OVINE MAMMITIS 615 



III. Micrococcus mammitis.' 



(The coccus of gangrenous mammitis in ewes.} 



Nocard has proved that gangrenous mammitis in milking ewes is due to 

 a coccus which has no tendency to form chains. 



Bridre believes that this organism is a normal inhabitant of the udder of 

 milking ewes and that mammitis only occurs when through some internal 

 lesion of the gland the organism can penetrate into its tissues. 



Mammitis in ewes is usually fatal in 24-48 hours. The mammary gland is hot, 

 red, painful and hard ; the lesion then extends into the sub-cutaneous cellular tissue 

 of the thighs and trunk, while the skin becomes infiltrated with a serous oedema 

 and has an erysipelatous appearance ; later the affected parts become gangrenous 

 and the animal dies. The coccus is present in large numbers in the milk, in the 

 mammary gland, and in the blood-stained fluid in the sub-cutaneous cellular tissue 

 and peritoneal cavity. The infection may perhaps be carried by the milker's hands : 

 Nocard certainly failed to cause infection by painting the teats of healthy ewes with 

 a virulent culture, but the injection of a few drops of the same culture into the milk 

 ducts resulted in infection even though the mucous membrane was intact. 



SECTION I. EXPERIMENTAL INOCULATION. 



Ewes readily contract the disease if a few drops of infected milk or of a 

 24-hour culture of the coccus be injected into the teats or substance of the 

 gland. 



Goats and laboratory animals are not susceptible. In rabbits an abscess 

 forms at the site of inoculation and the animals recover. 



SECTION II. MORPHOLOGY. 

 1. Microscopical appearance. 



The micro-organism of the mammitis of ewes is a very small coccus 

 measuring about O2//, in diameter. The cocci are arranged in pairs, in tetrads 

 or in small clumps. They stain very well with the basic aniline dyes and can 

 be seen but with difficulty in unstained preparations. They are gram- 

 positive. 



2. Cultural characteristics. 



Conditions of growth. The coccus of Nocard is indifferently aerobic. It 

 grows in the ordinary neutral or alkaline media. The optimum temperature 

 lies between 35 and 39 C. but it will grow at the ordinary temperature of 

 the room. 



To preserve its virulence sub-cultures should be re-sown daily. 



Like the Streptococcus mammitis of cows, Nocard 's coccus remains alive 

 longer in broth containing calcium carbonate than in ordinary broth. 



Characters of growth. Milk. The medium becomes strongly acid and is 

 coagulated in 24 hours. 



Broth. Ordinary broth or glucose broth become very markedly turbid 

 and a large white precipitate is deposited. A considerable amount of acid 

 is formed. 



Gelatin. Stab cultures. The coccus grows rapidly at 20 C. Liquefaction 

 commences after the second day and is conical below but the upper layers 

 are completely liquefied and turbid. 



1 For convenience of reference the organism causing mammitis in ewes will be con- 

 sidered here, though morphologically the infecting agent is distinct from that of the 

 mammitis of milch cows. 



