THE CLINICAL CHARACTERISTICS AND INFECTIOUS OUTCOMES OF FEBRILE INFANTS AGED 8 TO 12 WEEKS

We reviewed 356 consecutive cases of febrile infants aged 8 to 12 week s who received outpatient evaluation for sepsis over 4 years. Thirty-t hree infants (9.3%) had a serious bacterial infection (SBI), including bacterial meningitis, bacteremia, urinary tract infection (UTI), and Salmonella enteritis. The SBI rate, which was directly proportional to fever height, was significantly greater for infants with hyperpyrexia (35%) than those with lesser degrees of fever (7.7%) and for infants with peripheral blood leukocytosis (total WBC count greater-than-or-eq ual-to 15,000/mm3; 25%) than those with lesser total WBC counts (5.8%) . An attending-level physician judged that 67% of infants with SBI app eared to be ''well,'' including five of eight cases (63%) of bacteremi a, 14 of 17 cases (82%) of UTI, and all three cases of Salmonella ente ritis, whereas all five patients with bacterial meningitis appeared to be ''ill.'' Urinalysis abnormalities indicative of UTI were present i n 15 of 17 infants (88%) who had this infection. SBIs are not uncommon in febrile infants aged 8 to 12 weeks and occur significantly more of ten in those with either hyperpyrexia or peripheral blood leukocytosis .