CHAPTER XLIV 

 THE HIGHER BACTERIA 



Between the lower forms of bacteria, the unicellular rods, spheres and spirals, 

 which reproduce by fission only, and the true molds which have differentiated 

 parts, comparable to the roots, trunk and fruit of trees, there are intermediate 

 forms difficult to classify satisfactorily. Three groups in this class are of in- 

 terest to the medical bacteriologist: leptothrix, cladothrix and strep tothrix; 

 sometimes referred to collectively as trichomycetes. 



LEPTOTHRICES 



Leptothrices have been found in inflammatory lesions of the mouth; they 

 are frequently observed in saliva and sputum from healthy persons, more often 

 when there are decaying and ill-cared-for teeth. 



Morphology. They are rod-shaped and vary in length from 30 to 1 50 ju and 

 in width from o. 5 to 2 n; usually they are seen about i n wide and 50 n long. Some 

 are straight, others curved or twisted, and they are arranged singly, in filaments 

 and in clumps. Some forms are segmented, others are not. 



Staining. Leptothrices stain readily with the usual aniline dyes. 



Growth. Attempts to cultivate on artificial media have been unsuccessful. 



Pathogenesis. The leptothrices, in all probability, are non-pathogenic and 

 occur in the mouth, sputum or saliva as saprophytes. 



CLADOTHRICES 



Cladothrices are distinguished from leptothrices and streptothrices by false 

 branching. They are, therefore, distinguished from leptothrices, which do not 

 show branching. Whether or not reported cases of cladothrix infection were 

 such, is a mooted question, as differentiation between true and false branching 

 is difficult to determine. In any case, cladothrix infections are not common 

 if they do occur and clinically are similar to streptothrix infections. 



STREPTOTHRICES 



Streptothrices are distinguished by true branching, septate filaments and 

 reproduction by conidia, which form in rows. 



Long filaments may be observed singly and intertwined. Some appear 

 chiefly as short, stout rods. Frequently both short and long filaments terminate 

 in a club-shaped swelling. 



STREPTOTHRIX ACTINOMYCOSIS 



Streptothrix actinomycosis occurs upon grain and pasture land contaminated 

 with the discharges from open lesions of cattle, and in the pus and sinus dis- 

 charges of the disease, also in sputum when the lungs are involved. 



