Inducible resistance to vancomycin in Enterococcus faecium D366.
Strain D366, a clinical isolate of Enterococcus faecium, is resistant (minimum inhibitory concentration [MIC] 32 mg/L) to vancomycin. When exponential-phase cultures were exposed to half the MIC of vancomycin, a lag of 3-4 h occurred before growth resumed. Cells preexposed to 1/2 MICs of vancomycin did not show any lag. Pregrowth of D366 with vancomycin caused resistance to all glycopeptides tested. Pregrowth in vancomycin resulted in synthesis of a 3.95-kDa cytoplasmic-membrane-associated protein. This protein was correlated with resistance in mutants with high-level resistance, in the presence of NaCl, which inhibited the activity of vancomycin, and when several glycopeptides with varying activities were tested. Vancomycin-grown cells appeared abnormal and lysed at a much slower rate than did normal cells. We conclude that (1) vancomycin resistance in D366 is inducible; (2) resistance is correlated with the synthesis of 39.5-kDa cytoplasmic membrane protein; and (3) this protein play an additional role in the inhibition of normal lytic functions.
Williamson
R
R
Laboratoire de Microbiologie Médicale, Université de Paris VI, France.
Al-Obeid
S
S
Shlaes
J H
JH
Goldstein
F W
FW
Shlaes
D M
DM
D000368:Aged; D000369:Aged, 80 and over; D001433:Bacteriolysis / Q000187:drug effects; D002846:Chromatography, Affinity; D015169:Colony Count, Microbial; D004352:Drug Resistance, Microbial; D005260:Female; D006020:Glycopeptides / Q000378:metabolism / Q000494:pharmacology; D006801:Humans; D008562:Membrane Glycoproteins / Q000096:biosynthesis; D008854:Microscopy, Electron; D010457:Peptidoglycan / Q000096:biosynthesis / Q000378:metabolism; D013291:Streptococcus / Q000187:drug effects* / Q000254:growth & development / Q000648:ultrastructure; D014640:Vancomycin / Q000494:pharmacology*
D006020:Glycopeptides; D008562:Membrane Glycoproteins; D010457:Peptidoglycan; D014640:Vancomycin