Temperature sensitivity of R-plasmid transfer by clinical strains of bacteria of the family Enterobacteriaceae
Belokrysenko, S.S.; Riazanova, L.A.; Dugasheva, L.G.; Beloborodov, I.V.
Antibiotiki 25(2): 112-117
1980
ISSN/ISBN: 0003-5637 PMID: 6986843 Document Number: 161423
The temperature optimum for conjugation transfer of 19 plasmids by 14 clinical strains of Enterobacteriaceae with multiple resistance was studied. The cultures were isolated from specimens of patients with infections of nonintestinal localization. All of the strains studied had a capacity for conjugation transfer of the plasmid controlling the drug resistance by the recipient strain of E. coli K 12. For 14 plasmids the maximum transfer frequency was observed at 28.degree. C and for 5 plasmids it was at 37.degree. C. Under conditions of the optimal temperature the transfer frequency was on the average 100 times higher irrespective of the bacterial host. A number of the strains showed the donor activity only at a temperature of 28.degree. C. The plasmids with the transfer temperature optimum at 28.degree. C did not inhibit the bacterial host growth and did not segregate at 37 and 42.degree. C. A deletion mutant of R plasmid pP1220 which lost a number of the resistance markers and had a derepressed phenotype (drd) was isolated. Unlike the initial plasmid with the transfer temperature optimum at 28.degree. C, the mutant plasmid pP1233 could be transferred with a maximum effect at 37.degree. C. An ecologically different origin of the plasmid with different transfer temperature optima is suggested.