322 SPECIFIC MICRO-ORGANISMS 



fever and obtained pure cultures. Inoculation of monkeys with 

 pure cultures gives rise to a disease resembling in detail 1 Malta 

 fever in man. 



The organism is spherical or oval 0.3 by 0.4^ in size, and is 

 classed as a micrococcus by many bacteriologists. In gelatin 

 cultures the cell is somewhat longer and resembles that of a true 

 bacillus. The organisms are single, grouped in pairs or sometimes 

 in short chains of four to five cells. Capsules and spores have 

 not been observed. It is non-motile. Flagella have been de- 

 tected by Gordon but other investigators have failed to confirm 

 the observation. The organism stains readily and is Gram- 

 negative. 



Cultures are obtained on ordinary media and growth is possi- 

 ble between the extremes of 6 and 45 C. The colonies develop 

 in one to three days at 37 C. and are very homogeneous. Gela- 

 tin is not liquefied and neither gas nor acid is produced in media 

 containing the various sugars. The organism is killed by moist 

 heat at 57 C. in 10 minutes, by dry heat at 95 C. in 10 minutes 

 and in i per cent carbolic acid in 15 minutes. It survives drying 

 for several months and retains its vitality in culture without 

 transplantation for several years if drying is prevented. 



Many mammals are susceptible, including guinea-pigs, rabbits, 

 monkeys, rats and mice. Horses, cows, sheep and goats are not 

 only susceptible to inoculation but also contract the disease natu- 

 rally. In all animals the course of the infection is usually chronic 

 and characterized by an irregularly remittent fever. Death is 

 a common outcome in monkeys. Often the subcutaneous injec- 

 tion or the feeding of a minute quantity of the culture is sufficient 

 to infect, but for the smaller laboratory animals intracerebral in- 

 oculation may be necessary. 



Malta fever in man is a chronic disease characterized by an 



irregularly remittent fever. The spleen is enlarged and often 



the liver as well. Positive agglutination of a known culture of 



B. melitensis by the patient's serum in dilution of i to 1000 is an 



1 Eyre in Kolle and Wassermann, Handbuch, 1912, Bd. IV, S. 432. 



