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Characterization of Gentamicin‐Resistant Respiratory‐Deficient ( Res − ) Variant Strains of Staphylococcus aureus
Author(s) -
Lewis Leslie A.,
Li Koibong,
Bharosay Mohanie,
Cannella Maria,
Jorgenson Vincent,
Thomas Robert,
Pena Danny,
Velez Madeline,
Pereira Beryl,
Sassine Anne
Publication year - 1990
Publication title -
microbiology and immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.664
H-Index - 70
eISSN - 1348-0421
pISSN - 0385-5600
DOI - 10.1111/j.1348-0421.1990.tb01035.x
Subject(s) - biology , staphylococcus aureus , microbiology and biotechnology , gentamicin , locus (genetics) , gene , hemin , phenotype , dna , genetics , bacteria , enzyme , biochemistry , antibiotics , heme
Exposure of sensitive cells of Staphylococcus aureus to concentrations of gentamicin higher than the minimal inhibitory concentration, results in the recovery of low level resistant strains with a greatly altered phenotype (variants). Because the phenotypic alteration in these strains is so great the expected diagnostic characterization of these variants as S. aureus is obscured. Starting with a genetically‐marked parent strain, a comprehensive cytological, physiological, morphological, genetic and biochemical analysis of the variants isolated from it was carried out. The genetic lineage of the variants to the parent was also established by DNA/DNA hybridization. Variants result from mutations in the hemin biosynthesis locus, the effect of which is to disrupt the synthesis of components of the electron transport system, lipid synthesis and selected nucleotide synthesis. Thus the strains are defective in aerobic and anaerobic respiration, (res − ) , in active transport of aminoglycosides (which confers low level resistance), export of characteristic exoenzymes, and in cell wall composition and structure.