Studies on multiple antibiotic resistance in obligate anaerobes.

Forty-eight Gram-negative obligate anaerobic bacterial strains were isolated from faeces on selective media and their antibiotic resistance spectra were determined. R factor transfer was not detected in a series of experiments involving matings among the anaerobes, nor between the anaerobes and known donor and recipient facultative E. coli strains. Antibiotic resistance plasmids could not be demonstrated by treatment with acridine dyes and ethidium bromide in four multiply-resistant strains.