Bacterial infections of the skin Flashcards by Sharon Adeniran

What are two bacteria that commonly cause bacterial infections of the skin?

Staph Aureus, Streptococcus

How well did you know this?

Not at all

Perfectly

How does staph aureus express its virulence factors?

Binding to cell fibrin, found in abundance in wound surfaces such as ulcers and jt dermatitis

How well did you know this?

Not at all

Perfectly

Virulence factors expressed by Staph A.

Haemolysin
Leukocidin
a-toxin
exfoliative toxin
PVL

How well did you know this?

Not at all

Perfectly

What types of conditions can staph aureus cause?

Ecthyma,
Impetigo,
Cellulitis,
Folliculitis,
SSSS (Staph scalded skin syndrome)
Superinfects other skin conditions e.g. herpes

How well did you know this?

Not at all

Perfectly

How does streptococcus express its virulence factors?

Attaches to cell epithelium (lipoteichoic acid) using M protein (anti-phagocytic) and hyaluronic acid capsule

How well did you know this?

Not at all

Perfectly

What virulence factors does streptococcus express?

Erythrogenic Exotoxins, gives skin red appearance
Streptolysins S and O, causes cells to break apart

How well did you know this?

Not at all

Perfectly

What types of conditions can streptococcus cause?

Ecthyma,
Impetigo,
Cellulitis,
Erysipelas
Scarlet Fever,
Necrotising Fasciitis

How well did you know this?

Not at all

Perfectly

Folliculitis

Inflammation of the hair follicle

How well did you know this?

Not at all

Perfectly

How does folliculitis manifest

Follicular erythema, redness around the follicle
sometimes pustular, pus producing

How well did you know this?

Not at all

Perfectly

What is another term for non-infectious folliculitis?

Eosinophilic Folliculitis
associated with HIV

How well did you know this?

Not at all

Perfectly

How can recurrent cases of folliculitis arise?

Reservoir of Staph A. esp in nasal cavity.
(especially panton-valentine leukocidin - PVL - expressing strains)

How well did you know this?

Not at all

Perfectly

What is the treatment for folliculitis?

Antibiotics - erythromycin
incision and drainage for furunculosis

How well did you know this?

Not at all

Perfectly

Furuncle vs Carbuncle

Furuncle is a deep follicular abscess
Carbuncles are clusters of multiple boils, when the abscess involves multiple follicles

How well did you know this?

Not at all

Perfectly

What are carbuncles likely to lead to?

Cellulitis and Septicaemia

How well did you know this?

Not at all

Perfectly

Why are staph aureus infections so recurrent?

Microbial abundance in nasal flora
Immune deficiency (AIDS, DM)

How well did you know this?

Not at all

Perfectly

What is a strain of staph aureus that has a higher morbidity, mortality and transmissibility?

Panton Valentine Leukocidin Staphylococcus Aureus
PVL

How well did you know this?

Not at all

Perfectly

What is PVL staph A. characterised by

Leukocyte destruction
tissue necrosis

How well did you know this?

Not at all

Perfectly

What are the skin signs of PVL Staph Aureus?

Recurrent painful abscesses, folliculitis and cellulitis (in multiple sites)

How well did you know this?

Not at all

Perfectly

What are the extracutaneous signs of PVL Staph Aureus?

Necrotising Pneumonia,
Necrotising Fasciitis,
Purpura Fulminans - patches of dark purple skin, due to haemorrhage and thrombosis

How well did you know this?

Not at all

Perfectly

What are the 5 risks for acquiring PVL Staph Aureus?

5 Cs:
Contact,
Contamination,
Crowding,
Cleanliness,
Cuts

What are the treatments for PVL Staph Aureus?

Antibiotics, (tetracycline)
Decolonisation (chlorhexidine body wash, nasal antibacterial ointment, to remove the strain from the body)
treat close contacts

What is a type of folliculitis associated with hot tubs?

Pseudomonal Folliculitis (from pseudomonas aerugionsa)

What is cellulitis?

Infection of lower dermis and subcutaneous tissue

presentation of pseudomonal folliculitis

1-3d post exposure
diffuse truncal eruption of follicular erythematous papules (red spots)
usually mild tho can be treated with AB if severe

What are the characteristic signs of cellulitis?

oedema, tender swelling with ill defined blanching erythema

What are the main bacteria that cause cellulitis?

Strep P, Staph A

What is the treatment for cellulitis?

Systemic Antibiotics

What is impetigo?

Superficial bacterial infection

What is impetigo characterised by?

Honey-Coloured Crusts overlying an erosion

What are the two causes for impetigo?

Strep, Staph

Difference between impetigo caused by strep and staph

Strep - non blistering Staph - blisters, exfoliative toxin split epidermis

Where does impetigo usually target?

Face - oral, ears

How do you treat impetigo?

Topical and or systemic antibiotics

What is impetiginization?

Impetigo with atopic dermatitis, superficial infection of eczema skin

What is primary syphilis characterised by?

Painless ulcer with firm indurated border + painless localised lymph node swelling

What is a chancre and when does it appear in syphilis?

Painless genital ulcer, 10-90 days post exposure

When does secondary syphilis start?

~50 days after chancre

What is secondary syphilis characterised by?

rash, alopeica, lymphadenopathy, hepatosplenomegaly

What are the name of orogenital lesions in secondary syphilis?

Condylomata lata

What is a rare manifestation of secondary syphilis?

Lues maligna Skin lesions with pustules (due to blocked blood vessels)

When is lues maligna more frequently found?

HIV manifestation

What are the cutaneous signs of tertiary syphilis?

Gumma Skin Lesions (extend peripherally w/ central scarring) - can destroy cartilage, CNS (neurosyphilis) and blood vessels -> CVD

What is the treatment of syphilis?

Intramuscular Benzylpenicillin or Oral Tetracycline 1/2º syphilis can look similar to other conditions

What is the other term for Lyme disease?

Borreliosis

What is borreliosis caused by?

Borrelia-infected ticks

What is the cutaneous manifestation of borreliosis?

Annular erythema - erythematous papule

What are the secondary effects of borreliosis?

Secondary lesions, Neuroborreliosis (CN/facial palsy), Arthritis, painful and swollen jts Carditis

What are the problems with diagnosing borreliosis?

Serology not sensitive and histopathology non specific .: High index of suspicion (keep high on checklist when seeing patient)