Staphylococci and their Classification

Abstract

SUMMARY: The biochemical and fermentation reactions of 432 strains of aerobic, catalase-positive, Gram-positive cocci were examined in an attempt to produce an orderly classification of the group. The subdivision into Staphylococcus, Micrococcus, Gaflkya and Sarcina could not be justified, and, as Micrococcus is regarded as an invalid generic name, all aerobic species are placed in the genus Staphylococeus with the type species Staph. aureus Rosenbach.The primary subdivision was made on the coagulase reaction, with secondary subdivisions of the coagulase-negative strains based on the production of acid and acetoin from glucose. The characterization of the subdivisions is presented in a quantitative way.'The boundaries of the species, whereby msort them, are made by men.' (LOCKE, 168v.1The aerobic catalase-positive Gram-positive cocci present many taxonomic problems which must be resolved before a stable system of nomenclature can be applied to them. We visualize a series of organisms of similar gross morphology that show slight differences in cultural and biochemical reactions, a series that can be likened to a spectrum in that there is a gradual change from the inert non-pathogenic strains to the highly active pathogenic strains.To test this hypothesis we sought the help of other workers and collected strains from as many sources as possible, and, through the kindness of Dr Ruth E. Gordon, received subcultures of all coagulase-negative strains in the American Type Culture Collection. All strains received, and those in the National Collection of Type Cultures, were put through a standard series of tests which are described in this paper. All cultures were carefully checked for purity, and were dried in vacuo (Rhodes, 1950). METHODSOptimal temperature for growth. Three nutrient agar slopes, spread with a loopful of broth culture, were incubated a t 22, 30 and 37'. Growth was recorded after 24 ahd, 48 hr.Morphology. Broth cultures incubated a t 22' were examined for packet formation. Smears made from agar cultures incubated at the optimal temperature were stained by Lillie's modification of Gram's method.Biochemical tests were usually made on cultures incubated at the optimal temperature for growth; if an organism grew equally well at two temperatures, the higher temperature was used. Exceptions to this generalization were tests for the liquefaction of gelatin, and certain retests carried out after the main tests had been completed; details are given in the appropriate section.Pigment. Strains were grown on potato and on nutritent agar a t the optimal temperature for 24 hr. and kept a t room temperature for a week in diffuse daylight. Pigment was recorded as gold, lemon-yellow, or pink.

The Chemical Composition of the Cell Wall in some Gram-positive Bacteria and its Possible Value as a Taxonomic Character

“…These had been rejected on morphological grounds by Shaw, Stitt & Cowan (1951) and Cowan (personal communication) from their collection of Gram-positive, catalase-positive cocci, and this has been confirmed by us, since both cultures show diphtheroid forms several p. long, particularly in the case of M . cinnabareus.…”

Incidence and characteristics of Staphylococcus aureus in turkey products and processing plants

“…Baird-Parker's work confirmed the homogeneity of the species S. aureus based on its ability to form coagulase (Shaw et al, 1951)* The recognition of other species of staphy lococci and micrococci is controversial (Baird-Parker, 1962a). …”

“…The following is an attempt to compare the groupings of Shaw et al (1951), Hill (1959), and Pohja (i960).…”

The Intestinal Microflora of the Clothes Moth Larva Tineola bisselliella in relation to Wool Digestion

“…In pure culture the coccus grew optimally a t 28O, formed white colonies aerobically on nutrient agar, and anaerobically, slowly, a translucent growth. This coccus was catalase-positive, coagulase-negative (rabbit plasma), gave an acid clot in litmus milk, acid but no gas from glucose, produced no acetoin, and according to the classification of Shaw, Stitt & Cowan (1951) belonged to the Staphylococcus Zactis group of organisms which are often found in dairy products. …”