Opportunistic mycoses

OPPORTUNISTIC MYCOSESCLASSIFICATION ORGANISMS

Yeast CandidaCryptococcusTorulopsisTrichosporonRhodotorulaGeotrichium

Molds AspergillusPseudoallescheriaZygomycetes (Rhizopus, Mucor, and Absidia

Monday, January 16, 2012

OPPORTUNISTIC MYCOSES

True Pathogenic Fungi Opportunistic Fungi

Diseases HistoplasmosisBlastomycosisParacoccidioidomycosisCoccidioidomycosis

AspergillosisCandidiasisMucormycosisCryptococcosis

Host Normal Abrogated/Compromised

Portal of Entry

Primary infection is pulmonary

Various


OPPORTUNISTIC MYCOSESTrue Pathogenic Fungi Opportunistic Fungi

Prognosis 99% spontaneous resolution Recovery depends on the severity of impairment of host defenses

Immunity Resolution results to strong specific immunity

No specific resistance to infection

Host Response Tuberculoid granuloma, mixed pyogenic

Depends on degree of impairment necrosis to pyogenic to granulomatous

Morphology in Tissue

All agents showed dimorphism to a tissue form

No change in morphology

Distribution Geographically restricted Ubiquitous


CANDIDIASIS

C. albicans is the most common (4-6 um; budding)

Multiplication: blastospore formation producing either pseudohyphae or septate hyphae

Identification: assimilation and fermentation of CHOs; physiologic and morphologic responses they exhibit when grown under controlled nutritional conditions “germ tubes”


CANDIDIASIS

“chlamydoconidia”


FACTORS THAT AFFECT CANDIDA NORMAL POPULATION

poor oral hygiene

use of antibiotics

use of oral contraceptives

diet

presence of antagonistic inhibitory bacteria


Candida albicans is a resident flora of the skin, mouth, vagina and stool!

Imbalance will lead to infection....HOW?

Changes in the Physiology: e.g. pregnancy, use of steroids and diabetes

Prolonged administration of antibiotics

Immunocompromised patients


MUCOCUTANEOUS CANDIDIASIS (MC)

a condition caused by a fungus from the candida family (lives on the surface of skin) that develops a diffuse and persistent type of infection of the mouth, nails, skin, and at times other organs

affects infants (starts before age 3) and young adults, is rarely seen in adults with other diseases

including chronic mucocutaneous candidaisis or CMCC


SYMPTOMS: ORAL

“thrush” “glossitis” “stomatitis”

“cheilitis” “perleche”


SYMPTOMS: VAGINITIS & BALANITIS

“VAGINITIS = female”

“BALANITIS = male”


“Esophageal growth”

OTHERS: gastritis, peritonitis, enteric and perianal disease

SYMPTOMS: ALIMENTARY


CANDIDIASIS IN NAILS


CANDIDIASIS IN DIAPER RASH

“Candida may come from fecal origin”


SYSTEMIC INVOLVEMENT

Urinary tract

Endocarditis

Meningitis

Septicemia

Latrogenic candidemia

Dissemination to other organ systems


DISSEMINATED CANDIDIASIS

originate at a gastrointestinal site

CA enters epithelial microvilli through persorption of yeast cells or by germination (a,c)

In both cases, organisms enter the vasculature (b,d) for dissemination into tissues such as the kidney (e)

localizes in the cortex (f) where it grows as hyphae/pseudohyphae

A vigorous host response occurs at this site consisting of both mononuclear and polymorphonuclear leukocytes

Virulence factors (adhesins, morphogenesis, switch phenotypes, antioxidant proteins and invasive enzymes) promote the invasion of the organism


ALLERGIC CANDIDIASIS

Eczema

Asthma

Gastritis


LABORATORY DIAGNOSIS: CADIDIASIS

Direct microscopic examination

Specimen for examination can be sputum, skin scrapings, vaginal swabs, biopsy material, from any types of organs or even in blood.

The specimen is treated with 1-2 drops of 10-20% KOH.


LABORATORY DIAGNOSIS: CADIDIASIS

The presence of the capsule and budding yeast cells are considered as the positive results.

Aside from KOH, other stains can be used such as India ink and Papanicolaou stain.


GERM TUBE TEST

Most isolates of C. albicans produce a hyphal growth from blastospores when they are suspended in serum at 37°C for 2-3 hours.


IN CULTURE...

SDA at either room temperature or at 37°C

Colonies: usually develop in 2-3 days as white, typical yeast colonies

In vitro: monomorphic, growing as non encapsulated yeast cells at any temperature


IN CULTURE...


FROM CORN MEAL AGAR


TREATMENT OF CANDIDIASIS

Most localized, cutaneous, candidiasis infections may be treated with any number of topical antifungal agents (eg, clotrimazole, econazole, ciclopirox, miconazole, ketoconazole, nystatin).

For Candida onychomycosis, oral itraconazole (Sporanox)

For Genitourinary tract candidiasis, VVC can be managed with either topical antifungal agents or


TREATMENT OF CANDIDIASIS

Caspofungin acetate (Cancidas) as a 70-mg loading dose is followed by 50 mg/d IV for a minimum of 2 weeks after improvement or after blood cultures have cleared.

Chronic mucocutaneous candidiasis is treated with oral azoles, either fluconazole (Diflucan)


ASPERGILLOSIS

One of the largest of the fungal genera

Hundred of species have been recorded

The most important species:

A. fumigatus

A. flavus

A. niger


ASPERGILLUS FUMIGATUS

Aspergillus fumigatus

identified according to the pattern of conidiophore development, morphologic features and color of the conidia


IMPORTANT PARTS


SPECTRA OF ASPERGILLOSIS

Toxicity due to ingestion of contaminated foods

Allergy and sequelae to the presence of conidia or transient growth of the organism in body orifices

Colonization without extension in preformed cavities and debilitated tissues

Invasive, inflammatory, granulomatous, necrotizing disease of lungs and other organs

Systemic and fatal disseminated disease


ALLERGIC ASPERILLOSIS

Allergic aspergillosis maybe benign early on and severe as the patient grows older

In secondary colonization, a chronic clinical situation may exist with little distress except occasional bout of hemoptysis and some pathological changes in the lungs that may lead to the formation of fungus ball.


ALLERGIC ASPERILLOSIS

SKIN FUNGAL SPECIMEN IN THE TISSUE


SYSTEMIC ASPERGILLOSIS

An extreme serious disorder that is usually rapidly fatal unless diagnosed early and treated aggressively

The status of the host’s immune system contributes to the prognosis of the patient


SYSTEMIC ASPERGILLOSIS

FUNGUS BALL/ ASPERGILLOMA


Disease Etiologic Factors

Mycotoxicoses Ingestion of contaminated food products

Hypersensitivity peumonitis

Allergic bronchopulmonary disease

Secondary colonization

Colonization of preexisting cavity (pulmonary abscess) without invasion into contiguous tissue

Systemic disease Invasive disease involving multiple organs


DISSEMINATED ASPERGILLOSIS

Aerosols of Aspergillus fumigatus conidia are inhaled and travel to the alveoli

In the healthy host, alveolar macrophages (AM) phagocytose and kill the organism after swelling of the conidium, an essential pre-germination stage

The production of reactive oxygen intermediates by AM is required to eliminate the organism, but polymorphonuclear cells (PMNs) also contribute

In the immunosuppressed patient, reduced numbers of PMNs and inefficient AM allow growth of the fungus

Consequently, the conidia germinate and escape from the AM


LABORATORY DIAGNOSIS

Aspergillosis is easy to isolate and identify....BUT!

also important to distinguish a true pathogen from a contaminant

If sputum sample is to be collected, it is expected to be thick and gelatinous

In invasive sampling, lung aspirates or tissue biopsy is used


LABORATORY DIAGNOSIS

Direct microscopic examination will show hyaline, dichotomously branched and septate hyphae

Occasionally in sputum, in cases of pulmonary aspergillosis, one may also sees very small, rough walled spores (3-4 um in diameter).


PULMONARY ASPERGILLOSIS


TREATMENT

Amphotericin B was used for many years BUT!!! with disappointing results

In 1990 itraconazole was introduced as a new broad spectrum anti-fungal agent.


ZYGOMYCOSIS/PHYCOMYSIS

Class Phycomycetes

Rhizopus

Absidia

Mucor

They formed coenocytic hyphae and reproduce asexually by producing sporangiosphores within which develops sporangiospores


ZYGOMYCOSIS/PHYCOMYSIS

Repeated isolation of the organisms from consecutive specimens provides strong evidence that the organisms may be relevant, even though coenocytic hyphal elements are not seen in histopathologic examination of tissue.


MUCORMYCOSIS (ORAL CAVITY)


CATEGORIES COMMENTS

Rhinocerebral It is the most frequent presentation overall and classically affects diabetics with ketoacidosis.

Usually presents with facial and/or eye pain, proptosis and progressive signs of involvement of orbital structures (muscles, nerves and vessels).

Common complications include cavernous sinus and internal carotid artery thrombosis.

Pulmonary It occurs most frequently among neutropenic patients.

It presents with nonspecific symptoms such as fever, cough and dyspnea; hemoptysis may occur with vascular invasion.

Radiological presentation includes segmental consolidation that progresses to contiguous areas of the lung, with occasional cavitation.

Gastrointestinal Usually affects patients with severe malnutrition

May involve the stomach, ileum, and colon

Clinical picture mimics intra-abdominal abscess. The diagnosis is often made at autopsy.

Cutaneous It has been reported with minor trauma, insect bites, no sterile dressing, wounds, and burns.

The necrotic lesions progressively evolve from the epidermis into dermis and even muscle.

Others Heart, bone, kidneys, bladder, trachea, and mediastinum


DIRECT EXAMINATION: ZYGOMYCOSIS

A rapid diagnosis is critical

Fungal elements are usually not numerous in discharges

Scrapings from the upper turbinates, aspirated material from sinuses, sputum in pulmonary disease, and biopsy material mounted in 10% KOH typically contain thick-walled, refractile hyphae 6-15 um in diameter

Swollen cells (up to 50 um) and distorted hyphae may be present


IN CULTURE...

Sabouraud dextrose agar: Incubate at 30°C

DON’T: cycloheximide = sensitive

Sterile bread:

for recovery of Zygomycetes when other media fail

WHY bread??? Monday, January 16, 2012

TREATMENT

Control of the diabetes

Aggressive surgical debridement of involved tissue

High doses of amphotericin B are recommended


Health & Medicine

Opportunistic mycoses