[Determination of Streptomyces coelicolor A3(2) resistance to erythromycin]. / Determinatsiia ustoichivosti Streptomyces coelicolor A3(2) k éritromitsinu.

Resistance to erythromycin is genetically unstable in strains of Streptomyces coelicolor A3(2). The frequent loss of resistance as well as reversion of sensitive variants to the original unstable resistance phenotype excluded the possibility that plasmid elimination is involved. The spontaneous frequency of occurrence of sensitive clones was 0.14 to 1.5%, the rate of reversion ranging from 1.10(-6) to 1.10(-8). Resistance to erythromycin has been mapped on the chromosomes of two S. coelicolor A3(2) derivatives in different sites: between markers adeC (v 10) and ArgA1 in the strain A617, between pheA1 and SCP1 in the strain S18. It is suggested that genetic instability of erythromycin resistance determinants having chromosomal location is due to transposition of genetic material.

[Study of natural mutiple drug resistance in actinomycetes of the genus Streptomyes]. / Izuchenie prirodnoi mnozhestvennoi lekarstvennoi ustoichivosti u aktinomitsetov roda Streptomyces.

Natural strains of actinomycetes belonging to 3 systematic groups of the Streptomyces genera, i.e. blue, gray and globisporine were characterized for their resistance to antibiotics and sulfamids. The majority of the strains were shown to have stable inherited multiple resistence to a wide variety of antibiotics. Linkage analysis for resistance determinants in pairs showed random distribution of most of the determinants among the members of the blue and grey groups of the actinomycetes. Non-random distribution of the resistance determinants to Tc, Cm and Rm in TcCm, TcRm conbinations for the blue group actinomycetes and to Om, Rm, Fa, Lm, Em, Rm and Tc in OmRm, FaLm, EmPm, TcOm combinations among the members of the grey group of actinomycetes was found.

[Multiple antibiotic resistance in actinomycetes]. / Mnozhestvennaia ustoichivost' k antibiotikam u aktinomitsetov.

Native strains of Actinomycetes from three systematic groups of Streptomyces (blue, gray and globisporine) have been characterized for their resistance to antibiotics and sulfamids. Most strains are found to possess stably inheritable multiple resistance to many antibiotics. The resistance of a number of strains to the aminoglycoside antibiotics and penicillins appears to be due to the presence of inactivating enzymes in these strains. The resistance to erythromycin, lyncomycin, tetracycline and ristomycin is likely to have an inducible nature in S. coelicolor A3(2). Linkage analysis for resistance determinants in pairs suggests random distribution of the majority of determinants among tested strains. Non-random distribution has been shown for determinants of resistance to tetracycline, chloramphenicol and ristomycin in Tc Cm, Tc Rm combinations.