Genetic relatedness of antibiotic-resistant pneumococci isolated during case clusters.

Multilocus sequence typing of Streptococcus pneumoniae associated with two case clusters of disease is reported here for the first time. Isolates from the first cluster were serotype 19F, resistant to penicillin and erythromycin, and were characterized as ST 320. Isolates from the second cluster were serogroup 4, resistant to ciprofloxacin, and were characterized as ST 206. Therefore, the isolates from these clusters were antibiotic-resistant, of serotypes infrequently isolated, and of uncommon sequence types.