MISCELLANEOUS PATHOGENS

Coagulase Negative Staphylococcus spp.

Staph epidermidis, Staph chromogenes, Staph simulans, Staph hominis, Staph xylosus and others Staphs and Micrococci.

Non-hemolytic, catalase positive, coagulase negative Staphylococci spp., especially Staph epidermidis and micrococci are considered minor pathogens.  Their role in bovine mastitis is poorly understood.  It appears that these bacteria cause microscopic lesions and increase PMN in milk.  They are not as pathogenic as the hemolytic coagulase positive Staphylococci spp., but occasionally cause severe mastitis.  Some evidence suggests their presence helps resist colonization of the teat duct and teat skin by coagulase-positive Staphylococcus spp.  The prevalance of these infections is reduced by teat dipping and dry cow treatment.  Recent evidence suggests that these staph are free-living in the environment.

Corynebacterium bovis

1.  Commonly isolated from milk

2.  Mildly pathogenic.

3.  Can elicit leukocytosis, but rarely cause of clinical mastitis.  Infection limited to the streak canal.

4.  Can cause reduction in milk production, although mild infection.

5.  Teat dipping and dry cow treatment should control the prevalance.

Pseudomonas spp.

1.  Sporadic cause of mastitis.

2.  Resistant to treatment.

3.  Outbreaks traced to contaminated water used for washing udders.  Contaminated or common infusion cannulae, as well as home-mixed antibiotic preparations also related to outbreaks.

4.  Typically very chronic, characterized by clinical flare-ups.

Arcanobacter pyogenes 

1.  Sporadic cause of mastitis.

2.  Acute and resistant to treatment.

3.  Ability to cause disease increased by trauma or lesions from other causes.  Often follows teat injury.

4.  Can cause summer mastitis in dry cows and heifers.

5.  Infection is usually acute and suppurative.   The gland becomes firm and secretes pus.  Abscesses may open through the skin.  

6.  The bacteria is highly sensitive to penicillin in vitro, but antibiotic therapy is ineffective.

Mycotic mastitis

1.  Frequent cause of sporadic mastitis.

2.  Most common are of genera Candida, Cryptococcus and Trichosporon.

3.  Non specific clinical signs ranging from non clinical to life threatening systemic infections.

4.  Most mycotic agents are resistant to common antibiotics, so therapy unsuccessful.  Naturally occurring cases of Candida or Trichosporon can regress spontaneously.  More severe cases caused by Cryptococcus, Nocardia or Aspergillus are refractory to treatment and are treated by culling the cow.

5.  Most herd outbreaks are a result of contaminated equiapment or antibiotic mixtures used for the treatment of bacterial mastitis.

 

 

 

Copyright 1999-2001
New Bolton Center Field Service Department
Students:  Keith Javic - Class of 2003, C. Nikki Conroy - Class of 2003