Bilateral otitis media with conjunctivitis is suggestive of Haemophilus influenzae and treatment is with Amoxicillin-clavulanate as H influenzae commonly produces a beta-lactamase.
Most cases of otitis media are mixed infections with both viral and bacterial pathogens. The most common bacterial pathogens are Streptococcus pneumoniae, nontypeable Haemophilus influenzae, and Moraxella catarrhalis.
Around half of H influenzae isolates from otitis media cases produce a beta-lactamase making them resistant to amoxicillin. These strains would be covered by Amoxicillin-clavulanate or a second or third generation cephalosporin. Otitis media with conjunctivitis is suggestive of H influenzae and Amoxicillin-clavulanate acid is typically used for these infections.
Reference:
Lieberthal AS, Carroll AE, Chonmaitree T, Ganiats TG, Hoberman A, Jackson MA, Joffe MD, Miller DT, Rosenfeld RM, Sevilla XD, Schwartz RH, Thomas PA, Tunkel DE. The diagnosis and management of acute otitis media. Pediatrics. 2013 Mar;131(3):e964-99. PMID: 23439909