Opportunistic and Facultative Parasites Flashcards
Pneumocystis jirovecii
Fungus that is an important pathogen of immunocomprimised humans
Pneumocystis lifecycle
Asexual: trophic forms replicate by mitosis
Sexual: haplpid form conjugate»_space; cyst»_space; spores
Epidemiology of P. jirovecii
Host-specific = only infects humans
Transmission is airborne
Most people infected early in childhood
Mainly affects the immunocomprimised
Diagnosis of PCP
Bronchoalveolar lavage (BAL) Staining of clinical specimens
Treatment of PCP
Trimethoprim-sulfamethoxazole
Microsporidia
Significant cause of mortality in immunocomprimised patients
Fungi
Transmit via spores
Species of Microsporidia
Enterocytozoon bieneusi
Encephalitozoon intestinalis
Enterocytozoon bieneusi
Most common cause of microsporidiosis
Can cause chronic diarrhoea
Up to 11 genotypes
Does not respond well to albendazole
Encephalitozoon intestinalis
Inestinal parasite, less commonly detected
Responds well to treatment with albendazole
Encephalitozoon hellem
Ocular infection most common cause
Genetically diverse
Found in birds and humans
Involves the immunocompetent
Epidemiology of Encephalitozoon spp.
Via faecal-oral route
Recreational water contamination
Animal reservoirs may be important, maybe airborne spores
Diagnosis of Encephalitozoon
Staining specimens
Electron microscopy
Nucleic acid amplification
Chemotherapy of Encephalitozoon
Albendazole (for some)
Fumagillin
Primary amoebic meningoencephalitis (PAM)
Caused by Naegleria fowleri
Water contaminated with sewage
Often affects healthy young people
Diagnosis of PAM
Direct examination of CSF
Antibody staining
Brain imaging
PCR
Treatment of PAM
Few survivors - best treatment unknown
Amphotericin B
Miltefosine
Granulomatous Amoebic Encephalitis (GAE)
Causative organisms: Acanthamoeba spp. Balamuthia mandrillaris, Sappinia pedata
Ancanthamoeba spp.
Widely distributed throughout the environment
Exists as a trophozoite with long finger-like pseudopodia
Causes two diseases - GAE and Amoebic keratitis
Diagnosis of GAE
Brain imaging
Biopsy specimens
Treatment of GAE
Not known - miltefosine is a crucical component
Amoebic keratitis (AK)
Acanthamoeba spp. infect the cornea (both trophozoites and cysts)
Occurs mainly in contact lens wearers
Diagnosis of AK
Cornea scraping, staining with calcofluor or labelled antibodies
PCR
Treatment of AK
Wide variety of agents used Polyhexamethyene biguanide (PHMB), chlorhexidine gluconate and propamidine isethionate
Balamuthia mandrillaris
Free living amoeba that can cause GAE
Closely related to acanthamoeba
Infects both immunocompetent/comprimised
Lives in soil
