Last week I mentioned that, at times, you realize that what you were taught may have been … hmm… not fully correct. Recently a colleague raised a great question: in the infant (6 week old) who has a positive urinalysis, do you need to spinal tap? Well Dr. Listwa, it appears that it is a popular question to ask and what follow is the best answers that I could find… and represents my interpretation of the opinion of several respected people’s approach (sorry, no gold standard here).
a) UTI and infants
(1) Very common cause of pyrexia in young children presenting to the hospital (1-15%).
(2) Concurrent bacteremia in infants with UTI has been found to occur in 4-10%.
(3) Because of the permeable blood-brain barrier in the very young, meningitis is a concern for those with bacteremia.
(4) When UTI and meningitis are truly concurrent, it is often the same pathogen that is responsible for both (ex, gram-negative bugs).
ii) Research issues
(1) There are a multitude of studies that look at concurrent UTI and meningitis infants, but many have inherent flaws.
(a) How urine is obtained varies between studies.
(b) How UTI is defined varies between studies.
(c) Who received an LP to define co-infection also varies (those that were sicker looking often did, while those well appearing didn’t).
(2) Comparing studies is difficult.
(3) Recently this has been re-addressed with a retrospective study and meta-analysis (both, which have their inherent issues, but we won’t likely see a prospective, double-blinded case control study with thousands of patients on this subject ever).
b) Neonate (<28 days)
i) Have the greatest risk.
ii) Most likely to have concurrent bacteremia with UTI.
iii) Have most immature and permeable blood-brain barrier.
iv) Tebruegge found that risk of concurrent meningitis with UTI is as high as 4.36%.
c) Infants (>28 days)
i) Naturally there is a spectrum between 29 days and school-aged kids, but the collective group has been shown to have a low risk for concurrent meningitis with UTI.
ii) Tebruegge found this risk to be between 0% and 0.74% (so, very low).
d) My take on this (far from Gold Standard – lead or zinc perhaps):
i) Studies often fall short of truly answering clinical questions when it comes to individual patients.
ii) Your clinical exam is imperative.
(1) If the kid looks toxic or something doesn’t sit right with you in your gut… do everything even if you found a “source.”
(2) If the kid is too young for your exam to be reliable, then you should err on the side of being conservative.
(a) The neonate with a UTI still gets a full work-up with an LP. Finding a “source” only makes me more suspicious of meningitis in a neonate.
(b) We all have our own comfort with specific age groups. If you are not confident in the 12 week-old’s exam, be conservative.
(3) Always keep in mind that kids love to fool us… infants with E.coli meningitis can look well until they stop being all together (kind of like HSV).
iii) Be internally consistent!
(1) If you start the work-up for the 1-3 month old with a fever without a source using Rochester criteria and find a positive urinalysis, you have defined the child as being high-risk for serious bacterial infection. You haven’t necessarily “found a source.”
(2) In the ED (or initial clinic visit) it is not likely that you will actually be able define a source in these kids. As we know, it is the culture results that are the true determinant.
iv) Consider the next step.
(1) Management of meningitis and UTI are significantly different (naturally).
(2) The IM/IV ceftriaxone would cover both fairly well, but kids with UTI get transitioned to oral cephalosporins rather quickly now (like the next day).
(3) The oral cephalosporin you give to the UTI will not benefit the child with gram-negative meningitis.
(4) I personally still have trouble giving a 6-week-old ceftriaxone without having CSF.
v) Age breakdown:
(1) Neonate (<29 days)
(a) Do everything… do it quickly… and start the abx ASAP.
(2) 29 – 60 days
(a) The odds are in your favor that there is not a concurrent UTI with meningitis.
(b) However, I don’t gamble (really at all, but particularly with <2 month olds).
(c) I prefer to stay internally consistent with this group. Rochester Criteria analyzed: positive u/a places child at high risk and therefore gets the LP with the abx.
(3) 2 – 3 months
(a) The one is tougher for me personally… because the odds are now even more against concurrent meningitis with UTI… but, with regards to the two organs we are dealing with here, I am more concerned about the brain than the kidneys.
(b) This will likely involve a long conversation with the family and weigh the risks and benefits.
(c) Also, involving the admitting team in the decision would be paramount.
(4) >3 months
(a) Still the risk is not zero… but I am much more comfortable sending of the blood cultures and starting antibiotics for the UTI. If the blood cultures returned positive, then the kid likely needs an LP.
(b) You wouldn’t be wrong to LP from the start… but I get the sense that the further away you get from the 2 month age the less likely practitioners are to LP.
I extend my great appreciation to Dr. Amina Ahmed, our Peds ID guru, and Drs. Randy Cordle and Stacy Reynolds, our Ped EM Masters.
If you have more to add to this conversation, please feel free to do so via the “comment” section below.
Tebruegge M, Pantazidou A, Clifford V, Gonis G, Ritz N, et al. (2011) The Age-Related Risk of Co-Existing Meningitis in Children with Urinary Tract Infection. PLoS ONE 6(11): e26576. doi:10.1371/journal.pone.0026576
Tebruegge M, Pantazidou A, Curtis N. How common is co-existing meningitis in infants with urinary tract infection? Arch Dis Child 2011; 97:602-606. doi:10.1136/adc.2011.215277