Fecal microbiota transplants (FMTs) have been used in recent years to treat patients with recurrent Clostridium difficile infection. The infection is recurrent because physicians are able to temporarily decrease symptoms by administering antibiotics. C. difficile is a difficult bacterium to fully eliminate, however, in part due the ability of this Gram-positive bacterium to form endospores, or spores: extremely resistant, metabolically-dormant cell types that can endure the harsh antibiotic treatment. Once the environment reverts to a friendlier one, the spores can germinate to become vegetative bacteria again. In many cases, these endospore-generated bacteria germinate in an environment where most bacterial residents were eliminated through use of broad-spectrum antibiotics. Because many gut microbes don’t form endospore reservoirs, those that do (like C. difficile) can occupy a broader niche than they previously occupied if they germinate quickly in this drug-cleared niche.
Because of its extreme toxicity, some patients even turn to surgery to resect badly damaged sections of the colon – which hopefully removes large numbers of C. difficile as well. FMT is the process of replacing someone’s gut microbiota with that of a healthy donor – someone who hasn’t experienced C. difficile infection – and this replacement therapy has proven more effective than antibiotic treatment alone. Recipients have offered testimony on their improved quality of life, and replacement therapy appears to be growing as a treatment of choice for recurrent C. difficile infection.
But patients undergoing FMT have often suffered for years prior to the therapy. If their homes have been contaminated with the eradicated microbe, might continued exposure contribute to their disease? This was the problem addressed by a group of physician scientists, whose findings were recently published in Applied and Environmental Microbiology. Because C. difficile is transmitted by fecal-oral route, bacteria found in the nearby environment could potentially contribute to disease. The goal of this study was to understand how households may be contaminated and whether this could play a role in spread of the disease.
To test this idea, first author Megan Shaughnessy, working with senior author James Johnson, surveyed the residences of patients suffering from recurrent C. difficile infection 7 days prior to and 10 days after receiving FMT. Geographically- and age-matched healthy subjects also had their residences surveyed for controlled comparison. Samples were taken according to the household surveillance protocol used by the Center for Disease Control, assessed for C. difficile growth, and, when found, toxin type.
The research team found that all 8 of the household of pre-FMT patients had C. difficile-positive environmental samples, whereas only 3/8 control households did. The most-contaminated sites were the toilet, the vacuume clearner, and the bathroom sink/faucet. 10 households had more than one contaminated environmental sample, and 9 of these were identical by PFGE typing; the outlier contained 2 different PFGE types. These household contaminants are particularly interesting when considering that not all pre-FMT patients had C. difficile identified from their fecal samples.
The survey demonstrated that household of patients suffering chronic C. difficile disease do have more environmental contamination than households of healthy individuals. It also highlighted the areas most likely to be contaminated: intuitively, the bathroom fixtures (toilet and sink) used by colonized individuals, and the vacuum cleaner, which is likely exposed to a variety of household areas.
Hospitals where C. difficile infected patients stay have been extensively surveyed for spore presence, and must undergo rigorous decontamination processes to eliminate these hard-to-kill spores. The question becomes whether patient residences may also require similar decontamination for good health outcomes. Now that these residential contamination associations have been made, research efforts must focus on whether these contaminated areas affect patient (or other household resident) health. Future research must also determine whether C. difficile contamination is caused by, or a cause of, recurrent C. difficile infection in patients.
-- Julie Wolf