322 An Introduction to Medical Mycology 



Other Actinomycetes are said to cause actinomycosis in some cases, but 

 A. bovis is probably the chief offender. The clinical characteristics, the 

 etiology and other features of actinomycosis have been described in Chap- 

 ter X, pp. 177 ff. 



(a) Immune reactions.— Agglutination reactions are usually positive. 

 There is a cutaneous hypersensitivity to vaccine in patients with the infec- 

 tion. 



(b) Microscopic features.— In making a diagnosis of actinomycosis, one 

 relies chiefly on the search for the ray fungus in pus from a suspected lesion. 

 If pus is not exuding freely from a sinus tract, gentle pressure usually causes 

 some to appear. Occasionally it is necessary to wait for a day or two for 

 pus to form, and this is usually preferable to irrigating a sinus tract. If 

 pus is scanty, gauze drains may be inserted in the sinus tract or a gauze 

 pack applied to the site. After 24 hours granules will probably be found 

 enmeshed in the material. In the diagnosis of actinomycosis of the lung, 

 the presence of grannies in a direct smear of sputum indicates an active 

 infection. The observation of Actinomyces on culture may be misleading, 

 as it is frequently present in the buccal cavity as a saprophyte. 



The specimen of pus is placed on a slide, and over this a cover slip is 

 dropped. If a granule is present, it may be detected under the low power 

 of the microscope. For details of structure, higher magnification is neces- 

 sary. For a permanent mount a drop of pus containing a granule is placed 

 on a large cover slip and covered with a smaller cover slip. Glycerin may 

 be run under the smaller cover slip to replace pus and air. When the 

 glycerin has had time to permeate the preparation and the cover slips have 

 flattened as much as they will (several days), the cover slip preparation 

 may be attached to a glass slide by means of balsam inverted so that the 

 smaller cover slip is nearest the slide. If one wishes to bring out minute 

 details, the granule may be stained with Gram's stain or with carbolfuchsin 

 before the addition of glycerin. 



The granule consists of one or more colonies, each of which contains 

 twisted mycelium with pigment granules in the central zone and a pali- 

 saded arrangement of organisms forming a fringe at the periphery. These 

 latter organisms are noted for an enlargement at one end (the so-called 

 club form), and they are also striated. There are no spores. The ray fungus 

 is gram-positive. The central mycelium takes the basic dye, and the periph- 

 eral zone takes the acid dye. 



(c) Cultural characteristics.— It is usually necessary to begin growth 

 on an anaerobic medium, preferably one containing blood or meat. Em- 

 mons recommended dextrose-veal infusion agar. We have found the an- 

 aerobic medium recommended by Brewer to be of value (for the formula 



