Wilbur D. Jones

Bacteriopmage typing of Mycobacterium tuberculosis cultures from incidents of suspected laboratory cross-contamination

Bacteriophage typing was performed on 235 Mycobacterium tuberculosis cultures submitted from 31 laboratories. In each instance, either the attending physician questioned the misdiagnosis of tuberculosis or the laboratory supervisor suspected that laboratory cross-contamination had occurred. Phage typing data confirmed these suspicions. Phage typing is a useful adjunct in the investigation of suspected cross-contamination of laboratory cultures of M. tuberculosis.

Preliminary observations on the occurrence of a streptomycin R-factor in Mycobacterium smegmatis ATCC 607.

Abstract Evidence is presented to demonstrate that Mycobacterium smegmatis ATCC 607 has two forms of resistance to streptomycin dihydrochloride: (l) a genetically stable resistance that is not determined by the inactivation of the antibiotic; (2) a genetically unstable resistance that is determined by the synthesis of an inducible enzyme that inactivates the antibiotic. The latter form of resistance is eliminated by ultraviolet light and acriflavine treatment and is transducible at high frequency by mycobacteriophage D29. On the basis of this, evidence, it is suggested that the genetically unstable form of resistance is caused by extrachromosomal genetic determinants (R-factors).