DNA amplification fingerprinting for subtyping Neisseria gonorrhoeae strains

DNA amplification fingerprinting is used in most epidemiologic studies as a substitute for conventional typing methods. DNA amplification fingerprinting and conventional typing methods were compared in this epidemiologic study of Neisseria gonorrhoeae.

To differentiate 70 Neisseria gonorrhoeae isolates from untreated patients with urogenital gonococcal infection.

Gonococcal strains were characterized by auxotyping, serotyping, plasmid profile, antibiotic sensitivity, and DNA amplification fingerprinting. The method of unweighted pair-group average linkage was used for cluster analysis. Discriminatory power was calculated applying Simpson's index.

Amplification of Neisseria gonorrhoeae DNA with primers OPA-03 and OPA-13 produced well-resolved patterns of 15 and 22 DNA fragments, respectively, with a discriminatory power (0.978 with OPA-13 and 0.967 with OPA-03) comparable to that obtained with auxotyping/serotyping combination (D:0.968) or with auxotype/serotype/plasmid profile combination (D:0.983). Correlation between DNA amplification fingerprinting pattern and auxotype/serotype class was not always uniform. Some strains with the same auxotype/serotype/plasmid profile were subdivided by DNA amplification fingerprinting, and vice versa.

Although auxotype/serotype class and DNA amplification fingerprinting can be used in the epidemiologic characterization of strains, DNA amplification fingerprinting offers a better discriminatory index than the separate serotyping. It is especially useful for differentiating serologically identical strains and nontypable strains. A combination of serotyping and DNA amplification fingerprinting seems to be the best way to differentiate Neisseria gonorrhoeae strains in epidemiologic studies, bringing together the most simple techniques and the best discriminatory power among isolates.