Fungal Infections in Immunocompromised Hosts

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Fungal infections in immunocompromised host are common and are associated with significant mortality and morbidity. These are either endemic- caused by ubiquitous fungi such as: Histoplasma capsulatum and Mucor spps or opportunistic fungi such as: Candida species, Aspergillus species, pneumocystic jirovecii and Cyptococcus neoformans. Opportunistic fungal infections are the most common fungal infections seen in immunocompromised and are attributed to decline in CD4+ T cell counts, neutrophil counts and general immunity. They are seen in HIV patients, those who have undergone extensive surgery, patients with haematological disorders, and those who have corticosteroids, cytotoxic or suppressive chemotherapy. As a result, infections such as: candidiasis, cryptococcosis, pneumocystis pneumonia and aspergillosis are disseminated in these hosts.

Candidiasis is commonly caused by Candida albicans- a normal oral flora in the genitourinary tract, gastrointestinal tract and on the skin. It forms bio-films on any surface, and cause mucosal and systemic infections in immunocompromised hosts disseminated as: oral thrush, vulvovaginitis, and endocarditis, among others. Although Candida albicans remains the major cause of nosocomial infections, other non albicans candida species such as: Candida glabrata, Candida tropicalis and Candida parapsilosis are increasingly becoming common. According to Pfaller et al., 2007, Candida glabrata was the second most cause of invasive infections in the USA while the ARTEMIS Global Antifungal Surveillance Program revealed that Candida albicans caused the most fungal infections in the world followed by Candida glabrata, Candida tropicalis, and Candida parapsilosis respectively. The major predisposing factor...

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.... However aspergillosis-related infections namely: endophthalmitis, endocarditis, and abscesses in the myocardium, kidney, liver, spleen, soft tissue, and bone in may occur. (Reference). These infections could rapidly progress in severely immunosuppressed hosts such as: leukaemia patients, those receiving corticosteroids or cytotoxic therapy and those who have recently undergone bone marrow transplantation or patients with advanced AIDS or chronic granulomatous disease. As a result, fever, invasion of blood vessels that results into multifocal infiltrates and spread to the central nervous system, may occur [76]. The fungus evades the host's immune system to cause disease through expression of multiple gene products such as: cell wall assembly, conidial germination, hyphal elongation and growth, resistance to oxidative stress and nutrient acquisition among others.
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