THRUSH (SOOR OR SPRUE) Thrush is a local disease of the oral mucous membrane produced by the growth of a specific fungus (thrush fungus).
The disease was recognized and described by the Hippocratic yaiters under the general term aphthai, but the nature of the diseas.e was obscure until the deposits of the specific fungus were described by Langenbeck, Berg, and Gruby in 18.10, and at once the parasitic nature of the disease was established.
The name "soor" used by the Germans is derived from the low Saxon vvord sOr, that is, dry, parched, which probably arose from the fact that the thrush fungus grows with preference on a dry or withered mucous membrane. This stomatitis has been well known among the people for ages, on account of its characteristic appearance and there is scarcely a single disease which ba.s so many appellations as thrush. At least 25 different names for this affection appear in the literature.
Pathogenesis, Local onset of thrush is mani fested by the appearance of small round white spots upon the MUCOUS membrane of the mouth. The preferable seat of onset is the tongue (especially the fore part), the cheek, and the gums (see Plate 40). When an attempt at mechanical removal is made, we become convinced that it adheres more or less firmly to the base, a very important differential sign from the similar case in flocculcs which often adhere to the sides of the cheek in infants after vomiting. Furthermore, on inspecting the mouth, we observe objective signs of a simple stornatitis which is revealed by a redness and tenderness of the mucous membrane and which usually precedes the specific affection.
A microscopical examination of a mass which has been removed, shows that it is composed chiefly of a dense fungous growth, which con sists of jointed filaments and shining gonidia, the thrush fungus (Fig. 7), also epithelial cells and a few leucocytes. If this fungus is grown on the proper culture medium (obliquely hardened gelatin), it will be observed that the growth of the fungus is not restricted to the surface, but has a marked tendency to grow deeper, as an innumerable number of filaments from the superficial colonies have penetrated the whole depth of the culture medium.
A similar property, though in less degree, is shown by the fungus growing on the living mucous membrane; consequently, the deposit cannot be removed without leaving some of the growth and without removing some tissue cells, because the growth is implanted deeply with many radicles. The whole thickness of the epithelium to the con nective tissue seems to be perforated by the fungous masses.
Gradually, the process extends over a greater surface. The mucous membrane of the lips, the tongue, the palate, and the cheek becomes covered with numerous white spots. The intervening free mucous mem brane is inflamed, especially is this noticeable on the tongue, where the swollen papilla, protucle like pegs from the centre of an area encircled by the fungous growth.
The adjoining colonies usually become confluent and consequently the surface of the tongue and cheek appear to be overspread by a white coat. At this stage the membranes do not adhere so closely; their re moval is very easy, and they drop off piecemeal, spontaneously. A change in the color of the deposits is also manifest. They become yel lowish or dirty brown, which discoloration is mostly due to superficial luemorrhages.
The exfoliation of the thrush membranes is the consequence of a strong proliferation of the new epithelium under the deposit, and no visible alteration of the mucous membrane remains after healing.
a rule, the growth of the thrush fungus remains restricted to the epithelium; the epithelial cells appear loosened and perforated by the mycelia. The filaments may, however, grow into the connective tissue and even penetrate the walls of the blood vessels (Wagner). In this manner and by this route, as well as through the ul ceration of the mucous membrane. the thrush fungus may gain entrance to the circulation.