Fever in infants less than two months of age: spectrum of disease and predictors of outcome

Managing Febrile Infants

The authors hypothesized that sepsis workup recommendations are associated with practice recommendations published during the physician’s residency. The first published recommendations suggesting sepsis workups for nontoxic, young, febrile infants appeared in pediatric journals from 1975-1980 and in family practice journals from 1981-1987. Data are from the Community Tracking Study (3,272 pediatricians and 2,432 family physicians). “Percentage of sepsis workups recommended” was defined by response to a vignette about the percentage of well-appearing 6-week-old children with a fever of 101°F for whom the physician would recommend a sepsis workup. Multivariable regression with piecewise linear functions evaluated workup recommendations by timing of literature recommendations during residency. Pediatricians recommended sepsis workups 81.6% of the time and family physicians 67.7% (p < .001). Increased recommendations occurred among pediatricians who completed residency from 1975-1980 (p < .05) and among family physicians who completed residency from 1981-1987 (p < .005), when specialty-specific journals published recommendations for sepsis workups for febrile infants. The association between publication of sepsis workup recommendations during a physician’s residency and increased sepsis workup recommendations suggests an unrecognized and enduring impact of such publications.

Comparison of pediatric and general emergency medicine practice patterns in infants with fever

OBJECTIVES

To evaluate and compare the management approaches of pediatric and general emergency medicine physicians in infants presenting to the emergency department (ED) with complaint of fever.

METHODS

Infants 90 days of age or younger with a chief complaint of fever were included for review. Vital signs, laboratory workup, disposition, and final diagnosis were collected. Compliance with guidelines was assessed and compared between EDs.

RESULTS

Compliance with admission guidelines was not significantly different in any of the 3 age groups evaluated between the pediatric and general ED (PED and GED). Compliance with guideline recommendations for laboratory workup was not significantly different between the 2 EDs, nor was overall compliance with guideline recommendations.

CONCLUSIONS

No significant variations in the management of febrile infants or compliance with published guidelines between PED and GED physicians were observed. Young infants can be safely treated for fever in the PED or GED.

Adherence to guidelines for managing the well-appearing febrile infant: assessment using a case-based, interactive survey

OBJECTIVES

The objectives of the study were (1) to determine the relative use of strategies for managing the well-appearing febrile infant and (2) to determine clinician adherence to protocol recommendations.

METHODS

Members of the American Academy of Pediatrics Section on Emergency Medicine were asked to complete an online, interactive, case-based questionnaire. Infants with a temperature of 38.6°C who were otherwise completely well were presented. Respondents ordered laboratory studies and received results. Treatment and disposition decisions based on those results were queried. Clinicians reported which published set of guidelines they followed. Major discriminating features of guidelines were used to assess adherence.

RESULTS

Two hundred ninety-nine (30%) clinicians completed the survey. The relative use of the 3 main guidelines was as follows: Philadelphia, 20%; Rochester, 15%; and Boston, 13%. Of respondents reporting that their practice is based on the Rochester criteria, 98% performed a lumbar puncture, 86% administered antibiotics, and 93% admitted the 25-day-old infant to the hospital, despite recommendations that a lumbar puncture was unnecessary and that the infant be managed as an outpatient without antibiotics. Similar deviations were seen among respondents who reported using the other criteria.Many respondents treated the infants with antibiotics, without obtaining cerebrospinal fluid for culture, despite recommendations against this practice.

CONCLUSIONS

Although most physicians report following published guidelines for the management of the well-appearing febrile infant, compliance with recommendations is poor. The effect that deviating from the guidelines has on patient outcome is unknown. Despite recommendations to the contrary, many physicians administer antibiotics without obtaining cerebrospinal fluid for culture.

Predictors of cerebrospinal fluid pleocytosis in febrile infants aged 0 to 90 days

BACKGROUND

Young infants with fever routinely undergo laboratory evaluation, and many are treated with empirical antibiotics even when the infant seems well. The requirement of a lumbar puncture (LP) as part of a routine evaluation is debated; however, administration of antibiotics without an LP can cause concerns for partially treated bacterial meningitis and make subsequent evaluation of the cerebrospinal fluid (CSF) confusing. The ability to predict which febrile infants have a CSF pleocytosis would assist in the decision to perform LP in febrile infants.

OBJECTIVE

To develop a model to predict which febrile infants have a CSF pleocytosis.

METHODS

We conducted a retrospective review of febrile children aged 90 days or younger seen in the emergency department. Electronic data sources provided the age of the infant, the triage temperature, and all laboratory values. After univariate analysis, recursive partitioning analysis was performed to develop a decision tree to predict febrile infants at increased risk for CSF pleocytosis, defined as a CSF white blood cell (WBC) count of 25/microL or greater in infants 28 days old or younger and 10/microL or greater in those 29 to 90 days old.

RESULTS

Two thousand three febrile infants were studied; 176 (8.8%; 95% confidence interval [CI], 7.6%-10.1%) had a CSF pleocytosis. Presentation during the summer season increased the risk of pleocytosis from 5.0% during nonsummer months to 17.4% (95% CI, 14.6%-20.6%). During the nonsummer season, 7.3% (95% CI, 5.6%-9.5%) of febrile infants with a temperature of greater than 38.4 degrees C and a WBC count of greater than 6100/microL had a CSF pleocytosis, as opposed to 2.9% (95% CI, 1.9%-4.4%) of those with lower temperature or lower WBC count. The decision tree has an overall sensitivity of 89% (95% CI, 83%-92%) and a negative predictive value of 97% (95% CI, 96%-98%).

CONCLUSIONS

A significant number of well-appearing febrile infants will have a CSF pleocytosis. A simple decision tree based on objective clinical information can help identify those at greatest risk for CSF pleocytosis.

Clinical utility of the band count

Enumeration of band neutrophils has a long clinical tradition as a diagnostic test for bacterial infection. Yet, the band count is a nonspecific, inaccurate, and imprecise laboratory test. Review of the literature provides little support for the clinical utility of the band count in patients greater than 3 months of age. The white blood cell count and the automated absolute neutrophil count are better diagnostic tests for adults and most children. Absolute numbers of bands are required for the Rochester criteria, a diagnostic algorithm for acutely ill, febrile children less than 3 months of age. No studies, however, assess the independent contribution of bands to the performance of the algorithm, or the use of the automated total neutrophil count as a replacement for the band count. Band counts also are required to calculate an immature to total neutrophil ratio (I:T ratio), an index widely used to aid in the diagnosis of neonatal sepsis. Studies, however, show a wide range of sensitivity and specificity for the I:T ratio, indicating variable performance. In the near future, rapid analysis of inflammatory factors, adhesion molecules, cytokines, neutrophil surface antigens, or even bacterial DNA may be superior alternative tests for the early diagnosis of sepsis.

Evaluation of the infant with fever without source: an evidence based approach

The infant with fever without an obvious source upon physical examination offers a challenging clinical problem. A combination of detailed history, physical examination, and selected laboratory tests allows the clinician to discern which infants are at lower risk for bacterial illness. Implications for management and future research are discussed herein.

The history and physical assessments of the febrile infant

Grading patient clinical appearance using the Young Infant Observation Scale and the Yale Observation Scale can effectively classify approximately 75% of infants with a serious illness or infection as ill appearing and 95% who appear to be well as having low risk for serious illness or infection. Most children with invasive bacterial infections appear to be ill at the time of evaluation, although exceptions to this are not uncommon. Accuracy in distinguishing the etiology of fever in infants is an integrated evaluation including thorough assessment of historical data, clinical appearance, and physical findings.

Management of the febrile infant

The management of the febrile infant is truly a complex and evolving topic in pediatrics. The clinical practice guideline provides a map for physician decision making in this important clinical issue. An individual physician may alter the course of action based on his or her treatment threshold but must recognize the limitations of that approach. Documentation of management decisions that deviate from published guidelines are important for patient care. The medical record must carefully represent the appearance of the patient, the actions taken, and the discussion with the family regarding management. Close follow-up includes phone contact with documentation and reexamination of the patient in a reasonable period of time. All who deal with the common problem of fever in infants should follow this subject closely and be ready to adopt new management strategies when evidence from outcomes-based research emerges. In the mean time, the current practice guideline offers an excellent starting point in the management of this common and vexing clinical problem.

Initial approach to the infant younger than 2 months of age who presents with fever

Fever is common in infants presenting to their physicians for evaluation. Infants younger than 2 months of age are at increased risk of SBI because of their exposure to different pathogens and because of their immature immune systems. The bacteria that may infect them include E coli, group B Streptococcus, and L monocytogenes, as well as Pneumococcus, Neisseria meningitidis, S aureus, and H influenzae. They are also susceptible to viruses, parasites, and fungi. Clinical characteristics associated with increased risk of SBI have been identified. Infants who are ill-appearing, have abnormal hemograms or urinalyses, or have evidence of bacterial infection on physical examination are at higher risk. There has been an association of very high fever with SBI, although this has been inconclusive. Clinical judgment is important, although not always completely reliable in ruling out SBI. Young infants with fever should be evaluated with a thorough history, physical examination, and selected laboratory studies. Those younger than 29 days of age should usually be admitted for observation and parenteral antibiotics. Infants from 29 to 60 days of age may be evaluated carefully and considered for outpatient management, either with or without antibiotics.

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.

Selecting diagnostic tests to identify febrile infants less than 3 months of age as being at low risk for serious bacterial infection: a scientific overview

PURPOSE

To select diagnostic tests that confidently identify febrile infants less than 3 months of age seen at an outpatient facility as being at low risk for serious bacterial infection (SBI).

DATA IDENTIFICATION

An English-language literature search employing MEDLINE (1966 to 1991), Science Citation Index (1977 to 1991) using key citations, bibliographic reviews of primary research and review articles, and correspondence with authors of recent articles.

STUDY SELECTION

After independent review by two observers, 10 of 333 originally identified titles were selected on the basis of prespecified selection criteria.

DATA EXTRACTION

Two observers independently assessed studies by using explicit methodologic criteria for evaluating the quality of studies dealing with diagnostic tests. One reviewer extracted all the data from the articles; the second reviewer checked these data for accuracy.

RESULTS OF DATA ANALYSIS

On the basis of prespecified criteria, results were pooled from two studies that used the Rochester criteria, had high methodologic validity, and did not have significant heterogeneity (p = 0.32, Breslow-Day test), to give an estimate of the best negative likelihood ratio (95% confidence interval) for SBI = 0.03; 0 to 0.23).

CONCLUSION

The negative likelihood ratio of 0.03 allowed us to conclude that after the Rochester criteria for low risk of SBI have been satisfied, the probability of SBI in a febrile infant less than 3 months of age drops from a baseline rate of 7% (or 1 in 14 infants) to 0.2% (or 1 in 500). An expectant approach in these low-risk infants is therefore a reasonable choice.

Outpatient treatment of febrile infants 28 to 89 days of age with intramuscular administration of ceftriaxone

STUDY OBJECTIVE

To determine the outcome of outpatient treatment of febrile infants 28 to 89 days of age with intramuscular administration of ceftriaxone.

DESIGN

Prospective consecutive cohort study.

SETTING

Urban emergency department.

PATIENTS

Five hundred three infants 28 to 89 days of age with temperatures greater than or equal to 38 degrees C who did not appear ill, had no source of fever detected on physical examination, had a peripheral leukocyte count less than 20 x 10(9) cells/L, had a cerebrospinal fluid leukocyte count less than 10 x 10(6)/L, did not have measurable urinary leukocyte esterase, and had a caretaker available by telephone. Follow-up was obtained for all but one patient (99.8%).

INTERVENTION

After blood, urine, and cerebrospinal fluid cultures had been obtained, the infants received 50 mg/kg intramuscularly administered ceftriaxone and were discharged home. The infants returned for evaluation and further intramuscular administration of ceftriaxone 24 hours later; telephone follow-up was conducted 2 and 7 days later.

RESULTS

Twenty-seven patients (5.4%) had a serious bacterial infection identified during follow-up; 476 (94.6%) did not. Of the 27 infants with serious bacterial infections, 9 (1.8%) had bacteremia (8 of these had occult bacteremia and 1 had bacteremia with a urinary tract infection), 8 (1.6%) had urinary tract infections without bacteremia, and 10 (2.0%) had bacterial gastroenteritis without bacteremia. Clinical screening criteria did not enable discrimination between infants with and those without serious bacterial infections. All infants with serious bacterial infections received an appropriate course of antimicrobial therapy and were well at follow-up. One infant had osteomyelitis diagnosed 1 week after entry into the study, received an appropriate course of intravenous antimicrobial therapy, and recovered fully.

CONCLUSIONS

After a full evaluation for sepsis, outpatient treatment of febrile infants with intramuscular administration of ceftriaxone pending culture results and adherence to a strict follow-up protocol is a successful alternative to hospital admission.

Ambulatory care of febrile infants younger than 2 months of age classified as being at low risk for having serious bacterial infections

We prospectively examined whether febrile infants younger than 2 months of age who were defined as being at low risk for having bacterial infection could be observed as outpatients without the usual complete evaluation for sepsis and without antibiotic treatment. A total of 237 previously healthy febrile infants were seen at the Pediatric Emergency Room over 17 1/2 months. One hundred forty-eight infants (63%) fulfilled the criteria for being at low risk: no physical findings consisting of soft tissue or skeletal infections, no purulent otitis media, normal urinalysis, less than 25 white blood cells per high-power field on microsopic stool examination, peripheral leukocyte count 5000 to 15,000/mm3 with less than 1500 band cells/mm3. One infant appeared too ill to be included, and had sepsis and meningitis. None of the 148 infants at low risk had bacterial infections, versus 21 of 88 (24%) of those at high risk (P less than 0.0001); eight of 88 (9%) had bacteremia. Of the 148 infants classified as being at low risk for having bacterial infection, 62 (42%) were discharged to home, and 72 (49%) were initially observed for less than or equal to 24 hours and then discharged. Seventeen infants (11%) were hospitalized: in six, low risk became high risk; six had indications other than fever; and five because the study physicians could not be found. The 137 nontreated infants were closely observed as outpatients. The duration of fever was less than 48 hours in 42%, and less than 96 hours in 91%. All infants were observed for at least 10 days after the last examination. The fever resolved spontaneously in all infants but two, with otitis media, who were treated as outpatients. Our data suggest that management of fever in selected young infants as outpatients is feasible if meticulous follow-up is provided.