“This is a review/commentary article that provides a high-level overview of the literature dealing with C. diff colonization and the microbiome changes associated with C. diff colonization,” author Silvia Munoz-Price, MD, PhD, from the Medical College of Wisconsin in Milwaukee told our sister publication MD Magazine.
After reviewing the literature, authors of the study postulated that when it comes to the potential for C. diff colonization, exposure to and transmissions of the virus occurs outside of hospitals. In fact, it seemed like most of the patients became symptomatic during their hospital stay, rather than acquiring the virus while hospitalized.
For example, the investigators cited one study from Canada that had been conducted from 2006 to 2007 where more than 4000 patients were screened for C. diff colonization upon hospitalization, during their stay (on a weekly basis) and at discharge. They found that 4% of the patients were colonized upon hospitalization and 3% acquired C. diff during their stay in the hospital.
The authors also found evidence indicating that community-acquired C. diff appears to be on the rise. The authors discuss a decade-long study which took place in Minnesota where community-acquired C. diff infection rates rose from 2.8 to 14.9 per 100,000-person-years within the 10-year span. The patients in that study more likely to acquire C. diff were younger, female, and healthier than patients with hospitalization acquired C. diff. The reviewers also said that rates of community-acquired C. diff have also been rising in Finland, Australia, and England, according to published studies.
Most of the common risk factors for community-acquired C. diff infections still applied, the researchers found, including antibiotic exposure, household contact, and animals. A 2013 study showed that two-thirds of community-acquired C. difficile patients were exposed to antibiotics in the preceding 12 weeks of their infection, and about one-third had been exposed to proton pump inhibitors.
While studies examining transmissibility within households are difficult to come by, the study authors found one review from Quebec. The review consisted of 2222 cases of C. diff diagnosed between 1998 and 2009, and investigators found that 8 cases were designated to be transmitted by household contacts. However, the researchers noted, confirmation using strain typing was not performed in that study.
Looking at farm livestock, a 2013 Dutch study showed that individuals with daily contact with pigs showed rates of C. diff positivity of 25%; in those with weekly contact, it was 14%. In the same study, C. diff was found in the manure from all the farms in 10% to 80% of the samples per farm. The reviewers also said that C. diff has been found in the stool of farm chickens, calves, and retail ground meat. Dogs and cats are also known to culture positive for C. diff, and the researchers wrote that the bacteria can also be present in vegetables and water (tap water, swimming pools, as well as rivers, lakes, and seas). They hypothesized that the presence of C. diff in vegetables may come from the use of organic fertilizer.
“We envision that in the future we should be able to take advantage of our increasing knowledge about microbiome changes so that we will be able to: identify patients at risk for de novoC. difficile colonization during their hospitalization and manipulate our patients’ microbiome to prevent or reverse C. difficile colonization,” Dr. Munoz-Price said.
“Different from what we do now, the latter would be accomplished not by withholding or changing antibiotics but by correcting the deficient flora of a patient in an individualized fashion. This new approach would revolutionize the field of Infection Control and Antibiotic Stewardship,” she concluded.
It has access to the largest surface area of the body, alters drugs before they even enter the blood stream and could be a potent medicinal weapon… yet there is much we still don’t understand about the microbiome.
Here David Kirk and Ben Bradley tell us about their attempts to heal us from within
We are not alone. We are inhabited by hundreds of species of microbes, which represent millions of genes. Together, these microscopic organisms – bacteria, fungi, archaea and viruses – and their collective genomes make up the microbiome.
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In the gut, microbes break down otherwise indigestible dietary fibres and release nutrients, such as B-vitamins and short chain fatty acids, which can be absorbed by the intestines. They secrete other small molecules or peptides which interact with the body via the bloodstream and immune system. The majority of these have yet to be identified and characterised. In addition, commensal microbes deter opportunistic pathogens from invading the competitive niche of the intestinal tract.
LBPs are a recent concept and have their origins in a novel treatment for C. difficile infection: the faecal microbiota transplant… this is exactly what you think it is
The disruption of the microbiome, termed dysbiosis, is associated with an ever-growing list of conditions. Obesity and metabolic syndrome, for instance, are associated with a microbiome less diverse than that of a healthy individual. Inflammatory bowel disease (IBD) and colorectal cancer are associated with a decrease in butyrate-producing bacteria like Clostridia, and an increase in Enterobacteriaceae and Bacilli.
An air of scepticism comes with the phrase “associated”. Microbiome research is still a developing field, and the presence or absence of a single species or genus cannot be directly blamed for conditions like obesity or IBD in all patients. The complex interplay between host and microbiome depends as much on the host’s genetic susceptibility and environment as on the dysbiosis or lack of diversity in the microbiome. The million dollar question remains: What exactly constitutes a ‘healthy microbiome’?
A powerful tool
The microbiome is adaptive and changes in response to diet, environment and disease. It has become increasingly clear that many drugs interact with the microbiome, with some requiring microbiota derived enzymes for activation and others being rendered non-functional or even toxic via microbiota dependant conversion. As research in host-microbe interaction continues, more accurate relationships between the microbiome and human illness will be uncovered.
The gut microbiome presents an interesting medicinal target in itself. It interacts directly with one of the largest surface areas of the body. Therefore it has easy access to the bloodstream through diffusion of nutrients and small molecules, and via a mucosal layer rich in multiple cell types of the adaptive and innate immune systems. Due to the powerful delivering capacity of the gut, most microbial-based treatments in development aim to add to the microbiome rather than take away from it.
Microbial therapies using living organisms are known as live biotherapeutic products (LBPs). LBPs are a recent concept and have their origins in a novel treatment for C. difficile infection (CDI): the faecal microbiota transplant.
This is exactly what you think it is.
CDI occurs when the gut microbiome is wiped out by antibiotic use and becomes infected by C. difficile, an organism that is normally unable to compete against the natural microbiota. This illness may recur in spite of further antibiotic treatments, and can be fatal. The most effective treatment, in extreme cases, is a faecal transplant into the infected recipient. Transplanted microbes thrive and outcompete C. difficile, effectively reversing the infection in over 90% of cases. But due to the uncertainty of what constitutes a ‘healthy microbiome’, a faecal transplant cannot be considered a cure-all for dysbiosis-associated illness.
Daunting clinical trials
This “unknown” of host-microbe interaction sparked the need to develop defined microbiome therapies. Naturally, CDI was one of the first targets for a defined treatment. Several companies are developing and trialling defined cocktails of bacteria known to safely inhabit the gut with the goal of outcompeting C. difficile with Seres Therapeutics and Rebiotix entering phase 3 trials in 2018.
CHAIN Biotech is developing technology to deliver therapeutics to the gut microbiome using engineered Clostridium, a spore forming bacterium, and have a lead candidate targeting IBD. IBD is a collection of inflammatory diseases of the gut, commonly treated with steroid injections which cause numerous unpleasant side effects. Our approach is to deliver an LBP directly to the gut, where it can produce an anti-inflammatory in situ. We also make use of this species’ natural ability to produce spores, which survive the acidic environment of the stomach and germinates into therapeutic-producing cells only in the anaerobic environment of the lower intestine.
This elementary approach – adding one organism with a safe history of use in the human gut, and having it produce one novel product – minimizes the risk of disruption to the microbiome and delivers the treatment directly to the affected area. The next stages, taking LBPs to clinical trial, are daunting. A lot of unknowns exist around the human gut microbiome and these kinds of treatments. Few microbiome companies have LBPs in late-stage clinical trial, but those that do give hope to both patients and us that LBPs will someday heal us from within.
According to research, C. Diff is the most common infection in U.S. hospitals within the last decade.
The state of Minnesota has declared November“C. difficile Infection Awareness Month.”According to research, C. Diff is the most common infection in U.S. hospitals within the last decade.
Doctors at Mayo Clinic want people to know that they can get the infection even outside of hospitals. They also say once you get it, it’s easier to get it each time.
Dr. Sahil Khanna said ways to prevent C. diff is to wash hands and avoid unnecessary antibiotics.
He said Mayo Clinic is also studying whether or not there could be a vaccination for C. Diff.
“So there’s a large multi-center study that’s going on right now in people who may be at risk for C. Diff infection,” Khanna said. “So if you’ve been to the hospital, if you’ve received antibiotics, those patients can be enrolled in a vaccine study to see if this vaccine would prevent C. Diff from happening.”
Mayo Clinic is also working with Minnesota-based company Rebiotix on another form of treatment for the infection where people can simply ingest a tablet.
“Newer studies are being derived where you can actually take material from donor stool, process donor stool in a lab, and derive all the good bacteria that you need from the donor stool and put them in capsule form,” Khanna said.
Khanna said this capsule-based treatment has more advantages than a colonoscopy-based treatment that is currently being used to treat C. Diff.
These two leading topic experts will be discussing significant ways to unlock the mysteries of the human microbiome; how it affects our health, the immune system, and why it is so important to protect it.
As part of the Centers for Disease Control and Prevention (CDC) efforts to protect patients and slow antibiotic-resistance, the CDC is investing in research to discover and develop new ways to prevent antibiotic-resistant infections.
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