AOM Pearls

Question 1

What are the likely organisms?

Answer 1

S. pneumoniae
H. influenzae
M. catarrhalis

Question 2

What is the result of the introduction of the pneumococcal vaccine?

Answer 2

S. pneumo leading to AOM is less/less DRSP as well

BUT H. flu is rising

Question 3

Why does the initial therapy for AOM target S. pneumo?

Answer 3

1) It is the most common organism
2) causes the most complications (morbidity)
3) Least likely to remit spontaneously

Question 4

What is the DRSP mechanism? Is amox-clav effective for AOM?

Answer 4

No beta-lactamase production, via binding site alterations instead.
Amox-clav is no better than plain amox!
We can often overcome intermediate resistance with agressive dosing.

Question 5

What is the H. flu mechanism of resistance?

Answer 5

40-50% resistant by beta-lactamase production
H. flu has 6 capsulated antigens, b is most virulent (Hib vaccine)
- no impact to AOM b/c strains are unencapsulated

Question 6

H. flu genus name meaning?

Answer 6

Blood loving
Requires x factor and V factor, released by RBCs
Grows on chocolate agar (hemolyzed RBCs)