Subtyping of high-level plasmid-mediated tetracycline resistant Neisseria gonorrhoeae isolated in Scotland between 1992 and 1998

Tetracycline resistant Neisseria gonorrhoeae (TRNG) contain a 25.2 MDa TetM plasmid encoding a 68 KDa cytoplasmic protein which confers high-level tet racycline resistance. The aim of this study was to subtype all TRNG isolate d in Scotland between 1992 and 1998. Subtyping was performed by a polymeras e chain reaction (PCR) assay which characterizes the TetM plasmid as either the Dutch variant (443 base pair product) or the American variant (777 bas e pair product). Of the 78 TRNG isolates, 35 were the American variant and 43 were the Dutch variant. TRNG were distributed amongst 30 serovar/auxotyp e classes, the most common being 1A6/NR (11.5%), 1A6/P (14.1%) and 1B4/NR ( 14.1%). The country where infection was acquired was known for 36 of the 46 TRNG strains isolated between 1996 and 1998. All infections acquired in As ia and South America were the Dutch variant whereas all infections acquired in Africa were the American variant; A penicillinase plasmid was present i n 66% (23/35) of the American variant TRNG compared with 51% (22/43) of the Dutch variant: the 3.2 MDa penicillinase plasmid was found in 87% of the A merican variant TRNG whereas the 4.4 MDa penicillinase plasmid was found in 68% of the Dutch variant TRNG. We conclude that subtyping of TRNG by PCR i s a useful tool in studying the epidemiology of gonococcal infection due to plasmid-mediated resistant isolates.