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Sepsis survivors face ongoing immune system challenges



Survivors of sepsis face ongoing challenges, including repeat hospitalizations for infections and repeat sepsis. Although it isn’t clear if such episodes result from incomplete resolution of the index infection, or they are due to lingering changes in immune function, they do suggest that physicians should engage sepsis patients in an effort to improve long-term outcomes.

A strain of Candida auris cultured in a petri dish. Shawn Lockhart/CDC

A strain of Candida auris cultured in a petri dish.

It’s also an argument for biomarkers and precision immune modulation in these patients, Hallie Prescott, MD, a critical care physician at the VA Ann Arbor (Mich.) Healthcare System, said during a talk at the Critical Care Congress sponsored by the Society of Critical Care Medicine.

When sepsis was first defined in 1992, physicians tended to focus on the inflammatory component, but it’s now understood that multiple pathways become dysregulated, and inflammation is no longer part of the most current definition of sepsis. “We now recognize that there is early activation of both pro- and anti-inflammatory pathways, but over the course of sepsis the balance tips from this proinflammatory state in the first few days toward, for most patients, an anti-inflammatory or immune-suppressed state in the later days,” said Dr. Prescott.

As advances in care have increased initial survival rates, more patients go on to the later stages, leaving clinicians to address nosocomial and other secondary infections. An autopsy study showed that many patients who die of sepsis in the ICU have evidence of immune suppression. A study of patients at the end of a pneumonia hospitalization found that many patients had elevated inflammatory markers even after hospital discharge, and that such elevation was associated with increased mortality as far out as 1 year. The relationship was significant even after adjustment for age, comorbidity, and acute illness. “It suggests that this isn’t just identification of patients who had a more severe septic episode,” said Dr. Prescott.

That study implies that some patients take a long time to return to homeostasis, and other work suggests that about two-thirds of sepsis deaths occur after day 5. A study by Dr. Prescott’s group showed about a 40% 2-year mortality after sepsis hospitalization. When they compared sepsis survivors to matched controls, they found about half the deaths could not be explained by presepsis health status. “Rather, it [seems to be] due to the last sequelae of sepsis, or perhaps this increased risk of secondary infections,” Dr. Prescott said.

Studies of the organisms causing secondary infections found increasing incidence of opportunistic infections, from 9% in the first 5 days of sepsis, to 18% in days 16 through 150. The frequency of Candida infection similarly increased, from 13% to 30%. “So in these later phases of sepsis, you’re more likely to see [pathogens] that are relatively rare as the initial cause of sepsis,” said Dr. Prescott.

Unfortunately, several studies showed that prophylaxis does not improve outcomes. “My suspicion is that it’s because these infections are one marker of a broader problem with immune dysfunction, and we probably need to boost or restore immune function more broadly as opposed to trying to prophylax against very specifically what the patient is at risk for,” said Dr. Prescott.

The problems appear to continue after hospital discharge. A study from Dr. Prescott’s group showed that about 40% of sepsis survivors were readmitted at least once within the next 90 days. The most common reason, at 6.4%, was another sepsis episode. Compared with matched controls, sepsis patients had about a 2.5-fold higher risk for sepsis, and about a 1.5-fold increased risk an infection. “So there seems to be this heightened risk among people surviving sepsis that’s not fully explained by the things that put them at risk for developing sepsis in the first place,” said Dr. Prescott.

Another study looking at the reason for recurring infections in sepsis survivors found that in about one in five cases, the readmission was due to the same infectious organism in the same site, suggesting incomplete resolution. In about half of patients, the infection was due to a different organism, or the same organism at a different site, and in about a third of patients, the results were ambiguous due to culture-negative infections.

“I think this suggests a complex picture. Some people perhaps fail to fully eradicate the initial infection, and a larger group of people come back with something else. There’s also a very high rate of infection in the same site – about 70% with a new bug have it in the same site as their initial sepsis. Some of this may be just be a reflection of the type of people who get sepsis the first time, but it still tells us that among the patients we care for who survive sepsis, that they are over the long haul at increased risk of recurrent infections and recurrent episodes of sepsis,” said Dr. Prescott.

The findings suggest a need for real-time assessment of immune function and the potential benefit of immune modulation in the later phases of sepsis. Such strategies are not likely to be implemented immediately, however. In the meantime, there are simple steps that clinicians can take, including screening of sepsis survivors and making sure they are up to date on vaccines, and then educating them about the risk of reinfection. “We know that the lay public awareness of sepsis is low. Even people who have sepsis are often unaware that they had it, and they are certainly unaware that they’re at risk for having another episode,” she said.

Dr. Prescott has no financial disclosures

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