What is Candidemia?
Candidemia is a condition where a type of fungus, specifically Candida species, is found in the blood. This is the most frequent type of fungal bloodstream infection seen in hospital patients. Unfortunately, this infection can be quite serious, with death rates reaching nearly 50% in some cases.
While Candida albicans is still the most common type of Candida causing this infection, recently there’s been a rise in infections caused by other non-albicans Candida species. This could make treatment more difficult because different Candida species may respond differently to antibiotics.
This increase in other Candida species is likely due to a process called natural selection, where the species that are resistant to the most common anti-fungal medicines used to treat Candidemia are the ones which survive and multiply.
What Causes Candidemia?
The most common cause of candidemia, a bloodstream infection caused by the yeast known as Candida, is a species called Candida albicans. This species is found in 35% to 60% of cases. Other common types of Candida that can cause this infection include Candida parapsilosis, Candida tropicalis, Candida glabrata, and Candida krusei. It should be noted that Candida glabrata and Candida krusei are often resistant to a group of antifungal medications known as azoles.
Certain species of Candida, specifically Candida albicans, Candida tropicalis, and Candida glabrata, are more dangerous because they are more virulent, meaning that they cause disease more effectively. As a result, infections caused by these types of Candida can lead to a higher risk of death.
Risk Factors and Frequency for Candidemia
Candidemia is the most frequent fungal infection found in the bloodstream and is one of the typical infections seen in intensive care units. Both the elderly and the very young are at the highest risk of getting this disease.
There are several risk factors that increase the possibility of contracting candidemia. These include:
- Severe illness
- Long stays in intensive care units
- Use of a central venous catheter (a tube inserted into a large vein in the body)
- Exposure to antibiotics
- Undergoing abdominal surgery (especially repeated ones or when there is leakage)
- Having cancer (either in a solid organ or in the blood)
- Suffering from acute necrotizing pancreatitis (a severe form of inflammation in the pancreas)
- Being an organ transplant recipient
- Receiving total parenteral nutrition (a method of feeding a person intravenously, bypassing the usual process of eating and digestion).
Signs and Symptoms of Candidemia
Candidemia is a type of bloodstream infection that doesn’t have specific symptoms. This means it can present like other similar infections, ranging from mild issues to severe ones.
- On the mild side, patients may experience chills, shivering, and fever
- Severe cases can progress to what’s known as severe sepsis and septic shock, signs of which include damage to the body’s organs
Your medical professional might not find anything unusual upon examination, or they might discover signs of infection in certain deeper tissues. Such signs could involve:
- Endophthalmitis skin lesions, which are inflammatory conditions of the eyes
- Candiduria, which refers to the presence of yeast in the urine
- Signs that suggest the infection has reached the central nervous system
Testing for Candidemia
The most reliable way to diagnose candidemia, a fungal infection, is by identifying the fungus directly in your blood sample. This is done by using a method called “cultures” which can even determine the sensitivity of the fungus to different treatments. However, this method is not always accurate; in some cases, it’s only able to detect the illness 21% to 71% of the time. It also takes a while for the results to be available. Another drawback is that sometimes, even if the fungus is no longer in the bloodstream, it may have caused an ongoing infection in deeper tissues, which the cultures won’t pick up.
If you have symptoms at specific locations in your body, your doctor might take a tissue sample (biopsy) from that area and send it to the lab for culture and gram staining. This is a test that uses dye to aid in the identification of the organism.
Other markers that help detect infection, like Candida mannan antigen, anti-mannan antibodies, and B-d-glucan are faster to produce results, but can often indicate infection when there isn’t one. These are known as false-positives.
Newer tests that use a technique called polymerase chain reaction are being developed and tested in clinical trials, and the results are looking promising. One such test, T2Candida, is currently available. If your doctor suspects you may have invasive candidiasis, they should consider ordering both the traditional method of blood cultures and a non-culture method like B-d-glucan, for a more accurate diagnosis.
Treatment Options for Candidemia
If a critically ill patient shows signs of invasive candidiasis, a type of yeast infection, and they have certain risk factors, doctors may often start antifungal treatment right away. Some studies have shown that starting treatment early can help reduce the chance of death. The decision to start treatment usually depends on the doctor’s judgment, the patient’s risk factors, and certain markers of the infection in the body, such as B-d-glucan.
The initial treatment usually includes medicines from a group called echinocandins, which include drugs like caspofungin, micafungin, and anidulafungin. Another medicine called fluconazole may also be used if the patient is not critically ill and if the yeast is likely to respond to this drug. In case a patient can’t tolerate or is allergic to these treatments, a medicine called Amphotericin B can be used.
When blood tests confirm the presence of yeast in the bloodstream, the treatment usually starts with an echinocandin, and removal of any central venous catheters (tubes placed into a large vein for administering medicines or nutrients). Depending on how well the patient is doing and which type of yeast is found in the blood tests, doctors may switch the treatment to fluconazole. Additional blood tests should show that the infection in the bloodstream is clearing. If the yeast is resistant to other treatments, Amphotericin B may be administered.
In cases where the infection has spread to other parts of the body such as the brain, eyes, or urinary tract, or if the patient has previously been exposed to echinocandins, doctors may initiate treatment with a group of medicines called azoles.
Typically, the treatment continues for at least two weeks after tests confirm the infection is gone. However, for more serious infections, such as those involving the eyes, heart, or bones, the treatment might need to continue for up to four weeks.
Different types of yeast can respond differently to treatments. For example, a type of yeast called C. parapsilosis is less responsive to echinocandins. Doctors usually take this into account when deciding which medicine to start with and when adjusting treatment based on test results. Also, some yeasts can become resistant to certain drugs over time due to use, which can make treatment more complex.
What else can Candidemia be?
Various health conditions can share similar symptoms and it might not be readily clear which one is causing the issue. In such cases, a doctor may have to consider other illnesses such as:
- Ascending cholangitis
- Acalculous cholecystitis
- Bacterial meningitis
- Bacterial sepsis
- Bacterial endocarditis
- Chronic granulomatous disease
- Cholecystitis
- Graft-versus-host disease
- Granulomatous hepatitis
- HIV seropositive state
- Hepatic abscess
- Relapsed malignancy
- Tuberculosis
Identifying the right cause of an illness requires careful analysis and diagnosis.
