308 THE MENINGOCOCCUSGONOCOCCUS GROUP 



name first appears in Die Mikroorganismen (Fliigge), 3d edition, in 

 1896, credited to R. Pfeiffer. 



Morphology. Micrococcus catarrhalis occurs typically as a dipto- 

 coccus with the apposed surfaces of adjacent cocci flattened and 

 somewhat elongated. It measures about one micron in diameter. 

 Occasionally the organisms are arranged in tetrads, particularly in 

 young, active cultures in artificial media; in older cultures a tendency 

 toward short chain formation is frequently observed. Degenerated 

 cocci occur in older cultures. In sputum, bronchial secretions and 

 other material from inflammation of the upper respiratory tract, in 

 which Micrococcus catarrhalis is a primary or accessory factor, the 

 organisms occur both within and without the pus cells. In the acute 

 stages they are usually extracellular. 1 The organism is non-motile, 

 and it has no flagella. It forms neither spores nor capsules. It colors 

 readily with ordinary anilin dyes, some cells more intensely than their 

 fellows, and it is Gram-negative. 



Isolation and Culture. The organism grows with moderate vigor 

 upon agar; after twenty-four hours' incubation the colonies are 

 small, translucent and gray. After three to four days the colonies 

 are larger with an opaque centre, the periphery being translucent. 

 Old colonies tend to become somewhat brownish. Development is 

 more vigorous in media containing blood, blood serum, or ascitic 

 fluid. Hemolysis of the blood does not occur. The growth in gelatin 

 is slow, and usually feeble. A slight turbidity develops in broth. 

 Moderate development occurs in milk. Micrococcus catarrhalis 

 grows best at 37 C.; restricted development takes place at 16 C.; 

 no growth can be detected at 43 C. 



Products of Growth. The organism is culturally inert. It does not 

 produce any demonstrable proteolytic enzymes, and it produces no 

 acid in any sugar. No toxic products are known. Filtrates of broth 

 cultures have no apparent action upon white mice. No pathogenesis 

 for laboratory animals has been detected. 



Human Pathogenesis. Micrococcus catarrhalis has occasionally been 

 reported as a causative factor in catarrhal inflammations of the upper 

 respiratory tract, and even in atypical pneumonia 2 and in bronchitis. 3 

 Ordinarily it is an opportunist found in the upper respiratory tract. 



Bacteriological Diagnosis. The organism is of importance chiefly 

 through its striking resemblance to the meningococcus and the gono- 



1 Ghon, Pfeiffer and Sederl, Zeit. f. klin. Med., 1902, xliv, 262. 



2 Bernheim, Deut. med. Wchnschr., 1900. 3 Ritchie, Jour. Path, and Bact., 1900 



