Neisseria gonorrhoeae Auxotyping: Differentiation of Clinical Isolates Based on Growth Responses on Chemically Defined Media

Abstract

A system is described for differentiating clinical isolates of Neisseria gonorrhoeae based on their growth or absence of growth on a set of 11 chemically defined agar media. The complete medium, NEDA, contains all of the compounds required for gonococcal growth; but isolates differ in their ability to grow on NEDA from which selected compounds are individually omitted. The differential compounds include L-proline, L-arginine, L-ornithine, L-methionine, hypoxanthine, uracil, thiamine, and thiamine pyrophosphate. A distinctive pattern of growth responses on the standard media defines an auxotype. Twenty auxotypes were found among a group of 251 gonococci which were isolated from patients examined in the clinics of one city during a 3-month span of time. Another collection of 74 strains from several different countries yielded two additional auxotypes. The stability of the nutritional requirements on which the auxotyping depends was verified in two ways. Cultures isolated from different anatomic sites of a patient or from sexual partners represented the same auxotype, as did cultures which were repeatedly isolated from cases of presumptive treatment failures. Also, the auxotypes of gonococci remained the same after numerous subcultures. The reproducibility of results and the variety and number of auxotypes indicate the potential value of the auxotyping system as an epidemiological tool.

Molecular genetic methods for diagnosis and characterisation of Chlamydia trachomatis and Neisseria gonorrhoeae: impact on epidemiological surveillance and interventions

“…Auxotyping of N. gonorrhoeae isolates was described already in 1973 (80). Different auxotypes differ according to their nutritional requirements for amino acids, purines, pyrimidines, and vitamins.…”

The serological classification of Neisseria gonorrhoeae. I. Isolation of the outer membrane complex responsible for serotypic specificity.

“…These observations were confirmed by Danielsson (21) who also noted that N. sicca, Neisseria tiara, and Neisseria flavescens reacted with antigonococcal globulin. Recent investigations, most notably those of Carifo and Catlin (22) and LaScolea and Young (23), have dwelt upon the feasibility ofauxotyping, while others (24,25), though unsuccessful, have probed the possibility of bacteriocins as potential candidates for gonococcal serotyping. The isolation of pili as a discrete protein antigen of the virulent colonial types, T, and T2, by Buchanan et al (26) prompted the analysis of pill as having serotypic specificity.…”

Acrylamide gel electrophoresis of proteins of Neisseria gonorrhoeae as an epidemiological tool

“…A total of 93 colony type T2 patient isolates were examined to detect a possible association between the gel electrophoresis patterns and the auxotype groups. Six auxotypes were represented: Pro, 38 isolates; Arg-Hyx-Ura, 25 isolates; Zero, 14 isolates; Arg, 7 isolates; Arg-Orn-Hyx-Ura, 6 isolates; and Pro-Arg-Hyx-Ura, 3 isolates. The auxotype groups had no characteristic electrophoresis pattern.…”

“…Both methods, however, have certain limiting disadvantages. Auxotyping requires meticulous preparation of complex media, and although more than 20 gonococcal auxotypes have been described, only 4 account for 86% of clinical isolates (3,4,16). Despite the promise of gonococcal serotyping, antisera are not universally available, and the number of antigenic groups is limited.…”