Analysis of Neisseria gonorrhoeae in Ontario, Canada, with decreased susceptibility to quinolones by pulsed-field gel electrophoresis, auxotyping, serotyping and plasmid content

Abstract

The incidence of Neisseria gonorrhoeae with reduced susceptibility to quinolones increased from 0.18% (63 of 3285) in 1992 to 0.56% (15 of 2663) in 1993 and 0.62% (46 of 2846) in 1994. In all, 65 of the 67 isolates of Neisseria gonorrhoeae with decreased susceptibility to quinolones were characterised by pulsed-field gel electrophoresis (PFGE), auxotyping, serotyping and plasmid content. The strains were distributed among 14 auxotype/serovar (A/S) classes. Thirty isolates (46.2%) which were penicillinsusceptible 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 profiles with Nhe I restriction endonuclease. Fifteen isolates (23.1 YO) with MICs in the intermediate (or resistant) categories for penicillin and with ciprofloxacin and norfloxacin MIC90 of 0.25 and 4.0mg/L and (0.5 and 4.0 mg/L) respectively, belonged to A/S class P/IB-1. The 15 isolates showed nine different patterns with NheI and eight patterns with SpeI restriction endonucleases. Two of three P-lactamase-producing (PPNG) isolates belonged to A/S class P/IB-5 and had a dissimilar PFGE restriction profile with NheI endonuclease; the other isolate belonged to A/S class P/IB-8. The remaining 17 isolates were distributed among 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 belonging 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 but one isolate harboured the 2.6-MDa cryptic plasmid and 18 isolates carried the 24.5-MDa transferable plasmid. The three PPNG isolates carried the 4.5-MDa Asian plactamase-producing plasmid and a 25.2-MDa conjugative plasmid was found in the two TRNG isolates.

Molecular Basis of High-Level Ciprofloxacin Resistance in Neisseria gonorrhoeae Strains Isolated in Denmark from 1995 to 1998

“…Out of eight strains, each of which had a unique pattern of mutations in the gyrA and parC genes, seven also had unique SpeI and NheI patterns, indicating that these strains were genetically unrelated. Among the 11 strains with the most common mutation pattern (M9), 9 sified into one cluster with identical SpeI patterns (Fig. 3) as well as NheI patterns (Fig.…”

“…A single strain or closely related strains of N. gonorrhoeae have been demonstrated to be associated with a focal area of endemic transmission in Cleveland, Ohio, (12) and Ontario, Canada (9). Among quinolone-resistant N. gonorrhoeae strains a shift from multiple subtypes being imported to a limited number of subtypes sustained domestically was documented in Australia (26), and the spread of quinolone-resistant strains has been assumed to be due in part at least to the presence of these phenotypes in international commercial sex workers and their clients (26).…”

The use of molecular techniques for the diagnosis and epidemiologic study of sexually transmitted infections

“…The most common of these methods are pulsed-field gel electrophoresis of restriction digested chromosomal DNA [32][33][34] and sequence analyses of the genes encoding outer membrane protein PIB [33,35] or opa [35]. In addition, arbitrarily primed PCR [35] and whole-cell repetitive element sequence-based PCR [36] have been successfully used to detect variation within serovars.…”