Opportunistic Fungal Infections Flashcards
What is the fourth most common cause of nosocomial bloodstream infections?
Candida Spp
Candida albicans is the most common species isolated from clinical material
What is the morphology of Candida species?
Exist as oval yeast like forms that produce buds or blastoconidia
C. albicans forms germ tubes and terminal, thick-walled chlamydoconidia
What are the virulence factors of C. albicans?
Ability to adhere
Exhibit yeast-hyphal dimorphism
Cell surface hydrophobicity
Proteinase secretion
Phenotypic switching
What is unique about the hyphae of C. albicans?
Exhibit thigmotropism (sense of touch)
Allows them to grow along grooves and through pores and may aid in infiltration of epithelial surfaces
What is the primary site of colonization for Candida?
GI tract from mouth to rectum
What is oropharyngeal and oesophageal candidiases?
White patches on oral mucosa caused by Candida
Seen in immunocompromised patients like HIV, DM, antibiotics or steroids
What is Vaginal candidiases?
Yeast infection
Does not require immune dysfunction
Causes severe itching/burning and white like patches on the mucosal surface
How does the pseudomembranous type of candida infection present?
Raw bleeding surface when scraped
Erythematous type-flat, red, occasionally sore ares
What is Candidal Leukoplakia?
Non-removal white thickening of epithelium due to Candida
What is angular cheilitis?
Sore fissures at the corners of the mouth
Caused by Candida
How does a localized skin infection by Candida present?
Pruritic rash with erythematous vesiculopustular lesions
Occur in areas where skin surface is occluded and moist
What is onychomycosis?
Chronic candidiases
What are the diagnostic tests for Candida albicans?
KOH with calcofluor white stain
Germ tube test permits exact identification
What does candida look like on culture?
White, smooth, creamy
Unique color on chromagar
How is Candida treated?
Mucosal and cutaneous infections - Azole creams and ointments
Systemic - Amphotericin B IV, Flucytosine
What is the most frequent portal of entry for Aspergillus?
The respiratory tract
Their conidia (spore) are ubiquitous and constantly being inhaled
How does the clinical syndrome of Aspergillosis present?
Allergic manifestations based on the degree of hypersensitivity to Aspergillus antigens
Asthma, pulmonary infiltrates, peripheral eosinophilia, elevated IgE
How is aspergillus diagnosed?
Demonstration of the organism by both culture and examination of tissue
Immunoassays for the aspergillus galactomannan antigen in serum
What is the therapy for aspergillus?
Amphotericin B or 5-flucytosine
What is mucomycosis?
Diseases caused by fungi of the subphyla Mucoromycotina and Entomophothoromycotina
How is mucomycetes spread?
Nosocomial spread through air-conditioning systems, especially during construction
Focal outbreaks associated with contaminated bandages
What is the morphology of mucomycetes?
Seen as ribbon-like, aseptate or sparsely septate, nonpigmented hyphae
Haphazard and nonprogressive branching pattern
How does invasive mucormycosis present?
Clinically similar to aspergilliosis
Organ transplants with underlying DM
What is Rhinocerebral mucormycosis?
Occurs as terminal event in patient with uncontrolled diabetes
Facial pain, headache, blood-tinged nasal discharge, bulging, discolered eye
What is the therapy for mucormycosis?
Amphotericin B
Treat underlying condition
What are the etiological agents of Cryptococcosis?
Crytpococcus neoformans, gattii
How is cryptococcosis acquired?
Inhaling aerosolized cells of C neoformans/gattii
Disseminates from the lungs to the CNS
What is C. neoformans the most common cause of?
C. neoformans is the most common cause of fungal meningitis
What patient demographic is at high risk for C. neoformans?
Patients with AIDS
How does cryptococcosis present?
Most commonly as a CNS infection secondary to pulmonary infection
Pulmonary cryptococcosis is variable in presentation
How is the diagnosis of cryptococcal meningitis made?
Detection of capsular polysaccharide antigen in serum or CSF
How is cyrptococcal meningitis treated?
Amphotericin B plus flucytosine
Effective management of CNS pressure
What is Pneumocystis Carinii Pneumonia (PCP)?
Often the first opportunistic infection to develop in patients with AIDS
Diffuse interstitial plasma cell pneumonia
How is PCP diagnosed?
Gomori’s methenamine silver-stain
Demonstrates rounded cup shaped organism
What is the treatment for PCP?
Trimethoprim-sulfamethoxazole
Pentamidine Isothionate
