16S rRNA mutation associated with tetracycline resistance in a gram-positive bacterium.
A genetic basis for tetracycline resistance in cutaneous propionibacteria was suggested by comparing the nucleotide sequences of the 16S rRNA genes from 16 susceptible and 21 resistant clinical isolates and 6 laboratory-selected tetracycline-resistant mutants of a susceptible strain. Fifteen clinical isolates resistant to tetracycline were found to have cytosine instead of guanine at a position cognate with Escherichia coli 16S rRNA base 1058 in a region important for peptide chain termination and translational accuracy known as helix 34. Cytosine at base 1058 was not detected in the laboratory mutants or the tetracycline-susceptible strains. The apparent mutation was recreated by site-directed mutagenesis in the cloned E. coli ribosomal operon, rrnB, encoded by pKK3535.E. coli strains carrying the mutant plasmid were more resistant to tetracycline than those carrying the wild-type plasmid both in MIC determinations and when grown in tetracycline-containing liquid medium. These data are consistent with a role for the single 16S rRNA base mutation in clinical tetracycline resistance in cutaneous propionibacteria.
Ross
J I
JI
Department of Microbiology, University of Leeds, United Kingdom. micjir@leeds.ac.uk
Eady
E A
EA
Cove
J H
JH
Cunliffe
W J
WJ
D004269:DNA, Bacterial; D004926:Escherichia coli / Q000235:genetics; D006094:Gram-Positive Bacteria / Q000187:drug effects / Q000235:genetics*; D008826:Microbial Sensitivity Tests; D016297:Mutagenesis, Site-Directed; D010957:Plasmids / Q000235:genetics; D011424:Propionibacterium / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000235:genetics*; D013753:Tetracycline Resistance / Q000235:genetics*
D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S