Keri L. Carstairs

Serious Bacterial Infections in Febrile Infants in the Post―Pneumococcal Conjugate Vaccine Era

OBJECTIVES The objective was to identify the epidemiology of serious bacterial infections (SBI) and the current utility of obtaining routine complete blood counts (CBC) and blood cultures to stratify infants at risk of SBI, in the study population of febrile infants in the post-heptavalent pneumococcal conjugate vaccine (PCV7) era. METHODS A cohort study with nested case-controls was undertaken at a tertiary care military hospital emergency department (ED) from December 2002 through December 2003. Irrespective of clinical findings at the initial encounter, patients were included if they were under 3 months of age and had a home or ED temperature of >or=100.4 degrees F or if they were between 3 and 24 months of age with a temperature of >or=102.3 degrees F. Data abstracted included age, temperature, peripheral white blood cell (WBC) count, and discharge diagnosis. Culture (blood, urine, and cerebrospinal fluid [CSF]) and chest radiograph (CXR) results were obtained through review of the electronic hospital archives. SBI was defined as pneumonia, urinary tract infection (UTI), meningitis, or bacteremia. RESULTS A total of 985 children aged 0 to 24 months were enrolled. Fifty-five percent were male, the median age was 12 months (interquartile range = 8-17 months), and 79% had received at least one PCV7. A total of 132 cases of SBI were identified in 129 infants (13.1%): 82 pneumonias, 45 UTI, five bacteremias, and no cases of bacterial meningitis. The frequency of bacteremia was 0.7%. No statistical difference was detected in the WBC count between the SBI and non-SBI groups (13.8 +/- 5.8 and 11.7 +/- 5.6, respectively; p = 0.055). No readily available WBC cutoff on the receiver operating characteristic (ROC) curve proved to be an accurate predictor of SBI. No statistical difference was detected in mean temperature between the SBI and non-SBI groups (103.3 +/- 1.2 and 103.2 +/- 1.2 degrees F, respectively; p = 0.26), nor was there a difference noted when groups were broken down by age or height of fever. CONCLUSIONS The WBC count and height of fever were not found to be accurate predictors of SBI in infants age 3 to 24 months. UTI and pneumonias made up the vast majority of SBI in this population of infants. The overall bacteremia frequency was well below 1%. This calls into question the continued utility of obtaining routine complete cell counts and blood cultures in the febrile infant in the post-PCV7 era.

Urinalysis is not reliable to detect a urinary tract infection in febrile infants presenting to the ED

OBJECTIVE Urinary tract infections are a common source of serious bacterial infections in febrile infants younger than 2 years. Our objective was to compare urinalysis with urine culture in the emergency department evaluation of febrile infants. METHODS A febrile infant registry was instituted at a tertiary care hospital treating an average of 55000 patients annually (27% children), from December 2002 to December 2003. Patients were eligible if they were younger than 3 months and had a temperature of at least 38 degrees C or if they were between 3 and 24 months of age and had a temperature of at least 39 degrees C. Data abstracted included age, sex, and temperature. Urinalysis (UA) and urine culture (UCx) results were obtained from electronic hospital archives. RESULTS Nine hundred eighty-five patients were entered into the febrile infant registry. Male patients comprised 55%. The mean age of patients was 12.6 months; median was 12 months. Four hundred thirty-five (78% of eligible patients) had both a UA and UCx from the same specimen, and there were 45 (10.3%) positive UCx result. Females accounted for 33 (73%) of 45 positive results. The sensitivity of UA for predicting a positive UCx result was 64% (95% confidence interval [CI], 49%-78%), whereas the specificity was 91% (95% CI, 88%-94%). The positive predictive value was 46% (95% CI, 31%-53%), with a negative predictive value of 96% (95% CI, 93%-97%). CONCLUSION Urinalysis is not reliable for the detection of urinary tract infections in febrile infants when compared with urine cultures.

Oxygen saturation is not clinically useful in the exclusion of bacterial pneumonia in febrile infants

Background Acute respiratory infection remains a common presentation to Emergency Departments. Oxygen saturations (Sao2) may be useful in determining which febrile infants require chest x-rays (CXR) in investigation for bacterial pneumonia (PNA). This study aimed to determine whether Sao2 is clinically useful in excluding bacterial PNA in febrile infants <24 months. Methods A febrile infant registry was instituted at a tertiary care military hospital (55 000 annual patients, 27% children) from December 2002–December 2003. Eligible patients consisted of infants <3 months with temperature ≥38°C or 3–24 months with temperature ≥39°C. Bacterial PNA was defined in this cohort by a CXR revealing a ‘lobar infiltrate’ by a board-certified radiologist. Descriptive statistics are presented on groups who received CXR versus groups who did not, and on infants who had bacterial PNA versus those who did not. Student t tests were used to compare maximum temperature (Tmax), RR, and Sao2. Logistic regression for PNA was performed using age, sex, Tmax, RR, HR and Sao2. A Receiver Operator Characteristic (ROC) curve was created to show Sao2 cut-off points as related to sensitivity and specificity. Results 985 patients (55% boys; median age: 12 months) met entry criteria. 790 underwent CXR and 82 were diagnosed with bacterial PNA. Sao2 was lower in infants with bacterial PNA (96.6%±2.5% vs 97.7%±1.8%, p<0.001). Sao2 was also predictive of bacterial PNA by logistic regression (p=0.017) but the ROC curve yielded a poor sensitivity/specificity profile (area under curve (AUC) of 0.6786). Conclusions In febrile infants, Sao2 was not found to be clinically useful for excluding bacterial PNA.

Emergency department presentation of acute disseminated encephalomyelitis.

Acute disseminated encephalomyelitis is an acute demyelinating disorder of the central nervous system that usually occurs in children and young adults. We report the case of an 8-year-old girl who presented to the emergency department with acutely altered mental status. Standard workup including head computed tomography, lumbar puncture, and routine chemistries was unrevealing. Magnetic resonance imaging revealed findings consistent with acute disseminated encephalomyelitis. Response to treatment with steroids was dramatic. Both the rapidity of onset and resolution of this patients symptoms are unusual for the course of this disease.