Candida glabrata is a species of yeast that commonly resides within the human body. It is a usual inhabitant of the gastrointestinal, genitourinary tracts, and the mouth, typically coexisting without causing harm. While generally considered a normal part of the human microbiome, C. glabrata is also an opportunistic pathogen. This means it can cause infections when specific circumstances allow it to flourish or spread.
From Normal Flora to Infection
Candida glabrata transitions from a benign resident to an infectious agent when the body’s protective mechanisms are weakened, allowing it to overgrow or invade tissues. This opportunistic behavior is a significant aspect of its pathogenicity. Individuals with compromised immune systems are particularly susceptible to these infections.
Conditions such as HIV/AIDS, cancer treatments like chemotherapy and radiation, and immunosuppressive drugs in organ transplant recipients significantly weaken the body’s defenses, allowing C. glabrata to cause disease. Advanced age also contributes to a diminished immune response, increasing vulnerability.
Medical interventions can also create pathways for infection. Prolonged hospital stays, especially in intensive care units, and indwelling medical devices like catheters provide surfaces for C. glabrata to colonize and form biofilms. These biofilms are protective layers that enhance the yeast’s resistance to antifungal treatments and the immune system. Broad-spectrum antibiotics can disrupt the natural balance of microorganisms, inadvertently reducing bacterial competitors and allowing C. glabrata to proliferate. Uncontrolled diabetes, with its associated high blood sugar levels, contributes to an environment conducive to yeast growth.
Signs and Symptoms of Candida glabrata
The manifestations of a Candida glabrata infection vary depending on the site where the yeast has proliferated. When C. glabrata affects the vulvovaginal area, it can lead to symptoms similar to other yeast infections. These include vaginal itching, a burning sensation, soreness, and an abnormal vaginal discharge that may be thick or watery.
Candida glabrata can also cause urinary tract infections (UTIs), particularly in hospitalized patients or those with catheters. Symptoms include a frequent and urgent need to urinate, a burning sensation during urination, and sometimes cloudy urine. While less common than Candida albicans, C. glabrata can cause oropharyngeal candidiasis, often called oral thrush. This infection presents as white patches on the tongue, inner cheeks, or throat, which may cause discomfort or difficulty swallowing.
The most severe form of infection is candidemia, a bloodstream infection where C. glabrata enters the circulatory system. This systemic infection often occurs in very ill, hospitalized patients and can become life-threatening. Symptoms are non-specific but severe, including persistent fever and chills that do not respond to typical antibiotic treatments. If left untreated, candidemia can progress to sepsis, a dangerous inflammatory response, and potentially lead to multi-organ failure. Unlike some other Candida species, C. glabrata does not form hyphae, a filament-like structure, and requires a breach in tissue barriers to enter the bloodstream.
Diagnosis and Treatment Challenges
Diagnosing a Candida glabrata infection involves obtaining a sample from the suspected site, such as a vaginal swab, urine sample, or blood culture. This sample is sent to a microbiology laboratory where it is cultured to identify the specific yeast species. Identifying C. glabrata is important due to its inherent characteristics.
A significant challenge in treating C. glabrata infections is its high level of resistance to common antifungal medications, particularly azoles like fluconazole. This resistance can be intrinsic, meaning the yeast is naturally less susceptible, or acquired after exposure to these drugs. The resistance mechanism often involves mutations in genes like PDR1, which regulate drug efflux pumps that expel antifungal drugs from the yeast cells, or modifications in the ergosterol biosynthesis pathway. This reduced susceptibility makes standard first-line treatments ineffective, necessitating alternative approaches.
For serious or invasive infections like candidemia, more potent antifungal medications are required. The echinocandin class of drugs, including caspofungin, is often the preferred treatment option due to C. glabrata’s resistance profile. Another alternative is amphotericin B, a broad-spectrum antifungal. For severe systemic infections, these medications are typically administered intravenously in a hospital setting. The need for specific, stronger antifungals underscores why accurate species identification is necessary for managing C. glabrata infections.