The Effect of Inorganic Salts on the Production of Small Colony Variants by Staphylococcus Aureus

Abstract

Small colony variants, or G. forms, have been reported for a number of bacterial species (see Koser and Dienst (1934), Swingle (1935), and Haddow (1938), for reviews of the literature) but because of the infrequency of their occurrence as compared with many other bacterial variants they have not received an equivalent amount of attention. The characteristics of the small colony variants

Small Colony Variants of Escherichia coli

“…Confusion attending the small colony variant has taken some order with the evidence of Koser (1930Koser ( , 1934, Swingle (1935), Youmans (1937Youmans ( , 1942, Chinn (1936), and others that these organisms are merely cells of lowered metabolic activity due to interference or destruction of enzymes by conditions somewhat unfavorable for growth. The following points lend credence to this view: (a) The conditions under which small colony variants are found, as in aged cultures (Hadley, Delves, and Klimek, 1931;Koser and Dienst, 1934;Swingle, 1935) and as in the presence of lithium chloride (Hadley, Delves, and Klimek, 1931;Koser and Dienst, 1934;Swingle, 1935), barium chloride (Youmans, 1937(Youmans, , 1942, bacteriophage (Kuhn and Stemnberg, 1931), phenol (Duff, 1937), penicillin (Schnitzer, Camagni, and Buck, 1943), and 2-methyl-1,4-naphthoquinone, are somewhat inhibitory to bacterial growth. (b) At least two of the foregoing agents (barium chloride and 2-methyl-1,4naphthoquinone) favor the development of the small colony variant in medium poor in growth factors (meat-extract-activator peptone medium and synthetic asparagine medium); the same agents in more nutritious broths fail to induce this type of variation.…”

Characterization of Gentamicin‐Resistant Respiratory‐Deficient (Res−) Variant Strains of Staphylococcus aureus

“…Of the latter a phenotypically diverse assortment of small colony strains which showed different degrees of phenotypic variation from the parent strain, have been referred to as variants. Variants have been isolated after treatment of the parent cells with inorganic salts (48) or organic compounds (11). Resistant variants have been recovered following treatment with penicillin and related antibiotics (2,8,45) and aminoglycosides (21, 25 , 27, 28, 42, 47).…”

SMALL COLONY VARIANTS OFESCHERICHIA COLI

“…According to Youmans (1937) and Youmans and Delves (1942), many of the properties of small colony variants can be accounted for by an over-all lowering of the metabolic rate. Clowes and Rowley (1955) suggested that this explanation might account for the isolation of many of these variants from toxic environments, and proposed that the inhibitor (antibiotics, metal ions, etc.)…”