Auxanographic grouping and typing of Neisseria gonorrhoeae

Abstract

Nearly 96% of 1297 N. gonorrhoeae isolates in Hamilton [Canada] were assigned to 6 major auxanographic groups (non-requiring (NR) Pro-, Orn-, Pro-Cit-Ura-, Orn-Ura-Hyx-, Cit-Ura-Hyx-) as established by requirements for none, or any 1 or more of Pro, Ura, Hyx, Cit, or Cit replaceable by Orn on chemically defined medium. Seven other groups and strains not growing accounted for 4.2%. The most common groups were Orn-Ura-Hyx- (25.6%) and Pro-Cit-Ura- (31.8%). This latter group has not been previously described. These Pro Cit/Orn Ura Hyx criteria were among the most unequivocal to interpret; with rare exceptions for Pro, a requirement was shown by absence of growth at any time of the zones of inoculation from a replicator. For some strains, some of the possible additional requirements (Leu, Val, Ile, Glu, Thr, Ser, His, Etc.) could be less readily ascertained, because an occasional manifestation was to reduce the amount of growth, or to slow down the rate of growth, compared to complete medium. The first 4 of the 6 groups were the least fastidious, in that few strains had any additional requirements. About 2% of strains were inhibited by 0.25 mM Phe.