Paradoxical response of Enterococcus faecalis to the bactericidal activity of penicillin is associated with reduced activity of one autolysin.

Antimicrobial Agents and Chemotherapy
R FontanaG Satta

Abstract

Ten clinical isolates of Enterococcus faecalis were examined for susceptibility to the bactericidal activity of penicillin. Four of these had MBCs of penicillin equal to 2 to 4 x the MIC, and six exhibited a paradoxical response to penicillin, i.e., the bactericidal activity of the antibiotic had a concentration optimum at 2 to 4 x the MIC and decreased significantly at concentrations above this. We found that the paradoxical response to penicillin was an intrinsic and stable property of a strain, but that its phenotypic expression was not homogeneous; only a fraction of the cell population that died at low concentrations was able to survive at high penicillin concentrations. The size of this fraction increased with increasing antibiotic concentration and reached a maximum in the late-log phase of growth. All 10 strains produced a lytic enzyme that was active on Micrococcus luteus heat-killed cells, whereas only some strains lysed E. faecalis heat-killed cells. Strains producing large amounts of the latter enzyme did not show the paradoxical response to penicillin, whereas mutants of these strains that lacked this enzymatic activity paradoxically responded to the antibiotic activity. In addition, from strains that showed parado...Continue Reading

References

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Citations

Feb 15, 2001·Seminars in Nephrology·A G Kocheril
Feb 1, 1990·Antimicrobial Agents and Chemotherapy·S al-ObeidL Gutmann
Sep 1, 1991·Antimicrobial Agents and Chemotherapy·G AmalfitanoR Fontana
Oct 17, 2006·Journal of Bacteriology·Catherine EckertStéphane Mesnage
Jan 28, 2004·Annual Review of Pharmacology and Toxicology·Susan M Abdel-Rahman, Ralph E Kauffman
Jun 10, 2015·Proceedings of the National Academy of Sciences of the United States of America·Sonia A BallalWendy S Garrett
Dec 1, 1994·Journal of Chemotherapy·M PuntorieriS Stefani
Oct 31, 1998·Antimicrobial Agents and Chemotherapy·X QinB E Murray

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