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Mupirocin resistance in staphylococci: development and transfer of isoleucyl‐tRNA synthetase‐mediated resistance in vitro
Author(s) -
Thomas D. G.,
Wilson J. M.,
Day M. J.,
Russell A. D.
Publication year - 1999
Publication title -
journal of applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 1364-5072
DOI - 10.1046/j.1365-2672.1999.00718.x
Subject(s) - mupirocin , microbiology and biotechnology , staphylococcus aureus , staphylococcus haemolyticus , biology , staphylococcus epidermidis , micrococcaceae , plasmid , drug resistance , antibiotics , antibacterial agent , bacteria , methicillin resistant staphylococcus aureus , genetics , dna
Mupirocin resistance could be transferred from highly resistant clinical isolates of Staphylococcus aureus to highly sensitive recipients of Staph. aureus , Staph. epidermidis and Staph. haemolyticus . Transconjugants of the latter two organisms could transfer this resistance into mupirocin‐sensitive Staph. aureus . Moderately resistant strains did not transfer this resistance to sensitive recipients, nor did strains with high‐level mupirocin resistance developed by serial transfer or habituation. The inhibitory effects of mupirocin on crude isoleucyl‐tRNA synthetases (IRS) isolated from mupirocin‐sensitive and ‐resistant strains of Staph. aureus have been determined. Drug concentrations needed to produce 50% inhibition, I 50 values, were very low against IRS from a highly sensitive strain, somewhat higher against IRS from moderately resistant strains, much higher against enzyme from strains trained in vitro to high‐level resistance, and considerably higher still against IRS extracted from clinical isolates possessing high‐level mupirocin resistance and from the transconjugates of such strains resulting from crosses with mupirocin‐sensitive strains. It is concluded that high‐level resistance in clinical isolates is plasmid‐mediated involving a second, mupirocin‐resistant IRS whereas in moderately resistant strains, and in strains trained in vitro to high‐level resistance, chromosomal mutations are likely to be responsible for decreasing IRS sensitivity.