Tokyo Tech News
January 31, 2010
Staphylococcus aureus is a pathogenic bacterium that causes a variety of diseases including bovine mastitis, the inflammation of breast tissue in cows, which can have severe economic consequences. Some strains of the bacteria can become resistant to the standard antibiotic treatment, so there is a need for alternative treatments such as bacteriophage therapy. Now Yasunori Tanji at the Department of Bioengineering at Tokyo Institute of Technology and co-workers have found two promising candidate phages for this treatment.
The researchers isolated fifteen strains of S. aureus bacteria from the milk of mastitic cows and used polymerase chain reactions (PCR) to amplify and study their genetic expression. They also analyzed 52 bacteriophages from sewage, and identified two particular phages which bound to and in many cases killed the bacteria by breaking, or lysing, the cell membrane. One of the phages, ΦSA012, lysed eight out of the fifteen bacteria, while the other, ΦSA039, lysed twelve out of fifteen.
The two phages were found to be of similar size when characterized by transmission electron microscope (TEM). The researchers used them in a further culture with seven representative S. aureus isolates, which confirmed that ΦSA039 can bind to a wide number of different hosts, and that ΦSA012 has a very powerful lytic ability that can prevent the appearance of resistant bacteria. Therefore these two phages are proposed as strong candidates for phage therapy of bovine mastitis.
Figure caption: Electron microscope images of bacteriophages that could help prevent bovine mastitis. The scale bar is 100 nm, and arrows indicate contracted sheaths.
Graduate School of Bioscience and Biotechnology Bioengineering