Dogs have long been known to detect cancer, oncoming seizures and spikes in blood sugar, and now one more thing can be added to the list: C. difficile. A two-year-old beagle called Cliff has been trained by researchers in the Netherlands to sniff it out.
Clostridium difficile is a very dangerous and sometimes deadly superbug. It’s one of the most dangerous infections in the last few years, and targets elderly hospital patients who have recently taken antibiotics. It has become a superbug because of its resistance to antibiotics, due to the overuse of antibiotics in hospitals.
“The whole problem with C. diff is it’s transmissible,” according to Dr. Marije Bomers, the study’s lead author and a consultant internist and infectious disease specialist at VU University Medical Center. “If one patient has it in the ward and you don’t isolate the patient, it’s not just one patient – it’s two, it’s three, and then half your ward has C. diff. In order to try and prevent transmission in your hospital, it’s important to recognize C. diff patients as early as possible.”
In healthy persons this bacteria can go unnoticed in the gut. But when antibiotics are taken to kill harmful bacteria, the helpful bacteria, or gut flora, are destroyed. This leaves the body susceptible to rampant takeover by bacteria that can now become deadly. In essence, we need some of our germs to help maintain balance and keep harmful germs in check.
Bomers said the motivation for training a dog to detect C. difficile came when it occurred to her that humans can smell out this bacteria, and if humans can, dogs should have no problem.
“I was discussing a patient who had diarrhea and wondering if it could be caused by C. diff, and one of the nurses said it smells like it could be caused by C. diff,” Bomers said. “So, that made us think if humans can distinguish the smell, and detection dogs have a far superior sense of smell – maybe they can be trained to identify the sense of smell of C. diff.”
Bomers came to meet Hotsche Luik, a psychologist who became an animal trainer. Luik had trained police dogs, and decided she would try using her own dog for this project.
“It’s a known system of conditioning,” Luik said. “The value of the smell – we made it important and fun for him. First, we used lots of smells where I could almost smell it, and that was easy for him to find. Then it became more fun and a challenge to find it.”
From petri dishes to the woods, Cliff steadily improved. After just two months Cliff was given 50 stool samples testing positive for C. difficile, and 50 negative samples. He correctly identified all 50 of the positive samples, and 47 of the 50 negative samples.
At six months, Cliff seemed ready to put his sniffer to the test. Using real patients, he was able to identify 25 of 30 patients who did have the bacteria, an accuracy of 83 percent, and he identified 265 of 270 patients who did not have the bacteria, with an accuracy of 98 percent.
C. difficile affects about 14,000 people each year in the US, and with the help of super-sniffers like Cliff, perhaps that number could be reduced.
“At the moment, I can’t take it any further here,” Bomers said. “I’d have to go elsewhere and see where it goes… But if there are hospitals or areas with high C. diff incidence, this could really help lower that.”