A novel multiresistant Streptococcus pneumoniae serogroup 19 clone from Washington State identified by pulsed-field gel electrophoresis and restriction fragment length patterns

In 1997, a cluster of multiresistant invasive serogroup 19 pneumococcus inf ections, including two fatalities, was reported in Washington State. Furthe r investigation identified other cases. Fourteen Washington Streptococcus p neumoniae isolates, four from Alaska, and eight isolates from eastern Canad a with reduced penicillin susceptibility (MIC of greater than or equal to 1 mu g/ml) were included in the study. Pulsed-field gel electrophoresis (PFG E) with ApaI, SacII, and SmaI restriction enzymes and IS1167 and mef restri ction fragment length polymorphism (RFLP) pattern analysis were performed. Twenty of the 26 isolates had identical or related PFGE patterns, with two or all three enzymes, and identical or related IS1167 RFLP patterns, indica ting that they were genetically related. These 20 isolates contained the me f gene conferring erythromycin resistance and had identical mef RFLP patter ns. The PFGE and RFLP patterns were distinct from those of six multiresista nt clones previously described and suggest that a new multiresistant clone has appeared in Washington, Alaska, and eastern Canada. This newly characte rized clone should be included in the Pneumococcal Molecular Epidemiology N etwork.