Experimental otitis media with Moraxella (Branhamella) catarrhalis.
Two hundred fifty gerbils and 7 chinchillas were utilized in 11 experiments to determine the effect of inoculating viable and heat-killed suspensions of Moraxella (Branhamella) catarrhalis into the middle ear cavity. Development of otitis media was observed by otoscopy and histopathology. Gerbils were found to be susceptible to 2 x 10(4) viable M catarrhalis cells. Depending on the number of cells inoculated, the resulting untreated inflammation was a very mild to moderately severe, self-limiting disease with no permanent sequelae except in animals inoculated with high [10(6) to 10(7)] numbers of bacteria. Viable bacteria could not be isolated from the middle ears 24 hours after inflammation was induced. Heat-killed cells produced less severe acute inflammation with no permanent sequelae. We conclude 1) gerbils and chinchillas are susceptible to a self-limited inflammation caused by M catarrhalis, 2) no infection occurs, since viable bacteria cannot be recovered from middle ear aspirates, and 3) viable cells produce more severe inflammation than heat-killed cells.
Fulghum
R S
RS
Department of Microbiology and Immunology, School of Medicine, East Carolina University, Greenville, North Carolina, USA.
Marrow
H G
HG
D000818:Animals; D002682:Chinchilla; D004432:Ear, Middle / Q000382:microbiology / Q000473:pathology; D005849:Gerbillinae; D006097:Granulation Tissue / Q000382:microbiology / Q000473:pathology; D001936:Moraxella catarrhalis / Q000472:pathogenicity*; D010033:Otitis Media / Q000209:etiology / Q000382:microbiology* / Q000473:pathology