Identification of Mycobacterium smegmatis in bovine mastitis

ABSTRACT

Background: Rapidly growing mycobacteria (RGM) are ubiquitous in the environment, can be isolated from soil and water, and demonstrate visible growth on culture media within seven days. Mycobacterium smegmatis is an acid-alcohol fast bacterium, which belong to RGM group. The diagnosis of M. smegmatis infections may be quite difficult by conventional methods; therefore, biochemistry associated to nucleic acid-based approaches provided fast and accurate identification. Although this specie may be associated to animals and humans infections, there is few cases description. Nontuberculous mycobacterial bovine mastitis is uncommon, and bovine mastitis by M. smegmatis has been reported but non-confirmed case once in the past. This paper reports M. smegmatis recovered from a cattle with relapsing pyogranulomatous mastitis. Case Milk samples from an adult Holstein cow showing relapsing pyogranulomatous mastitis history and by pronounced glandular hardening were cultivated and analyzed accordingly to standard milk cultivation protocols. The animal had been subject to several intramammary and parenteral antibiotic therapies protocols without adequate response. After 48 h incubation, a slow and sparse growth of slightly pigmented, shiny and smooth colonies was observed on the blood agar plate. The bacterium isolated was named as strain 55/08. The morphological and biochemical profile [...]