Like many other bacterial species, Clostridium difficile, often referred to as C. diff, lurks in the guts of animals waiting for the chance to strike.
It lives peacefully amid a teeming community of other types of bacteria until something puts the gut ecosystem into disarray.
Usually the disruptor is a blast of antibiotics that kill large numbers of so-called healthy bacteria. It is in this chaos that C. diff thrives.
In many ways, C. diff behaves like an invasive weed that overgrows in disturbed environments. Imagine Russian thistle in a gravel pit.
Unleashed from the constrains that other bacteria normally impose on it, C. diff multiplies quickly and attaches to the gut lining where it secretes a slew of potent toxins.
C. diff is one of the most important bacterial infections to occur in hospitalized people and it is also an important cause of disease in animals.
In farm animals, C. diff is associated with variably severe diarrhea, particularly in young animals. Piglets usually become infected within the first few days of life. Not all piglets with the bacteria develop disease.
Affected pigs have diarrhea with colitis (colon inflammation) and edema, leading to dehydration, poor weight gain and possibly death. Ostrich chicks are also susceptible to C. diff diarrhea.
The role of C. diff in calf diarrhea is less clear, with several studies finding no association between infection and disease.
Animals like horses, rabbits and guinea pigs that ferment fibrous food in their colon (so-called hindgut fermenters) are highly susceptible to severe C. diff associated colitis.
Foals and adult horses infected with C. diff can develop severe colon inflammation, edema and diarrhea. Similar to the disease in people, C. diff in horses is frequently associated with antibiotic treatments.
About three percent of horses carry C. diff in their guts without showing signs of disease. These horses can spread C. diff in the environment. It is also thought that antibiotic treatment in these carriers sets up a perfect storm for C. diff to overgrow.
C. diff is diagnosed by identifying the bacteria and its toxins in feces. It is important to rule out other common causes of diarrhea such as E. coli, rotavirus, coronavirus, salmonella and cryptosporidum.
There are no vaccines available to prevent C. diff associated disease.
Animals become infected by ingesting the bacteria, which can persist in feces, soil and on environmental surfaces. C. diff forms highly resistant spores that can survive in the environment for months, so cleaning and disinfection may be helpful to reduce the amount of C. diff in animal environments.
There is evidence that in some cases, people may acquire C. diff from animals. A study of C. diff in pigs and pig farmers found that they were carrying identical strains.
More research is needed to fully understand the direction of transmission, which is challenging to uncover, even with modern molecular tests.
A healthy community of gut bacteria is needed for growth and production. The gut is a complex place. When things disrupt the bacterial community, like antibiotics, stress, transportation, mixing groups of animals and feed changes, pathogens like C. diff can take over.
Under a microscope, C. diff looks similar to the shape of a hot dog. It is tiny: about 100 will fit into the size of a grain of sand. Its only distinguishing feature is a pale spore offset at one end.
Difficile is Latin for difficult. C. diff was so named because it was difficult to identify and culture using traditional laboratory techniques.
Lately, one may be tempted to think the name also applies to its ability to cause disease and the difficulty in treating those conditions.