Genotyping Naegleria spp. and Naegleria fowleri isolates by interrepeat polymerase chain reaction.

All six Naegleria species recognized to date were studied by interrepeat polymerase chain reaction (PCR). Priming at repeat sequences, which are known to be variable among eukaryotes, yielded electrophoretic DNA banding patterns that were specific for any single species. With a single PCR and simple gel electrophoresis, species determination could be performed in less than 1 day. Unambiguous discrimination between the pathogen N. fowleri and nonpathogenic Naegleria species appeared to be possible. Analysis of DNAs obtained from 20 separate isolates of N. fowleri revealed that geographic variation of the genetic fingerprints rarely occurs. All but 3 of 20 isolates of N. fowleri which were investigated showed identical banding patterns; for two isolates from New Zealand and one from Australia, a limited number of additional bands was detected, independent of the PCR primers used. These data corroborate previous findings on the genetic stability of pathogenic N. fowleri.