Should amoxicillin still be the first line treatment for this common pediatric ailment? A late night rundown of Rx options.
It’s about midnight in the Pediatric ED and you enter room 6 to see two exhausted and disheveled parents with a very cranky 14-month old daughter. She has had a cough, congestion, runny nose and low-grade fever for several days and tonight woke up crying and wouldn’t settle down. She’s been a fairly healthy child and doesn’t have any significant past history. She is fully immunized and has been a regular in daycare since her mom went back to work about two weeks ago. Before starting daycare she was never sick and this is the first time she has had a fever. On exam she has a temperature of 39.3 rectally. She is fussy and clingy but consoles appropriately with her parents. Her little nose is running like a faucet and the crying has accentuated this. Her TMs are red, opaque and bulging bilaterally. The remainder of her exam is unremarkable.
Ok, this little girl has acute otitis media and she meets criteria for treating with antibiotics (temperature greater than 39 degrees, bilateral acute otitis media in a child 6 months to 23 months of age). You direct the nurse to give her some ibuprofen for her ear pain and sit down to write the prescription. Amoxicillin, right?
Is amoxicillin really the best choice here? There is nothing like the middle of the night to get one philosophical about life’s great questions. Could you make a better case for augmentin?
You don’t really know which bug is causing this child’s ear infection but the usual suspects are Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis. All three have been known to exhibit antibiotic resistance. Resistant strains of S. pneumoniae generally respond to treatment with high-dose amoxicillin (80-90 mg/kg/day). That’s less likely to be successful with H.influenzae or M.catarrhalis. Their mechanism of resistance is the production of beta-lactamase. Amoxicillin-clavulanate potassium (augmentin) overcomes this mechanism. So maybe you should prescribe augmentin.
Ok, if this infection is due to S. pneumoniae than high-dose amoxicillin is the best option. If the infection is due to H.influenzae or M.catarrhalis then augmentin is the better choice. How do you weigh your choices? Any other options?
What About Vaccinations?
High-dose amoxicillin is the best choice only if you’re dealing with S. pneumoniae. So what is the likelihood of that? In the days before the conjugate pneumococcal vaccine S. pneumoniae was the dominant organism causing acute otitis media. The first conjugate vaccine, PCV 7, was introduced in 2000. It was active against seven serotypes of S. pneumoniae. In the first few years after widespread use of the vaccine the incidence of S. pneumoniae cultured from middle ear aspirates declined and the incidence of H.influenzae increased to the point where its frequency exceeded that of S. pneumoniae. That would argue for using augmentin, rather than amoxicillin, as the first line of therapy for otitis media. However, later studies showed the incidence of S. pneumoniae rising as serotypes not covered by the vaccine became more prevalent, to the point where it ran neck and neck with H.influenzae. Fine, maybe you’re back to high-dose amoxicillin.
Ah, but the plot thickens. Enter PCV 13, the new conjugate vaccine active against 13 serotypes of S. pneumoniae including the ones that emerged to cause trouble after the PCV 7 vaccine came along. It is highly likely that this new conjugate vaccine, introduced in 2010, will again cause the proportion of ear infections due to S. pneumoniae to go down with a corresponding increase in infections due to H.influenzae. It’s like a see-saw; down goes one and up goes the other. If the odds are greater that the infection is due to H.influenzae than to S. pneumoniae then we should be using augmentin.
What about M.catarrhalis? If you are looking at beta-lactamase, your average M.catarrhalis is even more likely to produce this than your average H.influenzae. However M.catarrhalis seems to be a bit player in all of this. The ear infections it causes are more likely to resolve spontaneously than those due to the other two organisms and are less likely to produce serious complications, such as mastoiditis. It has never been as frequent a cause of infection. So it probably doesn’t need to come into your calculus.
Which Antibiotic is Best?
It is late and your brain is too tired to keep up with all these arguments. You still have to write this prescription. It seems like augmentin, not amoxicillin, should be your drug of choice here. Any downsides?
To start with, augmentin tastes bad, although the pharmacist can add a flavoring agent so that isn’t much of an obstacle. Augmentin is more likely to cause diarrhea and diaper rash than is amoxicillin, but the diarrhea is not that bad and the rash can be overcome with a good diaper paste. If the bug happens to be a resistant S. pneumoniae then augmentin may not have a high enough concentration of amoxicillin to overcome that resistance. That could be dealt with by using augmentin ES, which is formulated to allow you to give high-dose amoxicillin without bumping up the amount of clavulanate potassium, thus keeping the side effect profile the same as regular augmentin.
And then there is the cost issue. At your local Walmart, a 10-day course of amoxicillin will run you $4. A 10-day course of augmentin will be about $39. Ten days of augmentin ES gets you to about $49. The cost of a return visit if the initial treatment fails also needs to be considered.
Ok, enough already. Time to get this child and her tired parents out of here. You prescribe augmentin. Given the current bacteriology of acute otitis media, this seems to you to be a better choice than amoxicillin. You forego augmentin ES due to cost and the decreased likelihood that you are covering S. pneumoniae.
Amy Levine, MD, is an associate professor of pediatric emergency medicine at UNC Chapel Hill.
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