ROLE OF ENCAPSULATED BACTEROIDES SP IN UPPER RESPIRATORY-TRACT INFECTION

Bacteroides sp. are part of the normal oral and vaginal flora and have emerged as the predominant isolates from respiratory tract infections and bacteremias associated with these infections. Bacteroides melaninogenicus and Bacteroides oralis were recovered from aspiration pneumonia, lung abscesses, chronic otitis media, sinusitis, periodontal disease, and periapical abscesses. Bacteroides corrodens was isolated from periodontal and lung abscesses, and from patients with aspiration pneumonia. Bacteroides ruminicola has been recovered from these sites as well as from peritonsillar abscesses, chronic sinusitis, and mastoiditis. Although Bacteroides fragilis is not generally found as part of the normal oral flora, it can colonize the oral cavity of patients whose oral hygiene is poor. This organism can also be recovered in infections that originate from this area, such as aspiration pneumonia, lung abscesses, chronic sinusitis, chronic otitis media, and brain abscesses. Until recently, B. melaninogenicus and B. oralis were considered susceptible to penicillins. However, penicillin-resistant strains have been reported with increasing frequency in upper respiratory tract infections. These include chronic otitis media and mastoiditis, periodontal and peritonsillar abscesses, and cervical lymphadenitis. The appearance of penicillin resistance among Bacteroides has important implications for chemotherapy, as penicillin therapy directed against a susceptible pathogen might be rendered ineffective by the presence of a penicillinase-producing organism.