Assessing the significance of fever in young infants: the diagnostic and prognostic value of cerebrospinal fluid and other clinical and laboratory findings

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.

Practice guideline for the management of infants and children 0 to 36 months of age with fever without source. Agency for Health Care Policy and Research

STUDY OBJECTIVE

To develop guidelines for the care of infants and children from birth to 36 months of age with fever without source.

PARTICIPANTS AND SETTING

An expert panel of senior academic faculty with expertise in pediatrics and infectious diseases or emergency medicine.

DESIGN AND INTERVENTION

A comprehensive literature search was used to identify all publications pertinent to the management of the febrile child. When appropriate, meta-analysis was used to combine the results of multiple studies. One or more specific management strategies were proposed for each of the decision nodes in draft management algorithms. The draft algorithms, selected publications, and the meta-analyses were provided to the panel, which determined the final guidelines using the modified Delphi technique.

RESULTS

All toxic-appearing infants and children and all febrile infants less than 28 days of age should be hospitalized for parenteral antibiotic therapy. Febrile infants 28 to 90 days of age defined at low risk by specific clinical and laboratory criteria may be managed as outpatients if close follow-up is assured. Older children with fever less than 39.0 C without source need no laboratory tests or antibiotics. Children 3 to 36 months of age with fever of 39.0 C or more and whose WBC count is 15,000/mm3 or more should have a blood culture and be treated with antibiotics pending culture results. Urine cultures should be obtained from all boys 6 months of age or less and all girls 2 years of age or less who are treated with antibiotics.

CONCLUSION

These guidelines do not eliminate all risk or strictly confine antibiotic treatment to children likely to have occult bacteremia. Physicians may individualize therapy based on clinical circumstances or adopt a variation of these guidelines based on a different interpretation of the evidence.

What is fever? Normal temperature in infants less than 3 months old

To determine the normal temperature of healthy infants, we studied 691 infants less than 3 months of age being seen for regularly scheduled well-baby visits. All temperatures were taken rectally with an electronic thermometer. The mean temperature was 37.5 degrees C +/- 0.3 degrees C. Using a cutoff of 2 standard deviations (SD) above the mean, fever would be defined as a temperature > or = 38.1 degrees C. The 95th percentile was 38.0 degrees C, and > or = 38.1 degrees C would correspond to values above the 95th percentile. The most widely used definition of fever at present is a temperature > or = 38.0 degrees C; by this definition, 6.5% of these well infants would be considered to have a fever. A significant rise in temperature with age was noted. For infants from birth to 30 days old, 2 SD above the mean was 38.0 degrees C; for those 31 to 60 days old, it was 38.1 degrees C; and for those 61 to 91 days old, it was 38.2 degrees C. Similarly, the 95th percentile was 37.9 degrees C, 38.0 degrees C, and 38.1 degrees C, respectively. Temperature also varied significantly with the season of the year, being higher in the summer (2 SD above a mean = 38.3 degrees C) than in the winter (2 SD above a mean = 38.0 degrees C). Fever should be defined as a temperature > or = 38.0 degrees C in infants less than 30 days of age, > or = 38.1 degrees C in 1-month-olds, and > or = 38.2 degrees C in 2-month-olds.

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.

Febrile infants less than eight weeks old. Predictors of infection

Febrile infants less than eight weeks old frequently are admitted and receive parenteral antibiotics for treatment of possible sepsis. The authors assess 52 infants less than eight weeks old with a rectal temperature of 38.1 degrees C or higher as having either a readily identifiable focus of infection by physical examination, appearing "toxic" without a focus, or appearing well. The authors screened patients by using white blood cell (WBC) counts, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and chest radiographs in addition to blood, cerebrospinal fluid and urine cultures. The authors found a 9.6% incidence of bacteria in the 52 infants evaluated, with a 4.3% incidence in those febrile infants who appeared well. Five patients had positive blood cultures with Group B B Hemolytic streptococcus (four patients), and Viridans streptococcus (one patient). A clinical assessment of toxicity and a total band count greater than or equal to 0.5 x 10(3) cells/uL together were sensitive indicators of bacteremia, as were toxicity and a positive CRP. A "toxic" appearance, a WBC count greater than or equal to 15 x 10(3) cells/uL and an ESR greater than 30 were specific indicators of bacteria. Based on these data, identification of bacteremia in febrile infants may be possible with clinical assessment and screening laboratory tests. Because of the relatively small sampling size of this study, the authors feel that evaluation of a larger number of patients is warranted to evaluate these sensitivities in a more diffuse patient population.

Variability in the management of the febrile infant under 2 months of age

The management in the emergency department of febrile infants less than 2 months of age is influenced by the standard of practice in the community. We sought to determine if uniform practices existed across the United States. Individual academically based faculty from 154 (61%) United States pediatric residency programs responding to a questionnaire on the emergency department management of febrile infants less than 2 months of age showed great variability. Twenty-nine respondents reported written policies and 103 reported informal but defined guidelines for the evaluation and management of infants seen at their institutions. There was little consensus among the respondents as to the definition of fever in this age group. Those at institutions with formal policies reported using more laboratory tests in the evaluation. Respondents differed on the number and types of tests used and on antibiotic administration. University affiliation, type of population served, or presence of advanced training programs in ambulatory pediatrics were not related to the type of policy. The care of the young febrile infant varies greatly.