SUMMARYThe oxidase test of Kovacs (1956) was applied to 1660 strains of various genera, of which 210 gave a positive reaction and 64 gave a delayed positive reaction. Members of the Neisseriaceae and Pseudomonadaceae were generally oxidasepositive, whereas members of the Enterobacteriaceae and, with few exceptions, Gram-positive organisms, were oxidase-negative ; equivocal results were obtained in the Brucellaceae and the genus Bacillus. Kovacs test is simple and quickly performed, but very sensitive. Some taxonomic implications of the results are discussed.
SUMMARYKlebsiella strains are divided into six categories on the following reactions: fimbriation, production of gas from glucose a t 37", acid from lactose and dulcitol, methyl red test, acetoin production, citrate, urease, gluconate, malonate, lysine decarboxylase, growth in the presence of KCN and ability to produce gas from lactose a t 44". Five of the six categories are assigned specific rank, the sixth subspecific rank. The tests enable Friedlander's pneumobacillus to be distinguished from Aerobacter aerogenes. A new species, Klebsiella edwardsii, and a new subspecies, K . edwardsii var. atlantae, are named. Neotype strains of old species are proposed, holotypes of the new species and variety designated, and the catalogue numbers in the National Collection of Type Cultures and American Type Culture Collection given.
A simple device by which the characters of an unknown organism can be com pared with those of named genera and species is described. The comparison is made by using ‘diagnostic tables’ of characters found to have differential value.Separate tables for Gram-positive and Gram-negative bacteria were made; the first stage indicated the probable genus into which the unknown fell and a second (and occasionally a third) stage was needed to identify the species or subspecies.We wish to thank Dr Ruth E. Gordon for much unpublished data which were invaluable in constructing Table 1gg, Miss Helen E. Ross for helping with Table 1f, Dr Oleg Lysenko for letting us use data from a paper about to be published, and Mr W. Clifford for the photographs and figures.
By the urn of Kovacs' (1956) test, oxidass activity was demonstrated in 23 of 66 strains of coagulase negative staphylococci (or micrococci) but in none of 82 strains of coagulase positive staphylococci. Less sensitive methods showed fewer reactions or failed to demonstrate them at all. Oxidrrse activity could not be correlated with other bioahemical features.THE ABSENOE of oxidase activity in staphylococci was reported by Steel (1961). Of 97 strains tested by Kovacs' (1966) method, only one (a strain of Stuph+&ococcus Zactk) showed any oxidase activity. Steel (1961) recognized three reactions: first, a positive reaction in which the blue colour developed within 10 see; second, a delayed positive reaction in which the colouration developed in 10-60 sec; and third, a negative reaction in which colouration took longer than 60 sec or failed to develop at all.The late Dr. B. P. Eddy of the Low Temperature Research Station, Cambridge (pers. comm.) also recognized three reactions: first, a positive reaction as above; second, a slow positive reaction in which the reagent is slowly oxidized, the bIue colour taking 30-120 sec to reach its maximum intensity; and third, a negative reaction in which not only is the reagent not oxidized by the bacteria but its autoxidation is inhibited and the reagent spot dries with a white patch in the position of the bacterial mass. He found the negative reaction to be characteristic of Staph. aurew and Staph. saprophyticus and the slow positive to occur with some strains of Staph. csfemnentams, Staph. lactis and Staph, rosew.The strains tested by Steel (1961) were mostly coagulase positive (Staph. auww)
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