Invasive aspergillosis outbreak on a hematology-oncology ward

An outbreak of invasive aspergillosis occurred in a community hospital in temporal association with construction activity. Epidemiological investigation showed that patients who are at highest risk comprise a small group and are readily identifiable. Clinicians should strive to protect these patients, following guidelines published by the Centers for Disease Control and Prevention.

Quality of medical care delivered to Medicare beneficiaries: A profile at state and national levels

CONTEXT

Despite condition-specific and managed care-specific reports, no systematic program has been developed for monitoring the quality of medical care provided to Medicare beneficiaries.

OBJECTIVE

To create a monitoring system for a range of measures of clinical performance that supports quality improvement and provides repeated, reliable estimates at the national and state levels for fee-for-service (FFS) Medicare beneficiaries.

DESIGN, SETTING, AND PARTICIPANTS

National study of repeated, cross-sectional observational data collected in 1997-1999 on all Medicare FFS beneficiaries or on a representative sample of beneficiaries with a particular condition. Data were collected using medical record abstraction for inpatient care, analysis of Medicare claims for some ambulatory services, and surveys for immunization rates. Separate samples were drawn for each topic for each state.

MAIN OUTCOME MEASURES

Beneficiary patients' receipt of 24 process-of-care measures related to primary prevention, secondary prevention, or treatment of 6 medical conditions (acute myocardial infarction, breast cancer, diabetes mellitus, heart failure, pneumonia, and stroke) for which there is strong scientific evidence and professional consensus that the process of care either directly improves outcomes or is a necessary step in a chain of care that does so.

RESULTS

Across all states for all measures, the percentage of patients receiving appropriate care in the median state ranged from a high of 95% (avoidance of sublingual nifedipine for patients with acute stroke) to a low of 11% (patients with pneumonia screened for pneumococcal immunization status before discharge). The median performance on an indicator is 69% (patients discharged with heart failure diagnosis who received angiotensin-converting enzyme inhibitors; diabetic patients having an eye examination in the last 2 years). Some states (particularly less populous states and those in the Northeast) consistently ranked high in relative performance while others (particularly more populous states and those in the Southeast) consistently ranked low.

CONCLUSIONS

It is possible to assemble information on a diverse set of clinical performance measures that represent performance on the range of services in a health insurance program. These findings indicate substantial opportunities to improve the care delivered to Medicare beneficiaries and urgently invite a partnership among practitioners, hospitals, health plans, and purchasers to achieve that improvement. JAMA. 2000;284:1670-1676.

Challenges in electronic importing of health data

The objective of this article is to increase awareness among public health personnel of the complexities involved in integrating existing data systems. This article describes the electronic importing feature of the Centers for Disease Control and Prevention (CDC) software package called staffTRAK-TB, and users' experience with it.

staffTRAK-TB: software for surveillance of tuberculosis infection in healthcare workers

The Centers for Disease Control and Prevention (CDC) recommends periodic tuberculin skin testing of healthcare workers with potential exposure to Mycobacterium tuberculosis. However, many healthcare facilities have neither a system to identify workers due for their skin test nor a means of analyzing aggregate data. To illustrate some of the complexities involved in tuberculin skin test (TST) tracking and analysis, and how these might be addressed, this report describes a software package called staffTRAK-TB, developed by the CDC to facilitate surveillance of tuberculosis infection in healthcare workers. staffTRAK-TB records data for each healthcare worker, including demographic information, occupation, work location, multiple TST results, and results of evaluations to determine if clinically active tuberculosis is present. Programmed reports include lists of workers due and overdue for skin tests, and skin test conversion rates by occupation or worksite. Standardization of types of occupations and locations allows data from multiple facilities to be aggregated and compared. Data transfer to the CDC can be performed via floppy diskettes. staffTRAK-TB illustrates important issues in software structure, standardization of occupation and work-location information, relevant data items, and reports and analyses that would be useful in practice. Developing software that adequately addresses the epidemiological issues is complex, and the lessons learned may serve as a model for hospital epidemiologists, infection control personnel, occupational health personnel, and computer programmers considering software development in this area or trying to optimize their facility's TST surveillance.

A pseudoepidemic of postoperative scleritis due to misdiagnosis

OBJECTIVE

To describe a pseudoepidemic of infectious scleritis following eye surgery.

METHODS

Retrospective cohort study with selected procedural and laboratory investigations.

RESULTS

Twenty-one patients with postoperative scleritis were identified during a 2-month outbreak. Neither an infectious etiology nor a causative pre-, intra-, or postoperative exposure was found. The clinical findings, when carefully reviewed, were consistent with poor surgical-wound closure.

CONCLUSIONS

The art of clinical diagnosis involves the subjective interpretation of clinical history, physical findings, and laboratory results. A repeated error in the interpretation of clinical findings can simulate an outbreak of disease. Clinicians may be reluctant to concede misdiagnosis.

Klebsiella pneumoniae bloodstream infections in neonates in a hospital in the Kingdom of Saudi Arabia

OBJECTIVE

To identify risk factors for Klebsiella pneumoniae bloodstream infections (BSI) in neonates in a hospital in the Kingdom of Saudi Arabia (KSA).

DESIGN

Two case-control studies among hospitalized neonates during February 15-May 14, 1991, and a procedural and microbiological investigation.

SETTING

Hospital A, a maternity and children's hospital in KSA.

PATIENTS

Case patients had a blood culture positive for K pneumoniae after >2 days of hospitalization and had no evidence of a nonblood primary site of infection.

RESULTS

When the 20 case patients were compared with controls, hospitalization in a critical-care unit (odds ratio [OR], 5.5; 95% confidence interval [CI95], 1.20-51.1; P=.03) was identified as a risk factor. When the case patients were compared with a second set of controls matched by critical-care status, receipt of a particular intravenous fluid (D10%/0.2NS; OR, 11.0; CI95, 1.42-85.2; P=.009) or a blood product (OR undefined; P=.04) were identified as risk factors. Infusates were administered via umbilical catheters for most case and control patients (19/20 vs 15/20, P>.05); catheters were manipulated more frequently in patients in critical-care units. Umbilical catheter tip, skin, or mucus membrane K pneumoniae colonization occurred in 47% and 53% of evaluated case and control patients, respectively. Available K pneumoniae isolates from blood cultures and colonization sites had identical antimicrobial susceptibility patterns. Emphasis on handwashing, careful preparation and administration of infusates, and aseptic technique for catheter insertion, maintenance, and manipulation was temporally associated with resolution of the epidemic.

CONCLUSIONS

This outbreak was probably due to infusion therapy practices that led to BSI in nursery patients colonized with K pneumoniae. Both catheter-related infections and extrinsic contamination of infusates may have occurred. Hospital personnel should be aware of their potential to spread nosocomial pathogens from person to person and should implement Centers for Disease Control and Prevention recommendations to decrease nosocomial BSIs.

Tuberculosis among AIDS patients in the United States, 1993

To evaluate the demographic characteristics, risk factors, and reported mortality of adults and adolescents with AIDS and tuberculosis (TB), we analyzed surveillance reports of persons with AIDS from state, territorial, and local health departments. Of 72,306 persons with AIDS diagnosed in 1993, 3,589 (5%) were reported with TB; of these, 2,782 (78%) with pulmonary TB, 552 (15%) with extrapulmonary TB, and 255 (7%) with both pulmonary and extrapulmonary TB were reported. In multivariate analysis, black [odds ratio (OR) 3.3, 95% confidence interval (CI) 2.9-3.7] and Hispanic (OR 2.5, 95% CI 2.2-2.9) persons had a higher risk of TB than white persons; injecting drug users (IDUs: OR 2.3, 95% CI 2.0-2.5) and persons exposed to HIV by heterosexual contact (OR 1.4, 95% CI 1.2-1.7) had a higher risk than men who have sex with men, and persons who were foreign born (OR 2.1, 95% CI 1.8-2.4) had a higher risk than those born in the United States. The highest proportions of AIDS patients with TB were in New York (11%), Illinois (7%), Florida (6%), Georgia (6%), and Texas (5%). The 1-year mortality rate among AIDS patients with pulmonary TB only (26%) and among those with extrapulmonary TB only (28%) was lower than among those with other AID-defining illnesses (38%) (p<0.001 and p<0.001, respectively). The high rate of TB among persons with AIDS, particularly in specific areas of the country and HIV exposure groups, emphasizes the need for continued support of strong TB control measures among persons infected with HIV.

Epidemic aluminum intoxication in hemodialysis patients traced to use of an aluminum pump

This study was designed to identify the source, risk factors, and clinical consequences of an outbreak of aluminum intoxication in hemodialysis patients using case-control and cohort studies. In 1991, a dialysis center in Pennsylvania [Dialysis Center A (DCA)] identified a number of patients with elevated serum aluminum levels. All patients receiving dialysis at DCA during January 1, 1987 to March 26, 1992 were involved in the study. A case-patient was defined as any patient with a serum aluminum level > or = 100 micrograms/liter after > or = 5 dialysis sessions at DCA. Fifty-nine case-patients were identified. Risk factors for elevated serum aluminum levels were receipt of bicarbonate- (rather than acetate-) based dialysate, higher number of sessions using bicarbonate dialysis, receipt of acid concentrate (used in bicarbonate dialysis) passed through one of two electric pumps, and a greater number of sessions using this concentrate. The electric pumps had an aluminum casing, casing cover, and impeller. Elevated levels of aluminum were found in acid concentrate after passing through a pump. Seizures and mental status changes requiring hospitalization were associated with aluminum exposure. We found that epidemic aluminum intoxication was caused by the use of an electric pump with aluminum housing to deliver acid concentrate used in bicarbonate dialysis. This outbreak demonstrates why it is essential to insure that all fluid pathways, storage tanks, central delivery systems, and pumps are compatible with low pH fluids before converting from acetate to bicarbonate dialysis.

Postoperative infections traced to contamination of an intravenous anesthetic, propofol

BACKGROUND

Between June 1990 and February 1993, the Centers for Disease Control and Prevention conducted investigations at seven hospitals because of unusual outbreaks of bloodstream infections, surgical-site infections, and acute febrile episodes after surgical procedures.

METHODS

We conducted case-control or cohort studies, or both, to identify risk factors. A case patient was defined as any patient who had an organism-specific infection or acute febrile episode after a surgical procedure during the study period in that hospital. The investigations also included reviews of procedures, cultures, and microbiologic studies of infecting, contaminating, and colonizing strains.

RESULTS

Sixty-two case patients were identified, 49 (79 percent) of whom underwent surgery during an epidemic period. Postoperative complications were more frequent during the epidemic period than before it. Only exposure to propofol, a lipid-based anesthetic agent, was significantly associated with the postoperative complications at all seven hospitals. In six of the outbreaks, an etiologic agent (Staphylococcus aureus, Candida albicans, Moraxella osloensis, Enterobacter agglomerans, or Serratia marcescens) was identified, and the same strains were isolated from the case patients. Although cultures of unopened containers of propofol were negative, at two hospitals cultures of propofol from syringes currently in use were positive. At one hospital, the recovered organism was identical to the organism isolated from the case patients. Interviews with and observation of anesthesiology personnel documented a wide variety of lapses in aseptic techniques.

CONCLUSIONS

With the increasing use of lipid-based medications, which support rapid bacterial growth at room temperature, strict aseptic techniques are essential during the handling of these agents to prevent extrinsic contamination and dangerous infectious complications.

National trends in the concurrence of tuberculosis and acquired immunodeficiency syndrome

BACKGROUND

Elucidation of the relationship between tuberculosis (TB) and the acquired immunodeficiency syndrome (AIDS) is needed to help predict the future course of these two epidemics. We examined nationwide trends in TB and AIDS occurring in the same individual.

METHODS

Health departments in the 50 states, District of Columbia, Puerto Rico, and Guam matched their TB and AIDS case registries to determine the number of persons diagnosed with both TB and AIDS. The number of AIDS cases, TB cases, AIDS cases that matched with a TB case on the TB registry, and TB cases that matched with an AIDS case on the AIDS registry were reported to the Centers for Disease Control and Prevention, Atlanta, Ga. Data were analyzed for the period from 1981 through 1991. The number of matched TB-AIDS cases was compared with a modeled estimate of excess TB cases during the period from 1985 through 1990.

RESULTS

From 1981 through 1991 there were 11,299 AIDS cases that matched with a TB case on the TB registry, representing 5.1% (geographic variation, 0% to 9.3%) of AIDS cases. The TB cases that matched with an AIDS case on the AIDS registry represent 4.3% (geographic variation, 0% to 15.1%) of TB cases from 1981 through 1991. Since 1981, matched TB and AIDS cases increased yearly through 1990. When examined by year of AIDS report, the percentage of AIDS cases that matched with a TB case increased from 1981 to 1982 (1.9% to 5.1%), remained fairly constant from 1983 through 1987 (range, 4.0% to 4.7%), increased in 1988 (5.4%) after extrapulmonary TB was added to the AIDS case definition, and increased slightly through 1990 (5.8%). When examined by year of TB report, the percentage of TB cases that matched with an AIDS case increased steadily from 1981 through 1990 (0.1% to 9.5%). The calculated fraction of excess TB cases during the period from 1985 through 1990 that could be accounted for by identified TB-AIDS cases was 30%.

CONCLUSION

The risk of TB or AIDS among persons already diagnosed with one disease is much higher than among the general population. The percentage of persons with TB who are also diagnosed with AIDS has been increasing rapidly. Human immunodeficiency virus-induced immunosuppression is an important contributor to the TB epidemic and probably accounts for a minimum of 30% of excess TB cases during the period from 1985 through 1990.

Respirators, recommendations, and regulations: the controversy surrounding protection of health care workers from tuberculosis

Recent nosocomial outbreaks of tuberculosis have increased concern about the occupational acquisition of tuberculosis by health care workers. The Centers for Disease Control and Prevention (CDC), Department of Health and Human Services, and the Occupational Safety and Health Administration, Department of Labor, have issued recommendations and regulations in an effort to decrease health care workers' risk for exposure to patients with infectious tuberculosis. Within the CDC, the National Center for Infectious Diseases, the National Center for Prevention Services, and the National Institute for Occupational Safety and Health collaborated to produce the 1994 Guidelines for Preventing the Transmission of Tuberculosis in Health-Care Facilities. As stated in the Draft Guidelines, the major components of health care worker protection from Mycobacterium tuberculosis infection include administration or source controls, engineering controls, and respiratory protective devices. We review the evolution of the seemingly conflicting recommendations for respiratory protective devices made by these Centers of the CDC and explain how the recommendations in the current CDC Guidelines were reached.

Ceftazidime resistance among selected nosocomial gram-negative bacilli in the United States. National Nosocomial Infections Surveillance System

To examine temporal trends in ceftazidime resistance, susceptibility data reported to the National Nosocomial Infections Surveillance system during 1987-1991 were analyzed among nosocomial Enterobacter species, Klebsiella pneumoniae, and Pseudomonas aeruginosa. Linear increases in resistance were observed for Enterobacter species and K. pneumoniae. One hospital experienced a dramatic rise from 1.0% in 1987-1989 to 40% in 1990-1991 (P < .001) in ceftazidime resistance among K. pneumoniae isolates. No increase was observed during this period for P. aeruginosa. Logistic regression analysis confirmed these trends (or the lack thereof) for Enterobacter species and P. aeruginosa; for K. pneumoniae, ceftazidime resistance was found to be increasing among isolates from teaching hospitals and intensive care units. Ceftazidime resistance is an emerging problem that has the potential for dramatic increases. Selective pressures for the development of ceftazidime resistance need to be identified and addressed.

Nosocomial outbreak of tuberculosis in a renal transplant unit: application of a new technique for restriction fragment length polymorphism analysis of Mycobacterium tuberculosis isolates

From January 1990 through February 1991, tuberculosis (TB) developed in 10 renal transplant (RT) patients at one hospital; 5 patients died. Possible nosocomial transmission was investigated. Mycobacterium tuberculosis isolates were compared by restriction fragment length polymorphism (RFLP) by a polymerase chain reaction method. The source case occurred in an RT patient (source) who had posttransplant exposure to TB at another hospital. The source patient was rehospitalized on the RT unit; diagnosis of TB and thus isolation precautions were delayed. Epidemiologic and RFLP analysis showed transmission from the source to 5 RT patients and 1 human immunodeficiency virus-infected patient. M. tuberculosis isolates from 4 RT patients had other RFLP patterns. The median incubation period for TB in RT patients was 7.5 weeks (range, 5-11). Bronchoscopy and intubation of the source patient and inadequate ventilation on the RT unit possibly increased transmission. Early detection of TB and effective isolation are essential to prevent nosocomial transmission.

Gas exchange during constant flow ventilation with different gases

To investigate the mechanisms of CO2 transport during constant flow ventilation, we measured arterial blood gases using air, 80% He-20% O2 (He) or 80% SF6-20% O2 (SF6) as the insufflating gas. At any given flow rate (0.2 to 1.0 L/s), PaCO2 was greatest with He and lowest with SF6. Data for all gases could be described by the equation PaCO2/Pb = 0.044 V-0.64 v0.23, where Pb = barometric pressure, PaCO2 is in mm Hg, V = insufflated flow in L/s, and v = kinematic viscosity (cm2/s). At any given flow rate, the AaPO2 was greater using SF6 than using He. These results are consistent with a 2-zone model of gas transport in which the enhancement of gas transport as V increases may be due to an increase in the turbulent diffusivity in zone I (the region affected by the jet). The decreased gas transport with He compared to air and SF6 at any V may be due to either the decreased penetration depth of zone I caused by the greater kinematic viscosity of He, or the decreased rate of gas transport in the region affected by cardiogenic oscillations (zone II) secondary to the higher molecular diffusivity of He.

Effect of flow rate on blood gases during constant flow ventilation in dogs

We studied the effect of flow rate (V) on arterial blood gases during constant flow ventilation (CFV) in 9 anesthetized, paralyzed dogs weighing 9.5 to 26.5 kg. The constant flow was administered through catheters placed in each mainstem bronchus. Alveolar ventilation increased linearly with increasing V over the range of 0.18 to 1.0 L/s but was relatively constant at flows above 1.0 L/s. We found that CFV produced normocapnia at a mean V of 0.48 +/- 0.21 L/s (mean +/- SD). However, we did not find any significant relationship between body weight and the V required for normocapnia. At all flow rates we found a relatively large alveolar to arterial oxygen difference (48.9 +/- 8.8 mmHg, mean +/- SD), suggesting significant inhomogeneities in ventilation-perfusion. Our data are consistent with a 2-zone model of gas exchange where gas exchange is dominated by bidirectional convective streaming in the airways closest to the jets, cardiogenic induced flows in the most peripheral airways, and jet-induced turbulence in those airways between these 2 regions.

Effect of cardiogenic oscillations on gas mixing during tracheal insufflation of oxygen

In a previous study using tracheal insufflation of O2 (TRIO) at a rate of 2 l/min, we showed that anesthetized paralyzed dogs could be adequately oxygenated for up to 5 h, albeit with hypercapnia (mean arterial PCO2 approximately 160 Torr). To examine the contribution of cardiogenic oscillations in producing this gas exchange, we studied seven anesthetized paralyzed dogs weighing between 19.6 and 25.5 kg and quantified gas transport by analyzing continuous N2-washout curves in vivo and postmortem. We found that cardiogenic oscillations increase gas mixing roughly fourfold and that this value was independent of insufflation flow rate (0.2-10.0 l/min). Our results lend indirect evidence that, with regard to gas exchange, there are two mechanistically different zones in the lung during TRIO. One zone, located in the more peripheral areas of the lung, is dominated by the effects of cardiac oscillations and molecular diffusion and accounts for the increase in gas mixing found in the alive vs. dead dog. A second zone, close to the insufflated jet of O2, uses convective streaming to produce greater gas mixing at higher flows.