Surgical legend holds that infection can lengthen the lives of brain-tumor patients, but the idea has never been proved. Illustration by Patrik Svensson

As the chairman of the neurosurgery department at the University of California at Davis, Paul Muizelaar saw patients on Wednesdays, at a clinic housed in a former cannery in East Sacramento. Among the people waiting to see him on the afternoon of November 10, 2010, was Terri Bradley, a fifty-six-year-old woman on whom he had operated the previous May, to remove a malignant brain tumor the size of a lime. Sitting in his office, Muizelaar reviewed Bradley’s file. He read a letter from her oncologist, asserting that Bradley was doing well: a brain scan had found no evidence of the tumor. “I think, This sounds great,” Muizelaar, a sixty-eight-year-old Dutchman, recalled. “So I go to her exam room with a big smile on my face, and there she is with her daughter, crying, not able to speak.”

Muizelaar hadn’t seen Bradley’s latest test results. Her condition had suddenly deteriorated, and new scans revealed that her tumor—a deadly type known as glioblastoma multiforme, or GBM—had returned. It had spread from the right side of her brain to the left frontal lobe, acquiring an ominous winged shape that doctors refer to as a butterfly glioma. A second tumor had sprouted in the region of her brain associated with speech. Bradley, partially paralyzed and dependent on a wheelchair, had already undergone chemotherapy and radiation; her doctors believed that more drugs were pointless. “The radiologist said, ‘I’ve never seen anything grow so fast,’ ” Bradley’s daughter Janet recalled. “He said, ‘Call hospice.’ That scared the hell out of me.”

Bradley, a fiercely self-reliant woman who had raised four daughters on her own, refused hospice care. Finally, Janet took her to Muizelaar, who said that he was unable to help. “It’s a blessing to most patients not to linger,” Muizelaar, who practiced medicine in California under a license reserved for eminent foreign-trained physicians, told me. “Within four weeks, this woman had regrown a massive tumor, plus a second tumor. There was clearly nothing I could do about it.”

Yet the conversation did not end there. An hour before Bradley’s appointment, Muizelaar had received tantalizing news about a patient on whom he had performed an exceedingly unusual procedure. The previous month, he had operated on Patrick Egan, a fifty-six-year-old real-estate broker, who also suffered from glioblastoma. Egan was a friend of Muizelaar’s, and, like Terri Bradley, he had exhausted the standard therapies for the disease. The tumor had spread to his brain stem and was shortly expected to kill him. Muizelaar cut out as much of the tumor as possible. But before he replaced the “bone flap”—the section of skull that is removed to allow access to the brain—he soaked it for an hour in a solution teeming with Enterobacter aerogenes, a common fecal bacterium. Then he reattached it to Egan’s skull, using tiny metal plates and screws. Muizelaar hoped that inside Egan’s brain an infection was brewing.

Muizelaar had devised the procedure in collaboration with a young neurosurgeon in his department, Rudolph Schrot. But as the consent form crafted by the surgeons, and signed by Egan and his wife, made clear, the procedure had never been tried before, even on a laboratory animal. Nor had it been approved by the Food and Drug Administration. The surgeons had no data to suggest what might constitute a therapeutic dose of Enterobacter, or a safe delivery method. The procedure was heretical in principle: deliberately exposing a patient to bacteria in the operating room violated a basic tenet of modern surgery, the concept known as “maintaining a sterile field,” which, along with prophylactic antibiotics, is credited with sharply reducing complications and mortality rates. “The ensuing infection,” the form cautioned, “may be totally ineffective in treatment of the tumor” and could cause “vegetative state, coma or death.”

For four weeks, Egan lay in intensive care, most of the time in a coma. Then, on the afternoon of November 10th, Muizelaar learned that a scan of Egan’s brain had failed to pick up the distinctive signature of glioblastoma. The pattern on the scan suggested that the tumor had been replaced by an abscess—an infection—precisely as the surgeons had intended. “A brain abscess can be treated, a glioblastoma cannot,” Muizelaar told me. “I was excited, although I knew that clinically the patient was not better.”

In Terri Bradley’s examination room, Muizelaar impulsively shared what he had just learned. “It escaped my mouth: ‘I just got this news about this treatment we tried on this one patient. Even though he is clinically not better, it appears that his tumor is disappearing. I think this might be your only chance.’ ”

Muizelaar is six feet three and solid, with a ruddy, earnest face and a disarmingly forthright manner. His hands are conspicuously large, his fingers like sausages. It’s a myth that neurosurgery requires delicate digits, he said recently, over dinner in Huntington, West Virginia, where he now practices neurosurgery, at Marshall University. “A lot of it is very hard work; to get through the spine, you need lots of strength.”

In addition to his medical degree, Muizelaar has a Ph.D. in neurophysiology, and, according to a recent analysis in the journal Neurosurgery, three of his papers are among the top hundred most cited in the field. Yet he has devoted far more time to repairing bodies than to testing theories. “This is the crux of my whole thinking: What would you do for your mother, yourself, your daughter, or your granddaughter?” he told me. “I know several neurosurgeons who would say, ‘If I ever have a glioblastoma, I would have it infected.’ ”

The prognosis for glioblastoma is grim. Even with the standard treatment—surgery, radiation, and chemotherapy—the median survival time from diagnosis is little more than fourteen months. But for decades talk has circulated in the field about glioblastoma patients who, despite hospitals’ efforts to keep the O.R. free of germs, acquired a “wound infection” during surgery to remove their tumors. These patients, it was said, often lived far longer than expected. A 1999 article in Neurosurgery described four such cases: brain-tumor patients who developed postoperative infections and survived for years, cancer-free.

Three of the patients were infected with Enterobacter, the fecal bacterium, and although the cases were anecdotal, and the alleged connection between the bacterium and survival was unproven, the notion became operating-room lore. One neurosurgeon, currently in private practice, told me that his former boss would joke during operations, “If I ever get a GBM, put your finger in your keister and put it in the wound.”

Muizelaar had heard a similar, if less graphic, plea from Harold Young, until recently the chair of neurosurgery at the Virginia Commonwealth University School of Medicine, in Richmond, where, in 1981, he obtained a fellowship, his first job in the United States. “It’s true,” Young said, when I called him to confirm Muizelaar’s account. “There is no other treatment for it.” (In 2009, in an attempt to put the wound-infection rumor to rest, neurosurgeons at Columbia University analyzed the records of nearly four hundred GBM patients, and found “no significant survival difference” between the vast majority who did not have an infection and the eighteen who did. However, a 2011 study of nearly two hundred GBM patients by researchers at the Catholic University School of Medicine, in Rome, found that the ten who had wound infections lived, on average, twice as long as those who did not.)