Use of a novel real-time PCR technique to monitor and quantitate Mycoplasma bovis infection in cattle herds with mastitis and respiratory disease.

Mycoplasma bovis infection of cattle tends to persist in affected herds and can be resistant to treatment. Given that the level of shedding of the organism can reflect the state of ongoing infection, a study was established to quantify the degree of such shedding in milk samples from infected herds using a novel real-time PCR technique. While the M. bovis load in herds with clinical disease was significantly higher than in disease-free herds (P<0.001), infection persisted in the latter. Similarly, M. bovis was detected more frequently in conjunctival swabs from calves with respiratory disease when compared with samples from animals that did not exhibit such clinical signs. This novel real-time PCR assay is specific for M. bovis and can detect bacterial loads as low as 100 colony forming units/mL of milk.