CIBICI   14215
CENTRO DE INVESTIGACION EN BIOQUIMICA CLINICA E INMUNOLOGIA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Comparison between optochin and rifampicin tests to assess mutation frequency in Streptococcus pneumoniae
Autor/es:
CORTES P; PIÑAS G; ALBARRACIN ORIO A; ECHENIQUE J
Lugar:
Mar del Plata
Reunión:
Congreso; XLIII Reunión Anual Sociedad Argentina de Investigación en Bioquímica y Biología Molecula; 2007
Institución organizadora:
SAIB
Resumen:
Rifampicin
test is the most common assay to assess mutation rate in bacteria. Here, we
evaluated the subinhibitory concentration (SIC) effects on the mutation rate of
S. pneumoniae using an additional assay,
the optochin test. Three capsulated strains were exposed to SIC of penicillin,
chloramphenicol and erythromycin (corresponding to 75% of each minimum
inhibitory concentration) for 2 hours, and the mutation rate to optochin and
rifampicin was determinated. While optochin test showed that the exposure only
to penicillin increased the mutation rate between 2.0-3.2 fold for all three
strains, we could not detect this phenomenon using the classical rifampicin
test. With the purpose to investigate the cause of this difference, we analysed
the atpAC and rpoB point mutations (that conferred optochin and rifampicin
resistance, respectively) in the optochin- and rifampicin-resistant strains
generated by penicillin exposure. We found differences in the GC content corresponding
to the 20 pair bases surrounding the point mutation that conferred rifampicin
or optochin resistance, suggesting that it could influence the repair
efficiency, and in consequence, the mutation rate. We proposed that optochin
test was more appropriated than the rifampicin test to detect transient hypermutator
state in S. pneumoniae and it should
be considerate for further mutability analysis.