Enterobacter aerogenes pathogen (Image: Dr. Richard Kessel and Dr. Gene Shih/Getty)

It sounds like a particularly lurid episode of the TV medical drama House: in a last-ditch attempt to help people with advanced brain cancer, their surgical wounds are deliberately infected with “probiotic” bacteria to stimulate their immune systems into fighting the tumours.

Rather than ending with miraculous recoveries, however, this incident led to two surgeons at the University of California, Davis, being banned from conducting research on human volunteers.

News of the surgeons’ reprimand, revealed by the Sacramento Bee newspaper, has alarmed bioethicists. “There are a lot of red flags,” says Jonathan Kimmelman of McGill University in Montreal, Canada, who studies the ethics of clinical research.


The case raises tough questions about the standards of evidence that should be met before experimental therapies are tested in people – even those with just weeks to live who may feel that they have nothing to lose.

It also reveals a clash of cultures between surgeons, who are free to try experimental procedures with little regulation, and medical researchers who typically have to present reams of evidence from animal studies before winning approval to test new drugs or biological therapies on human volunteers.

Paul Muizelaar and Rudolph Schrot infected the surgical wounds of three people suffering from glioblastoma with Enterobacter aerogenes bacteria. Each patient was expected to die within weeks, and the pair reasoned that the only hope was to test the intriguing suggestion that people with glioblastoma tend to survive for longer if their surgical wounds get infected.

Bacterial boost

The idea is that an infection stimulates an inflammatory response that may also help fight the cancer. Despite multiple anecdotal reports, the idea has been investigated systematically in just two studies.

The first, published in 2009, looked at 382 people who underwent surgery for glioblastoma at Columbia University in New York. It found no evidence that the 18 who developed a post-operative infection survived for any longer.

A second study, run at the Catholic University of Rome in Italy and published in 2011, did find that patients whose wounds got infected lived longer. However, just 10 out of 197 patients developed infections, and the researchers conceded that the study was “not definitive”.

Divided opinion

Specialists in glioblastoma are divided on whether the idea is worth pursuing. “The data is soft at best,” concludes Mitchel Berger, head of neurological surgery at the University of California, San Francisco. But Jeffrey Bruce of Columbia University, a member of the team that found no evidence that infection helps, is more optimistic: “It’s a reasonable thing to investigate,” he says.

The three patients treated by Muizelaar and Schrot all died – although Muizelaar notes that one lived for many months longer than had been expected. In a letter sent to the US Food and Drug Administration (FDA), the university authorities say that two of the patients died of sepsis – a systemic response to bacterial infection. Muizelaar disputes this conclusion, arguing that two died from cancer and just one from sepsis.

Muizelaar also maintains that he wasn’t, as the university asserts, conducting clinical research without approval from a local ethical review board and the FDA. “It was not my intention to do a clinical trial,” says Muizelaar, who describes his attempts to treat patients using bacterial infections as “innovative care”.

For Kimmelman, the case illustrates the different standards that apply in experimental surgery, compared to research on drugs and biological therapies. “The realm of surgery is virtually unregulated,” says Kimmelman. “There’s very little pressure on surgeons to rigorously evaluate their procedures.”

When Muizelaar and Schrot started infecting patients with bacterial cultures, however, they moved from the realm of surgery into a therapy that the FDA would classify as an experimental drug. “There probably is a clash of cultures here,” Kimmelman observes.