ANALYSIS OF NEISSERIA-GONORRHOEAE IN ONTARIO, CANADA, WITH DECREASED SUSCEPTIBILITY TO QUINOLONES BY PULSED-FIELD GEL-ELECTROPHORESIS, AUXOTYPING, SEROTYPING AND PLASMID CONTENT

The incidence of Neisseria gonorrhoeae with reduced susceptibility to quinolones increased from 0.18% (63 of 3285) in 1992 to 0.56% (15 of 2 663) in 1993 and 0.62% (46 of 2846) in 1994. In all, 65 of the 67 isol ates of Neisseria gonorrhoeae with decreased susceptibility to quinolo nes were characterised by pulsed-field gel electrophoresis (PFGE), aux otyping, serotyping and plasmid content. The strains were distributed among 14 auxotype/serovar (A/S) classes. Thirty isolates (46.2%) which were penicillin-susceptible with ciprofloxacin MIC90 of 0.12 mg/L and norfloxacin MIC90 of 1.0 mg/L belonged to a single A/S class, OUHL/IA -2. All but two of the 30 isolates had identical PFGE restriction prof iles with NheI restriction endonuclease. Fifteen isolates (23.1%) with MICs in the intermediate (or resistant) categories for penicillin and with ciprofloxacin and norfloxacin M1C90 of 0.25 and 4.0 mg/L and (0. 5 and 4.0 mg/L) respectively, belonged to A/S class P/IB-1. The 15 iso lates showed nine different patterns with NheI and eight patterns with SpeI restriction endonucleases. Two of three beta-lactamase-producing (PPNG) isolates belonged to A/S class P/IB-5 and had a dissimilar PFG E restriction profile with NheI endonuclease; the other isolate belong ed to A/S class P/IB-8, The remaining 17 isolates were distributed amo ng 11 A/S classes, Three isolates within the common A/S class NR/IB-1 were subdivided into two types by PFGE as were three isolates belongin g to A/S class NR/IB-2. Overall the 65 isolates of N. gonorrhoeae were distributed into 30 NheI and 26 SpeI macrorestriction profiles. All b ut one isolate harboured the 2.6-MDa cryptic plasmid and 18 isolates c arried the 24.5-MDa transferable plasmid, The three PPNG isolates carr ied the 4,5-MDa Asian beta-lactamase-producing plasmid and a 25.2-MDa conjugative plasmid was found in the two TRNG isolates.