Table 3. Misclassified Patients With SBIs^a.

Age, d	Qualifying Temperature, °C	YOS	Clinician Suspicion, %	Disposition of Infant After ED Visit	Urinalysis	WBC, /μL	ANC, /μL	Bands, %	PCT, ng/mL	CSF	SBI
30	38.1	6	6-10	Admitted	Negative	6700	2700	0 (B:N 0)	0.14	Negative	Enterobacter cloacae bacteremia
55	38.4	8	1-5	Discharged	Negative	3800	2200	3 (B:N 0.05)	0.20	Negative	Escherichia coli UTI
36	38.5	6	1-5	Admitted	Negative	2300	900	12 (B:N 0.3)	0.16	Negative	Pseudomonas aeruginosa UTI

Abbreviations: ANC, absolute neutrophil count; B:N, band-to-neutrophil ratio; CSF, cerebrospinal fluid; ED, emergency department; PCT, procalcitonin; SBI, serious bacterial infection; UTI, urinary tract infection; WBC, white blood cell count; YOS, Yale Observation Scale score.

^aThe first patient had Enterobacter cloacae bacteremia and was in the derivation data set. This patient was admitted to an observation unit for poor feeding without antibiotic treatment. After notification of the positive blood culture at 17 hours, a repeated blood culture was obtained, and the patient started receiving parenteral antibiotics. The repeated blood culture (prior to antibiotics) was negative and the patient was treated for 7 days with antibiotics, had an uneventful clinical course, and had a final diagnosis of transient bacteremia. The other 2 patients with SBIs who were misclassified were in the validation data set and had positive urine cultures with normal urinalyses (one with Escherichia coli growing 55 000 cfu/mL and the other with Pseudomonas aeruginosa growing >100 000 cfu/mL). Both were treated with uneventful courses.