Occult bacteremia in the emergency department

Fever in geriatric emergency patients: clinical features associated with serious illness

STUDY OBJECTIVE

To determine the clinical significance of fever in geriatric emergency department patients.

DESIGN

Case series with follow-up.

SETTING

Urban, university-affiliated community hospital.

PARTICIPANTS

Consecutive patients over the age of 65 years who presented to the ED during a 12-month period with an oral temperature of 100.0 degrees F (37.8 degrees C) or higher.

RESULTS

We considered the following features indicators of serious illness: positive blood culture(s), related death within 1 month of ED visit, need for surgery or other invasive procedure, hospitalization for 4 or more days, IV antibiotics for 3 or more days, and repeat ED visit within 72 hours for related condition. Four hundred eighty-nine patients were eligible for study. Of the 470 patients with complete follow-up data, 357 (76.0%) had indicators of serious illness. Clinical features found to be independently associated with serious illness included oral temperature of 103 degrees F (39.4 degrees C) or more, respiration rate of 30 or more, leukocytosis of 11.0 x 10(9)/L or more, presence of an infiltrate, and pulse of 120 or more. At least one indicator of serious illness was present in 63 of 128 patients (49.6%) with none of these independently predictive clinical features. The most common final diagnoses were pneumonia (24.0%), urinary-tract infection (21.7%), and sepsis (12.8%).

CONCLUSION

Fever among geriatric ED patients frequently marks the presence of serious illness. All such patients should be strongly considered for hospital admission, particularly when certain clinical features are present. The absence of abnormal findings does not reliably rule out the possibility of serious illness.

Difficulty in predicting bacteremia in elderly emergency patients

STUDY OBJECTIVES

To characterize the clinical presentation and identify factors predictive of bacteremia in elderly patients.

DESIGN

Retrospective review of emergency department charts, hospital records, and microbiology reports.

SETTING

Community teaching hospital with annual ED census of 65,000 adults.

PARTICIPANTS

Seven hundred fifty elderly patients (aged 65 to 99 years) who were evaluated by the emergency physician, had blood cultures obtained in the ED, and were hospitalized with a suspected infectious process during a 12-month period.

MEASUREMENTS

Records were analyzed for demographic information, underlying diseases, clinical presentation, laboratory findings, sources of infection, and causative organisms. Using contingency tables, 79 patients with positive blood cultures were compared with a random sample of 136 patients with sterile blood cultures to identify clinical variables significantly (P less than .05) associated with bacteremia. Logistic regression analysis was performed with significant factors to develop a model to predict bacteremia. Sensitivity, specificity, and predictive values were calculated for the model.

MAIN RESULTS

The prevalence of bacteremia was 10.6%. Escherichia coli was the most commonly isolated pathogen (29% of cases), and the urinary tract was the most common source of infection (44.3% of cases). Logistic regression analysis showed that altered mental status (odds ratio, 2.88; 95% confidence interval [Cl], 1.52 to 5.50), vomiting (odds ratio, 2.63; 95% Cl, 1.16 to 6.15), and WBC band forms of more than 6% (0.06) (odds ratio, 3.50; 95% Cl, 1.58 to 5.27) were independent predictors of bacteremia. The presence of at least one of these three factors had a sensitivity of 0.85 (95% Cl, 0.75 to 0.92) and a specificity of 0.46 (95% Cl, 0.38 to 0.55) for predicting bacteremia in the study group. The positive predictive value was 0.16 (95% Cl, 0.12 to 0.19) and the negative predictive value was 0.96 (95% Cl, 0.94 to 0.98) for the ED patient group that met inclusion criteria.

CONCLUSION

Elderly patients fail to manifest identifiable clinical features indicative of bloodstream infection. The sensitivity and specificity of the best statistical model for identifying bacteremic elderly patients suggest that clinical indicators alone are unreliable predictors of bacteremia in the geriatric ED population studied.

Use of blood cultures in the emergency department

While the use of blood cultures to detect septicemia is a time-honored and valuable laboratory technique, guidelines for obtaining such cultures are vague. Several controversies exist regarding the utilization of blood cultures in the ambulatory setting, including when and on whom cultures should be obtained, how many cultures should be obtained, and how much blood should be obtained with each venipuncture. The guidelines have become slightly more confusing with the recognition of an entity known as occult bacteremia. A number of studies that bear relevance to these issues are reviewed. The utility of obtaining blood cultures in the ambulatory setting is examined, and guidelines are offered for obtaining blood cultures in adult and pediatric populations. Areas in which further research may be appropriate also are noted.

Occult bacteremia in the emergency department: diagnostic criteria for the young febrile child

We studied a selected series of febrile infants (N = 201) in an attempt to prospectively identify risk factors for bacteremia. Infants with fever less than 39.4 C, vomiting and diarrhea, croup, or viral exanthem or enanthem were not included. Twenty-one infants (9.5%) had positive blood cultures despite the initial judgment of their physician that only viral illness or localized bacterial infection existed. WBC count of more than 15,000 correlated with bacteremia, with a sensitivity of 0.71 and a specificity of 0.73. Extensive multivariate linear regression analysis attempting to increase predictive values was completed. The combination of fever higher than 39.4 C present for more than 12 hours and absolute polymorphonuclear count of more than 9,000 cells/mm3 had a sensitivity of 0.62 and a specificity of 0.78 for bacteremia. Descriptive statistics for groups with and without bacteremia are summarized. We have defined prospectively a population of infants with a high probability of bacteremia and a lower probability of viral illness. Identification of such a group is useful to the emergency physician because early antibiotic therapy may lessen morbidity and mortality. We conclude that an easily obtained data base may be useful in the prospective identification of those at risk for bacteremia.