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Impact of Invasive Fungal Infection on Patients Undergoing Solid Organ Transplantation-Section 3
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Mohammad Ghahri   |
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Abstract: (19 Views) |
The spectrum of organisms capable of causing life-threatening infections in transplant recipients is very broad and, in a simple classification system, includes: true pathogens, occasionally pathogenic organisms, and nonpathogenic organisms. True pathogens include influenza, bubonic plague, smallpox, etc. which produce various toxins and damage tissue surfaces, and specific immunity or effective antimicrobial therapy is necessary for their control. Some of these pathogens normally reside on mucosal surfaces of the skin without clinical effect. Damage to these surfaces provides these organisms with access to sites vulnerable to invasive infection (such as peritonitis after colon perforation). Non-pathogens are those saprophytes that are ubiquitous in the environment and are controlled by innate immune mechanisms, causing disease only in individuals with significant immunodeficiency (such as Aspergillus species, Pneumocystis jiroveci, Zygomycetes, and other types of microbes).
The term opportunistic infection refers to an invasive infection caused by a nonpathogen or to an infection caused by an organism that causes insignificant infection in the normal host but life-threatening infection in the immunocompromised individual (e.g., candidal vaginitis versus disseminated candidiasis). Transplant patients are at risk for all three categories of infections by enhancing a specific clinical syndrome caused by the immunosuppressive state.
In general, fungal infections that occur in transplant patients are caused by two of the above-mentioned groups of microorganisms, namely opportunistic and non-pathogenic organisms, and can be practically divided into three general categories:
Endemic systemic mycoses, geographically limited (caused by Blastomyces dermatitidis, Coccidioides immitis, Histoplasma capsulatum, and others). These microorganisms have a number of common features: they are dimorphic in their growth pattern, with the mycelium or mold form present in the soil of endemic areas, which in this state produces spores that are contagious to humans. Inhalation of these infectious agents and their deposition in the respiratory tract, followed by the transformation of conidia into invasive yeast, initiates the infectious process.
Opportunistic fungal infections, The most common causes of invasive fungal infections in transplant recipients are commensal organisms found on mucosal surfaces (Candida species) and saprophytic organisms that are ubiquitous in the environment. (such as Aspergillus, Cryptococcus, and Zygomycetes). Factors that contribute to the overgrowth of these microorganisms include decreased immune surveillance due to immunosuppression or neutropenia, diabetes mellitus and other endocrine diseases, and elimination of competing microbial flora by the use of broad-spectrum antibiotics.
New and emerging fungi, The nature of fungal species causing invasive infections in transplant recipients is changing significantly. Although fluconazole-susceptible Candida albicans, Aspergillus fumigatus, and Cryptococcus neoformans remain the most common causes of invasive fungal infections in solid organ transplant recipients, 2 to 10% of invasive fungal infections are now caused by organisms such as fluconazole-resistant Candida (including both albicans and non-albicans strains), Scedosporium, Trichosporon, Fusarium, and other unusual organisms. The selective pressures of antifungal prophylaxis strategies, the increasing potency and potency of modern immunosuppressive regimens, and increased exposure (both in the hospital and community) have undoubtedly contributed to the growing importance of this class of infections.
Of particular importance is that many of these organisms respond poorly to amphotericin B and require voriconazole or some other novel therapy. This group of infections will almost certainly increase in importance in the next few years, requiring not only new therapies but also new diagnostic approaches.
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| Keywords: Opportunistic Infections, Invasive Fungal Infections, Aspergillosis, Mucormycosis, Cryptococcosis, Life-Threatening Infections, Past Transplant Infections |
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Full-Text [PDF 967 kb]
(11 Downloads)
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Type of Study: Review |
Subject:
قارچ شناسی
Received: 2025/07/1 | Accepted: 2025/07/2 | Published: 2025/07/2
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