PCR-Oligonucleotide Ligation Assay for Detection of Point Mutations Associated with Quinolone Resistance in Streptococcus pneumoniae

We have developed a PCR-oligonucleotide ligation assay to rapidly identify base substitutions in topoisomerase genes that are associated with quinolone resistance in clinical isolates of Streptococcus pneumoniae. Thirty-seven strains for which the ciprofloxacin MICs were >/=4 micro g/ml and 16 strains for which the MICs were </=2 micro g/ml were assayed. Compared with sequence data, the assay correctly identified the DNA bases that encoded amino acids at the four positions most commonly associated with quinolone resistance (Ser79 and Asp83 of ParC and Ser81 and Glu85 of GyrA). Therefore, this procedure can rapidly distinguish single base substitutions associated with quinolone-resistant topoisomerases in S. pneumoniae.