Pulsed-field gel electrophoresis patterns of Mycoplasma isolates from various body sites in dairy cattle with Mycoplasma mastitis.

Abstract

OBJECTIVE: To determine whether Mycoplasma strains typically associated with mastitis in dairy cattle can be isolated from body sites other than the mammary gland. DESIGN: Prospective clinical trial. ANIMALS: 7 Holstein cows in various stages of lactation with intramammary Mycoplasma infection. PROCEDURE: Milk samples, antemortem swab specimens from various body sites, and postmortem swab and tissue specimens were submitted for Mycoplasma culture. Pulsed-field gel electrophoresis (PFGE) was performed on chromosomal digests of all Mycoplasma isolates. Isolates with the same number and size of chromosomal digest bands were considered to be of the same type. RESULTS: For each cow, all isolates obtained from milk, mammary gland parenchyma, and supramammary lymph nodes had the same PFGE pattern. All cows had at least 1 isolate from nonmammary system tissues that had the same PFGE pattern as isolates from the mammary system. Overall, 44 of the 70 (63%) Mycoplasma isolates obtained from body sites other than mammary system sites had the same PFGE pattern as did mammary system isolates. CONCLUSIONS AND CLINICAL RELEVANCE: Results confirmed our hypothesis that Mycoplasma strains isolated from the milk of dairy cattle with Mycoplasma mastitis frequently have PFGE patterns identical to those for strains isolated from other body sites, suggesting that there is at least a potential for internal transmission of Mycoplasma organisms.