Production of opacity in egg‐yolk broth by staphylococci from various sources

Abstract

GILLESPIE and Alder (1952) described an egg-yolk (E.Y.) reaction of Staphylocoecw aurew (coagulase-positive staphylococcus). About 80 per cent. of strains isolated from human Bources outside hospital produced opacity when grown in egg-yolk broth and were called egg-yolk-positive (E.Y. +) strains. The remaining 20 per cent. were egg-yolk-negative (E.Y. -).The distribution of the reaction among strains isolated from in-patients of this hospital was very different. Most of t'he hospital cultures were E.Y.-.The difference was found to be due to the widespread dissemination among in-patients of a few strains that were penicillin-resistant and E.Y.-at the same time. , 411 of the 60 coagulase-negative staphylococci examined were found t,o be E.Y.-.Egg-yolk reactivity was found to be a stable property of staphylococci. A strong but not absolute correlation was demonstrated between it and the lipolytic activities of the organisms against triglycerides of higher fatty acids, but the mechanism of the reaction was not elucidated.In the present paper we report the reault,s of a further survey of' the distribut,ion of the E.Y. reaction among staphylococci from human and animal sources and describe the relationship found between the react,ion and the clinical evidence of pathogenicity of human coagulasepositive strains. MATERIALS AND METHODSCultures of staphylococci were maintained on infusion-base nutrient-agar stabs, which, after incubation overnight at 37' C., were stored a t c. 4' C.Coagulase tests were done on freshly-isolated cultures by the slide method (Cadness-Graves et al., 1943). Most of the coagulase-positive cultures, including all that were found to be E.Y.-, were re-tested by the tube method (Gillespie, 1943). This extra precaution was taken to ensure that no coagulase-negative strain was listed in error as coagulase-positive. This sort of mistake would have been serious, since all coagulase-negative strains were E.Y.and most coagulasepositive strains E.Y. +. All the coagulase-negative staphylococci examined were tested by the tube method. The E.P. reactions of the organisms were tested by growing them at 37" cin glucose-yolk broth, with and without antitoxin, as previody described. Known E.Y.+ and E.Y.strains were included as controls with each batch of tests. Experience has shown that storage of the yolk broth at ca. 4' C. for 1-2 months before use speeds up the reaction and increases the tendency of the separated material to form a curd. Medium which had been thus allowed t o mature was used ip the later part of the work. A few Staph. aurew strains from animals produced relatively faint turbidity J. PATH. BACT.-VOL. LXVI (1953) 205

Staphylococci and Their Classification

“…Other methods used to type Staph. aureus strains include hemolysin production (Elek & Levy, 1951) lipase production (Alder et al, 1953;Delmotte, 1958), hydrolysis of casein (Lieb & Brenneis, 1961); and pigmentation (Willis et al, 1964). The results of Willis et al on the pigmentation of hospital isolates of Staph.…”

Changes in the Ultrastructure of Egg Yolk by the Growth of Streptococcus faecalis var liquefaciens

“…THE MICROBIOLOGY of the shell eggs, albumen and whole egg magma has been studied extensively (Haines, 1939;Romanoff and Romanoff, 1949;Brooks and Taylor, 1955;Board, 1964Board, , 1965Board, , 1966Board, , 1968Board, , 1973Vadehra and Nath, 1973). However, no detailed studies of the physicochemical changes produced by growth of microorganisms in egg yolk have been reported except for the egg yolk reaction caused by coagulase-positive staphylococci, Clostridium perfringens and Bacillus species (Gillespie and Alder, 1952;Alder et al, 1953;Macfarlane et al, 1941;Mc-Gaughey and Chu, 1948;Calmer, 1948). Gravani et al (1972) and Gravani (1975) reported that Streptococcus faecalis var liquefaciens produced an "egg yolk separation factor" which caused the separation of homogeneous yolk into two weIl defined layers; the upper layer was clear and oily and the lower layer was thick, viscous and gummy.…”

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

“…Gillespie & Alder (1952) found that about 80 yo of coagulase positive strains of staphylococci isolated from human sources outside hospital were egg yolk positive, whereas all of the 60 coagulase negative staphylococci they examined were egg yolk negative. Alder, Gillespie & Herdan (1953) found that the coagulrtse negative staphylococci of human origin were all egg yolk negative and that most of the coagulase positive staphylococci of human origin were egg yolk positive. Ti1 view of these finchgs i t was decided to investigate tlie possibility of utilizing the egg yolk reaction ill t h r p q~a r a t i o n of a solid selective and differential medium for coagulase positive staphylococci.…”