Abstract: Objective To evaluate the ability of restriction endonuclease analysis by pulsed field gel electrophoresis (PFGE REA) and random amplified polymorphic DNA (RAPD) analysis for molecular typing of Neisseria gonorrhoeae isolates.Methods Genomic DNA from 36 Neisseria gonorrhoeae isolates were digested with SpeI and analysed by contour clamped homogeneous electric fields electrophoresis.The 36 isolates were also characterised by RAPD analysis with arbitrary primer OPA 03.Results 12～19 DNA fragments from 5 to 600kb were obtained among the 36 isolates after PFGE REA.The 36 isolates were discriminated into 20 PFGE patterns.Amplification of Neisseria gonorrhoeae DNA with primer OPA 03 produced 15 different DNA fragments (280～1900bp),and 3～9 fragments per strain could be seen.The 36 isolates showed 18 different RAPD patterns.Strains sharing common auxotypes and antibiotic spectrum could be differentiated by PFGE REA and RAPD analysis.General agreement was found between these two techniques.Isolates from different geographic areas and even some isolates in the same area showed considerable amount of DNA polymorphism.In addition,some isolates shared common or very similar patterns were unique to a given geographic area.Conclusion It is concluded that both PFGE REA and RAPD analysis are useful,sensitive molecular techniques for differentiation of clinical isolates of Neisseria gonorrhoeae.They should be helpful in the investigation of strain origin,clonal relation among strains and spread of antibiotic resistance.Compared with PFGE REA,RAPD analysis is faster,relatively simple and more economical.

Key words: Neisseria Gonorrhoeae, Genotyping, PFGE, RAPD