Serogrouping and auxotyping for epidemiological study of beta-lactamase-producing Neisseria gonorrhoeae strains isolated in Sweden

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Abstract
.beta.-Lactamase (penicillinase) producing gonococci (PPNG) (98), isolated from 97 patients in Sweden who had contracted their infections in the Far East or West Africa, were subjected to auxotyping and to serogrouping by co-agglutination (COA) in the previously described serogroups WI, WII and WIII. Twenty non-PPNG strains from patients in Sweden who had contracted their infection in the Far East were examined in the same way. There were 72 PPNG strains that originated from the Far East; 69 of these were from Thailand. Six strains originated from Africa, 1 from the Canary Islands and 19 were of unknown epidemiology. Auxotyping showed that the majority of the PPNG strains from Thailand were proline-dependent (Pro-) (81.2%), or prototrophic (15.9%). Two of the 6 strains from Africa were arginine-dependent (Arg-), 3 prototrophic and 1 Pro-. Among the non-PPNG strains from the Far East, 50% were Pro-, 45% prototrophic and 5% (1 strain from the Philippines) Arg-Hyx-Ura-. Serogrouping showed that 27.6% of the PPNG strains had serological markers for group WI, 55.1% for serogroup WII and 17.3% for WIII. Corresponding figures for the strains from Thailand were 23.2%, 62.3% and 14.5%, respectively. All 6 isolates from Africa were grouped as WI. The non-PPNG strains from the Far East all belonged, with 1 exception, to serogroup WII. This exception was the Arg-Hyx-Ura- isolate from the Philippines, which was grouped as WI. The most common combination serogroup/auxotype was WII/Pro- among PPNG strains as well as among non-PPNG isolates from Thailand, 55.1 and 52.9%, respectively. Non-PPNG strains in Sweden only occasionally have markers for serogroup WIII; 17.3% of the PPNG isolates belonged to this group and as many as 36.8% of the prototrophic strains. Serogrouping and auxotyping will evidently be valuable tools for the clinical epidemiological understanding of gonorrhea.