Unique gonococcal phenotype associated with asymptomatic infection in men and with erroneous diagnosis of nongonococcal urethritis.

The percentage of gonococcal isolates in King County, Washington, requiring citrulline and uracil (CU auxotype) increased from 1.6% in 1986 to 16.5% in 1997. Among men, urethral infection with the CU auxotype (n=93), in comparison with infection by other auxotypes (n=1211), was associated with coexisting chlamydial infection, younger age, heterosexual contact, and fewer new recent partners (P<. 05). Among heterosexual men, urethral infection with the CU auxotype, compared with infection with other auxotypes, less often produced symptoms of urethral discharge (75% vs. 92%) or dysuria (47% vs. 74%) or signs of moderate or profuse urethral discharge (57% vs. 89%, P<.05 for each comparison), produced symptoms of longer duration (7. 0 vs. 4.5 days, P<.01), less often resulted in urethral smears showing gram-negative intracellular diplococci (67% vs. 95%, P<.01), and thus more often was erroneously diagnosed as nongonococcal urethritis. Several mechanisms could explain reduced inflammatory response to the CU auxotype and its recent spread.