Gonorrhea among men who have sex with men:: Outbreak caused by a single genotype of erythromycin-resistant Neisseria gonorrhoeae with a single-base pair deletion in mtrR promoter region

During 1995-1997, an outbreak of 66 cases of gonorrhea caused by an erythromycin-resistant (Ery(r); MIC greater than or equal to 1.0 mu g/mL) prototrophic (proto) auxotype IB-1 serovar of Neisseria gonorrhoeae occurred in King County, Washington; 65 cases involved men who have sex with men (MSM), which accounted for similar to 37% of infections among MSM during this period. Isolates from 19 of these 65 cases of infection were analyzed by DNA sequencing of the polymerase chain reaction-amplified promoter region of the mtrR gene and by pursed-field gel electrophoresis (PFGE) analysis of genomic DNA after NheI and SpeI digestion. Eighteen of the 19 isolates had a 1-bp A/T deletion in a 13-bp inverted repeat of the mtrR promoter region and shared a single PFGE type. Among MSM who provided data about sexual behavior, 37 (64%) of 58 MSM infected by the proto/IB-1 Ery(r) strain reported having >2 sex partners during the past 60 days, compared with 32 (30%) of 106 MSM infected by other strains (P < .001), This clonal outbreak of gonorrhea illustrates the ongoing need for behavioral preventive interventions among MSM.