Poor Treatment Procedures Can Lead to Nocardia and Yeast Mastitis

Although uncommon, mastitis can be caused by Nocardia, most frequently, N. asteroides. The reservoir and vectors of Nocardia mastitis have not been well established. Nocardia are found naturally in the environment, and presumably the soil is the source of teat skin contamination by Nocardia. Often contaminated mastitis treatment preparations and infusion needles are suspected as the vector of Nocardia mastitis transmission. However, cases of mastitis infections by Nocardia have been reported in heifers which never received intramammary treatment.

Like many mastitis pathogens, Nocardia can cause subclinical, clinical, or acute mastitis. Often it is associated with chronic mastitis as evidenced by fibrosed udders. As with any mastitis infection, milk production and quality is reduced by Nocardia infections. Nocardia are resistant to a number of antibiotics used to treat mastitis. Thus, if an antibiotic preparation is contaminated by Nocardia, the organisms can survive in the preparation and be infused into the gland during subsequent use of the antibiotic. In addition, if the teat end is not properly cleaned, dried, and thoroughly disinfected prior to infusion, organisms present on the teat may be forced through the streak canal into the udder during treatment. Although some herds may experience an outbreak of Nocardia mastitis, usually it is restricted to only a few cows within a herd. Generally Nocardia is not a problem in herds which follow a good hygiene program.

Mastitis caused by yeast and yeast-like fungi is similar in nature to Nocardia mastitis. Sources of outbreaks include contaminated antibiotic preparations and inadequate preparation of teat ends prior to treatment. Yeast are not bacteria and are, therefore resistant to antibiotics. Yeast will colonize the skin of cows, but generally are not considered invasive or contagious. Thus, they are opportunists and gain entrance into the gland through improper treatment procedures. Mastitis caused by yeast is rarely acute, but will cause a subclinical, chronic condition. Milk quality and quantity are adversely affected by yeast mastitis. Treatment is difficult; antimycotics have to be used.

The best protection against Nocardia and yeast mastitis infections is cleanliness. Keep stalls and loafing areas clean and dry; avoid dirt lots if possible. When treating, either during lactation or the dry period, use an aseptically prepared antibiotic and thoroughly clean and disinfect the teat end with alcohol prior to infusion. Avoid "home-brew" treatments and use of multiple infusions from the same bottle or syringe.