SOURCE IDENTIFICATION

GOAL: Locate probable cause of infection to most appropriately address the source.

Approach to Source Identification:

- Gather a complete patient history of recent and/or ongoing illnesses.
- Conduct a thorough head-to-toe exam to look for evidence of infection – wounds, bites, etc. Be sure to examine the genitourinary and perirectal areas, as these are common sites of missed infections.
- Perform rapid malaria, dengue, and point of care source tests if in an endemic area, as well as urine dipstick and i-STAT labs.9

Sepsis may be of bacterial, fungal, viral, or parasitic origin. Bacterial infections are the most common causes of sepsis followed by parasitic (mainly malaria), viral (e.g., dengue, influenza, COVID-19), and finally, fungal diseases.10 The prevalence of each is directly related to a given region.11 Identifying the cause of sepsis is challenging in the PFC environment where advanced diagnostic tests are unavailable, and antiviral and antifungal therapies are rarely available. This CPG focuses on the most common etiologies of sepsis, and the treatments of those forms of sepsis that the austere provider can reasonably manage. Advanced preparation is important, and a medical area study and/or medical threat-model analysis should be done prior to traveling to gather data on microbes specific to that given region.

For a given region, bacterial sepsis is most often due to a limited number of common pathogens to include streptococci (including S. pneumoniae, which causes pneumonia and meningitis), Staphylococci, Neisseria meningitidis (also a cause of meningitis, particularly common in regions of sub-Saharan Africa), and gram-negative bacteria arising in the gut. Treatment of many of these infections is complicated by rising rates of antibiotic resistance worldwide.12

Malaria must be considered high on a differential diagnosis list as a leading cause of any febrile illness in an endemic region. In the typical patient from an industrialized country without prior exposure to the infection, malaria can be rapidly fatal in the absence of early and specific therapy.13

A significant minority of sepsis cases (up to 15%) are due to fungal infections. Candida species are normal flora in the human gut and vaginal canal and are the most common causes of fungal sepsis, followed by invasive mold infections such as Aspergillus and by endemic fungi causing community-acquired disease, including Histoplasma, Coccidioides, and Talaromyces. In the PFC environment, Candida infections may follow penetrating abdominal trauma with perforation of the gut, while invasive molds may arise after blast injuries with devitalized tissue (such as after a high lower extremity amputation). Therapeutic options for both of these scenarios are very limited in a PFC setting.

Because war wounds are considered grossly contaminated wounds, they must be attended to meticulously. Unattended wounds can lead to acute infection and sepsis within days (or possibly within hours for very large and contaminated wounds).14 Quality wound care is essential to infection and sepsis prevention as detailed in the JTS Acute Traumatic Wound Management in the Prolonged Field Care Setting CPG.15