Studies on experimental anaerobic infections of the middle ear and on the polymorphonuclear leukocyte function under anaerobic conditions
1984 (English)Doctoral thesis, comprehensive summary (Other academic)Text
Despite the clinical importance of anaerobic bacteria in otitis media and the uncertainty regarding the proper treatment of the anaerobic focal infection, few experimental studies focused upon the role of these microorganisms in otitis media have been published. In the present investigation a guinea-pig model for the induction of anaerobic monoinfections in the middle ear was described. Bacteroides fragilis and Propionibacterium acnes (4.0-10x10 colony forming units) injected via the tympanic membrane were capable of inducing clinical and histological otitis media with persistent seguele in the middle ear cavity. Bacteroides asacc-harolyticus, Peptostreptococcus micros and Peptost repto- coccus anaerobius failed to induce otitis media.
B. fragilis otitis was accompanied by increased serum IgG and IgM antibody titres against the challenge organism, whereas P. acnes and P. anaerobius did not induce a humoral immune response. The results suggested true virulence of B. fragilis in guinea-pig middle ear monoinfections.
Metronidazole was found to accelerate the elimination of B.fragilis from the middle ear. However, even high doses of metronidazole were nojt fully effective perhaps reflecting an incomplete anaerobiosis at the site of infection in some instances. At present, nitroimidazoles in chronic otitis media must be regarded as a possible alternative reguiring further study, particularly with regard to the dosage.
In order to gain further knowledge of the interaction between polymorphonuclear leukocytes and bacteria under anaerobic conditions an in vitro model was established. It was shown that P. acnes was readily phagocytosed with the aid of C3 activated either via the classical or alternative pathway and that killing of P. acnes was inefficient during anaerobiosis. The results suggest that P.acnes is maintained in the pus in chronic otitis media because it survives phagocytosis.
Finally, the interaction between the most common pathogen in acute purulent otitis media, Streptococcus pneumoniae, and human polymorphonuclear leukocytes under anaerobic conditions was studied. Since purulent maxillary sinus effusion (and probably also purulent middle ear effusion), invariably has a pO^ approaching zero, such studies are highly relevant with regard to the host defence in sinuitis and perhaps also in otitis media.
S. pneumoniae was killed by the phagocytes under anaerobic conditions although at a slower rate than in air. Degradation of pneumococcal teichoic acid, DNA and RNA took place after phagocytosis under aerobic as well as anaerobic conditions, whereas degradation of unsaturated cell membrane lipids took place only under aerobic conditions. Furthermore, the pneumococcal autolytic system did not participate in the killing or the degradation of the bacteria.
Place, publisher, year, edition, pages
Umeå: Umeå universitet , 1984. , 65 p.
Umeå University medical dissertations, ISSN 0346-6612 ; N.S., 127
Otitismedia, anaerobicbacteria, experimental, nitroimidazoles, antibody, phagocytosis, anaerobiosis
IdentifiersURN: urn:nbn:se:umu:diva-118694OAI: oai:DiVA.org:umu-118694DiVA: diva2:924199
1984-06-12, Farmakologens föreläsningssal, Regionsjukhuset i Umeå, Umeå universitet, Umeå, 09:00
Diss. Umeå, Umeå universitet, 1984, härtill 6 uppsatser2016-04-282016-03-292016-04-28Bibliographically approved