3 groups of infants:
- Neonates <30 days (i.e < 1month)
- Young infants 30-90 days (i.e < 3months)
- Old infants 3 months-1 year
- Young children 1 year-3 years
Let’s classify the infants into low and high risk:
- The most widely used is Rochester criteria (applied to <2 months infants)
- Toxic looking infants is a no brainer for us.
- What about well appearing infants? Which criteria should we be using?
Risk of SBI (serious bacterial infection) in well appearing group according to ages:
Summary is excpet in neonates, the risk of occult SBIs in infants (>1 month) is ~2-4% if focal infections (including otitis media) have been excluded and low risk lab criteria (i.e no leucocytosis, UFEME is clean and stool WBC is negative).
- Low risk criteria is controversial in them. In view of the 7% risk of occult SBI, a full septic workup should be done in every febrile infant, including getting a LP.
2. Young infants (not vaccinated yet)
- Apply Rochester criteria + UFEME.
- Routine LP is (maybe) not indicated.
– However, this is controversial. Some other criteria eg Philadelphia use LP to stratify infants into low risk category while some others eg Rochester do not use.
– In five studies of the risk of SBIs in infants < 3 months of age in which examination of CSF was not performed,
872 of 1,713 febrile young infants with FWS were classified as low risk. Ten had an SBI; none had occult meningitis.
- CXR should be done if the febrile infant has leucocytosis, fever>1 days, cough/other resp.signs or abnormal auscultatory findings. Use of pulse oximetry may also help in deciding whether a CXR should be done, although a normal pulse oximetry does not exclude occult pneumonias.
- If the infant has diarrhea, make sure no blood (not dysenteric) and stool WBC should be done. Stool culture should be done if stool WBC is positive.
3. Older infants (vaccinated)
- Rochester criteria is NOT validated in this group of infants.
- Vaccination reduces the risk of pneumonia and meningitis, but it is not to risk = 0.
- Occult bacteremia in this group is usually due to Salmonella (most have diarrhea) or N.meningitidis.
– If patient has diarrhea, stool WBC should be done.
– Unfortunately, no way to detect occult meningococcemia unless if there are physical signs.
– Compared to occult pneumococcal infections, occult Salmonella bacteremia and meningococcemia often have NORMAL WBC count.
- Routine UFEME (by urethral catherization) should be done in febrile infants (>39 celcius):
– In all circumsized males < 6 months
– In all females and uncircumsized males <24 months
– In infants with prior history of UTI (possibility of urinary tract anatomic anomalies)
- Pyuria is falsely negative in 20%, use of leucocyte esterase and/or nitrite together will increase sens & spec.
- Occult pneumonias are most probably(and mostly) due to viral infections.
– bacterial pneumonia is often secondary to viral infections. However, CXR and lab cannot differentiate viral vs bacterial
– Need to identify those who need CXR:
i) Febrile + resp.signs or abnormal ausc.findings
ii) Leucocytosis (WBC >20,000: more likely to be bacterial)
Larry J. Baraff, MD. Management of Infants and Young Children with Fever without Source. PEDIATRIC ANNALS 2009:37(10);673-79