Topnotch Microbiology Supertable by Dr.cocoy Calderon Jaffar Pineda Troy Soberano UPDATED NOVEMBER 2017
NAME Malassezia furfur AN-AN AP-AP View more...
RESERVOIR N aturally found on the skin surfaces of many animals, including humans.
Isolated in 18% of infants and 90-100% of adults.
Depending on the particular species
Microsporum Trichopyton Epidermophyton floccosum
Soil (geophilic) Animals (zoophilic) Human (anthropophilic)
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
Desert areas of the southwestern United States and northern Mexico Respiratory transmission
Mississippi valley Present in bird and bat droppings Respiratory transmission
Normal flora of the skin, mouth and gastrointrointestinal tract
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 Aspergillus pneumonia (or chronic necrotizing pulmonary aspergillosis [CNPA]) • Aspergilloma • Invasive aspergillosis Saprophytic molds
Mucor Pneumocystis jirovecii
Unicellular fungi found in the respiratory tracts of many mammals and humans
MORPHOLOGY “Spaghetti and meat balls” Dimorphic, lipophilic fungi
CLINICAL SYNDROME Tinea/Pityriasis versicolor - a common, benign, superficial cutaneous fungal infection usually characterized by hypopigmented or hyperpigmented macules and patches on the chest and the back. In patients with a predisposition, tinea versicolor may chronically recur. The fungal infection is localized to the stratum corneum. Dermatophytosis Tinea corporis (body): “ringworm” Tinea cruRis (groin): “jock itch” Tinea pedis (feet): “athlete’s foot” Tinea capitis (scalp) Tinea unguium (nail): Onychomycosis
Suppurating subcutaneous nodules that progress proximally along lymphatic channels (lymphocutaneous sporotrichosis)
Mycelial forms with spores at 25ºC Yeast forms at 37ºC
Asymtomatic (in most persons) Pneumonia Disseminated: can affect the lungs, skin , bones and meninges
Mycelial forms with spores at
Asymptomatic (in most persons)
25 C o
Yeast forms at 37 C
Pneumonia: lessions calcify, which can be seen on chest X-ray (may look similar to PTB) Disseminated: can occur in almost any organ, especially in lung, spleen, or liver
Mycelial forms with spores at
25 C o
Yeast forms at 37 C
Pneumonia: lesion rarely calcifies Dessiminated (most common): present with weight loss, night sweats, lung involvement and skin ulcers Cutaneuos: skin ulcer Blastomycosis is usually localized to the lungs and may present with: 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
Yeast form only (Not dimorphic) Subacute or chronic meningitis Pneumonia: usually self-limited and asymptomatic Skin lesions: look like acne Pseudohyphae and yeast
Candidiasis in a normal host Oral thrush Vulvovaginal candidiasis Cutaneous Diaper rash Rash in the skin folds of obese indivi duals 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
Branching septated hyphae O
Allergic bronchopulmonary aspergillosis (IgE mediated): asthma type asthma type reaction with shortness of breath and high fever
(acute angles, 45 )
Asperigilloma (Fungus ball): associated with hemoptysis (blood cough) Invasive aspergillosis: necrotizing pneumonia. May disseminate to other organs in immunocompromised patients Aflatoxin consumption (produced by Aspergillus flavus ) can cause liver damage and live cancer Broad, non-septated, branching o
hyphae (right angles, 90 )
Rhinocerebral (associated with diabetes): starts on nasal mucosa and invades the sinus and orbit
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)
Pulmonary mucormycosis PJP – Pneumocystis jirovecii 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 il lness. Activated alveolar macrophages without CD4+ cells are unable to eradicate Pneumocystis organisms. Increased alveolar-capillary permeability is visible on electron microscopy.
Dandruff shampoo (containing selenium sulfide)
Potassium hydroxide (KOH) prep: reveals short, curved, unbranched hyphae with spherical yeast cells ( look like “spaghetti and meatballs”)
Malassezia is extremely difficult to propagate in laboratory culture and is culturable only in media enriched with C12- to C14-sized fatty acids.
Topical imidazole Oral griseofuivin is used for tinea unguium and tinea capitis Oral terbinafine
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. If the above clinical evaluations are inconclusive, a polymerase chain reaction (PCR) assay for fungal deoxyribonucleic acid (DNA) identification can be used.
Itraconazole Fluconazole Oral potassium iodide
Dimorphic Culture at 25ºC will grow branching hyphae Culture at 37ºC will grow yeast cells
Definitive diagnosis of sporotrichosis at any site requires the isolation of S schenckii in a specimen culture from a normally sterile body site. The organism can be recovered with fungal culture from sputum, pus, subcutaneous tissue biopsy, synovial fluid, synovial biopsy, bone drainage or biopsy, and cerebrospinal fluid (CSF).
Amphotericin B Itraconazole Fluconazole
Biopsy of affected tissue: lung biopsy, skin biopsy, etc. Silver stain or KOH prep Culture on Sabouraud’s agar Serology Skin test
Amphotericin B (in immunocompromised patients
Silver stain specimen Culture on Sabouraud’s agar will reveal hyphae o
at 25 C and yeast at 37 C Serology Skin test (test for exposure only) Urine antigen test Itraconazole Ketoconazole
Biopsy of affected tissue: lung biopsy, skin biopsy, etc. Silver stain specimen
Culture on Sabouraud’s agar
Skin test (test for exposure only) Sputum specimens processed with 10% potassium hydroxide, cytology smears, or a fungal stain Enzyme immunoassay (EIA) techniques on sputum, tissue, or bronchoscopic specimens
Amphotericin B and flucytosine (is superior to amphotericin B alone)
India-ink stain of cerebrospinal fluid (CSF): observe encapsulated yeast Cryptococcal antigen test of CSF: detects polysaccharide antigens Fungal culture
The choice of antifungal agent depends on the area involved and its severity.
KOH stain of specimen Silver stain of specimen Blood culture: growth must be respected Blood assay for beta-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: treat with voriconazole, possibly caspofungin. (very high mortality)
Invasive aspergillosis: sputum examination and culture
Amphotericin B and surgery
Biopsy Black nasal discharge
A lactic dehydrogenase (LDH) study is performed as part of the initial workup. 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.
ANATOMIC LOCATION SUPERFICIAL (SKIN)
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.
Primary pulmonary infection SUBCUTANEOUS (pulmonary sporotrichosis) is rare, as is direct inoculation into tendons, bursae, or joints. Osteoarticular sporotrichosis is caused by direct inoculation or hematogenous seeding. In rare cases, disseminated S schenckii infection (disseminated sporotrichosis) occurs, characterized by disseminated cutaneous lesions and involvement of multiple visceral organs; this occurs most commonly in persons with AIDS.
Common oppurtunisitc infection SYSTEMIC in AIDS patients from the southwest United States SPHERULES WITH ENDOSPORES
Can survive intracellularly within SYSTEMIC macrophages
YEASTS WITHIN MACROPHAGES
Most cases occur in immunocompromised person
MCC of meningoencephalitis in HIV YEAST WITH A HALO YEAST WITH PSEUDOHYPHAE
CUTANEOUS or SYSTEMIC (normal host, or opportunistic)
Rarely found in individuals who are immunocompetent
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 severely immunocompromised adults who are at high risk of developing these infections. Aflatoxins contaminate peanuts, grains, and rice The disease is rapidly fatal
The taxonomic classification 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 synthesis not found in protozoa,