Genetic relatedness of recently collected Spanish respiratory tract Streptococcus pneumoniae isolates with reduced susceptibility to amoxicillin

Of Streptococcus pneumoniae isolates from 17 hospitals, 9.8% were amoxicillin nonsusceptible (MIC > or = 4 microg/ml). The genetic relatedness of 138 isolates was studied by pulsed-field gel electrophoresis. Although 44 different clones were detected, more than 62% of these isolates were related to four clones (Spain(23F)-1, Spain(6B)-2, Spain(9V)-3, and Spain(14)-5).