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Broths or peptone waters containing concentrations of agar less than that needed for a firm gel, but sufficient to indicate the presence of motile bacteria.  

Solid culture media designed to encourage the growth of specified bacteria and inhibit others which may be present in a mixed flora.  

Bacteriological filters composed of disposable asbestos discs clamped into a metal holder and funnel. The coarser discs (K or FCB) are for clarification; only the normal, ‘special EK’ or GS discs retain test bacteria.  

Bacterium the colonies of which acquire pigment while growing in the dark, an identifying feature of certain mycobacteria.  

Surface bacterial count performed by pressing a 2-inch length of tape on the surface under review, peeling off and presenting the adhesive side to an agar plate, then again peeling off. Colonies are counted on the incubated plate.  

Literally ‘fission fungi’—the Class of micro-organisms which includes the bacteria, but not the true fungi, rickettsia or viruses.  

Staining of bacterial spores with hot malachite green, the vegetative bacteria being then counterstained with weak safranine or basic fuchsin.  

The tendency of some bacterial species to colonize mainly (or to best advantage) around colonies of a second unrelated species, the latter providing some growth factor not present in the bulk of the medium.  

Gram-positive cocci which (by division in 3 planes) produce small packets of cells, and which oxidize but do not ferment glucose. A genus of gram-positive cocci of the family Micrococcaceae. These bacteria are saprophytes and tend to appear in packets of four or eight following binary fission.  

Broths or agar containing 8 – 10 per cent of sodium chloride, such media being selective for Staphylococci, but inhibitory to other bacteria.