Supplements - Polymixin B

Polymyxin B has become popular again in clinical practices due to dry antibiotic developments. Polymyxin B is produced by bacillus polymyxa, and the sulfate functions by binding to the cell membrane and interfering with its permeability. This type of chemical is used for the prevention of bacterial contamination of cell cultures. This antibiotic is highly active against gram-negative bacteria. Polymyxins are antibiotics that have recently regained public interest from the microbiology world due to the increasing number of infections related to drug-resistant, gram-negative bacteria. Polymyxin B is considered as a last-resort antibiotic in many scenarios where drug resistance is taking place. It is a selective supplement that is used for the isolation and enumeration of bacillus cereus from food samples, can also be used for the preparation of MYP agar for testing food samples.

Polymyxin B antibiotics are used for inhibition of gram-negative bacteria in media items. Polymyxins bind to the cell membrane and disrupt the structure to make it more permeable, since osmotic pressures draw water into the cell. Conversely, the cell membrane ruptures and kills the cell. Due to the thick cell walls, polymyxin effect on gram-positive bacteria is very low. Polymyxin B supplements are used together with a number of oxoid-based media, usually agar bases. This kind of product tends to be sterile, comes in powder format, has a limited shelf life, and must be kept in storage. The most common applications are the fields of clinical testing, environmental testing, food and beverage safety, and microbiology. Polymyxin B has re-emerged in the past few years as a medical practice, and its use is predicted to continue increasing. However, there are still many gaps of knowledge when it comes to Polymyxin B pharmacology that need to be overcome. Also, despite the fact that Polymyxin B has reasonable efficacy, there are major drawbacks that question the validity behind those studies. Therefore, more investigations are needed on pharmacokinetics, pharmacodynamics and toxicodynamics of Polymyxin B, its efficacy is urgently needed.

As far as commercial formulations go, there are more than 30 polymyxin molecules available in the market. Within those molecules, there are five main chemical compounds, each containing multiple components. Polymyxin B is often applied with veterinary medicine, and is usually dissolved by using the methods of broth or agar dilution. Polymyxin B sulfate is produced by bacillus polymyxa, and it functions by binding the cell membrane and interfering with its permeability. It is often used to prevent bacterial contamination of cell cultures. It is an antibiotic that is highly effective against gram-negative bacteria. The basic structure of this antibiotic consists of a polycationic peptide ring and a tripeptide side chain with a fatty acid tail. Polymyxin B contains five amino groups, a mixture of a t least four closely related components. The four components differ from each other by fatty acid moiety. In regards to the similar colistin, Polymyxin B only differs with this antibiotic by one amino acid difference. Another difference is that Polymyxin B is administered parenterally as a sulphate salt, while colistin is administered as a sodium salt. Polymyxin B does not react to gram-positive bacteria and anaerobes, but it does act against a variety of gram-negative bacteria. Its spectrum of activity is nearly identical to that of colistin.

TAAG Life Sciences offers a Polymyxin B supplement for MYP Agar Base (10.000IU), which is used as an additive reagent for culture media. The characteristics of the product is a MYC Agar Base mixed with MYP Agar (mannitol, egg, yolk, polymyxin agar). It is used as a medium for the enumeration of Bacillus Cereus in food samples. What polymyxins do is that they bind to the cell membrane and alter its structure, making it more permeable. The resulting water uptake leads to cell death. The vial should be opened by following the arrow mark on the aluminum cap. However, before opening the vial, one must disinfect the surface of the vial with 75% alcohol cotton. Under aseptic conditions, the aluminum should be opened in the direction of the arrow on the aluminum cap. To use the reagent, one must add 1ml of sterile saline to each tube to dissolve the reagent completely, and then add each tube to 100ml to make mannitol yolk polymyxin agar, or add to 100ml to make into tryptone Polymyxin B broth. Finally, it must be kept between 2-8°C.