CHAPTER XXVIII 

 MICROCOCCUS MELITENSIS 



Micrococcus melitensis, first found in Malta, has been reported as occurring 

 in many regions adjacent to the Mediterranean, also in China, Central Africa 

 and England, and may have a still wider distribution. 



This organism is found in the soil of regions where the disease prevails and 

 in the milk of infected goats and the urine of infected patients. 



Morphology. The micrococcus melitensis is a small, round or oval organ- 

 ism arranged singly, in pairs and short chains, the latter often parallel to each 

 other. According to early observers this organism is a coccus. Recent authori- 

 ties classify it as a bacillus. It is a non-motile, stains with the usual anilin 

 stain and is Gram negative. 



Growth. Micrococcus Melitensis is an obligate aerobe and grows best at 

 37C. 



Bouillon. Incubated at 37C. s'hows cloudiness in 3 to 5 days. 



Agar. Small white colonies appear in 3 to 5 days. Growth is most abundant 

 on glycerin agar, even on this medium it is scant. 



Gelatin. No apparent growth occurs on this medium, it is not liquefied. 



Potato. Does not show growth. 



Milk is not acidulated and is not coagulated. 



Indol is not formed, spores are not formed, sugars are not fermented. 



Resistance. Micrococcus melitensis is somewhat more resistant to the 

 various germicidal agencies than the typhoid bacillus. 



Toxin. Toxin production in culture is slight. 



Agglutinins. Specific agglutinins occur in the blood of immunized animals. 



The saliva, blood, and sometimes the urine, of infected persons will aggluti- 

 nate the micrococcus melitensis in low dilutions after the first week of the 

 disease. 



Pathogenesis. The micrococcus melitensis produces a disease in man 

 known as Malta fever or Mediterranean fever, a condition simulating typhoid 

 fever or malarial fever. The majority of cases result from drinking the milk 

 of goats infected with the micrococcus melitensis; some result from contact with 

 patients, especially when handling urine, as in nursing. It is possible that 

 infection may be acquired from other sources, as dust and soil. 



Diagnosis. Diagnosis is based on the discovery of the organism in the urine 

 and its agglutination with the serum of an immunized animal. 



After the first week of the disease the patient's serum may be tested, in 

 dilutions of 1:10, 1:20 and 1:40 for agglutinations. 



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