Prevalence of Single Mutations in Topoisomerase Type II Genes among Levofloxacin-Susceptible Clinical Strains of Streptococcus pneumoniae Isolated in the United States in 1992 to 1996 and 1999 to 2000

Abstract excerpt

Levofloxacin resistance in Streptococcus pneumoniae is rare, requiring at least two mutations in the quinolone resistance-determining region (QRDR) of topoisomerase IV and DNA gyrase. The prevalence of single QRDR mutations in these genes is unknown. Of 9,438 levofloxacin-susceptible pneumococci from the TRUST 4 surveillance study (1999-2000), 528 strains (MICs of 0.5 to 2.0 microg/ml) were selected for analysis....