Candida parapsilosis is a species of yeast that has become a notable opportunistic pathogen in healthcare environments. This yeast is a common inhabitant of the human body, often existing without causing any harm. However, under specific conditions, it can lead to infections. The incidence of C. parapsilosis infections has risen over the past two decades, making it a significant cause of invasive candidiasis. Its ability to thrive in hospitals and affect vulnerable individuals makes it a subject of clinical interest.
Sources and Transmission
Candida parapsilosis is frequently found on the skin of healthy people, particularly on the hands. This characteristic plays a role in its transmission within hospitals, where it can be spread from person to person, often via the hands of healthcare workers.
A significant factor in its ability to cause infections is its proficiency at forming biofilms. A biofilm is a community of microorganisms that attach to a surface and produce a protective, slimy matrix. This matrix helps the yeast adhere firmly to materials like plastics, which are commonly used in medical devices such as intravenous (IV) catheters and prosthetic joints. The biofilm shields the yeast from both the host’s immune system and antifungal medications, making infections difficult to treat. The yeast can also proliferate in glucose-rich solutions, such as those used for intravenous feeding, which can become a direct source of infection if contaminated.
Populations at Risk
Certain groups of people are more susceptible to infections from Candida parapsilosis due to their health status or medical treatments. Neonates, especially those born prematurely or with a low birth weight, are one of the most vulnerable populations. Their immature immune systems and frequent need for indwelling medical devices create an environment where the yeast can readily cause disease.
Patients in intensive care units (ICUs) also face a heightened risk. These individuals are often critically ill, may have multiple medical devices in place, and may be receiving broad-spectrum antibiotics that disrupt their normal microbiota. Another major at-risk group includes individuals with compromised immune systems. This encompasses cancer patients undergoing chemotherapy and organ transplant recipients who take immunosuppressive drugs to prevent rejection.
Associated Infections and Symptoms
Candida parapsilosis can cause a spectrum of infections, ranging from localized and superficial to severe and life-threatening. Among the more common superficial infections is onychomycosis, an infection of the nails that causes them to become thickened, discolored, and brittle.
Of greater concern are the invasive infections this yeast can cause. The most frequent serious condition is candidemia, a bloodstream infection. This occurs when the yeast enters the circulatory system, often from a contaminated medical device or through a break in the skin. Symptoms of systemic infections like candidemia are often nonspecific and include fever and chills that do not resolve with standard antibiotic treatment.
In some cases, the infection can spread from the bloodstream to internal organs, leading to severe complications. Endocarditis, an infection of the inner lining of the heart chambers and valves, is a particularly dangerous outcome that has been associated with C. parapsilosis. Another serious condition is peritonitis, an inflammation of the membrane lining the inner abdominal wall, which can occur in patients receiving peritoneal dialysis.
Diagnosis and Treatment Approaches
Diagnosing a Candida parapsilosis infection begins with collecting a sample from the suspected site of infection, such as blood, tissue, or fluid. In the laboratory, these samples are cultured to grow and isolate the yeast. The organism is then identified to the species level to confirm that C. parapsilosis is the causative agent, which is important for guiding appropriate treatment.
Treatment for infections typically involves antifungal medications. The main classes of drugs used are echinocandins and azoles, and the choice can depend on the severity and location of the infection. For serious systemic infections, intravenous antifungals are required.
A growing challenge in managing these infections is the emergence of antifungal resistance. To address this, laboratories often perform antifungal susceptibility testing on the isolated yeast to determine which medication is most likely to be effective. A fundamental part of successful treatment involves the removal of the source of the infection, such as an infected catheter or other medical device.