Topnotch Microbiology Supertable by Dr.cocoy Calderon Jaffar Pineda Troy Soberano UPDATED NOVEMBER 2017

March 8, 2019 | Author: JB Sarmiento | Category: Aspergillus, Candidiasis, Public Health, Infection, Pneumonia
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Microbiology...

Description

NAME Malassezia furfur   AN-AN  AP-AP

RESERVOIR N aturally found on the skin surfaces of many animals, including humans.

Isolated in 18% of infants and 90-100% of adults.

DERMATOPHYTES

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

Coccidioides immitis

Desert areas of the southwestern United States and northern Mexico Respiratory transmission

Histoplasma capsulatum

Mississippi valley Present in bird and bat droppings Respiratory transmission

Blastomyces dermatitidis

Cryptococcus neoformans

Pigeon droppings

Candida albicans

Normal flora of the skin, mouth and gastrointrointestinal tract

 Aspergillius fumigatus

Ubiquitous

 Aspergillius flavus

 Aspergillius niger 

Rhizopus Rhizomucor 

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)

Dimorphic:

Coccidiodomycosis

Mycelial forms with spores at 25ºC Yeast forms at 37ºC

Asymtomatic (in most persons) Pneumonia Disseminated: can affect the lungs, skin , bones and meninges

Dimorphic :

Histoplasmosis

Mycelial forms with spores at

Asymptomatic (in most persons)

o

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

Dimorphic:

Blastomycosis

Mycelial forms with spores at

Asymptomatic (uncommon)

o

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

Polysaccharide capsule

 

Cryptococcus

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

 Aspergillosis

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 )

Mucormycosis

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.

TREATMENT

DIAGNOSIS

Dandruff shampoo (containing selenium sulfide)

Potassium hydroxide (KOH) prep: reveals short, curved, unbranched hyphae with spherical yeast cells ( look like “spaghetti and meatballs”)

Topical imidazole

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

 Itraconazole

Lung biopsy

Amphotericin B (in immunocompromised patients

Silver stain specimen Culture on Sabouraud’s agar will reveal hyphae o

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

Amphotericin B

Culture on Sabouraud’s agar

Serology

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

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.

NOTES

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

BROAD-BASED BUD

SYSTEMIC

Most cases occur in immunocompromised person

SYSTEMIC

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

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 severely immunocompromised adults who are at high risk of developing these infections. Aflatoxins contaminate peanuts, grains, and rice The disease is rapidly fatal

OPPORTUNISTIC

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,

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