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Skin Infections (1) Fungal infections: # Tinea infections, including: 1.Tinea pedis (feet) 2.Tinea cruris (groin) 3.Tinea corporis (body) 4. Tinea capitis (head) # Candidiasis of skin, nail or feet # Pityriasis versicolor, caused by Malassezia furfur, and characterized by non-itchy hypo-or hyperpigmented macules.

Skin Infections (1) Fungal infections: # Tinea infections, including: 1.Tinea pedis (feet) 2.Tinea cruris (groin) 3.Tinea corporis (body) 4. Tinea capitis

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Text of Skin Infections (1) Fungal infections: # Tinea infections, including: 1.Tinea pedis (feet) 2.Tinea...

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Skin Infections

Fungal infections:

# Tinea infections, including:

1.Tinea pedis (feet) 2.Tinea cruris (groin) 3.Tinea corporis (body) 4. Tinea capitis (head)

# Candidiasis of skin, nail or feet

# Pityriasis versicolor, caused by Malassezia furfur, and characterized by non-itchy hypo-or hyperpigmented macules.

Pityriasis versicolor(2) Pediculosis pubis, caused by crab lice; and affects the head, body, pubic area.

(3) Scabies, caused by the insect Sarcoptes scabiei, and characterized by:

* Affects finger clefts, forearms and genitalia * Acquired by sexual close contact.

(4) Viral skin infection, caused by herpes virus, enteroviruses, Measles virus, & Rubella virus

(5) Commensal skin bacteria cause acne vulgaris

Acne vulgarisTinea infections

Symptoms:

@ Scaly lesions with raised margins. @ Commonly seen during childhood. @ Infect skin, nails and hair. @ Acquired from domestic or farm animals

Aetiology:

@ Caused by three fungal genera: * Trichophyton, * Microsporum * Epidermophyton

Trichophyton EpidermophytonMicrosporumFeatures of tinea infections:

@ Tinea pedis (feet): Infects interdigital spaces and causes itching, and blisters. * It is caused by Trichophyton rubrum and Trichophyton interdigitale

@ Tinea cruris (groin): Causes genitourinary infection.

@ Tinea corporis (body): Known as 'ringworm. * It infects the arms, trunk and legs. * It caused by Trichophyton rubrum

@ Tinea capitis: Infects scalp and hair. Causes scaling of scalp, dandruff, broken hairTinea pedis Tinea capitis Lab. Diagnosis of tinea infections:

@ Presence of scales is diagnostic. Woods ultraviolet lamp shows Microsporum (only) as green illumination.

@ Specimens collected are: Skin scales, nail clippings, and hair. Skin scales are obtained from edge of the lesion. Swabs are unsuitable.

@ Microscopy: Using potassium hydroxide.

@ Culture: Selective Sabouraud agar containing cycloheximide. Incubation at room temp. up to 3 weeks.

Acquired from animal (cats, dogs, rodents, cattle)

Microsporum canis Acquired from soil Microsporum gypseumAcquired from school mates and colleagues Trichophyton rubrum Epidermophyton floccosumSources of Tinea infections

Infections of Wounds, Abscesses, Burns

Possible Pathogens:

# Pseudomonas aeruginosa, Proteus, E. coli, Bacteroides, Klebsiella, Pasteurella.

# Staph. aureus, Strep. pyogenes, Enterococci, Ana. streptococci, Cl. tetani, Mycobacteria, Cl. perfringens, Actinomycetes

# Mycetoma, Histoplasma, Blastomyces, Candida albicans, Cryptococcus neoformans.

C. albicansAssociation with Pyogenic Infections:

@ S. aureus causes abscesses & skin infection

@ P. aeruginosa is associated with burns and hospital cross infections.

@ E. coli, Proteus, Pseudomonas, & Bacteroides are isolated from abdominal abscesses.

@ Cl. perfringens causes deep wounds infections and gas gangrene.

@ Cl. tetani causes umbilical neonatal infection.

@ Myco. tuberculosis causes cold abscesses.

TB cold abscess Lab. Diagnosis of of Wounds,Abscesses, and Burns infections

Collection and Transport:

@ Collect pus. If pus is absent, use a swab and transport in Amies transport medium.

@ If mycetoma is suspected, collect from sinus

@ If tuberculosis is suspected, aspirate pus.

Macroscopy:

@ Report pus colour: red, brown, grey, [email protected] Examine granules: colour, shape, size, and consistency.

Colour of pus Microscopy

@ Examine Gram smear for: Staphylococci, streptococci, enterococci, Proteus, E. coli, Pseudomonas, Bacteroides, Cl. perfringens.

@ Examine for ZN stain for acid fast bacilli.

@ Examine KOH smear for:

# Budding (Candida and Cryptococcus)

# Branching (Nocardia)

# Mycetoma granules (black, red, yellow, etc)

# Actinomyces yellow granules.

MycetomaCulture:

@ Inoculate blood agar and Mc Conkey agar plates and incubate aerobically overnight.

@ Inoculate a neomycin plate & another blood agar plate and incubate anaerobically for 48 hr

@ Inoculate a cooked meat medium and incubate up to 72 hours.

@ Decontaminate TB specimens by adding 4% sodium hydroxide for 10 min., and inoculate an LJ slope and incubate for 8 weeks

@ For fungi, inoculate a Sabouraud agar

Examination of Cultures

@ LJ slope: M. TB with raised, dry, creamy colonies.

@ Blood, neomycin, Mac Conkey agar: Look for colonies of aerobic and anaerobic bacteria

@ Cooked meat medium, Look for: # Turbidity, reddening of meat, and gas bubbles (Cl. Perfringens) # Decomposition and blackening of the meat (Bacteroides)

@ Subculture the cooked meat medium if the anaerobic plates were sterile.