Our US distributor Microbiology International carried out this in-depth interview with Dr. William Weiss, a Whitley Workstation user from University of North Texas.
Dr. William Weiss is the Director of Pre-Clinical Services at University of North Texas in Fort Worth, working to develop animal models in infectious disease for the evaluation of new and novel therapies in antibacterial, antifungal and antiviral research. He has been using a Don Whitley Scientific DG250 and an A35 anaerobic workstation for about two decades.
Read more about his research on novel antibiotics for the treatment of Clostridium difficile infection here.
Q: What manner of specimens are you working with and which bacteria do you cultivate in the anaerobic workstation?
A: Here in the Pre-Clinical Services group, we are essentially a contract research organization, and the majority of our work in the A35 anaerobic workstation involves C. difficile. We are carrying out various research projects for different pharmaceutical companies, and biotechnology companies, here in the US, as well as Europe and South America. There are various experimental models for reproducing C. difficile disease, for example, the “gold standard” model involving the hamster, and there is also one that involves mice.
Basically, in this model, spores from C. difficile are introduced into the animal, and they colonise in the gut. C. difficile spores come from the environment and are ubiquitous, but because they are held in check by the normal gut flora, they never proliferate and they never cause disease. It’s only when patients are treated with broad spectrum antibiotics that healthy bacteria are destroyed and C. difficile then proliferates and causes disease. That’s why often, people going into the hospital and receiving multiple antibiotics can develop C. difficile disease.
Q: So what is the role of the A35 workstation in your C.diff. research?
A: The model we are using to test novel therapies designed to combat this disease depends strongly on the A35: we grow the C. difficile culture by streaking the frozen cultures onto appropriate media, incubate them in the A35 chamber at 0% oxygen, and then harvest the vegetative cells and treat them to form spores, which we store. The spores are then introduced into the animals, the animals are treated with a broad-spectrum agent, they develop the disease, and we try different forms of therapy. The end-points in terms of efficacy are increased survival, as well as the amount of C. difficile that can be found in the fecal pellets of the hamsters, or in the contents of the cecum. We process the fecal pellets or a cecal sample and plate it, then we place those plates inside the chamber to incubate for about 48 hours. An animal that might have the disease could have 6 logs of C. difficile in their gut, whereas one that has seen successful treatment, such as with vancomycin, the gold standard right now, might be reduced from 6 logs to 2 logs or even less. All that incubation is being done inside the A35.
Q: The A35 isn’t your only workstation though, tell us about that.
A: With C. difficile being a larger problem than it used to be, we are seeing a real uptick in the number of companies interested in it, thus explaining our need for the A35 workstation. The C. difficile in the environment is very hardy, because it can form spores, but in order to count the spores, they have to germinate into the vegetative state, and that’s what you need the workstation for. Prior to the A35, we had the smaller DG250 model, and at the time, when we were just working with some bacteroides, not a lot, it sufficed. But when we started working with C. difficile, the amount of studies and the type of studies we did really expanded. So at that time, we contacted Microbiology International since we needed a larger workstation in order to accommodate all those studies. The A35 is now our second Whitley workstation, but we are still using the DG250, too. We’ve converted the DG250 to a microaerophilic environment, because we do Helicobacter pylori work in there. It’s a facultative anaerobe, so when we need to grow up plates or process samples, we use that smaller workstation with a 5% oxygen mix.