Bad Virus, Good Virus (MRSA Killer!)

Scientific American June 2020 pp22 THE SCIENCE OF HEALTH “Viruses Can Be Saviors, Too”. “As superbugs spread, researchers are turning to viruses that kill bacteria” By Claudia Wallis

This article by Claudia Wallis covers the reemergence of using a virus to kill antibiotic resistant bacteria. While we currently are hating viruses due to the death and destruction caused by the SARS-CoV-2, AKA COVID-19, viruses known as bacteriophages are the most abundant organisms on earth and they function to kill bacteria. As examples, we are currently plagued by “treatment resistant bacteria such as MRSA (methicillin-resistant Staphyloccocus aureus) and Acinetobacter haumannii, sometimes dubbed “Iraqibacter” because so many soldiers from Iraq were infected by it”. The scope of the problem is not well appreciated but WHO predicts that these resistant bacteria or “superbugs” kill 700,000 today but will rise to 10,000,000 by 2050.

Today, leveraging molecular biology, virologists can accurately match bacteriophage to vulnerable bacteria. Although the therapy is experimental, Tom Paterson was saved from an overwhelming Iraqibacter infection using a bacteriophage cocktail identified by his infectious-disease-epidemiologist wife, Steffanie Strathdee. They published this story “The Perfect Predator” (2019) and are both professors at UCSD.

The bacterial killing is mediated by the bacteriophage enzyme “lysin”. After the bacteriophage has completed reproducing itself lysin levels rise within the bacterial host. Lysin then interacts biochemically with bacterial walls causing them to breakdown thereby freeing the virus and ultimately killing the bacteria.

A group led by Vincent Fischetti, Rockefeller University, cloned a phage gene for lysin which was used to produce pharmaceutical-grade lysin was made. Lysin is produced by ContraFect (CFRX) under the name Exebacase (CF-301). In a yet to be published clincal trial, Exebacase was highly effective in resolving MRSA infections. “The infection was cleared in 74% of MRSA patients given the lysin plus standard antibiotics but in only 31% of those who got antibiotics plus placebo. The respectively mortality rates after 30 days were 3.7% and 25% respectively”.

These therapies are not yet available but offer promise in fighting these resistant bacterial invaders. “Other lysin drugs are in the pipeline at ContraFect and elsewhere.