Bacterial infections Flashcards
Functions of the skin x2
Physical and immunological barrier due to presence of tough epidermal layer and antimicrobial peptides
Classification of bacterial skin infections x4
Primary
Secondary
Skin lesions manifesting in the presence of existing infections
Reactive changes resulting from distant infections eg oslers nodes
Define folliculitis
Infection on the mouth of a hair follicle
Define ecthyma
Infection of full thickness of epidermis
Difference between erysipelas and cellulitis
Erysipelas is infection that extends down to the upper half of the dermis ie papillary layer
Cellulitis is infection that extends to the lower half of the dermis ie reticular layer
Name of staphylococcus infection in dermis and hair follicle x2
Ecthyma
Furuncle
Name 2 clinical patterns of impetigo
Bullous and non bullous
Common sites of non bullous impetigo x3
Perioral
Nares
Extremities after trauma
Pathophysiology of bullous impetigo
Staphylococcus aureus releases toxin A which cleaves desmoglein to form bullae
Population commonly affected by bullous impetigo x2
Neonates and older infants
Describe the bullae and how it forms
Vesicles rapidly progress to bullae ie well defined, clear with non erythematous surrounding
Describe what ecthyma looks like and what causes it’s development x2
Thickly crusted erosions or ulcerations
Poor hygiene and neglect
Differential diagnosis for bullous impetigo x5
Bullous tinea
Bullous drug eruption
Bullous insect bites
Bullous pemphigoid
Pemphigoid vulgaris
Bullous fixed drug reaction
Differential diagnosis for non bullous impetigo x5
Atopic dermatitis
Seborrheic dermatitis
Allergic contact dermatitis
HZ, VZV, HSV
Scabies
Management of mild to moderate impetigo x3
Clean and remove crusts
Topical antibiotics mupirocin
PP potassium permanganate soaks or GV gentian violet paint
Treatment options for severe or complicated cases of impetigo x4
Augmentin ie amoxicillin clavulinic acid
Erythromycin
IV ceftriaxone
IV ampicillin
Define carbuncle
Collection of furuncles with multiple discharging sinuses extending into the subcutaneous tissue
When to give systemic antibiotics in abscesses x4
If close to external auditory canal and nares
If lesions are large and recurrent
If unresponsive to conservative treatment
If associated with cellulitis
Define deeper infections x5
Acute tender spreading edematous suppurative inflammation of the dermis, subcutaneous tissue and muscle
Causes of erysipelas and cellulitis x4
Staphylococcus aureus
Group A streptococcus
H. Influenza
E. Coli
Risk factors of deeper infections x5
DM
Obesity
Tinea pedis
Lymphedema
Peripheral vascular disease
Prodrome of erysipelas x4
Fever chills malaise nausea
Describe erysipelas
Erythematous plaque like edema and peau d’orange characteristic
Complications of deeper infections x5
Damaged lymphatics
Thrombophlebitis
Necrotising fasciitis
Acute glomerulonephritis
Subacute Bacterial endocarditis
Define gangrenous cellulitis
It is a process that occurs in superficial or deep fascia with secondary changes on skin
Predisposing factors of cellulitis x5
Diabetic ulcer
Decubitus ulcer
Peripheral vascular disease
Alcoholics
Immunocompromised
Common areas of necrotising fasciitis x3
Extremities
Abdominal wall
Around operative wounds
What bacteria causes gas gangrene
Clostridium perfringens
Treatment options for erysipelas and cellulitis x4
Oral or IV penicillin
Cephalosporin
Erythromycin
Clindamycin
Variants of gangrenous cellulitis x3
Necrotising fasciitis
Fournier’s gangrene
Gas gangrene
