DNA fingerprinting shows C. difficile may be spread through the food source.
A British doctor has presented research at the 27th European Congress of Clinical Microbiology and Infectious Diseases showing evidence that Clostridium difficile (C. difficile) may be spread through the food source.
The research that Dr. David Eyre, a clinical lecturer at the University of Oxford in the United Kingdom, presented to the Congress used DNA fingerprinting to identify the bacteria that were causing infections and how widely they were distributed throughout Europe.
Dr. Eyre and his team found that some strains were clustered within a country, while other strains were found dispersed over several countries. The team hypothesized that the strains remaining within a country’s borders were hospital transmissions, which is a common route—and a dangerous one to susceptible patient populations because of its resistance to commonly used antibiotics.
The team further hypothesized that the strains found scattered over several countries could be transmitted via food sources. “We know that C. difficile lives in the gut in a small proportion of healthy people, where it causes no symptoms,” Dr. Eyre told the Congress, according to a news release. “However, its resistance to antibiotics means it can grow uncontrollably in patients treated with the drugs, causing diarrhea that can be severe or even fatal. It is the most frequent cause of infectious diarrhea in hospitalised patients, and the increase in the use of antibiotics has allowed C. difficile to spread more effectively.”
Dr. Eyre went on to tell the audience, “Lots of effort has gone into controlling its spread including infection control interventions such as hand washing campaigns, and reducing the use of antibiotics that can lead to infection. Despite these measures, people are still getting C. difficile infections and the routes of transmission are not completely understood.”
The research that Dr. Eyre and his team conducted included all of the stool samples that were collected from 482 European hospitals on 1 day in the summer and 1 day in the winter in 2012-2013. They chose the 10 most common types of C. difficile found in the samples, and used DNA fingerprinting to examine how widespread each of the 10 types was within each country and between countries.
Five types were clustered inside countries, and the other 5 were spread across countries. One type was found in Bulgaria, the Czech Republic, Finland, France, Germany, Hungary, Italy, The Netherlands, Poland, Romania, Slovakia, Spain, Sweden, and the United Kingdom. Another type, associated with pig farming, was found in Austria, France, Germany, Greece, Ireland, Italy, Portugal, Spain, and the United Kingdom.
To explain their theory of the 5 types of C. difficile that moved across borders, Dr. Eyre said, “We know that C. difficile infection can spread within hospitals. If this was the only route of transmission, we would expect to see each type of the bacteria concentrated within one area. However, because we also saw some types that were spread around several countries, this suggests the bacteria are moving around by other means.”
While Dr. Eyre acknowledged that the study didn’t give researchers any definitive answers, the suggestion that other routes other than hospital transmission are possible in the spread of C. difficile creates an urgent need for more research to discover what those routes are. He hopes to repeat the study, but obtain samples from food, the wider environment, and hospitals, in order to better understand where the source of the infection may be.
“We don’t know much about how C. difficile might be spread in the food chain, but this research suggests it might be very widespread,” Dr. Eyre told his audience. “If that turns out to be the case, then we need to focus on some new preventative strategies such as vaccination in humans once this is possible, or we might need to look at our use of animal fertilisers on crops.”
The 27th European Congress of Clinical Microbiology and Infectious Diseases was held in Vienna, Austria, April 22-25, 2017.