Inadequacy of Temperature and White Blood Cell Count in Predicting Bacteremia in Patients with Suspected Infection

doi:10.1016/j.jemermed.2010.05.038

The Journal of Emergency Medicine

Volume 42, Issue 3, March 2012, Pages 254-259

These data were originally presented in abstract form at the national meeting of the American College of Emergency Physicians (ACEP), Seattle, Washington, October 2007.

https://doi.org/10.1016/j.jemermed.2010.05.038 Get rights and content

Abstract

Background

Early treatment of sepsis in Emergency Department (ED) patients has lead to improved outcomes, making early identification of the disease essential. The presence of systemic inflammatory response criteria aids in recognition of infection, although the reliability of these markers is variable.

Study Objective

This study aims to quantify the ability of abnormal temperature, white blood cell (WBC) count, and bandemia to identify bacteremia in ED patients with suspected infection.

Methods

This was a post hoc analysis of data collected for a prospective, observational, cohort study. Consecutive adult (age ≥ 18 years) patients who presented to the ED of a tertiary care center between February 1, 2000 and February 1, 2001 and had blood cultures obtained in the ED or within 3 h of admission were enrolled. Patients with bacteremia were identified and charts were reviewed for presence of normal temperature (36.1–38°C/97–100.4°F), normal WBC (4–12 K/μL), and presence of bandemia (> 5% of WBC differential).

Results

There were 3563 patients enrolled; 289 patients (8.1%) had positive blood cultures. Among patients with positive blood cultures, 33% had a normal body temperature and 52% had a normal WBC count. Bandemia was present in 80% of culture-positive patients with a normal temperature and 79% of culture-positive patients with a normal WBC count. Fifty-two (17.4%) patients with positive blood cultures had neither an abnormal temperature nor an abnormal WBC.

Conclusion

A significant percentage of ED patients with blood culture-proven bacteremia have a normal temperature and WBC count upon presentation. Bandemia may be a useful clue for identifying occult bacteremia.

Introduction

Sepsis is a significant cause of morbidity and accounts for approximately 500,000 emergency department (ED) visits in the United States each year (1). Early identification and treatment of sepsis may lead to improved outcomes; thus, emergency physicians must recognize varied clinical presentations of potential sepsis, as well as patients at risk for developing sepsis.

“Sepsis” embodies a large spectrum of clinical disease and is classically defined as a syndrome based on clinical suspicion of infection and two or more parameters suggestive of systemic inflammation, known as the “Systemic Inflammatory Response Syndrome” (SIRS) criteria. These criteria include body temperature < 36°C (96.8°F) or > 38°C (100.4°F), heart rate > 90 beats/min, respiratory rate > 20 breaths/min, and a white blood cell (WBC) count of > 12,000 cells per μL or < 4000 per μL. Although abnormal vital signs and laboratory values define SIRS, the specificity of these markers for clinical infection is variable (2). Bacteremia, alternatively, refers to the presence of bacteria in the bloodstream; it definitively indicates infection regardless of clinical presentation, vital signs, or laboratory data, and may place patients at risk for developing sepsis.

As part of the SIRS criteria, abnormal body temperature and WBC count are often used as markers for infection despite undocumented accuracy. Changes in WBC count are also classically associated with infection, but data of its utility are mixed, and values for leukocytosis as a predictor of infection are not standardized 3, 4, 5, 6, 7. Although fever has been incorporated into prediction rules for blood stream infections, proven infection may be present in the absence of fever 3, 6, 8, 9, 10, 11, 12, 13, 14, 15. Hypothermia may also be indicative of infection and is associated with increased mortality among septic patients in the intensive care unit (10).

Whereas abnormal body temperature and WBC count have been studied in hospitalized patients, we are unaware of an evaluation of ED patients in this regard. This study aims to quantify the ability of abnormal temperature, WBC count, and bandemia to predict bacteremia in ED patients with clinically suspected infection.

Section snippets

Study Design

We performed a post hoc secondary analysis of data collected for a prospective, observational, cohort study. The study was approved by the hospital’s institutional review board. Briefly, in the original study, blood cultures were obtained on all patients with suspected infection. The original study used “the treating clinicians’ decision to obtain a blood culture as a surrogate marker for a patient at risk for infection” based upon patients’ complaints, comorbidities, and physical examination

Results

There were 3563 patients enrolled, of which 289 (8.1%) had positive blood cultures and were included in the analysis. All patients had an initial temperature recorded in the ED, and all had a CBC measured. Two hundred ten patients (72.7%) had a full differential performed by the laboratory, ordered at the discretion of the primary physician caring for the patient. Table 1 summarizes the baseline characteristics of the culture-positive patients. Thirty-three percent of patients with a positive

Discussion

Our study is novel in that it has examined patients who presented to the ED with suspected infection based on symptom report or examination findings and who were ultimately found by positive blood culture results to have bacteremia. Our data demonstrate that 17.4% of patients with proven bacteremia had a normal temperature, normal WBC count, or both, on initial evaluation in the ED, suggesting that these variables are poor indicators of bacteremia. Among this cohort, the presence of bandemia

Conclusions

A significant percentage of ED patients with blood culture-proven bacteremia have a normal temperature and WBC count upon presentation. A bandemia, even in the setting of a normal WBC count, seems to be a useful clue to the clinician that a patient may have a serious occult infection. Emergency medicine physicians need to maintain a high level of suspicion for bacteremia and sepsis, and cannot necessarily rely upon normal temperature or WBC count to effectively exclude these diseases from the

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Original ContributionsInadequacy of Temperature and White Blood Cell Count in Predicting Bacteremia in Patients with Suspected Infection

Abstract

Background

Study Objective

Methods

Results

Conclusion

Introduction

Section snippets

Study Design

Results

Discussion

Conclusions

Chest

J Emerg Med

Ann Emerg Med

Ann Emerg Med

Am J Infect Control

National estimates of severe sepsis in United States emergency departments

Crit Care Med

Predicting bacteremia in hospitalized patients. A prospectively validated model

Ann Intern Med

A simple index to estimate the likelihood of bacterial infection in patients developing fever after abdominal surgery

Am Surg

Infection Probability Score (IPS): a method to help assess the probability of infection in critically ill patients

Crit Care Med

Original Contributions
Inadequacy of Temperature and White Blood Cell Count in Predicting Bacteremia in Patients with Suspected Infection