High-level tetracycline-resistant Neisseria gonorrhoeae in Ontario, Canada--investigation of a cluster of isolates, showing chromosomally mediated resistance to penicillin combined with plasmid-mediated resistance to tetracycline.
Between 1991 and 1994, plasmid-mediated, tetracycline-resistant Neisseria gonorrhoeae (TRNG) increased from 61.8% to 85.96% of all resistant isolates in Ontario, Canada. Ninety-nine isolates with tetracycline MICs >32 mg/L were characterized by auxotype/serovar (A/S) class, plasmid profile, hybridization with eight tetracycline-resistant probes, and pulsed-field gel electrophoresis (PFGE) of genomic DNA after digestion with NheI and SpeI restriction endonucleases. A cluster of 82 isolates with penicillin MICs of 2-4 mg/L and tetracycline MICs of 128 mg/L (chromosomally mediated resistance) belonged to A/S class NR/IB-1 and had identical or closely related PFGE profiles. Seventeen isolates, TRNG (10) and penicillinase-producing TRNG (7), with tetracycline MICs of 64-256 mg/L, belonged to eight A/S classes and displayed 12 different PFGE profiles. The 99 isolates hybridized only with the TetM probe. Phenotypic and molecular characterization indicated a diverse population throughout the Province of Ontario.
Harnett
N
N
Central Public Health Laboratory, Ontario Ministry of Health, Toronto, Canada.
Brown
S
S
Terro
R
R
Krishnan
C
C
Pauzé
M
M
Yeung
K H
KH
D002876:Chromosomes, Bacterial; D016521:Electrophoresis, Gel, Pulsed-Field; D006801:Humans; D008826:Microbial Sensitivity Tests; D009344:Neisseria gonorrhoeae / Q000187:drug effects*; D010403:Penicillin Resistance; D010957:Plasmids; D013753:Tetracycline Resistance