Usefulness of Low Risk Criteria for Serious Bacterial Infection Among Febrile Infants Younger than Three Months of Age

ABSTRACT

PURPOSE: A retrospective study was undertaken to evaluate the usefulness of low risk criteria for identifying febrile infants younger than three months unlikely to have serious bacterial infection. METHODS: We conducted a retrospective study of 527 infants younger than three month with a axillary temperature >or=37.4degrees C. If they met the following all four criteria, appear well, WBC 5,000-20,000/mm3, urine stick WBC(-) and nitrite(-), CSF WBC <10/mm3, they were considered at low risk for serious bacterial infection(SBI). SBI was defined as a positive culture of urine, blood, or cerebrospinal fluid. The sensitivity, specificity, negative predictive value and positive predictive value of the low risk criteria were calculated. RESULTS: Of 527 febrile infants, 110(21.0%) had serious bacterial infections. The 2.7% who met the low risk criteria had SBI and negative predictive value was 97.3%. SBI was diagnosed in 103 infants(38.6%) who didn't meet the low risk criteria including urinary tract infection(78.6%), most commonly, bacteremia(16.5%), bacterial meningitis(8.7%), Salmonella gastroenteritis(1%), osteomyelitis(1%), septic arthritis of hip joint(1%). There were no differences in the sensitivity and negative predictive value according to the monthly-age-group. CONCLUSION: This low risk criteria to identify infants unlikely to have SBI early is available, however low risk infants must be carefully observed.