An Animal Model of Acute Otitis Media Consequent to β-Lactamase-Producing Nontypable Haemophilus Influenzae

Abstract

A chinchilla model of acute otitis media with effusion consequent to β-lactamase-producing nontypable Haemophilus influenzae was developed using the method of direct inoculation of 145 colony-forming units (CFU) or 252 CFU of β-lactamase—producing nontypable H influenzae into the right superior bullae of 40 chinchillas. The course of the disease was documented longitudinally by otomicroscopy, tympanometry, and periodic culturing of the middle ears. Onset of the disease occurred in 100% of the animals between two and six days postinoculation and resolution was complete in all ears by day 36. Results of rechallenge with the same organism support the combined effect of a local and weaker systemic middle ear protective mechanism rendering resistance to reinfection with a homologous organism in the chinchilla.