Sepsis is a life-threatening emergency which occurs when the body’s response to an infection damages vital organs and can result in death. It is important to remember that sepsis is not an infection itself, but the body’s life-threatening response to an infection. Essentially, sepsis is when an infection in any part of the body, triggers a chain reaction throughout the body causing organ dysfunction.

Sepsis affects over 30 million people worldwide, with 35% of people who develop sepsis dying. Those who survive are left with life-altering effects.

Sepsis can progress to severe sepsis, which can further develop into septic shock, which requires intensive care admission and doctors often describe these patients as “the sickest people in ICU.” The effects of severe sepsis often results in the need for the patients to be mechanically ventilated to help them breathe, as one of the results of severe sepsis is extreme breathlessness.

Antibiotic resistance

The growing global threat of antimicrobial resistance is a major challenge in the treatment of sepsis. As pathogens become resistant to available antibiotics, the more sepsis becomes a threat.

When a strain of bacteria develops resistance, the infection that the bacteria causes becomes difficult or sometimes impossible to treat. It is thought that key evolutionary patterns are responsible for antimicrobial resistance. The concept of “survival of the fittest,’ as a key evolutionary concept is particularly pertinent in this case.

Over the millennia of their existence, bacteria have developed enormous genetic variation to evade destruction. When someone develops an infection, if any of the bacteria have mutated to switch to a genetic variation that has been developed to combat the toxic effects of the antibiotic prescribed, it will quickly multiply to “survive” the antibiotic.

The more people are exposed to antibiotics, the greater the chance that the bacteria can use their repertoire of genetic variation to evade destruction. The change in genetics of the bacteria alters either the DNA and/or the proteins expressed within the bacteria, meaning those sites that the antibiotic is designed to target is no longer a threat for the bacteria.

Neutropenia and Sepsis

Neutropenia refers to a low number of a specific type of white blood cell in the blood called Neutrophils.

When patients have a low number of neutrophils in the blood, the immune system is weakened, making it harder for the body to fight infections. During neutropenia, patients are more likely to catch infections, and they can become more serious and take longer to treat.

Neutropenia can be caused by some leukemias themselves; as the leukemia blasts occupy space in the bone marrow, normal healthy neutrophil production is supressed.

However, the usual treatments for leukemia – chemotherapy and radiotherapy can also cause neutropenia. As well as killing the leukemia blasts, they also kill healthy white blood cells, including neutrophils.

During the chemotherapy for leukemia, the levels of neutrophils in the blood is constantly monitored whilst in a state of neutropenia. Patients are advised to adapt a “neutropenic diet,” to avoid foods that are likely to contain more fungi or bacteria. It is also common for patients to be prescribed a prophylactic (protective) dose of antibiotics, antivirals and antifungals. However, it is important to note that whilst prophylactic treatment with antibiotics is critical to protect the neutropenic patient, prolonged exposure also provides the bacteria that normally live in the body, the opportunity to develop resistance to these antibiotics.

If the mutated bacteria, which normally live in the body (e.g. in the gut) then manage to infect another part of the body (e.g. the skin), the bacteria will cause an infection at the new site and will have developed resistance to the antibiotics used as a prophylaxis.

As discussed above, an infection that can not be easily treated, can result in a whole body reaction called sepsis – which can develop into severe sepsis and then ultimately, multiple organ failure.