GENETICAL STUDIES ON THE DRUG RESISTANCE OF STAPHYLOCOCCI.
Rept. no. 2 (Final) Aug 67-Aug 68,
GUNMA UNIV MAEBASHI (JAPAN) DEPT OF MICROBIOLOGY
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Naturally occurring strains of staphylococci which are resistant to chloramphenicolCM inactivate this antibiotic. One of the inactivation products of CM showed the chromatographic behavior of 3-acetoxychloramphenicol. Induction of resistance occurred after prior exposure to subinhibitory concentrations of the antibiotic. The resistance of induced populations, as well as CM-inactivation ability, was decreased when they were grown in CM-free medium. The CM-inactivation property was transduced together with CM resistance. Transductional analysis and CM-resistance elimination experiments indicated that CM resistance in naturally occurring strains of staphylococci is mainly accounted for by inactivation of the drug. A genetic analysis of resistance to tetracyclineTC, streptomycinSM, sulfanilamideSA, and penicillin GPC was carried out through transduction with phage lysates obtained from a multiple resistant strain of Staphylococcus aureus by ultraviolet irradiation. All transductants acquired resistance to both TC and SA, even when singly selected for either SA or TC resistance. The locus responsible for TC resistance could not be separated genetically from that for SA resistance. On the other hand, in transduction of SM resistance, about 30 of the transductants jointly acquired resistance to both TC and SA. These observations suggest that the loci governing resistance to TC, SA, and SM exist close together on a Single genetic unit, this probably being chromosome. Author
- Anatomy and Physiology