CHAPTER XV. 



MALTA FEVER. 



Micrococcus Melitensis (Bruce 1 ). 



Working in Malta in 1887 Brnce succeeded in finding 

 in every fatal case of Malta fever a micrococcus which 

 could readily be isolated in pure cultures from the spleen, 

 liver, and kidney, which grew readily and when injected 

 into monkeys produced all the phenomena of the disease. 

 The serum from cases of Malta fever also caused aggluti- 

 native phenomena when allowed to act upon the micro- 

 organism. 



The Micrococcus melitensis is described as of a round 

 or slightly oval form and measures about o. 3 fx in diame- 

 ter. 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 proba- 

 bly not motile. 



The organism stains well with aqueous solutions of 

 gentian violet, but not by Gram's method. 



The best medium for cultivation is said to be ordinary 

 agar-agar. After inoculating either by a stroke or punct- 

 ure 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 colony, while the 

 needle track becomes strongly marked, solid looking, 

 and yellow-brown in color, with serrated edges. After a 

 lapse of some months the growth remains restricted in 

 area and its color deepens to buff. 



When the sloping surface of the agar-agar is examined 

 by transmitted light, the appearance of the colonies is 

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



1 Practitioner, xxxiv., p. 161. 



573 



