NTA Level 5 • Semester 1 • PST05103

Superficial Mycoses

Pharmaceutical Microbiology • Source Session/Topic 33

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Session 33: Superficial Mycoses

Total Session Time: 60 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 Superficial mycoses (causative agents,

transmission, signs and symptoms)

• Describe treatment, prevention and control of superficial 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: Features and Treatment of Superficial Mycoses (45 minutes)

• Superficial fungal infections arise from a pathogen that is restricted

to the stratum corneum, with little or no tissue reaction

• Important superficial mycoses are Tinea versicolor, Piedra and Tinea

nigra

• Tinea versicolor (Pityriasis versicolor)

o It is a superficial chronic infection of stratum corneum

o It is common worldwide and is caused by Malassezia spp, which are

human saprophytes that sometimes switch from yeast to pathogenic

mold forms

o Three species of Malassezia are linked to tinea versicolor;

▪ Malassezia furfur

▪ Malassezia globose

▪ Malassezia sympodialis

o Signs and symptoms are;

▪ Hyperpigmented or depigmented maculae on chest, back, arms

and abdomen

▪ Does not illicit immune response, no discomfort

▪ Limited to the stratum corneum

o Treatment

▪ Topical antifungal e.g. whitfield’s ointment, miconazole,

itraconazole

▪ Oral azole

• Piedra

o (White and black piedra) is common in tropical regions of the world

o White piedra is also endemic in temperate climates

o Black piedra is caused by Piedraia hortae

o White piedra is a superficial fungal infection of the hair shaft is

caused by Trichosporon species e.g. Trichosporon beigelii

o Signs and symptoms

▪ White piedra shows irregular, white, cream-colored, or brown

soft nodules or gelatinous sheaths along the hair shaft

▪ They can be easily detached from the hair shaft

▪ White piedra is found in the hair of the beard, moustache,

genitals, and axilla

▪ Eyebrow and eyelash involvement can also be present, while on

the scalp, white piedra appears to be less common

o Treatment involves shaving and application of topical antifungal

agents e.g. terbinafine, and ketoconazole shampoo

• Tinea nigra (Tinea nigra palmaris)

o Is common in tropical areas

o Is a superficial chronic and asymptomatic infection of the stratum

corneum caused by the dematiaceous fungus Hortaea (Exophiala)

werneckii

o Lesions appear as a dark (brown to black) discoloration, often on

the palm

STEP 3: Key Points (5 minutes)

• Superficial mycoses are among the most common of all communicable

diseases

• They are mainly caused by Malassezia species which presents as patches

of hyper and hypopigmentation on skin

• Piedra affects the hairy parts of the body

STEP 5: Evaluation (5 minutes)

• What is piedra?

• How is Tinea nigra palmaris treated?

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