Evaluation of fever in infants less than 8 weeks old.

We evaluated fever in 342 hospitalized infants less than 8 weeks of age. Sixteen infants (5%) had bacteremia or bacterial meningitis. Fifty-two percent of the infants were admitted during the months of July through September. We found no significant relationship between season, sex, height of fever, or erythrocyte sedimentation rate and the recovery of bacteria from the blood or CSF. A WBC less than or equal to 5,000/cu mm or a ratio of immature to total neutrophils greater than or equal to 20% correlated significantly with bacteremia or bacterial meningitis, though the sensitivities of these tests were unacceptably low. Prospectively, of 61 infants whose clinical appearance did not suggest sepsis, none had bacterial pathogens in the blood or CSF, whereas four of 36 infants with a septic appearance did have pathogens. Recent investigations support the initial clinical impression as important in assessing these febrile infants. We found that bacteremia is more likely to occur in infants less than 4 weeks of age (8%) than in the older infants (2.9%).