Tellurite‐egg Agar, a Selective and Differential Medium for the Isolation of Coagulase Positive Staphylococci

Innes, A. G.

doi:10.1111/j.1365-2672.1960.tb00184.x

Cited by 25 publications

(16 citation statements)

References 9 publications

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“…Tests on the tellurite, glycine medium of Zebovitz et al (1955) confirmed previous observations by Hoeprich, Croft & West (1960), Sevel & Plommet (1960 and Innes (1960) that it is inhibitory to many strains of Staph. aureus on primary isolation.…”

Section: Preliminary Experimentssupporting

confidence: 77%

“…Phage typing is a valuable means of identifying enterotoxic strains of staphylococci (Allison, 19491, but only when the phage type has been isolated from a food incriminated in a food poisoning outbreak (Elek, 1959). The in vitro enterotoxin test of Levi, Matheson & Thatcher (1956) awaits confirmation, as does the suggested correlation between ability to cause opacity in egg yolk broth and enterotoxin production (Innes, 1960). If the latter relationship is confirmed it could be said that enterotoxic types are mainly of human origin, as most strains of Staph.…”

Section: Discussionmentioning

confidence: 99%

“…However, it was later found that the presence of a fermentable carbohydrate reduced the size of these zones, and by omitting mannitol from the MTG medium better clearing was obtained. Phosphates, found by Ludlani (1949) to reduce the toxicity of tellurite, were included in the niodificetions of this medium described by Zebovitz et al (19551, Sevel &Plommet (1960) andInnes (1960). I n the presence of pyruvate, however, phosphates had no stirnulatory effect and were not tested further.…”

Section: Preliminary Experimentsmentioning

confidence: 99%

“…It was found, however, that some strains of Staph. aureus formed similar opaque zones after incubation for 24-48 hr (see Carter, 1960;Innes, 1960) and some egg yolk clearing strains of Staph. eayophyticus failed to develop inner opaque zones.…”

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confidence: 93%

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An Improved Diagnostic and Selective Medium for Isolating Coagulase Positive Staphylococci

Baird‐Parker

1962

Journal of Applied Bacteriology

255

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Summary This paper describes the development and use of a selective and diagnostic medium (ETGPA) for isolating coagulase positive staphylococci from food. It combines an improved form of the selective medium of Zebovitz, Evans & Niven (1955) with the ability to clear egg yolk as a diagnostic character. The new medium is noninhibitory but selective to coagulase positive staphylococci from a variety of sources, and its performance is better than that of four recently published media.

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Section: Preliminary Experimentssupporting

confidence: 77%

Section: Discussionmentioning

confidence: 99%

Section: Preliminary Experimentsmentioning

confidence: 99%

mentioning

confidence: 93%

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An Improved Diagnostic and Selective Medium for Isolating Coagulase Positive Staphylococci

Baird‐Parker

1962

Journal of Applied Bacteriology

255

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“…To facilitate the examination of large numbers of strains, a solid egg yolk medium was developed by one of the authors (B. J. C.); similar media have been described by Colbeck (1956), Carter (1960), Innes (1960 and Baird-Parker (1962). The formula which was found to give optimal results in tests which will be described separately (Collins, to be published) was yeastrel agar containing 5 % egg yolk and 5 % horse serum.…”

Section: Methodsmentioning

confidence: 99%

The egg yolk reaction ofStaphylococcus aureusisolated from burns

Lowbury

Collins

1964

J. Hyg.

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A large majority of strains of Staphylococcus aureus were found by Gillespie & Alder (1952) to produce opacity when grown in egg yolk broth, apparently through the action of a lipase on certain triglycerides. Of the strains isolated from outpatients, 82 % were 'egg yolk positive' (EY+), but only 45 % of those isolated from in-patients gave a positive reaction; there was a strong association between penicillin-resistance and a negative egg yolk (EY-) reaction. Parker (1958) confirmed the association of negative egg yolk reaction with penicillin resistance, and found that such strains were particularly common in superficial lesions, including wounds; strains which caused deep lesions usually showed a positive egg yolk reaction.We have tested strains of Staph. aureus isolated from burns in three periods (1958, 1960 and 1962) and from several other sources for egg yolk reaction; the association of this reaction with some other features, including phage type, antibiotic sensiiivity and mercuric chloride resistance (Moore, 1960) has been examined. The relevance of these data to the epidemiology of staphylococcal infection is discussed. MATERIALS AND METHODSTests for egg yolk reaction A liquid egg yolk medium was prepared in the manner described by Gillespie & Alder (1952).To facilitate the examination of large numbers of strains, a solid egg yolk medium was developed by one of the authors (B. J. C.); similar media have been described by Colbeck (1956), Carter (1960), Innes (1960 and Baird-Parker (1962). The formula which was found to give optimal results in tests which will be described separately (Collins, to be published) was yeastrel agar containing 5 % egg yolk and 5 % horse serum. Yeastrel agar contained the following ingredients: Yeastrel, 3 g.; peptone (Oxoid), 5 g.; sodium chloride, 5 g.; sodium dihydrogen phosphate, 3 g.; agar (Oxoid No. 3), 8 g.; and distilled water, 1000 ml. The mixture was steamed, filtered, adjusted to pH 7-4-7*6 and autoclaved at 1210 C. for 15 min. To 18 ml. amounts of this medium cooled to approximately 500 C. were added 1 ml. of horse serum and 1 ml. of egg yolk (obtained aseptically from fresh farm eggs). The medium was poured into sterile plastic Petri dishes, 10 ml. per plate.Plates of egg yolk agar were spot-inoculated with Staph. aureus, 16 strains per

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Staphylococcal lipolysis and pigmentation

Willis

Turner

1962

J. Pathol.

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GILLESPIE and Alder (1952) and Alder, Gillespie and Herdan (1953) showed that most strains of coagulase-positive staphylococci of human origin produced an opacity due to lipolysis when grown in egg yolk broth, whilst coagulase-negative staphylococci caused no such change in the medium. These workers were unable to obtain satisfactory results on agar media containing egg yolk, but subsequently Innes (1960) and Willis (1960) noted the development of strong reactions on such media. Innes utilised these reactions in the preparation of an indicator medium for coagulase-positive staphylococci ; 24-hr colonies of egg-yolk-positive coagulase-positive staphylococci grown on his tellurite mannitol egg agar were surrounded by wide zones of clearing or opacity. With further incubation the clear zones became opaque and were sometimes replaced by zones of pearly layer. The egg-yolknegative coagulase-positive strains studied by Innes were sometimes surrounded by clear zones, but opacity never appeared. Innes did not comment on the egg yolk reactions of the coagulase-negative strains that he studied. He noted that in the absence of tellurite the pigmentation of coagulase-positive staphylococcal colonies was excellent.We have observed somewhat similar changes in plain egg yolk agar plate cultures of staphylococci, and have also noted that this medium favours pigmentation of colonies by comparison with simple nutrient agar. These findings suggested that the egg yolk reaction of lipolytic staphylococci in plate cultures might provide a ready means of distinguishing between coagulase-positive and coagulase-negative strains of human origin; we have, therefore, studied this reaction and the similar lipolytic activity of staphylococci on some other fat media.In the subdivision of staphylococci, the pathogenic speoies Staphy-2ococcu.s aurew is distinguished from non-pathogenic species by the coagulase test. In practice, however, the selection of primary cultures for this test depends on the detection on agar media of colonies possessing the characteristic golden pigmentation. This remains for most purposes the essential starting point in the isolation of the organism from mixed cultures, despite the fact that there is marked variation in the intensity and quality of the pigmentation of both coagulasepositive and coagulase-negative staphylococci (Elek and Levy, 1950 ;

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Tellurite‐egg Agar, a Selective and Differential Medium for the Isolation of Coagulase Positive Staphylococci

Cited by 25 publications

References 9 publications

An Improved Diagnostic and Selective Medium for Isolating Coagulase Positive Staphylococci

An Improved Diagnostic and Selective Medium for Isolating Coagulase Positive Staphylococci

The egg yolk reaction ofStaphylococcus aureusisolated from burns

Staphylococcal lipolysis and pigmentation

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