Difficile

She contracted a bacterial infection called Clostridium difficile which turned into sepsis.

Clostridioides difficile is an example of anaerobic bacteria.

Some cutting-edge doctors have used so-called fecal transplants to treat severe bacterial infections, including Clostridium difficile or C. diff, which releases toxins as it grows, attacking the lining of the intestines.

[…] forasmuch as he was to judge of an internall beauty, of a difficile knowledge, and abstruse discovery.