Disseminated candidiasis (DC) is a severe, life-threatening invasive fungal infection. It occurs when Candida yeast species enter the bloodstream and spread to distant organs, moving beyond superficial sites like the mouth or vagina. This systemic disease, also known as invasive candidiasis or candidal sepsis, affects the entire body. If not treated quickly, DC can lead to multi-organ failure and is a significant cause of morbidity and mortality, particularly in healthcare settings.
The Fungal Agent and Susceptible Patients
The infection is primarily caused by fungi from the Candida genus, yeasts that normally live harmlessly in the human body. The most common species responsible is Candida albicans. Non-albicans species, such as C. glabrata, C. tropicalis, and C. parapsilosis, are also increasingly identified, especially in hospitalized patients.
A particularly concerning agent is Candida auris, an emerging, multi-drug resistant species that has caused global outbreaks in healthcare facilities. C. auris is frequently resistant to multiple antifungal medications, which significantly complicates treatment and poses a serious public health threat.
Disseminated candidiasis is an opportunistic infection that almost exclusively affects patients with significantly weakened body defenses. Individuals with neutropenia, a low count of white blood cells due to cancer or chemotherapy, are at extremely high risk. Patients with hematologic malignancies, such as leukemia, are also highly susceptible to this severe fungal spread.
The infection is strongly associated with the hospital environment, particularly the Intensive Care Unit (ICU), where patients are often critically ill. Major risk factors include the presence of central venous catheters, which provide a direct entry point for the fungus into the bloodstream. Prolonged treatment with broad-spectrum antibiotics can also disrupt the body’s natural balance, allowing Candida to overgrow and invade. Other circumstances that compromise the body’s defenses include major abdominal surgery, receiving total parenteral nutrition (IV feeding), and having an organ transplant.
The Process of Systemic Spread
Dissemination begins when Candida, usually a harmless commensal, breaches a bodily barrier. In many cases, the fungus originates from the patient’s gastrointestinal tract, where it naturally colonizes the mucosal lining. Damage to this lining, often caused by chemotherapy-induced mucositis or extensive abdominal surgery, allows the yeast to cross into the deeper tissues and blood vessels.
Once the fungus enters the circulation, the condition is called candidemia, meaning Candida is present in the blood. Candidemia is the precursor to disseminated candidiasis, as the bloodstream transports the yeast cells throughout the body. The fungus can also enter the bloodstream directly through contaminated medical devices, such as central venous catheters.
From the bloodstream, yeast cells lodge in small blood vessels of various organs, establishing a deep-seated infection. The fungus adheres to vessel walls and invades the surrounding tissue. This hematogenous spread results in the formation of microabscesses in distant organs, marking the transition to disseminated candidiasis.
Identifying Symptoms and Affected Organs
The initial presentation of disseminated candidiasis is often non-specific and difficult to distinguish from a severe bacterial infection. The most common systemic symptom is a persistent, spiking fever accompanied by chills, which typically does not respond to broad-spectrum antibacterial medications. Patients may also experience hypotension, or low blood pressure, indicating a severe systemic response resembling bacterial sepsis.
Once the fungus has spread, it can colonize nearly any organ, leading to localized symptoms. The eyes are frequently involved, with nearly half of all cases showing signs of candidal endophthalmitis. This condition begins with white lesions on the retina and can lead to irreversible vision loss or blindness if left untreated.
The kidneys are also commonly affected, sometimes resulting in acute candidal pyelonephritis or the formation of fungal balls that can obstruct the urinary tract. A distinct form, known as chronic disseminated candidiasis or hepatosplenic candidiasis, involves the liver and spleen. This condition is characterized by multiple small abscesses and usually occurs in patients with hematologic cancer recovering from neutropenia.
Less frequent but serious sites of infection include the central nervous system, which may lead to abscess formation, and the skin, which can manifest as a rash of small, firm, pink or red papules that sometimes develop into pustules. Untreated, the progression of organ damage can rapidly lead to multisystem organ failure and death.
Confirmatory Tests and Medical Management
Diagnosis relies on a combination of microbiological, laboratory, and imaging tests. The traditional method for confirmation is a positive blood culture for a Candida species, confirming the presence of candidemia. However, a significant limitation of this method is that blood cultures can be negative in up to 40% of patients who have deep-seated, disseminated infection.
Due to this lack of sensitivity, non-culture-based diagnostics are frequently used to support a diagnosis. One widely used test detects (1,3)-beta-D-glucan, a component of the Candida cell wall, in the patient’s serum. A positive result suggests systemic fungal infection. Rapid molecular tests, such as the T2Candida Panel, can also detect the DNA of the five most common Candida species directly from a blood sample within a few hours.
Imaging studies are essential for identifying deep-seated organ involvement, especially in chronic disseminated candidiasis. Computed tomography (CT) or magnetic resonance imaging (MRI) scans visualize microabscesses in the liver, spleen, or kidneys. Ocular examination, specifically indirect ophthalmoscopy, is routinely performed to look for the characteristic retinal lesions of endophthalmitis.
The treatment requires immediate and aggressive antifungal therapy. The preferred initial treatment for most patients, particularly those who are critically ill or in the ICU, is an echinocandin class drug, such as caspofungin or micafungin. Echinocandins are favored because they are fungicidal against most Candida species and generally have a favorable safety profile.
For clinically stable patients whose Candida strain is susceptible, a step-down to an azole drug like fluconazole may be considered after initial echinocandin therapy. In cases of drug resistance, an Amphotericin B formulation may be used, though its use is limited by potential side effects like nephrotoxicity. A mandatory part of treatment is the prompt removal of any indwelling central venous catheter, as the device can serve as a persistent source of infection. Treatment duration is typically 14 days after the last negative blood culture and resolution of the patient’s symptoms.