NTA Level 5 • Semester 1 • PST05103

Opportunistic Mycoses

Pharmaceutical Microbiology • Source Session/Topic 35

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Session 35: Opportunistic Mycoses

Total Session Time: 120 minutes

Pre-requisites

• Human anatomy and physiology

Students Learning Tasks

By the end of this session students are expected to be able to:

• Classify and describe Oppotunistic mycoses (causative agents,

transmission, signs and symptoms)

• Describe treatment, prevention and control of oppotunistic mycoses

Resources Needed:

• Flip charts, marker pens, and masking tape

• Black/white board and chalk/whiteboard markers

SESSION OVERVIEW

SESSION CONTENTS

STEP 1: Presentation of Session Title and Learning Tasks (5 minutes)

READ or ASK students to read the learning tasks and clarify

ASK students if they have any questions before continuing

STEP 2: Introduction to Opportunistic Mycoses (20 minutes)

• Opportunistic mycoses are fungal infections that occur immunocompromised

patients

• The common causes of immunocompromised immunity include AIDS, azotemia,

diabetes mellitus, lymphoma, leukemia, other hematologic cancers, burns,

and therapy with corticosteroids, immunosuppressants, or antimetabolites

• Patients who spend more than several days in an ICU can become

compromised because of medical procedures, underlying disorders, and/or

undernutrition

• Fungi which cause opportunistic mycoses include Candida albicans,

Cryptococcus neoformans, Coccidioides immitis, Histoplasma capsulatum,

Pneumocystis jiroveci

• Systemic mycoses affecting severely immunocompromised patients often

manifest acutely with rapidly progressive pneumonia, fungemia, or

manifestations of extrapulmonary dissemination.

STEP 3: Candidiasis (30 minutes)

• Cause and Transmission

o Candidiasis is an opportunistic mycosis and the most the most

prevalent systemic mycosis caused mainly by Candida albicans

o Other Candida species causing candidiasis include Candida

parapsilosis, Candida glabrata, Candida tropicalis, Candida

guilliermondii, and Candida dubliniensis

o Candida species are members of the normal flora of the skin, mucous

membranes, and gastrointestinal tract

o Candida species colonize the mucosal surfaces of all humans soon

after birth, and the risk of endogenous infection is ever present.

o Candidiasis is usually precipitated by prolonged use of

contraceptive pills, AIDS, pregnancy, diabetes, prolonged use of

antibiotics, corticosteroid use, and immunosuppressive treatment

o Candida species cause both cutaneous or mucocutaneous and systemic

opportunistic infections

• The signs and symptoms

o Cutaneous and mucosal candidiasis

▪ Oral thrush

• Oral lesions characterized by white, adherent mucosal plaques

(a patchy to confluent, whitish pseudomembrane) on the lips,

gums, tongue or the palate

▪ Vaginal candidiasis (vulvovaginitis)

• Itchy, curd-like whitish vaginal discharge, dysuria and

dyspareunia

▪ Cutaneous candidiasis

• Erythematous, moist exudate in the skin folds and accompanying

satellite pustules

▪ Onychomycosis

• Painful swelling of the nail bed and folds, with pus discharge

and is made worse by contact with water

▪ Gastrointestinal candidiasis

• Painful swallowing (odynophagia)

• Characteristic lesions are seen on endoscopy

▪ Systemic candidiasis

• Occult lesions develop anywhere, especially the kidney, skin

(maculonodular lesions), eye, heart, and meninges

• Treatment and Prevention

o Cutaneous candidiasis

▪ Topical clotrimazole

▪ Topical miconazole

o Oral candidiasis

▪ Nystatin oral suspension

o Vaginal candidiasis

▪ Nystatin (vagina) pessaries

▪ Miconazole (vaginal) pessaries

▪ Systemic fluconazole

o Gastrointestinal candidiasis

▪ Systemic fluconazole

o Prevention

▪ Avoid disturbing microbial normal flora

STEP 4: Cryptococcosis (20 minutes)

• Cause and Transmission

o Cryptococcus neoformans causes cryptococcosis which is a fungal

infection of the brain resulting in Cryptococcal

meningoencephalitis.

o C neoformans occurs in immunocompetent persons but more often in

patients with HIV/AIDS, haematogenous malignancies, and other

immunosuppressive conditions

o C. neoformans commonly found in avian faeces, is transmitted through

inhalation of desiccated yeasts (or basidiospores) to pulmonary

alveoli

o Infection is initiated by inhalation of the yeast cells, which in

nature are dry, minimally encapsulated, and easily aerosolized

o The primary pulmonary infection may be asymptomatic or may mimic an

influenza-like respiratory infection, often resolving spontaneously

o In immunocompromised patients the yeasts may multiply and

disseminate to other parts of the body but preferentially to the

central nervous system, causing cryptococcal meningoencephalitis

• Signs and Symptoms

o Headache

o neck stiffness

o Disorientation

o There may be lesions in skin, lungs, or other organs

o Chronic meningitis, (which can resemble a brain tumour, brain

abscess, degenerative central nervous system disease, or any

mycobacterial or fungal meningitis)

• Treatment and Prevention

o Combination therapy

▪ Amphotericin B and Flucytosine

o Prevention

▪ Care in handling avian faeces

STEP 5: Pneumocystis Pneumonia (20 minutes)

• This is fungal pneumonia caused by Pneumocystis jiroveci in

immunocompromised patients

• P. jiroveci was thought to be a protozoan for many years, but now proven

to be a fungus with a close relationship to ascomycetes

• Pneumocystis species are present in the lungs of many animals (rats,

mice, dogs, cats, ferrets, rabbits) but rarely cause disease unless the

host is immunosuppressed

• Pneumocystis carinii is found only in rats

• Before the introduction of effective chemoprophylactic regimens, this

disease was a major cause of death among AIDS patients

• The disease is acquired through inhalation

• Acute cases of Pneumocystis pneumonia are treated with trimethoprim-

sulfamethoxazole or pentamidine isethionate

• Prophylaxis can be achieved with daily Trimethoprime/Sulfamethoxazole

(Co-trimoxazole) or aerosolized pentamidine

STEP 6: Key Points (5 minutes)

• Opportunistic mycoses are caused by globally distributed fungi that are

either members of the human microbiota, such as Candida species, or

environmental yeasts and moulds

• Among the categories of fungal infections, the incidence, severity, and

mortality of systemic opportunistic mycoses are the highest

• Most patients with HIV/AIDS develop mucosal candidiasis (e.g. thrush,

esophagitis)

• HIV/AIDS patients with CD4 counts less than 100 cells/μL are at risk for

cryptococcosis, pneumocystis pneumonia, aspergillosis, penicilliosis,

endemic mycoses, and other infections

• Successful management of opportunistic mycoses involves early diagnosis,

rapid administration of appropriate antifungal therapy, and control of

the underlying condition or disease.

STEP 7: Evaluation (5 minutes)

• What is an opportunistic mycosis?

• How is candidiasis caused in immunocompromised individual?

• What is the treatment of oral candidiasis?

References

Hugo and Russell (2011), Pharmaceutical Microbiology 8th Edition, Willey-

Blackwel publications

Karen C. Carroll et al (2013); Jawetz, Melnick and Adelberg’s Medical

Microbiology 26th Ed. McGraw Hill Co. Inc.

Greenwood et al (2012); Medical Microbiology, 18th edition Churchill

Livingstone

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