Transfer of multiple antibiotic resistance between subspecies of Bacteroides fragilis.

Resistance to clindamycin, erythromycin, streptogramins, and tetracycline was shown to be transferable from a clinical isolate of Bacteroides fragilis subspecies distasonis to a sensitive strain of B. fragilis subspecies fragilis. Resistance to clindamycin, erythromycin, and streptogramins was transferable from a clinical isolate of B. fragilis subspecies fragilis to the sensitive strain of B. fragilis subspecies fragilis. Except for tetracycline, resistance to all of these antibiotics was spontaneously curable en bloc at a frequency of approximately 10(-2). These results suggest that resistance to these antibiotics is determined by a plasmid.