Invasive candidiasis (IC) is a type of fungal infection that is caused by a type of yeast called Candida, where the fungus spreads throughout the body, usually beginning in the bloodstream. In contrast to the other forms of Candida fungal infections, such as vaginal yeast infections and infections of the throat and mouth, invasive candidiasis is a very serious condition. These infections can affect the heart, circulatory system, brain, and many other parts of the body. If left untreated, they can eventually lead to death.
Definition & Facts
Candida is a yeast-type fungus that is usually found in the gastrointestinal tract and skin of most humans, and it generally does not cause problems. Invasive candidiasis generally results when this normally harmless fungus travels into the bloodstream and spreads throughout the body. This usually happens in immunocompromised individuals, which is why invasive candidiasis is the fourth most common cause of blood infections in hospital patients. It occurs in 8 out of every 100,000 people each year.
Symptoms & Complaints
IC that has infected the bloodstream causes a number of different symptoms in patients. Some develop a syndrome in which they suffer from symptoms similar to those developed in bacterial sepsis, such as acute kidney failure and disseminated intravascular coagulation. Disseminated intravascular coagulation causes blood clots in small blood vessels.
Those that develop esophageal candidiasis will usually end up with dysphagia, which means difficulty swallowing. If the Candida spreads to the eyes, or candida endophthalmitis, white retinal lesions may develop. These lesions will not cause any symptoms at first; however, if they are allowed to progress, they may eventually cause scarring and blindness that cannot be reversed.
Retinal haemorrhages are also possible in those with candida endophthalmitis, but this is usually only seen in patients that have neutropenia. If the infection is allowed to spread to the brain, it is likely to cause meningitis, a swelling of the membranes covering the brain, along with a number of other complications. In other patients with IC, possible organ failure can occur if the infection goes untreated. If the fungal infection is allowed to progress without treatment, death is possible.
The cause of invasive candidiasis is a fungus known as Candida, of which there are several types, such as Candida albicans, Candida tropicalis, Candida glabrata, Candida krusei, and Candida parapsilosis. These fungi are usually found in the gastrointestinal tract and skin of most humans where they have been found to cause no issues. However, IC usually arises when the fungus begins to spread throughout the body, usually spreading into the bloodstream first.
The spreading of the fungal infection routinely occurs because a person has a severely weakened immune system; examples include a person who has HIV or who is recovering from major surgery. Those with neutropenia, low neutrophils, have a very high likelihood of contracting the illness when compared to other patients. The Candida fungus uses the immunocompromised status of a patient to its advantage and begins to spread throughout the body, causing symptoms.
Other possible causes of IC are contaminated medical equipment entering a patient’s body. One potential place that this occurs is during surgery. Patients that have had major surgery are more likely to develop IC. Another common source of infection is through a patient’s catheter. Broad-spectrum antibiotics have also been noted as increasing a patient’s risk of contracting invasive candidiasis.
Diagnosis & Tests
Invasive candidiasis is usually diagnosed through the use of blood cultures and tissue cultures, as well as blood testing. Patients with invasive candidiasis usually test positive for serum β-glucan, whereas those without the systemic infection are likely to test negative, so it is a common test that is run on those suspected of having IC.
Because Candida is common in numerous parts of the body, such as the mouth, urine, and skin, samples for testing must be taken from sites that are normally sterile, such as the blood. For a positive test to be confirmed, a certain type of clinical lesion must be observed and histopathologic evidence of invasion of the tissue must be noted, such as yeasts being present in these samples. Eye examinations are recommended with anyone that has been diagnosed with invasive candidiasis to check for endophthalmitis, which is an inflammation of the eye.
Treatment & Therapy
Invasive candidiasis is generally treated with antifungal medication; however, the exact treatment is dependent on how stable the patient is and which type of Candida the patient is suspected to be infected with.
If not possible, and the patient is critically ill, echinocandin is recommended for treatment. This same drug is also recommended for the Candida strains C. glabreta and C. krusei. If the patient is stable, fluconazole is generally used. Fluconazole is also used for Candida albicans and Candida parapsilosis infections. Possible alternatives are voriconazole and amphotericin B.
Prevention & Prophylaxis
Increasing adherence to the proper placement of catheters is also essential. Educational programs promoting the guidelines for catheters have shown instances of decrease in bloodstream infections, including infections with Candida.
Controlling antimicrobial use is also essential in preventing IC from occurring, since it is shown to increase the chances of Candida spreading throughout the body. Antifungal prophylaxis is also being used as a preventative measure against IC. This is usually given to neutropenic patients (those with a low level of neutrophils). Antifungal prophylaxis has been shown to cause a decrease in cases of IC in patients with neutropenia.