Bacteraemia due to a rifampicin-resistant strain of Bacteroides fragilis

A strain of Bacteroides fragilis with high-level chromosomal resistance to rifampicin was isolated by blood culture from a patient with bacteraemia after gastrointestinal surgery. He had been receiving antituberculous therapy with rifampicin for nine months. This resistance led to some difficulty in the recognition and identification of the isolate by methods that depended upon antibiotic sensitivity patterns.