CHAPTER XV. 

 MALTA FEVER. 



MICROCOCCUS MELITENSIS (BRUCE). 



General Characteristics. A non-motile, non-flagellate, non-spo- 

 rogenous, non-chromogenic, non-liquefying, pathogenic coccus, staining 

 by the ordinary methods, but not by Gram's method ; characterized 

 by remarkably slow growth and by pathogenic action upon monkeys. 



In 1887, while working in Malta, Bruce* succeeded in 

 finding in every fatal case of Malta fever a micrococcus 

 which could be isolated in pure cultures from the spleen, 

 liver, and kidney, which grew readily on artificial media, 

 and which, when injected into monkeys, produced the 

 disease. The serum from cases of Malta fever also caused 

 agglutination of the cocci. 



Morphology. Micrococcus melitensis, as he called it, 

 is a round or slightly oval organism measuring about 0.3 fi 

 in diameter. It is usually single, sometimes in pairs, but 

 never in chains. When viewed in the hanging drop, it is 

 said to exhibit active "molecular" movements, but is not 

 motile and has no flagella. 



Staining. It stains well with aqueous solutions of the 

 anilin dyes, but not by Gram's method. 



Cultivation. The best medium for its cultivation is 

 said to be ordinary agar-agar. After inoculating by a punc- 

 ture, from an organ of a fatal case of Malta fever, the tubes 

 should be kept at 37 C. No growth appears for several 

 days. At length, however, minute pearly white spots appear 

 scattered around the point of puncture and along the needle 

 path. After some weeks the colonies grow larger and join 

 to form a rosette-like aggregation, while the needle tract be- 

 comes a solid rod of yellow-brown color. After a lapse of 

 months the growth still remains restricted to the same area 

 and its color deepens to buff. 



When the sloping surface of inoculated agar-agar is ex- 

 amined by transmitted light, the appearance of the colonies 

 is somewhat different. At the end of nine or ten days, if 

 * "Practitioner," xxxiv, p. 161. 

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