FIG. 1.

Genetic diversity among all large por-opa clusters (≥20 gonorrhea patients) as shown in a phylogenetic tree constructed for two N. gonorrhoeae isolates from each large cluster of gonorrhea patients at the STI Clinic in Amsterdam, The Netherlands. POR MspA1 I, RFLP patterns of por with restriction enzyme MspAlI; OPA Taq1, RFLP patterns of opa with restriction enzyme TaqI; Isolate nr., isolate number; Location, anatomical site of culture; C, cervix; R, rectum; T, tonsil; U, urethra; Date, date of visit to STI clinic (year-month-day); poC, por-opa cluster number. Numbers indicate the sizes of the clusters in the phylogenetic tree. The scale in the upper left-hand corner shows the percentage of similarity between the RFLP patterns of por and opa genes.