Clostridium difficile, or C. diff, is a type of bacteria that can live in our digestive system without causing any problems. In fact, it is present in around 1 in 30 of us. But it can also cause a nasty infection and is the most common cause of hospital diarrhoea. It particularly affects people who have recently received antibiotics. These infections are difficult to treat and often recur. So what is C. diff, and why is it such a tricky infection?
This blog explains the basic biology of C. diff, as well as the causes, symptoms, treatments and outcomes of infections.
Basic biology of C. diff bacteria
C. diff bacteria are rod-shaped individual cells that make up a colony. The cells and nuclei (the part of the cell that contains the genetic information) can vary in size, but each cell is 3-4µm (micrometres, or microns) in size. This is far, far smaller than can be seen with the naked eye. The bacterial cells themselves are anaerobic, which means that they cannot survive in an environment that contains oxygen.
There are a number of features that make C. diff a particularly interesting, but also dangerous, bacterium. First, C. diff bacteria can produce flagella, which are whip-like appendages that they can use to move through liquid or semi-solid environments. Not all bacteria are able to move like this, so it provides it with a great advantage.
Second, and perhaps most importantly, they are ‘spore forming’. This means that although the cells require an environment without any oxygen to survive, they can produce spores. These spores are a dormant form of the bacteria that survive in the presence of conditions that would kill the bacteria. For example, spores can survive some cleaning products, high temperatures and the presence of oxygen. Then, when they are in a suitable environment again, they germinate into bacterial cells once more. This means that it is possible to pass on a C. diff infection from person to person, even though that would normally involve transmission through an oxygenated environment.
C. diff is a commonly occurring bacterium and can often be found in soil, as well as the human body, where it is often part of our natural collection of bacteria (our microbiome). It can, of course, also cause infections.
C. diff bacterial infections
Data from 2017/18 shows more than 13,000 cases were reported in England. This is a small increase (<4%) over the previous year, but a promising decrease of 76% from ten years before. Around 36% of C. diff infections occurred within four days of a patient being admitted to hospital, so are considered to be ‘hospital acquired’. Preliminary data for 2019/2020 show around 13,000 cases were reported, a similar number to 2017/18.
According to NHS information about C. diff, these infections most often affect the following people:
- Those who have recently been treated with antibiotics
- especially broad-spectrum antibiotics (those that treat many different types of bacteria), or
- more than one type of antibiotic at the same time, or
- long-term antibiotics of any kind
- Those who have recently stayed in a hospital, care home or other healthcare setting.
- People aged over 65 years (this accounts for more than 80% of cases).
- People with underlying health problems, such as inflammatory bowel disease, cancer and kidney disease.
- Those with a compromised immune system, e.g. people receiving steroid or chemotherapy treatment, or who have diabetes.
- People taking medicines called proton pump inhibitors (PPIs) to reduce their stomach acid.
- Those who have had surgery on their digestive system.
The bacteria cause illness by producing toxins. Not all strains of C. diff produce these toxins, and even the ones that do must be present in significant numbers to produce enough toxin to make someone sick.
There are two important toxins produced by C. diff. Toxin A is an enterotoxin, meaning a bacterial protein that affects the intestines (in this case, Toxin A causes the diarrhoea associated with C. diff infections). Toxin B is a cytotoxin, which means it negatively affects cells and the way they function. If you need more technical information about how these toxins cause illness, you can read Clostridium difficile Toxins: Mechanism of Action and Role in Disease (Roth & Ballard, 2005).
Why do antibiotics seem to cause C. diff infections?
The antibiotics themselves do not cause the infection, but they do create an environment that can encourage it. Antibiotics, especially broad-spectrum antibiotics, kill bacteria – including the good bacteria in our stomachs. These good bacteria are usually well balanced, with different species that help to keep each other in check and digest our food. After antibiotics are stopped, these bacteria usually come back.
However, instead of recolonising with a healthy balance, sometimes one species will ‘take over’. For example, C. diff. These bacteria produce toxins that are harmful to our body when present in large enough quantities. That is when it becomes an infection.
It is also important to note that people receiving antibiotic treatments are already unwell, and therefore are more susceptible to infections – particularly if they are already harbouring the bacteria that cause them. This means that although those illnesses/vulnerabilities cause the infection to take hold, it can appear that hospitals, care homes and antibiotics ‘cause’ the problem.
Diagnosis of a C. diff infection
The symptoms are also the symptoms of many other illnesses and infections, such as:
- diarrhoea (sometimes with blood)
- a fever (high temperature)
- loss of appetite
- nausea (feeling sick)
- tummy pain.
To diagnose a C. diff infection, doctors send a stool (poo) sample to a lab. Here, it will be tested to see if it contains the toxins associated with a C. diff infection. If it comes back positive, doctors may also request a blood test to establish how severe the infection is. Sometimes, other scans and tests are required, such as to check for damage to the bowels.
Treatments and outcomes
According to the NHS, most people will receive antibiotics (such as vancomycin) and recover within two weeks of a C. diff infection. However, around 20% of people will experience another infection after this.
A newer treatment being used is a faecal microbiota transplant, or poo transplant. This involves taking a poo sample from someone with a healthy balance of bacteria in their gut and then placing it into the intestines of the patient to encourage colonisation with a range of bacteria. Find out more about this treatment.
If repeated treatments fail, this infection can cause severe damage, particularly to the bowels. It can cause colitis, toxic megacolon and even death. While rarely life threatening, it is most serious in eldery patients, particularly those who are unwell with other conditions too.
If you or someone you know is affected by any type of antibiotic-resistant infection, you can contact our Patient Support Service for free information and a friendly chat.
The human side of the story
So far we have examined the bacteria, and the disease caused by C. diff. But what about the people it affects?
Our Head of Fundraising, Alison Staples, has personal experience of losing a much-loved family member.
“My grandad Burt went into hospital for a routine hip replacement operation. He was almost 97 years old. The operation was successful, but he contracted C. diff in hospital and died shortly afterwards. We were worried about the operation – it never entered our minds that the antibiotics wouldn’t work. We were completely blind-sided.”
Every year, thousands of families go through a similar experience, believing that their loved one will make a full recovery from a routine procedure. Part of the reason we are fighting to preserve our antibiotics is to prevent this becoming a reality for tens of thousands of people, or even millions.
Preventing the spread of C. diff
This infection is highly contagious, particularly due to those spores that we mentioned earlier. If someone has C. diff in a healthcare setting they will often be isolated from other patients.
At home, ideally the person will use separate washing and toilet facilities to other members of the household throughout the duration of their illness. They will also need to maintain good hand hygiene, wash their towels and bedding on a high heat and try to stay separate from others where possible until at least 48 hours after their symptoms have stopped. Find out more about the NHS recommendations for those with a C. diff infection.
The best way to avoid getting a C. diff infection is to wash your hands thoroughly and regularly, particularly after going to the loo, and follow our tips to prevent the spread of antibiotic resistance. These apply to preventing the spread of all types of bacterial infection.
Professor Colin Garner, CEO of Antibiotic Research UK, explains:
“Many patients who have been hospitalised with COVID-19 have been treated with antibiotics. This is to protect them against, or treat them for, bacterial infections that might occur while their immune system is compromised by the COVID virus. Unfortunately, this could cause an increase in C. diff infections as we know that they often occur in people who have received antibiotics.
“This is one of the many reasons that our charity advocates for proper antibiotic stewardship, including the use of antibiotics only when a bacterial infection has been proven and analysed. This prevents the inappropriate use of our precious antibiotics, reducing the risk of both C. diff infections and antibiotic resistance.”
There is a huge amount of information about C. diff available online. Some sources we recommend if you wish to know more include:
- LIVE with Scientists: a recording of an Antibiotic Research UK-sponsored webinar featuring two scientists talking about their work, the first of whom is currently researching C. diff.
- The Mid and South Essex NHS Foundation Trust have produced a detailed, technical summary of C. diff infections.
- Find out more about the global disease burden of C. diff.
- Our website includes lots of information about antibiotics, bacterial infections, gut bacteria and more.