TRANSFERABLE LINCOSAMIDE-MACROLIDE RESISTANCE IN BACTEROIDES

Inter- and intraspecies transfer of resistance to clindamycin, lincomycin, and erythromycin in the strict anaerobe, Bacteroides, is described. This lincosamide-macrolide resistance was found to be specified by a 27 × 106-dalton plasmid, designated pBF4, originally identified in a clinical Bacteroides fragilis isolate. Transfer of this plasmid to a strain of Bacteroides uniformis was demonstrated to occur by a deoxyribonuclease insensitive process which required cell-to-cell contact. Chloroform sterilized donor cell supernatants or filtrates of donor cells did not mediate resistance transfer. Transfer of the antibiotic resistance and pBF4 plasmid deoxyribonucleic acid (DNA) were always coincident. Drug resistant progeny recovered from such matings were able to transfer the pBF4 plasmid and its associated resistance markers to a suitable B.fragilis recipient strain. Compared to interspecies matings, resistance transfer was 100- to 1000-fold greater between isogenic donor and recipient strains, suggesting the possibility of a host controlled restriction-modification system. © 1979.