Skin and soft tissue infections - therapeutics

What bacteria are the majority of skin/soft tissue infections caused by?

Gram positive staphylococcus aureus and streptococcus pyogenes

How do most skin/soft tissue infections occur?

Due to bacteria penetrating dermis or subcutaneous tissues

What is impetigo?

Common, superficial bacterial infection of epidermis mostly seen in children and is highly contagious 

What are the two types of impetigo?

Non-bullous impetigo and bullous impetigo 

What is the more common type of impetigo?

Non-bullous

How does non-bullous impetigo start?

Erythematous macules, papules or pustules that evolve into vesicles that rupture

What are the crusts like in non-bullous impetigo?

Honey coloured crusts that usually appear on the face around the nose and mouth 

How is non-bullous impetigo spread?

Autoinoculation

What are the systemic symptoms of non-bullous impetigo?

Minimal symptoms

What age group is bullous impetigo most common in?

Infants 

What causes bullous impetigo?

Toxin-produing strains of S. aureus

How does bullous impetigo start?

Flaccid bullae rupture that leave yellow fluid and crusting

What are the systemic symptoms in bullous impetigo?

Mild fever and malaise

What are erythematous macules?

Small, flat spots on the skin that are red in colour 

What are papules?

Small, solid raised bumps on the skin less than 1cm in size

What is a pustule?

Small, pus-filled skin sore that has a white or yellow centre

What are flaccid bullae?

Large fragile blisters with walls that rupture easily 

What are risk factors for impetigo?

Skin barrier disruption e.g., eczema, trauma, insect bites, hot and humid climates, overcrowding, poor hygiene, immunosuppression and diabetes

What can complications of impetigo be?

Cellulitis, lymphangitis, scarring and post-streptococcal glomerulonephritis

What is the localised treatment for impetigo?

Fusidic acid

When is mupirocin used for impetigo?

If MRSA causes it

What is more extensive impetigo treated with?

Oral Abx for 7-10 days e.g., flucloxacillin for staphylococcus and penicillin V for streptococcus

What is cellulitis?

Acute infection of skin involving deeper dermis and subcutaneous tissues 

What bacteria frequently causes cellulitis?

Streptococcus groups A and G and staphylococcus aureus

What is erysipelas?

A more superficial form of cellulitis with more sharply, more defined raised borders

What are the symptoms of erysipelas?

Heat, erythema/redness, induration and localised tenderness, patients unwell and have pyrexia

What are the typical signs of cellulitis local to the infection?

Redness/erythema, swelling/oedema, warmth, pain or tenderness, lymphangitis or regional lymphadenopathy 

What is lymphadenopathy?

Enlargemenet/swelling of lymph nodes 

What is lymphangitis?

Inflammation/infection of lymphatic vessels 

What are systemic symptoms associated with cellulitis?

Fever, malaise, rigors in more severe cases

What can be present and can relate to the entry of bacteria in cellulitis?

Portal of entry e.g., ulcer, fissure, trauma, tinea pedis, eczema but not always apparent

What are risk factors for cellulitis?

Obesity, diabetes, immunosuppresion e.g., CKD, previous episodes of cellulitis, chronic oedema, lymphodema, poor skin conditions and hygiene/environmental factors 

How is progress of cellulitis monitored?

Drawing a line around the extent of the infection with a surgical marker pen

What bacteria should be suspected to cause cellulitis in diabetic or immunocompromised patients?

Gram negative or anaerobic

What status should be obtained before treating for cellulitis?

MRSA status 

Where can cellulitis usually be treated?

Community as long as symptoms not severe

What complications may mean cellulitis needs to be treated in hospital?

Orbital cellulitis, osteomyelitis or sepsis

What treatment is first line for cellulitis?

High dose IV flucloxacillin 

What is the first line treatment for cellulitis in the case of a penicillin allergy?

Clarithromycin

What treatment should be used in cellulitis if gram negative or anaerobic infection suspected?

Broad-spectrum antibacterials e.g., co-amoxiclav or metronidazole

What is a necrotising skin/soft tissue infection?

Severe and life threatening infection with a systemic inflammatory response involving deep tissues and associated tissue destruction 

What are the symptoms of a nectrosiing skin/soft tissue infection?

Severe, constant pain, blistering and bruising, oedema, gas in tissues, systemic inflammatory response and multi-organ failure

What is necrotising skin/soft tissue infections predominantly caused by?

Gram positive cocci - streptococcus pyogenes and staphylococcus aureus

What is orbital cellulitis?

Serious infection of soft tissue behind the eye, inside the bony socket 

What is osteomyelitis?

Bone infection causing inflammation and infection of the bone, caused by bacteria, viruses or fungi