Emergence of a high-level cefotaxime-resistant Streptococcus pneumoniae strain in New Zealand

An increase in the number of cefotaxime-resistant pneumococci referred for surveillance to a central laboratory in New Zealand occurred in 1997-1998. The MIC of cefotaxime for 113 of 216 cefotaxime-resistant isolates of Streptococcus pneumoniae referred was > or = 4 mg/L. Most of the 113 isolates exhibited the same antibiotic resistance pattern and belonged to serotype 19F. To investigate the genetic relatedness of the isolates, 48 serotype 19F pneumococci with varying susceptibility to cefotaxime were further typed by macro-restriction analysis by use of pulsed-field gel electrophoresis. These results suggested that a multiresistant 19F strain of S. pneumoniae with high-level cefotaxime resistance had emerged from a pre-existing serotype 19F strain.