Hugh Young

The por gene of Neisseria gonorrhoeae encodes the Protein I porin responsible for serovar specificity. In this study the por genes have been sequenced from clinical isolates which exhibited anomalous serovar reactivity. One group of 'intermediate' strains differed significantly from both Protein IA and IB strains, were more closely related to IA but appeared to represent a distinct class of Protein I. Another strain was closely related to Protein IB of serovar IB-6 but contained a deletion of six amino acids in surface exposed loop 6 which removed epitopes recognized by IB specific monoclonal antibodies. The third group of strains, which reacted with both IA and IB specific monoclonal antibodies, expressed hybrid Protein I molecules containing both IA and IB epitopes. These strains appeared to originate from a double crossover between Proteins IA and IB with the amino and carboxy terminal residues homologous to IB while the surface exposed loop 6 demonstrated close homology to IA. This is the first demonstration of naturally occurring gonococci expressing a hybrid Protein IA/IB.

The aims of this study were determine the frequencies of infection with Neisseria gonorrhoeae at various sites in homosexual men who were attending clinics for treatment of sexually transmitted diseases in central Scotland and to appraise the diagnostic tests used. Specimens for culture were taken from the urethra, pharynx, and anorectum of every homosexual man in the study. When the first cultures of pharyngeal and rectal specimens were negative, these cultures were repeated twice at weekly intervals. The urethra was infected in 169 (60.8%), the anorectum in 114 (41.0%), and the pharynx in 23 (8.3%) of 278 patients who had gonorrhea. By reliance on only one set of tests, eight (7.0%) of 114 patients who had rectal gonorrhoea and six (26.1%) of 23 patients with pharyngeal infection would have been missed. The results indicate the importance of obtaining specimens for culture from all sites that might possibly be infected, regardless of the symptoms.

Auditing the sensitivity of microscopic diagnosis of gonorrhoea is recommended by the current guidelines. A retrospective study was performed of 596 cases of positive cultures for Neisseria gonorrhoeae in modified New York City culture (MNYC) media diagnosed from 1995 to 1999. The sensitivity of the cervical slides in women was 51% while in men who have sex with men (MSM) the sensitivity of urethral and rectal slides were 89% and 54% respectively. The sensitivity of urethral slides in heterosexual men was 84%. Neisseria serovar 1B02 among MSM and serovar 1B31 among women were mostly undiagnosed with microscopy. Serovars 1A05, 1A21, B08 among heterosexual men were exclusively associated with negative microscopy. Microscopy is important in the rapid detection and treatment of gonorrhoea. Infections with certain serovars are less likely to be detected by microscopy; making them more likely to spread within the community. Culture from different ano-genital sites is essential to maximize detection of gonorrhoea in all patients.