Category: S

  • Straight wire

    Straight length of (platinum, Nichrome) wire in holder for the subculture of small colonies, and the inoculation of stab culture- introducing minimal air.  

  • Stormy clot

    The break-up of the acid-coagulated clot in a milk culture of Cl. welchii and of some other saccharolytic organisms-e.g., Cl. butyricum—due to the action of gas formation.  

  • Starch hydrolysis test

    Characterization test applicable to various groups of bacteria. One volume of 10 per cent sterile soluble starch is added to 5 of melted nutrient or yeast extract agar. Inoculated and incubated plates are flooded with dilute iodine. A colourless zone surrounds colonies where starch is hydrolysed, the remaining areas being deep blue.  

  • Staphylokinase

    Enzyme co-factor produced by staphylococci. It activates plasminogen (a plasma enzyme precursor) which is then capable of dissolving coagulated plasma. An exotoxin produced by some strains of Staphylococcus aureus that may be used clinically as a thrombolytic drug.  

  • Stability test

    Test of the stability and activity of use-dilutions of a disinfectant. One tube (A) of a pair of identical dilutions is inoculated with a suspension of Ps. aeruginosa on Day 1, leaving it and the uninoculated tube (B) at room temperature for 7 days. On Day 8, 5 subcultures of tube (A) are made into…

  • Stab culture

    Inoculation of a solid butt of agar or gelatin with a straight wire. Agar cultures may be used for the production of anaerobiasis or observation of motility, and gelatin for its liquefaction by proteolytic bacteria. A bacterial culture made by thrusting into the culture medium an inoculating needle with the bacterial specimen.  

  • Spreaders

    Glass items for distributing inoculum evenly over a plate of culture medium. An instrument for distributing something evenly over a tissue or culture plate. A compound incorporated into an atomizer to facilitate uniform dispersion across the intended surface.    

  • Spore strips

    Paper strips incorporating a sporing organism (usually Bacillus stearothermophilus) for testing autoclave efficiency.  

  • Spirochaetales

    Order of Gram-negative micro-organisms with slender spiral bodies (6-500 pm long) by the flexion of which they move, being non- flagellate. Free-living, saprophytic, and parasitic forms occur. Demonstrable often only by dark-ground illumination, or by Giemsa stain, taking aniline dyes poorly if at all. Comprises the families Spirochaetaceae and Treponemataceae; only the latter is of…

  • Spirillum minus

    Spiral organisms 2-6 μm long, with broad coils at 1 pm intervals, one of the infective agents of rat-bite fever. Seen by dark-ground illumination the spirillum is actively motile (darting moves are characteristic) due to terminal flagella. Romonovsky films of lymph gland juice, skin lesions and sometimes blood may show the parasite, and inoculation of…