title: Resistance to cefotaxime and peptidoglycan composition in Enterococcus faecalis are influenced by exogenous sodium chloride.
abstract: The influence of NaCl on the susceptibility of Enterococcus faecalis to cefotaxime was tested with JH2-2, a laboratory strain, and 20 clinical strains grown on tryptic soy agar supplemented with 5% horse blood. Growth with 3% NaCl in the medium resulted in an increase in cefotaxime resistance and the appearance of a heterogeneous resistance phenotype: for the majority of the strains, the MICs of cefotaxime increased from 4 to 512 micrograms ml-1. By a competition assay using cefotaxime and [3H]benzylpenicillin, it was shown for strain JH2-2 that at the MIC penicillin-binding protein (PBP) 2 and PBP3 were the apparent essential PBPs in medium without NaCl, whilst the low-affinity PBPs 4 and 1 were the apparent essential PBPs for cell growth in medium containing 3% NaCl. Analysis of JH2-2 peptidoglycan by HPLC and MS after growth in the presence of 3% NaCl showed a relative increase in unsubstituted monomers and a relative decrease in alanine- and dialanine-substituted monomers. It is therefore hypothesized that modification of the number of alanine-substituted precursors in the presence of NaCl could interfere with the functions of the different PBPs and thus play a role in cefotaxime resistance in E. faecalis.
authors.affiliation: LRMA, Universite Paris VI, 15, rue de I'Ecole de MCdecine, 75270 Paris Cedex 06,France.|HBpital Saint-Joseph, Service de Microbiologie Clinique, 185 rue Raymond Losserand,75674 Paris Cedex 14,France.
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Mainardi
authors.affiliation: LRMA, Universite Paris VI, 15, rue de I'Ecole de MCdecine, 75270 Paris Cedex 06,France.
authors.forename: Daniele
authors.initials: D
authors.lastname: Billot-Klein
authors.affiliation: HBpital Saint-Joseph, Service de Microbiologie Clinique, 185 rue Raymond Losserand,75674 Paris Cedex 14,France.
authors.forename: Anne
authors.initials: A
authors.lastname: Coutrot
authors.affiliation: Physics Department, Roussel UCLAF,93230 Romainville,France.
authors.forename: Raymond
authors.initials: R
authors.lastname: Legrand
authors.affiliation: Physics Department, Roussel UCLAF,93230 Romainville,France.
authors.forename: Bernard
authors.initials: B
authors.lastname: Schoot
authors.affiliation: LRMA, Universite Paris VI, 15, rue de I'Ecole de MCdecine, 75270 Paris Cedex 06,France.
authors.forename: Laurent
authors.initials: L
authors.lastname: Gutmann
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism; D002439:Cefotaxime / Q000494:pharmacology*; D018550:Cephalosporin Resistance; D002511:Cephalosporins / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid; D019281:Dimerization; D004187:Disaccharides / Q000032:analysis; D013293:Enterococcus faecalis / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D006602:Hexosyltransferases; D006801:Humans; D013058:Mass Spectrometry; D008826:Microbial Sensitivity Tests; D008954:Models, Biological; D008970:Molecular Weight; D002267:Muramoylpentapeptide Carboxypeptidase / Q000378:metabolism; D009154:Mutation; D046915:Penicillin-Binding Proteins; D010455:Peptides / Q000032:analysis; D010457:Peptidoglycan / Q000737:chemistry* / Q000378:metabolism; D010458:Peptidyl Transferases; D010641:Phenotype; D012965:Sodium Chloride / Q000494:pharmacology*
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; D002511:Cephalosporins; D004187:Disaccharides; D046915:Penicillin-Binding Proteins; D010455:Peptides; D010457:Peptidoglycan; D012965:Sodium Chloride; D010458:Peptidyl Transferases; D006602:Hexosyltransferases; D002267:Muramoylpentapeptide Carboxypeptidase; D002439:Cefotaxime