THE INFECTIOUS DISEASES. 253 



CONCURRENT INFECTION IN TUBERCULOSIS. 



A concurrent infection with the tubercle bacillus and the pyogenic 

 micro-organisms is of extreme significance in that phase of tuberculous 

 inflammation of the lungs commonly called phthisis.' While the so- 

 called cold abscesses may be caused by the tubercle bacillus alone, this 

 germ is not infrequently found under these conditions to be associated 

 with other pyogenic micro-organisms, especially the streptococcus and 

 staphylococcus. 



Bacteria Resembling the Tubercle Bacillus. 



There are several species of bacteria which after deep staining resist the decolorizing 

 action of dilute acids. These have been called, collectively, "acid-resisting" or acid- 

 proof bacteria.' 2 We shall consider only two of these. 



THE SMEGMA BACILLUS. This organism is often present and sometimes in large 

 numbers in the preputial smegma and elsewhere about the external genitals. It so 

 closely resembles the tubercle bacillus in size, shape, and staining reactions that it is 

 liable by morphological examinations alone to be mistaken for it. It has been culti- 

 vated on artificial media and is not pathogenic. The smegma bacillus, when stained as 

 above recommended for the tubercle bacillus, resists the decolorizing action of the acid ; 

 but it is usually decolorized by alcohol, thus differing from either the tubercle bacillus 

 or the leprosy bacillus. But this color reaction is not certain ; individual bacilli not in- 

 frequently remain unstained. Various special methods for differentiation have been 

 suggested, but none of them is wholly satisfactory. 3 In doubtful cases, therefore,' and 

 when serious operative procedures are dependent upon the bacterial diagnosis, recourse 

 should be had to animal inoculations. 



THE "HAY BACILLUS." This resembles the tubercle and smegma bacilli in form 

 and staining peculiarities. It is called the "hay bacillus" or "grass bacillus" because 

 oi' its common occurrence upon grass heads in the fields. It is not pathogenic and is 

 readily cultivated. 



Lupus and Other Forms of Tuberculosis of the Skin. 



Local tuberculous inflammation of the skin may occur in the form of small nodules 

 or wart-like thickenings, as the result of accidental inoculation. Local skin infection 

 may occur about the orifices of the body in tuberculous persons from contact \vith secre- 

 tions or excretions containing the tubercle bacilli, or about sinuses leading to tubercu- 

 lous abscesses, joints, etc., or in the vicinity of tuberculous lymph-nodes. 



A chronic form of tuberculous inflammation which presents special clinical features 

 has long been known under the name of lupus. 



Lupus. This form of inflammation most frequently occurs in the skin of the face, 

 but also in the mucous membrane of the mouth, pharynx, conjunctiva, vulva, and 

 vagina. The lesion consists of small, multiple nodules of new-formed tissue, in the cutis 

 or mucosa and submucosa. By the formation of new nodules and a more diffuse cellu- 

 lar infiltration of the tissue between them, the lesion tends to spread, and by the conflu- 

 ence of the infiltrated portions a dense and more or less extensive area of nodular in- 



1 See Spengler, Zeitschr. f. Hygiene, etc., Bel. xviii., p. 342, 1894, bibliography. See 

 reference to Prudden, p. 478. 



' 2 See for resume and bibliography, Abbott and Gilder sleeve, Trans. Assn. Amer. 

 Phys., vol. xvii., p. 37; also lloseiiberger, Proc. Path. Soc. of Phila., January, 1904. 



;i Critical review, with bibl., Dahms, Jour. Am. Med. Assn., vol. xxxiv., pp. 983 

 and 1045, 1900. Consult also Come, Jour. Exp. Med., vol. v., p. 205, 1900. 



