Bacteriologist taking a bacterial culture from a Petri dish. Image: Tim Sandle
Sexually transmitted infection rates are on the rise, including syphilis, a disease that was nearly eradicated in many countries. The bacterial infection affects some 18 million people worldwide.
One major challenge is over the lack of an effective treatment. This is partly the result of the bacterium not being able to be cultured, which hampers study in the laboratory setting. The reason it is so hard is that the bacteria require very strict microaerophilic conditions (1.5 percent oxygen).
This has been overcome by Virginia Tech researchers who have succeeded in propagating the disease-causing agent in vitro. This opens the door to new medicines to help to prevent infection.
The solution was the use of a mammalian cell line, inoculated, and held within appropriate atmospheric conditions. Twelve ingredients need to be combined to create the culture medium make the media, and this needs to equilibrate overnight.
From this basis the Virginia Tech researchers set out to determine if there were possible treatment options that could serve as an alternative for the millions of people impacted by the disease each year.
The University’s College of Agriculture and Life Sciences researchers discovered another treatment option to benzathine penicillin G based on two antimicrobial agents named Azlocillin and Mezlocillin. This represents the first large-scale drug screen for syphilis treatment alternatives. The agents were selected through a process of elimination and hundreds of tests.
These new agents are more effective in treating the helically coiled microorganism – the disease-causing agent Treponema pallidum – when efficacy is compared with existing regimens.
The new medications have been approved by the Food and Drug Administration, which could accelerate the rollout.
According to Kathryn Hayes, the lead author, she was inspired to undertake the research as a result of a longstanding interest in sexual health and in infectious diseases. She states this was a product “My own queer identity and how disproportionally impacted the queer community is by sexually transmitted diseases motivated me. The other is the stigma around sexually transmitted infections [STIs].”
The new medicines will be further improved by examining the protein drug interaction and how those interactions affect overall drug efficacy.
The research has been published in the journal Antimicrobial and Resistance. The research is titled “A large screen identifies beta-lactam antibiotics which can be repurposed to target the syphilis agent.”