Using this method to identify specific days of hospitalization due to Staphylococcus aureus nosocomial infection, we find: 1) length of stay is increased for only a minority of patients (38%); 2) an average of 20 additional days of stay occurred for patients with 1 or more days attributed to NI; and 3) an average of 52% of length of stay of patients with 1 or more days attributed to NI can be attributed to the NI. Application of the AEP-based method is a useful alternative for identifying additional days of stay due to NI.

Reliability of reporting nosocomial infections in the discharge abstract and implications for receipt of revenues under prospective reimbursement

Proper reporting of discharge diagnoses, including complications of medical care, is essential for maximum recovery of revenues under the prospective reimbursement system. To evaluate the effectiveness of abstracting techniques in identifying nosocomial infections at discharge, discharge abstracts of patients with nosocomial infections were reviewed during September through November of 1984. Patients with nosocomial infections were identified using modified Centers for Disease Control (CDC) definitions and trained surveillance technicians. Records which did not include the diagnosis of nosocomial infections in the discharge abstract were identified, and potential lost revenues were estimated. We identified 631 infections in 498 patients. On average, only 57 per cent of the infections were properly recorded and coded in the discharge abstract. Of the additional monies which might be anticipated by the health care institution to assist in the cost of care of adverse events, approximately one-third would have been lost due to errors in coding in the discharge abstract. Although these lost revenues are substantial, they constitute but a small proportion of the potential costs to the institution when patients acquire nosocomial infections.

Variation in methicillin-resistant Staphylococcus aureus occurrence by geographic location and hospital characteristics

A survey of 162 Veterans Administration Medical Center (VAMC) laboratories performing antimicrobial susceptibility testing was performed to determine variation in reported rates of methicillin-resistant Staphylococcus aureus (MRSA) isolation by geographic location and hospital characteristics. Of the 162 VAMC laboratories surveyed, 136 (84%) provided usable data. The percentage of S aureus isolates reported as resistant to methicillin ranged from 0% to 52% with a mean value of 10% among the 136 survey respondents. MRSA were isolated in every VA Medical District and 96% of all respondent laboratories reported isolating at least one MRSA isolate during the preceding year. These data are considered an underestimate of the time MRSA rate in the VA system due to the fact that many laboratories failed to follow key methodologic guidelines for optimal detection of MRSA. A positive correlation was found between MRSA isolation rate and several measures of hospital size and activity including total beds, total admissions, and total antimicrobial susceptibility tests performed. Geographic clustering of MRSA isolation was observed with distinct areas of very high and very low percentages of S aureus isolates reported as MRSA. The data suggest that the geographic distribution of MRSA within the VA system should be monitored closely for evidence of spread from areas with high-MRSA rates to areas of mid- or low-MRSA rates. Evidence of increased MRSA isolation within these areas may necessitate increased caution in patient referral and transfer patterns within the VA system.

Numbers that count: analytic methods for hospital epidemiology, Part 1

The hospital epidemiologist is responsible for generating information that will be used to evaluate and assure high quality, minimal risk medical care. To accomplish this objective, the epidemiologist uses standard epidemiologic methods. Although used primarily in infection control, these methods are also applicable in the analysis of other types of institutional risks and in the assessment of quality of care. This review provides the reader, who we assume has minimal formal training in epidemiology and statistics, with some basic tools for analyzing data and generating useful information. We consider three major topic areas: basic concepts regarding numbers and data, analysis of nominal data, and analysis of discrete and continuous data. Hypothetical problems that may be encountered in the hospital illustrate the application of epidemiologic methods to studies of risk control, quality assurance, and infection control. The infection control practitioner who is adept in using epidemiologic methods to solve infection control problems should be able to adapt these methods to other programs in her or his institution.

Usefulness of a test for slime production as a marker for clinically significant infections with coagulase-negative staphylococci

The usefulness of a test for slime production as a marker for clinically significant infections with coagulase-negative staphylococci and its implications for therapy were examined. Hospital records were reviewed for 59 patients from each of whom more than one isolate of coagulase-negative staphylococci was obtained. In patients with a prosthetic device, 81% of 59 infectious episodes were due to a slime-positive coagulase-negative staphylococci. In contrast, 22 noninfectious episodes (in which the organisms were contaminants) were equally distributed between episodes due to slime-positive or slime-negative isolates (P = .005). Only 32% of infections caused by slime-positive organisms, in contrast to 100% of infections caused by slime-negative organisms, were improved by treatment with antibiotics alone (P = .02). Prosthetic device removal in addition to antibiotic treatment significantly improved the outcome in patients with infections due to slime-positive organisms when compared with treatment with antibiotics alone (93% vs. 32% improvement; P = .00025).

An outbreak of community-acquired Legionnaires' disease pneumonia

In October 1981, an outbreak of 29 cases of community-acquired pneumonia occurred among adult residents of Johnson County, Iowa. Retrospective study revealed 12 cases (41 per cent) had laboratory evidence of Legionnaires' disease (LD). No significant differences in clinical or epidemiological features were found between LD cases and the other pneumonias in the outbreak. All LD cases received erythromycin; one case died for a case-fatality rate of 8 per cent. The outbreak's focus could not be identified.

Cytomegalovirus infection with acute erosive esophagitis

A healthy young adult is described in whom acute erosive esophagitis developed four weeks after undergoing splenectomy and receiving six units of blood because of trauma. Cytomegalovirus inclusion bodies were identified in esophageal mucosa, and cytomegalovirus was cultured from blood and throat. Within three weeks, the patient's anticytomegalovirus antibody had increased four-fold. The patient was initially anergic and had a titer of antinuclear antibody of 1:10,240. His symptoms and histopathologic findings disappeared over five weeks, and his immunologic abnormalities were partially corrected. It is suggested that cytomegalovirus was the primary cause of gastrointestinal disease in this nonimmunocompromised patient.

Brain abscess due to penicillin- and clindamycin-resistant Bacteroides melaninogenicus

The case of a patient with severe anaerobic infection, a brain abscess, is presented. The causative organism was a penicillinase-producing, clindamycin-resistant strain of Bacteroides melaninogenicus. Treatment with adequate doses of penicillin G failed. Findings in this case suggest caution when basing therapy on the untested assumption that B. melaninogenicus is routinely susceptible to penicillin and clindamycin therapy.

Legionnaires' disease associated with a hospital water system: a cluster of 24 nosocomial cases

Over a 10-month period, 24 cases of Legionnaires' disease pneumonia occurred among patients admitted to an Iowa hospital, most of whom were immunosuppressed. Eleven patients died. Twenty-one patients were admitted to a recently completed hospital addition, 16 of these to a new hematology-oncology unit. Legionella pneumophila serogroup 1 was isolated from the patients, water outlets, and hot water in the new addition. Water quality variables in the hospital addition were adequate. Shock chlorination, temporary elevation of the hot water temperature, and continuous chlorination of hospital water decreased the frequency of isolation of Legionella. Water use by patients in the hematology-oncology unit was restricted until the water was free of Legionella. The incidence of Legionnaires' disease decreased. Indirect evidence supports an hypothesis of water-borne disease in this cluster of cases. Current variables of acceptable water potability may not guarantee water free of L. pneumophila.

Differing degrees of susceptibility to experimental allergic encephalomyelitis among inbred strains of hamsters

Susceptibility to experimental allergic encephalomyelitis was examined in five highly inbred strains of hamsters. The frequency of disease was reproducible within a given strain, but differed remarkably from strain to strain. Two strains--Bio 15.16 and Bio 87.20--appeared to share similar major histocompatibility genes. Despite genetic similarities, susceptibility to acute paralytic EAE was remarkably different in the two strains. Strain 15.16 hamsters consistently developed acute paralysis 10-21 days after sensitization with heterologous nervous tissue and immunologic adjuvants. Strain 87.20 hamsters never developed disease acutely. Protection from EAE was not absolute, however, for some animals developed histopathologic evidence of EAE. Using alternative methods to induce EAE did not alter susceptibility in 87.20 hamsters. Genetic analysis of offspring of susceptible 15.16 and resistant 87.20 hamsters suggested that a single autosomal gene, unrelated to the major histocompatibility locus, accounted for differences in EAE susceptibility in these two strains. This gene had a more profound influence on clinical patterns of EAE than on histopathologic markers of disease.

Experimental allergic encephalomyelitis. I. Optic nerve and central nervous system manifestations

Experimental allergic encephalomyelitis (EAE) was produced in six adult rhesus monkeys. The animals were evaluated serially by ocular, ophthalmoscopic, fluorescein fundus angiographic, pupillary, visual evoked potential, neurologic, cerebrospinal fluid (CSF), and hematologic examinations and by postmortem detailed histopathologic examination. All the animals developed acute EAE. Four of the monkeys, surviving longer than 1 month, developed chronic relapsing EAE and were sacrificed 3 to 14 months after sensitization. All 12 eyes developed acute optic neuritis (with variable degrees of optic disc edema and visual loss). Later on, all the eyes of animals with chronic EAE developed optic atrophy with total or almost total blindness. Histopathologic examination of the optic nerve and central nervous system revealed inflammatory infiltrates, extensive demyelination, and axonal degeneration, without inflammation in the retina or optic nerve head (i.e., nonmyelinated neural tissue). Relapsing EAE was reflected in episodic increases of CSF proteins and pleocytosis. The various findings are correlated.

Candida meningitis in patients with CSF shunts

Two adult patients with CSF shunts contracted Candida albicans meningitis. In both patients, these infections were either preceded by or occurred simultaneously with bacterial meningitis. Treatment with antimicrobials alone failed to sterilize the CSF. Cure was obtained only after removal of the shunt tubes. The simultaneous or subsequent development of Candida meningitis should be considered in selected patients who do not make appropriate recovery from a bacterial meningitis, especially one that complicates shunt placement.

Suppression of tuberculin hypersensitivity during influenza infection in mice

Tuberculin hypersensitivity was examined during acute influenza infection in mice. Employing the footpad test as a measure of delayed-type hypersensitivity, it was noted that tuberculin hypersensitivity was suppressed temporarily beginning on day 3 and continuing through days 10 to 16 following intranasal infection with influenza A/PR8. These changes occurred at a time when influenza virus was replicating in lung tissue. Suppression of footpad swelling was not detected when mice were administered live virus intravenously, were given Formalin-inactivated virus intranasally, or were immunized against influenza before intranasal infection. Transient reduction of total circulating lymphocytes also occurred during influenza infection but did not correlate with the duration of footpad suppression. Because this model system reproduces many of the alterations in immunological function reported to occur during influenza infection in humans, it should provide a useful tool for investigating mechanisms of influenza-induced immunosuppression.

Potentiation of experimental allergic encephalomyelitis in hamsters with persistent encephalitis due to measles virus

To clarify mechanisms underlying acute disseminated encephalomyelitis (ADE) in patients with infection due to measles or other viruses, a new animal model was devised. Adult hamsters that had clinically recovered from acute encephalitis induced by prior intracerebral injection of the HBS strain of measles virus were challenged with neuroantigen plus adjuvant. Such hamsters, which had a high likelihood of carrying persistent HBS measles virus in the central nervous system (CNS), exhibited a significantly higher incidence of experimental allergic encephalomyelitis (EAE) following challenge as compared with simultaneously challenged but previously uninfected littermates. Occurrence of EAE in hamsters previously injected with heat-inactivated virus was not potentiated, a finding suggesting that persistence of the virus in the CNS renders that organ system more vulnerable to immunologic attack. This new model has promise for the probing of relationships between persistent viral infections of the CNS and host autoimmune responses directed against that target organ system.

Haemophilus influenzae Type D meningitis

This report describes an unusual pathogen associated with post-traumatic meningitis. Haemophilus influenzae type D was isolated from both cerebrospinal fluid and blood of this patient with meningitis.

The efficacy of rifampin as adjunctive therapy in selected cases of staphylococcal endocarditis

Three patients with bacterial endocarditis (one case due to Staphylococcus aureus and two to S epidermidis) failed to improve on standard therapeutic regimens which were judged adequate by in vitro testing for sensitivity. Rifampin was added to the regimen in each case and resulted in increased bactericidal activity in the serum, sterilization of the cardiac valves, and clinical cure. The apparent clinical success that was achieved suggests that further investigation of the effectiveness of therapy with rifampin in selected cases of staphylococcal endocarditis is warranted.

Room humidifiers as the source of Acinetobacter infections

Twenty-four patients contracted systemic infections with Acinetobacter calcoaceticus during a four-month period. Unheated room humidifiers at the patients' bedsides were implicated as the source of infection in six. The outbreak was terminated with the removal of the humidifers.