Meningitis Prophylaxis


    Meningitis Prophylaxis

    Have you ever taken care of really critical, undifferentiated patient, only later to find out that they were diagnosed with a serious, contagious illness? We are exposed to innumerable pathogens each day in the ED, but there are only a few that necessitate antimicrobial prophylaxis and even fewer that require prophylaxis from simply being very close to the patient. Neisseria meningitidis, a common cause of bacterial meningitis, is one of these pathogens.

    Who gets treated? Essentially all close contacts. A close contact is defined as someone who has had prolonged (>8 hours) contact while in close proximity (<3 feet) to the patient, or someone who has been directly exposed to the patient’s oral secretions during the 7 days before the onset of patient’s symptoms and until 24 hours after antibiotic initiation.

    How do you treat? Three choices:


    • Adults (non-pregnant): 600mg every 12 hours for 2 days
    • Children >1 mo: 10 mg/kg every 12 hours for 2 days
    • Children <1 mo: 5 mg/kg every 12 hours for 2 days

    Ciprofloxacin (non-pregnant adults only)

    • 500mg ONCE


    • Adults: 250 mg single IM dose
    • Children <15 years old: 125 mg single IM dose

    So what about the IM vs IV routes? There was some thought that ceftriaxone should be give IM in order to get the “depot effect” (slow release at the injection site ensures constant stimulation of the immune system for production of high antibody titers). However, when you look at the package insert, the average plasma concentration 24 hours after 500 mg IV and 500 mg IM is essentially identical. The only difference is that the concentration of IM appears to be lower and more steady, whereas that of IV starts high and gradually declines.

    So, either way is fine. If the patient has an IV, go ahead and use that. If not, remember that the IM injection is REALLY painful. If you want to be kind, mix the ceftriaxone with some 1% lidocaine (see ALiEM post for how to do this below).

    Thanks to Dr. Kathy Li for inspiring this post!


    UpToDate on prophylaxis:

    ALiEM on IV vs IM:

    ALiEM on CTX + lido:

    • Welcome! This is the website for the Mount Sinai Emergency Ultrasound Division. It serves as an information resource for residents, fellows, medical students and others seeking information about point-of-care ultrasound. There is a lot ofRead more

    • renal handling of water

      If you were on a tea & toast diet, how much water would you need to drink before you develop hyponatremia? I haven’t seen anyone work out the numbers before so here are my calculations. AndRead more

    • acute acidemia physiology

      As alluded to in the first post, don’t be fooled by a “normal” potassium in the setting of DKA because osmotic diuresis and H+/K+ exchange means that total body potassium is actually LOW. You all knowRead more

    • renal handling of potassium

      the first symptom of hyperkalemia is death Earlier post covered temporizing measures to counter hyperkalemia — namely, intracellular shift, increasing cardiac myocyte threshold potential. Give furosemide if the patient still urinates and consider dialysis, but then askRead more

    • bicarbonate revisited

      Previous post reviewed the safety of balanced crystalloids in hyper K. But what was up with serum bicarbonate decreasing with saline administration? This post introduces a new way of looking at the anion gap to possiblyRead more

    • hyperkalemia and balanced crystalloids

      Is it safe to give LR or plasmalyte to a hyperkalemic patient (these balanced crystalloids have 4-5 mEq/L K as opposed to 0 mEq/L K in normal saline)? Postponing the discussion of renal handling of potassium toRead more

    • hyperkalemia physiology

      You’ll likely encounter hyperkalemia on your next Resus / Cardiac shift, and you’ll instinctively treat it. But take a moment to review the fascinating physiology behind the “cocktail”! First, consider how K+ is buffered byRead more

    • Slow down your tachycardia (but not really)

      You’re sitting in resus bemoaning the departure of your most beloved attending when suddenly a patient wheels in without warning. The patient looks relatively stable but the triage RN tells you her heart rate wasRead more

    • Otitis externa: use the ear wick!

      Acute otitis externa (AOE) is a common complaint seen in pediatric as well as adult emergency departments. AOE is typically not accompanied by acute otitis media, although concurrent cases are possible. Also called “swimmer’s ear”Read more