Fungus in the bloodstream, known medically as fungemia, occurs when fungal organisms enter and circulate throughout the body via the bloodstream. This condition represents a serious systemic infection, often life-threatening, particularly if left untreated. While various fungi can cause fungemia, Candida species are the most common culprits, leading to a specific type of fungemia called candidemia. This invasive form of candidiasis can spread from the bloodstream to internal organs, potentially causing organ failure.
Understanding How Fungi Enter the Body
Fungi, especially Candida yeasts, are naturally present on human skin and in areas like the gastrointestinal and female genital tracts in small, usually harmless quantities. However, certain conditions can allow these fungi to overgrow and breach the body’s protective barriers, leading to bloodstream entry. One frequent pathway involves medical devices, such as central venous catheters, which can provide a direct route for fungi from the skin surface into the bloodstream. Up to 10% of bloodstream infections in hospitals are caused by Candida, often developing within three weeks of intensive care unit admission.
Surgical procedures, particularly those involving the abdomen, can also create openings that allow fungi to enter the bloodstream. Damage to the skin barrier from severe burns or wounds presents another opportunity for fungal invasion. Disruptions to the natural balance of microorganisms in the gastrointestinal tract, often due to broad-spectrum antibiotic use, can lead to Candida overgrowth and translocation into the bloodstream.
Recognizing the Symptoms
Symptoms of a fungal bloodstream infection are often non-specific and can resemble those of bacterial infections, making diagnosis challenging without laboratory tests. Individuals commonly experience persistent fever and chills that do not improve even after antibiotic treatment. Other general indicators can include fatigue, generalized weakness, muscle aches, and low blood pressure.
If the infection progresses and spreads to other organs, more specific and severe symptoms may develop depending on the affected area. For instance, involvement of the eyes can lead to vision changes or eye pain. Headaches and neurological deficits may occur if the brain is affected, while abdominal pain could indicate spread to organs like the liver or spleen. Without prompt treatment, such dissemination can result in organ failure.
Identifying and Treating Fungal Bloodstream Infections
Healthcare professionals primarily diagnose fungal bloodstream infections through blood cultures. While blood cultures are highly specific, their sensitivity can vary, detecting Candida species in about 50% of cases. Results from these cultures may also take several days to become positive.
To aid in early detection, other diagnostic tests are utilized, such as beta-D-glucan (BDG) assays, which detect a component of fungal cell walls. These assays can often yield positive results before blood cultures, providing an earlier indication of infection. Molecular methods, like PCR amplification of Candida DNA, are also being explored for their potential to offer more rapid and sensitive diagnosis.
Treatment typically involves the prompt administration of antifungal medications. Echinocandins, such as caspofungin, micafungin, and anidulafungin, are often recommended as initial therapy due to their effectiveness and favorable safety profiles. Other classes of antifungals include azoles (e.g., fluconazole, voriconazole) and polyenes, notably amphotericin B and its lipid formulations. The choice of antifungal depends on the specific fungal species identified and its susceptibility to different drugs. In cases where a medical device, like an infected catheter, is the source of the infection, its removal is also a part of the treatment strategy.
Factors Increasing Susceptibility
Several factors can increase an individual’s susceptibility to fungal bloodstream infections. A weakened immune system is a significant risk, often seen in patients undergoing chemotherapy for cancer, those who have received organ transplants, or individuals with HIV/AIDS. These conditions compromise the body’s ability to fight off infections. Prolonged hospitalization, particularly in intensive care units, also raises the risk.
Major surgery, especially abdominal surgery, and certain underlying medical conditions such as diabetes and kidney failure requiring dialysis, also contribute to increased vulnerability. Premature infants with very low birth weights are another group at higher risk for developing candidemia.