Skin, Soft Tissue And Bone Infections Flashcards
Name the skin layers starting from the outer layer to the inner layer
Epidermis
Dermis
Subcutaneous
What features does the epidermis have
Waterproof
What features does the dermis have
Connective tissue
Sweat glands
Hair follicles
What features does the subcutaneous layer have
Fat
Connective tissue
Which bacteria can colonise onto the skin
Staphylococci: staph aureus
Streptococci: group a (s.pyogenes)
Corynebacteria
When does infection occur in the skin
When the immune system is overcome e.g the physical barrier
Which cells are involved in the innate defeneces of the skin
Macrophages
Langerhans
Lymphocytes
Antibodies
Name a infection that tends to occur in the face
Impetigo/folliculitis
What is impetigo
A golden crusting rash on the face
What is folliculitis
Infection of the hair follicles
Which organism tends to cause impetigo/folliculits
S.aures
What is cellulitis
Infection of the skin and the subcutaenous tissues i.e it is deeper infection
When can cellulitis occur
When the skin is breached
How does bacteria breach the skin
- Bacteria penetrate the skin
- Bacteria multiple in the skin
- Host fails to control the multiplication to cause cellulitis
What are the risk factors for cellulitis
Poor blood supply: arterial, venous or lymphatic
Diabetes
Immunosuppressed: chemotherapy, steroid use, malnutrition
Where does cellulitis commonly occur in the body
arms and legs i.e limbs
Give examples when the skin can be breahed
Cut Scratch Ulcers Athletes foor Burns Foreign bodies e.g drains Eczema
What are the local symptoms of cellultis
Redness
Warmth
Pain
Swelling
What are the systemic symptoms of cellulitis
Fever
Malasie
Chills
What investigations can we do for cellulitis
Bloods: FBC, CRP- Raised WBC
Superficial swab
Blister fluid
Blood culture- take if the patient is febrile and unwell
What is erysipelas
A subgroup of cellulitis that is limited to the dermis therefore does not include the subcutaenous tissue and is superficial
What is the feature of erysipelas
Demarcated and raised
Which organism tends to cause erysipelas
streptococci
What is the treatment of erysipelas
Penicillin
Clindamycin
What is the management of cellulitis
Broad specturm antibiotics as we dont known the organism to direct the antibitoics towards
What is the organism for cellulitis likely to be
Staph aueres
Streptococci
In cellulitits if there is MRSA positive what is the treatment
Vancomycin
Co trimoxazole/clindaymycin
In cellulitis if its MRSA negative what is the treatment
Beta lactams e.g flucloxacillin
Macrolide e.g clindamycin
What are the other management of cellulitis
Analgesia
Elevation of limb to prevent swelling
Fluid
Treat predisposing factors e.g diabetes
What can occur in severe cellulitis
Toxix shock
Why can toxic shock occur in severe cellulitis
streptococci can produce superantigens which are proteins that cross link t cell receptors and antigen presenting cells to cause them a release of cytokines
What is the treatment for severe cellulitis
Adjunctive therapy e.g IVIG
How can we prevent cellulitis in the first place
- Reduce skin bacteria colonisarion by skin hygiene, MRSA eradications, prophylatic antibodies
- Prevent skin breaks, clean wounds, treat eczema and atheletes foot
- Maxmise defences: treat vascular disease, reduce oedema, and good diabtes control
What is necrotising Fasciitis
Severe infection of the deep fascial layers
What are the featuers of necrotising fasciitis
Pain
Dusky bruised apperance
What is the management of necrotising fasciitis
Surgical emergency for surgeons (cutting away the tissue) and clindamycin antibiotics
What is pyomyositis
Acute bacterial infection of the skeletal muscle
What are the features of pyomyositis
Muscle pain
Tenderness
Swelling
Which organism is the most common cause of pyomyositis
Staph aureus
What typical history does pyomyositis have i,e when does occur
After trauma or vigourous exercise
What is the diagnosis of pyomyositis by
MRI scan: can show muscle odema
CT scan
What is the management of pyomyositis
Drainage
Antibiotics
What is septic arthritis
Infection of the joint space that becomes acutely swollen
Which bacteria are involved in septic arthritis
Streptococci
Staphylococci
TB
How does the ogranism enter the joint space
Directly to the blood stream
Haemtogenous deposition
How is the diagnosis of septic arthritis made
By clinical picture
Imaging: US and MRI
Joint aspiration- sample then looked at with microscopy and PCR
What is the management of septic arthritis
Surgical washing out
Antibiotics
What is osteomyelitis
Bacterial infection of the bone
How does bacteria spread into the bone
Haemtogenous deposition
Direct inoculation: trauma, surgery or spread from skin
What is the management of osteomyelitis
Surgery
Antibiotics
What is chronic osteomyelitis characterised by
Reactive bone
Sinus formation
Trapped necrotic bone formation
Biofilm
What are the investigations for osteomyelitis
X-ray
MRI
Ct- to aid surgery
Ultrsound for biopsy
Which organism is common to cause osteomyelitis
S.aureus
What is the antibiotic management of osteomyelitis
Beta lactam: fluxloxacillin, cephalosporins
Lincosamide: clindamycin
Fluroquinolones: ciprofloxacin, moxifloxacin
Linezolid, fucidic acid, rifampicin, cotrimoxazole