Subtyping of Neisseria gonorrhoeae auxotype-serovar groups by pulsed-field gel electrophoresis.

Genomic DNA from 48 Neisseria gonorrhoeae isolates was digested with low-frequency cleavage (LFC) endonucleases (SpeI and NheI) and analysed by contour-clamped homogeneous electric fields electrophoresis (CHEF). The restriction patterns generated were reproducible, stable, easy to read and offer a more practical approach than restriction endonuclease analysis (REA) with high-frequency cleavage (HFC) endonucleases. Strains sharing common auxotypes and serovars could be differentiated and correlation with auxotype/serovar (A/S) classes was demonstrated for some, but not all strains. The strains were distributed into 18 A/S classes and 38 SpeI and 40 NheI restriction patterns. This greater discriminatory power of CHEF REA should allow subdivision of strains within common A/S classes.