Frequency of mutation to rifampin resistance in Streptococcus pneumoniae clinical strains: hexA and hexB polymorphisms do not account for hypermutation.
The frequency of mutation to rifampin resistance of 200 clinical Streptococcus pneumoniae isolates was examined. Two peaks were observed in the distribution, with mode frequencies of 2.5 x 10(-7) (20% of isolates) and 2.5 x 10(-8). The hexA and hexB gene entire sequences were analyzed in 13 isolates. Sequences from both hypermutable and "normomutable" strains were conserved relative to that of the R6 S. pneumoniae control strain. The phenotypic Hex system proficiency, in terms of transforming efficiency, was also maintained irrespective of the variations in mutation frequency values.
Morosini
María-Isabel
MI
Servicio de Microbiología, Hospital Universitario Ramón y Cajal, Madrid, Spain. mmorosini.hrc@salud.madrid.org
Baquero
María-Rosario
MR
Sánchez-Romero
J M
JM
Negri
María-Cristina
MC
Galán
Juan-Carlos
JC
del Campo
Rosa
R
Pérez-Díaz
J C
JC
Baquero
Fernando
F
D001426:Bacterial Proteins / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics*; D009154:Mutation; D011110:Polymorphism, Genetic; D012293:Rifampin / Q000494:pharmacology*; D013296:Streptococcus pneumoniae / Q000187:drug effects* / Q000235:genetics
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; C084499:HexA protein, bacteria; D012293:Rifampin