Skin & Soft Tissue Infection Flashcards
Name the 3 common bacterial infections of the skin
Impetigo (surface)
Cellulitis (dermis)
Eryipleas (cellulitis)
What re the 2 most common bacterial infections of the skin?
Gram Positive Staphylococcus Aureus
Strep Pyogenes
What is the classical presentation of Impetigo?
Honeycomb well circumscribe lesion on the nose and face, children aged 2-5
What is the treatment of impetigo?
Topical fusidic acid
Or if severe or longer than 7 days then Flucloxacillin
What is the most common cause os erysipelas?
Superficial dermal infection with strep progenies
what are the clinical features of erysipelas?
Painful red areas, no central clearing with associated fever and lymohadenopathy
Which condition does Erysipelas have the same treatment as?
Cellulitis
what is cellulitis?
This is infection of the deep dermis caused by PS or SA
What are 3 predisposing factors to cellulitis?
CM
Tinea pedis
Lymphedema
What are the clinical features of cellulitis?
Hot, swollen, oedematous diffuse skin rash, which is painful, associated with fever and lymphadenopathy
What is the management of cellulitis and therefore also eriypleas?
Elevate the leg
Benzylpenicillin + Flucloxacillin
If serve or extensive then admit
What is folliculitis?
Pustular SA infection of the hair follicle LESS than 5mm
What is furniculosis?
Single hair follicle associated inflammatory nodule, infection to the subcutaneous tissue
What is a carbuncle
Extensive Furniculosis leading to an access and purulent discharge
What is the management for F and F?
Nothing or topical antibiotic
What is the management of a carbuncle?
Admission
Drainage
Oral antibiotics
What is Necrotising Fasciitis?
This is an infection of the deep subcutaneous fat, dermis and muscle, leading to necrosis
Is NF an emergency?
Yes
What are the risk factors for necrotising fasciitis?
DM
Trauma
Syrgery
Venous thrombosis
What are the 2 types of necrotising fasciitis?
what are the common causes of each?
Type 1 = Mixture of aerobic and anaerobic bacteria
Staphylococci
Steptococci, enterococci
Gram negative bacilli
Type 2 = mono microbial and caused by STREP PYOGENES
What site is affected in necrotising fasciitis?
Any site in the body
What are the clinical features?
Rapid onset with development of erythema, extensive oedema, sever unremitting pain, haemorrhage bull, systemic symptoms, skin necrosis, crepitus
ANASTHESIA at the site of infection is particularly indicative
How do you diagnose necrotising fasciitis?
Clinical diagnosis
Imaging can help but delays the treatment
What Is the first line management of NF?
Surgical review -open wound, don’t close
IV fluid
IV broad spectrum antibiotics = flucloxacillin
Gentamycin
Clindamycin
IV opiates
What is the mortality rate of NF?
17-40%
What is the definition of pyomyositis?
This is an access within any muscle in the body but is usually un the lower limbs and is caused from an area of cellulitis or endocarditis
What is the causative organism in pyomyositis?
Staphylococcus aureus
What are the predisposing factors to PM?
DM Immunocompromised IVDU Steroid use Malignancy Rheumatological disease Liver cirrhosis
What are the common clinical features of PM?
Fever
WOODY INDURATION od the affected muscle
Pain
What can PM develop into?
Sepsis and septic shock
What is the key investigation of PM?
CT/MRI
What are the 2 key treatments for PM?
Surgical drainage and broad spectrum antibiotics
What is septic bursitis?
This is infective inflammation of the bursae
What is the causative organism in SB?
Staphylococcus Aureus
What 2 bursae are commonly affected?
Patellar
Olecranon
What re the symptoms of SB?
Pain Inability to kove Fever Oedema Erythematous
What is the single KEY investigation of SB?
Aspiration (may not actually do though because it introduces the infection into the joint
Who is particularly at risk of septic bursitis?
Rheumatoid Arthritis patients
DM
IVDU
Immunocompromised
What is the management of septic bursitis?
This would be antibiotics
What is infective tenosynovitis
This is infection of the synovial tendon flexor sheaths
What is the most common cause of IT?
Penetrating trauma
What is the most common causative organism of IT?
Staphylococcus aureus
Strep
What tendons are usually affected?
The flexor muscle tendons or the tendon sheaths of the hands
What are the 3 main clinical findings in IT?
Erythematous fusiform swelling of the finger
Hand held in a semi flexed position
Pain on extension of the finger
What are the management options for IT?
Empirical antibiotics
Hand surgeon review ASAP
What is toxic shock syndrome?
This is acute septicaemia in women usually from a retained tampon
What are 2 causes of toxic shock syndrome?
Retained high absorbance tampon
Small skin infections such as staph aureus that secretes TSST1
what are the 2 causative organisms of toxic shock syndrome?
Staph aureus
Streptococci
How does toxic shock syndrome come about pathogenesis wise?
The retained tampon becomes colonised with SA
Creates a super antigen that doesn’t activate the immune system normally
Superantigen binds directly to T cell receptors activating 20% and this leads to a massive cytokine release causing endothelial leakage, haemodynamic shock, multi-organ failure, death
What are the diagnostic criteria symptoms?
Fever Hypotension Diffuse macular rash, + involvement of 3 or more of the following organs: Liver Blood Renal GI CNS Muscular
What are the 3 clinical investigation findings than contribute to TSS?
Isolation of SA
Production of TssT1 by isolate
Development of an antibody to toxin during convalescence
If it is confirmed Streptococcal TSS, then what is this usually associated with?
Strep in depp seated infection such as necrotising fasciitis
What are the investigations and results in TSS?
FBC etc
Increased CPK and low platelets
What are the general measure of management of TSS?
Remove the offending agent IV fluids IV antibiotics Inotropes Immunoglobuins
What antibiotic therapy is suitable for TSS?
Flucloxacillin
If it streptococcal infection then what other measures do you wish to take?
Urgent surgical debridement of the infected tissues
What is the mortality rate for Staph
Strep?
5%
50%
What is Staphylococcal Scaled Skin Syndrome?
This occurs in children and is caused by a toxin secreting SA
What is the pathogenesis of SSSS?
The toxin, exfoliatin, causes intra-epidermal cleavage at the level of the stratum corneum leading to the formation of large flaccid blisters that shear readil
What are the clinical presentations of SSSS?
Widespread bull and skin exfoliation
What re the 2 managements for SSSS?
IV fluids
IV antibiotics
What organisms causes a IV associated infection?
Staph Areus
MSSA
MRSA
what re the 4 risk factors of a IV AI?
Continuous infection over 48 hours
Cannula in situ for more than 72 hours
Cannula in the lower limb
Patients with neurological. neurosurgical issues
How can you diagnose it?
With positive blood cultures
Do ECHO to check for endocarditis
What organism is the cause of a surgical site wound infection?
Staphylococcus Aureus including MRSA, MSSA
Coagulase negative streptococci
What re the 4 classes of a surgical wound infection?
Class I: clean wound (respiratory, alimentary, genital or infected urinary systems not entered)
Class II: clean contaminated wound (above tracts entered but no unusual contamination)
Class III: contaminated wound (open, fresh, accidental wounds or gross spillage from GI tract)
Class IV: infected wound (existing clinical infection, infection present before operation)
What re the managements of these 2 infections?
Remove the cannula
Express pus
Antibiotic for 14 days
