Less common aetiological agent of bovine mastitis - Serratia marcescens

Serratia marcescens was considered originally a saprophytic bacteria in the environment, and many decades after the discovery it was actually recognized as a pathogen of plants and a wide range of invertebrates and vertebrates. It has been identified as an important human pathogen that causes a number of hospital-acquired infections. Due to the increase of resistance to a variety of antibiotics, the bacteria is recognized as an important public health issue. S. marcescens causes subclinical, chronic mastitis in dairy cows, which makes it significantly different from other members of Enterobacteriaceae family, such as coliform bacteria. In infected cows clinical signs are mostly mild, but for months, or even years, the bacteria is secreted in milk and infection of other cows in the herd may occur via the milking system. The antibiotic treatment of mastitis caused by S. marcescens is considered less efficiant. Most isolates of S. marcescens from the environment are characterized by a production of red pigment - prodigiosin, with the unknown function in bacterial physiology. This secondary metabolic product of S. marcescens is the subject of research in the field of pharmacy and bioengineering, because of its anfibacterial, antifungal, antiprotozoal (antimalaric) and immunomodulatory effects, as well as anticancer activities.