Per the Caviness study in The Pediatric Infectious Disease Journal: May
2008 - Volume 27 - Issue 5 - pp 425-430,
neonatal herpes is unrelated to RBCs in the CSF. Chronic herpes meningitis
in adults may be associated with some RBCs in the CSF, but for children the
RBCs should be considered part of a traumatic tap and their presence/absence
should not be allowed to mislead decision making. Just one more thing you
were taught in residency that has proven to be erroneous. Drop it in the
Given the U.S. pandemic of genital herpes since the 1980s, HSV is a more
likely pathogen than listeria.
However, asking the question in that form (incidence) misses most of the
risk/benefit equation. Ampicillin therapy carries much less risk of adverse
events than acyclovir. The risk of acyclovir increases further if your PCR
isn't back from the lab in 48 hrs. Ampicillin is very effective against
Listeria. Acyclovir's benefit to the patient (not the malpractice lawyer) is
Most studies of using CSF laboratory values to differentiate bacterial and
viral meningitis have not included many patients in the 5 week old age group
and I would suggest extreme caution in applying those rules in this
situation. In the largest study by Nigrovic et al.
they did go down to 29 days old. Their prediction model predicted "very low
risk" of bacterial meningitis in 1714 patients, about half the patients in
the study. The only 2 rule breakers, spoiling a 100% accurate model, were
both under 2 months of age. Kids are NOT small adults, neonates aren't small
children, and premees shouldn't be trusted under any conditions.
As a hospitalist who has admitted many neonates with completely normal lab
values for a two-day rule out, I'm not that concerned about admitting a
young infant with proven CSF pleocytosis for a day or two of observation.
Those cases aren't the ones breaking the health care financing bank. In the
Nigrovic study, 80% of children (not young infants, but all children) with
viral meningitis were admitted.
There is literature to support almost all neonatal HSV occurring before 3
weeks of age.
Acyclovir use in well appearing febrile neonates with CSF pleocytosis is a
marginal value to begin with:
Use of acyclovir beyond the 2 or 3 week age should be reserved for cases
with clear accompanying signs/symptoms, like seizures, obtundation, etc.
While nonvaccine strains of pneumococcus are becoming more prevalent, in
general high dose ampicillin remains the best empiric drug against sensitive
and intermediate strains as far as I have heard. I would reserve vancomycin
for probable cases of pneumococcus. For Group B strep, a more likely
pathogen at 5 weeks of age, amp and gent remains the best combination.
Kevin Powell MD PhD FAAP
Saint Louis, MO
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