Use of gonococcal W serogrouping in the evaluation of a clinical trial of rosoxacin.

Serogrouping by co-agglutination was used for the characterization of isolates of Neisseria gonorrhoeae in a clinical trial of rosoxacin in Stockholm. Twenty-four isolates (56%) belonged to serogroup WI, 17 (40%) to WII, and two (5%) to WIII. The proportion of WI isolates in Stockholm was reported in earlier studies to be approximately 40%. On the basis of serogrouping data and clinical information, five (10%) of 48 patients in this study were classified as therapeutic failures. Of the initial WI isolates, 22 (92%) of 24 were inhibited by less than or equal to 0.03 microgram of rosoxacin/ml, as compared with ten (59%) of 17 of the initial WII isolates (.05 greater than P greater than .01). Thus, this study might underestimate the failure rate as compared with that for patient populations in which WII isolates are more prevalent, since WI isolates are more susceptible to rosoxacin than WII isolates. A certain WII serovar was correlated with decreased susceptibility to rosoxacin (P less than .001). Correlations were found between decreased susceptibility to rosoxacin and decreased susceptibility to other antibiotics (P less than or equal to .01). A high frequency of side effects (40%) was seen among the patients studied.