Diagnostic testing for serious bacterial infections in infants aged 90 days or younger with bronchiolitis

Objectives: To describe the different laboratory tests that are performed o n young infants aged 90 days or younger with bronchiolitis and to identify historical and clinical predictors of infants on whom laboratory tests are performed. Design: Cross-sectional study whereby information was obtained by retrospec tive review of medical records from November through March 1992 to 1995 of all infants with a clinical diagnosis of bronchiolitis. Setting: Urban pediatric emergency department. Patients: Two hundred eleven consecutive infants aged 90 days or younger (m edian age, 54 days) with 216 episodes of bronchiolitis. Main Outcome Measures: Historical and clinical data on each infant in addit ion to laboratory data that included a white blood cell count, urinalysis, and blood, urine, and cerebrospinal fluid cultures. Results: Two or more laboratory tests (not including chest radiographs) wer e obtained in 48% of all infants and 78%, of febrile infants. Of the 91 inf ants with a history of a temperature of 38.0 degrees C or more or temperatu re on presentation of 38.0 degrees C or moro, white blood cell counts were obtained in 77%, blood cultures in 75%, urinalyses in 53%, urine cultures i n 60%, and analyses-cultures of cerebrospinal fluid in 47%. Febrile infants were 10 times more likely to get at least 2 laboratory tests than afebrile infants (P<.01), All 6 studies were done in 42 (58%) of 72 febrile infants compared with 7 (16%) of 43 afebrile infants (P<.001). Multiple logistic r egression analysis identified a history of a temperature of 38.0 degrees C or more or temperature on presentation of 38.0 degrees C or more (odds rati o [OR] 10.0; 95% confidence interval [Cr],4.8%;-21.0%; P<.001), oxygen satu ration less than 92%;, on presentation (OR, 4.7; 95% CI, 1.9%-12.1%; P <.01 ), and history of apnea (OR, 0.1; 95% CI, 0.02 - 0.35; P<.001) as significa nt clinical predictors of whether laboratory studies were obtained. History of preterm gestation, aged younger than 28 days, previous antibiotic use, and presence of otitis media were not associated with obtainment of laborat ory studies. No cases of bacteremia, urinary tract infection, or meningitis were found among all infants with bronchiolitis who had blood, urine, and/ or cerebrospinal fluid cultures. Conclusion: There is nide variability in the diagnostic testing of infants aged 90 days or younger with bronchiolitis. The risks of bacteremia, urinar y tract infection, and meningitis in infants with bronchiolitis seems to be low. History or a documented temperature of 38.0 degrees C or more; oxygen saturation of less than 92%, and history of apnea were associated with lab oratory testing for bacterial infections.