Transcript
N AME Malassezia furfur AN-AN AP-AP
RESERV OIR
M ORPHOLOGY
N aturally found on the skin s urfaces of “Spaghetti and meat balls” many animals, including humans. Dimorphic, lipophilic fungi
Isolated in 18% of infants and 90-100% of adults.
DERMATOPHYTES
Depending on the part icular species
Microsporum Trichopyton Epidermophyton floccosum
Soil (geophilic) Animals (zoophilic) Human (anthropophilic)
CLIN ICAL SYN DROME TREATM EN T Tinea/Pityriasis versicolor - a common, benign, Dandruff shampoo (containing superficial cutaneous fungal infection usually selenium sulfide) characterized by hypopigmented or hyperpigmented macules and patches on the chest and the back. In patients with a predisposition, tinea versicolor may Topical imidazole chronically recur. The fungal infection is localized to the stratum corneum.
D IAGN OSIS Potassium hydroxide (KOH) prep: reveals short, curved, unbranched hyphae with spherical yeast cells ( look like “spaghetti and meatballs”)
Dermatophytosis Tinea corporis (body): “ringworm” Tinea cruRis (groin): “jock itch” Tinea pedis (feet): “athlete’s foot” Tinea capitis (scalp) Tinea unguium (nail): Onychomycosis
KOH : branched hyphae Wood’s lamp: ceratin species of Microsporum will fluoresce under ultraviolet light A fungal culture, which is often used as an adjunct to KOH for diagnosis, is more specific than KOH for detecting a dermatophyte infection. Therefore, if the clinical suspicion is high yet the KOH result is negative, a fungal culture should be obtained.
Topical imidazole Oral griseofuivin is used for tinea unguium and tinea capitis Oral terbinafine
Infections due to zoophilic or geophilic dermatophytes may produce a more intense inflammatory response than those caused by anthropophilic microbes Sporothrix schenkii
Found on rose thorns
Coccidioides immitis
Desert areas of the s outhwestern United States and northern Mexico
Histoplasma capsulatum
ANATOMIC LOCATION SUPERFICIAL (SKIN)
Malassezia is extremely difficult to propagate in laboratory culture and is culturable only in media enriched with C12- to C14-sized fatty acids.
Secretes the enzyme keratinase, CUTANEOUS which digests keratin For atypical presentations of tinea corporis, further evaluation for HIV infection and/or an immunocompromised state should be considered.
If the above clinical evaluations are inconclusive, a polymerase chain reaction (PCR) assay for fungal deoxyribonucleic acid (DNA) identification can be used. Suppurating subcut aneous nodules t hat progres s proximally along lymphatic channels (lymphocutaneous sporotrichosis)
Itraconazole Fluconazole Oral potassium iodide
Respiratory transmission
Dimorphic: Mycelial forms with spores at 25ºC Yeast forms at 37ºC
Amphotericin B Coccidiodomycosis Asymtomatic (in most persons) Itraconazole Pneumonia Fluconazole Disseminated: can affect the lungs, skin , bones and meninges
Mississippi valley
Dimorphic :
Histoplasmosis
It Itraconazole
Present Present in bird r d and and bat bat dropping droppings
Mycelial forms with spores spores at
A sy symptomatic (in most pers on ons)
A mp mphot ericin B (in immunocompromised patients
Respiratory transmission
Yeast forms at 37 oC
o
25 C Pneumonia: lessions calcify, which can be seen on chest X-ray (may look similar to PTB)
Blastomycosis
Dimorphic:
Mycelial forms with spores at
Primary pulmonary infection SUBCUTANEOUS (pulmonary sporotrichosis) is rare, as is direct inoculation into tendons, bursae, or joints. Definitive diagnosis of sporotrichosis at any sit e Osteoarticular sporotrichosis is requires the isolation of S schenckii in a caused by direct inoculation or specimen culture from a normally s terile body hematogenous seeding. site. The organism can be recovered with fungal In rare cases, disseminated S culture from sputum, pus, subcutaneous tissue schenckii infection biopsy, synovial fluid, synovial biopsy, bone (disseminated sporotrichosis) drainage or biopsy, and cerebrospinal fluid occurs, characterized by (CSF). disseminated cutaneous lesions and involvement of multiple visceral organs; this occurs most commonly in persons with AIDS. Dimorphic Culture at 25ºC will grow branching hyphae Culture at 37ºC will grow yeast cells
Biopsy of affected tissue: lung biopsy, skin biopsy, etc. Silver stain or KOH prep Culture on Sabouraud’s agar Serology Skin test Lung biopsy
o
Can survive intracellularly within SYSTEMIC macrophages
Silver stain specimen Culture on Sabouraud’s agar will reveal hyphae
I tr tra co na na zo zo le
A symptomatic (uncommon)
Ketoconaz ole
Pneumonia: le les ion ra rarely ca calcifies
A mp mphot ericin B
Skin test (test for exposure only) Urine antigen test B io ps ps y o fa ffec tte ed t is su su e: l un un g b io ps ps y, y, s ki ki n biopsy, etc. Silver stain specimen
25oC Yeast forms at 37 C
Common oppurtunisitc infection SYSTEMIC in AIDS patients from the southwest United States SPHERULES WITH ENDOSPORES
YEASTS WITHIN MACROPHAGES
at 25oC and yeast at 37oC Serology
Disseminated: can occur in almost any organ, especially in lung, spleen, or liver
Blastomyces dermatitidis
NOTES
Culture on Sabouraud’s agar
Dessiminated (most common): present with weight loss, night sweats, lung involvement and skin ulcers
Serology
Cut aneuos : s kin ulcer
Skin test (t est for exposure only)
BROAD-BASED BUD
SYSTEMIC
Blastomycosis is usually localized to the lungs and may present with:
Sputum specimens processed with 10% potassium hydroxide, cytology smears, or a fungal stain Enzyme immunoassay (EIA) techniques on sputum, tissue, or bronchoscopic specimens
A self-limited flulike illness with fever, chills, myalgia, headache, and a nonproductive cough An acute illness resembling bacterial pneumonia, with high fever, chills, a productive cough, and pleuritic chest pain; mucopurulent or purulent sputum Chronic illness, with low-grade fever, a productive cough, fatigue, night sweats, and weight loss Rapidly progressive, and severe disease, eg, multilobar pneumonia or ARDS, with fever, shortness of breath, tachypnea, hypoxemia, and finally hemodynamic collapse Cryptococcus neoformans
Pigeon droppings
Polysaccharide capsule
Cryptococcus
Yeas t form only ( Not dimorphic) Subacut e or chronic meningitis Pneumonia: usually self-limited and asymptomatic
A mphot ericin B and flucyt os ine India-ink stain India-ink stain of cerebrospinal fluid (CSF): (is superior to amphotericin B observe encapsulated yeast alone) Cryptococcal antigen tes t of CSF: det ects polysaccharide antigens Fungal culture
Most cases occur in immunocompromised person
SYSTEMIC
MCC of meningoencephalitis in HIV
Skin lesions: look like acne Candida albicans
Aspergillius fumigatus
Normal flora of the skin, mouth and gastrointrointestinal tract
Ubiquitous
Pseudohyphae and yeast
Branching septated hyphae (acute angles, 45 O)
Aspergillius flavus
Aspergillius niger
Rhizopus Rhizomucor Mucor
Aspergillus may cause a broad spectrum of disease in the human host, ranging from hypersensitivity reactions to direct angioinvasion. Aspergillus primarily affects the lungs, causing the following four main syndromes: • Allergic bronchopulmonary aspergillosis (ABPA) • Chronic necrotizing necrotizing Aspergillus Aspergillus pneumonia (or chronic necrotizing pulmonary aspergillosis [CNPA]) • Aspergilloma • Invasive aspergillosis Saprophytic molds
Candidiasis in a normal host Oral thrush Vulvovaginal candidias is Cut aneous Diaper rash Rash in the skin folds of obese individuals Candidiasis in an immunocompromised host Thrush, vaginitis and/or cutaneous, plus: Esophageal Disseminated candidiasis: acquired by very sick hospitalized patients, resulting in multi-organ system failure Chronic mucocutaneous candidiasis Aspergillosis Allergic bronchopulmonary aspergillosis (IgE mediated): asthma type asthma type reaction with shortness of breath and high fever
Asperigilloma (Fungus Asperigilloma (Fungus ball): associated with hemoptysis (blood cough)
The choice of antifungal agent depends on the area involved and its severity.
KOH stain of specimen Silver stain of specimen Blood culture: growt h mus t be respect ed Blood as say for bet a-D-glucan
Allergic bronchopulmonary aspergillosis -> treat with corticosteroids
Allergic brochopulmonary aspergillosis: High level of IgE (IgE level > 1000 IU/dL) Sputum culture Wheezing patient and chest X-ray with fleeting infiltrates Increased level of eosinophils Skin test: immediate hypersensitivity reaction Aspergilloma: diagnose with chest X-ray or CT scan
Aspergilloma: removal via thoracic surgery
Invasive aspergillosis: necrotizing pneumonia. May Invasive aspergillosis: treat with disseminate to other organs in voriconazole, possibly immunocompromised patients caspofungin. (very high mortality) Aflatoxin consumption (produced by Aspergillus flavus ) can cause liver damage and live cancer Broad, non-septated, branching Mucormycosis A mphot ericin B and s urgery o Rhinocerebral (associated with diabetes): starts on hyphae (right angles, 90 ) nasal mucosa and invades the sinus and orbit Pulmonary mucormycosis
Invasive aspergillosis: sputum examination and culture
Biopsy Black nasal discharge
YEAST WITH A HALO YEAST WITH PSEUDOHYPHAE
Rarely found in individuals who are immunocompetent
CUTANEOUS or SYSTEMIC (normal host, or opportunistic)
OPPORTUNISTIC
The FDA has approved an intravenous formulation of the triazole antifungal posaconazole (Noxafil), which is indicated for the prophylaxis of invasive Aspergillus and Candida infections in s everely immunocompromised adults who are at high risk of developing these infections. Aflatoxins contaminate peanuts, grains, and rice The dis eas e is rapidly fatal OPPOR TUNISTIC
Pneumocystis jirovecii
Unicellular fungi found in the respiratory tracts of many mammals and humans
The organism is found in 3 distinct morphologic stages, as follows: The trophozoite (trophic form), in which it often exists in clusters The sporozoite (precystic form) The cyst, which contains several intracystic bodies (spores)
PJP – Pneumocystisjirovecii pneumonia occurs when both cellular immunity and humoral immunity are defective.
Once inhaled, the trophic form of Pneumocystis organisms attach to the alveoli. Multiple host immune defects allow for uncontrolled replication of Pneumocystis organisms and development of illness. Activated alveolar macrophages without CD4+ cells are unable to eradicate Pneumocystis organisms. Increased alveolar-capillary permeability is visible on electron microscopy.
TMP-SMX
A lactic dehydrogenase (LDH) study is performed as part of the initial workup.[24] LDH levels are usually elevated (>220 U/L) in patients with P jiroveci pneumonia (PJP). They are elevated in 90% of patients with PJP who are infected with HIV. The study has a high sensitivity (78%-100%); its specificity is much lower because other disease processes can result in an elevated LDH level. [Clin Invest Med. 1992 Aug. 15(4):309-17. Quantitative PCR for pneumocystis may become useful in distinguishing between colonization and active infection, but these assays are not yet available for routine clinical use.
The taxonomic clas sificat ion of the Pneumocystis genus was debated for some time. It was initially mistaken for a trypanosome and then later for a protozoan. In the 1980s, biochemical analysis of the nucleic acid composition of Pneumocystis rRNA and mitochondrial DNA identified the organism as a unicellular fungus rather than a protozoan. Subsequent genomic sequence analysis of multiple genes including elongation factor 3, a component of fungi protein
