Infection - Immunisations + skin infections Flashcards
What are the different types of vaccines?
Live attenuated
Inactivated
Detoxified exotoxin
Subunit of micro-organism
How are detoxified vaccines detoxified?
Toxin treated with formalin to form toxois
How are recombinant vaccines formed?
DNA segment coding for antigen mixed with plasmids, removed and purified
Inserted into yeasts + fermeneted to form more antigen
What is immunological memory?
Where cells remember the antigen and produce the antibody much quicker, instead of having to “develop” it first
What is the disadvantage of killed vaccines over live vaccines?
Multiple doses required to get same response
Who is vaccinated against TB?
Healthcare workenrs
New immigants
Areas of high prevelance
Anyone below 35 who had contact with TB patient
What is passive immunisation?
Use of immunoglobulins to give immunity to disease
What are common immunisations for travellers?
Tetanus Polio Typhoid Hep A Yellow fever Cholera
What drugs offer prophylaxis to malaria?
Malaron (proquanil + atovaquone_ daily
Doxycycline daily (photosensiticity)
Mefloquine (weekly)
Choloquine weekly + proqunail daily
Choice depends on country
What is impetigo?
Superficial skin infection + multiple vesicular lesions on erythematous base
Golden crust highly suggestive of diagnosis
What organisms cause impetigo?
Most commonly - staph A
Less commonly - Strep pyogenes
Who is most likely to get impetigo?
Children 2-5 in age
Where does impetigo occur?
Highly infectious - occurs on exposed parts of body
Face + scalp
What are predisposing factors of impetigo?
Skin abrasions Minor Trauma / Burns Poor Hygiene Insect bites Chicken Pox Eczema / Atopic Dermatitis
How do you treat impetigo?
Small - topical antibiotics
Large areas - topical treatment + oral antibiotics
What is erysipelas?
Infection of upper dermis
Painful red area with elevated borders
What are the symptoms of erysipelas?
Painful red area with no central clearing
Associated fever
Regional lymphadenopathy
Regional lymphangitis
What is the most common causative agent of erysipelas?
Strep pyogenes
What is the recurrance rate of erysipelas?
30% in 3 yrs
Where does erysipelas occur?
70-80% on lower limb
5-20% face
Often in pre-exisiting lymphodema, obesity, DM
What is the treatment for erysipelas?
Combination of anti-staphylococcal + anti-streptococcal agents
What is cellultitis?
Diffuse skin infection involving deep dermis + subcut fat
Erythematous area with no distinct borders
What organisms are most likely to cause cellultitis?
Strep pyogenes
Staph aureus
Rare - H.influenzae
What are the predisposing factors for cellultitis?
Diabetes
Tinea pedis
Lymphoedema
What are the symptoms of cellultitis?
Erythematous area with no distinct border
Fever common
Regional lymphadenopathy + lympangitis
What is the treatment for cellultitis?
Combination of anti-staphylococcal + anti-streptococcal agents
Severe - IV agents
What are the ahir related inections?
Folliculitis
Furunculosis
Carbuncles
What is superficial follulitis?
Erythema and pustule in a single follicle
What is follultitis?
Circumscribed pustulat infection of hair follicle
Present as small red papules
Central area that may rupture/drain
What is the most common causative agent for folliculitis?
Stap A
Where is folliculitis commonly found?
Head
Back
Buttocks
Extremities
What is Furunculosis?
AKA boils
Single hair follicle inflammatory nodule
Extends into dermis + Sub cut tissue
May sponateously drain
What are the common areas for furunculosis?
Moist, hiary areas (with no friction) Face Axilla Neck Buttocks
What is the most common causative organism of furnculosis?
Staph A
What are the risk factors for furunculosis?
Obesity Diabetes Mellitus Atopic dermatitis Chronic kidney disease Corticosteroid use
What is a carbuncle?
Deep follicular abscess of several follciles and draining points (multisepated abscesses)
When infection has extended to involve multiple follicles (furuncles)
What locations are common sites for carbuncles?
Back of neck
Posterior trunk
Thigh
How do you treat hair-associated infections?
No treatment or topical antibiotics if needed for folliculitis + furnculosis
Can administer oral antibiotics for furunculosis if no improvement
Carbuncles require admission + surgery + IV antibiotics
What is necrotising fascitis?
Infectious disease emergency
Infection where bacteria consumes soft tissue/flesh
What are the predisposing factors to necrotising fascitis?
Diabetes mellitus Surgery Trauma Peripheral vascular disease Skin popping
What are the types of necroitisng fascitis?
Type 1 (mixed aerobi/anarebic) Type 2 - monomicrobial (oten strep pyogenes)
What organisms are associated with type 1 necrotising fascitis?
Streptococci Stapylococci Enterococci Gram negative bacilli Clostridium
What are the symptoms for necroitisng fascitis?
Rapid onset with sequential development of:
Erythema, extensive oedema + severe, unremitting pain
Haemorrhagic bullae, skin necrosis and crepitus may develop
Systemic features: fever, hypotension, tachycardia, delerium + multiorgan failure
How do you manage necrotising fascititis?
Surgical review is mandatory Broadspectrum antibiotics Fluclocacilling Gentamicin Clindamycin
What is the mortality rate of necrotising fascitis?
17-40%
What is pyomyositis?
Deep purulent straited muscle infection
Often abscess
Infection secondary to damaged muscle
What are the common sites for pyomyositis?
Thigh Calf Arms Gluteal region Chest wall Psoas muscle
What are the predisposing factors of pyomyositis?
Diabetes mellitus Immunocomprimised IV drug use Rheumatological disease Malignancy Liver cirrhosis
What is the presentation of pyomyositis?
Fever, pain and woody induration of affected muscle
Can lead to septic shock
What is the most common causative organism of pymyositis?
Staph A
What other organisms can be involved in pyomyositis?
Gram positives/negatives
TB
Fungi
How do you treat pyomyositis?
Antibiotics based on investigations (culture results)
How do you investigate pyomyositis?
Gram stain + culture
CT/MRI
What is septic bursitis?
Bursae that have been infected from adjacent skin infection
What are the predisposing factor to septic bursitis?
Rheumatoid arthritis Alcoholism Diabetes mellitus IV drug use Immunosupression Renal insufficiency
How do you diagnose septic bursitis?
Aspiration of synovial fluid
What are the common sites of septic bursitis?
Elbow
Knee
How do you treat septic burisitis?
Antibiotics
What is infectious tenosynovitis?
Infection of tendon sheathes
Which sheathes are most commonly affected in infectious tenosynovitis?
Flexor muscle tendons of hand
What is the most common causative agent of infectious tenosynovitis?
Staph A
Streptococci
How does infectious tenosynovitis present?
Erythematous fusiform swelling around tendons
Fingers in flexed position
Tenderness on tendon sheath
Pain on extension of finger
How do you treat infectious tenosynovisitis?
Empiric antiobiotics
Hand surgeon to review
What causes toxin-mediated syndromes?
Superantigens - a group of pyrogenic exotoxins
How are these superantigens different?
The antigens bypass normal measures and activate the T cell receptors directly (~2000% times more)
Massive burst in cytokine release
What does this burst in cytokine release lead to?
Leads to endothelial leackage, multi-organ failure and death
Also haemodynamic shock
What are the most likely agents to cause toxin-mediated syndromes? (what antigens do they release?)
Staph A (TSST1 + ETA/ETB) Strep pyogenes TSST1
How do you diagnose staphyloccoal toxic shock syndrome?
Fever Hypotension Macular rash (diffuse) Multiple organs involved Isolation of staph a from sterile sites
What is stretococcal TSS associated with?
Streorocci in deep seated infections - erysipelas/necrotising fascitis
How do you treat TSS?
Remove offending agent IV fluids Inotropes Antiobiotics IV immunoglobulins
What is staphyloccoal scaled skin syndrome?
Infection via staph A releaseing ETa/B (exfoliative toxin)
More common in children
How does staphyloccoal syndorme present?
Widespread bullae and skin exfoliation
How do you treat staphyloccoal scalded skin syndrome?
IV fluids + antimicrobials
What is panton-valentine leuconcidin toxin?
Gamma haemolysin
Often staph A
How do patients present with panton valentine leucoidin toxin?
Skin + soft tissue infection
Haemorrhagic pneumonia
Recurrent boils
How do you treat panton-valentine leucocidin toxin?
Antiobiotics that reduce toxin production
What type of infection is an IV catheter infection?
Nosocmial
What is the presentation of an IV catheter infection?
Local skin and soft tissue inflammation –> cellultitis
Sometimes tissue necoris
Associated bacteraemia
What are the risk factors for IV cather assocaited infection?
24hr + continuous infection
72+ canula in situ
Lower limb cannula
What are the common causative agents in IV catheter infections?
Staph A
What is the normal pathway for an IV catheter infection?
Biofilm which spills into bloodstream
Can seed other places (endocarditis etc)
How do you diagnose IV catheter infection?
Clinically or blood cultures
How do you treat an IV catheter infection?
Remove cannula
Excise any pus
Antibiotcs for 14 days
Echocardiogram
PREVENTION first
What are the classifications for surgical site wounds?
4 classes Clean wound Clean contaminated wound Contaminated wound Infected wound
What is a class 1 (clean wound) surgical infection?
Respiratory, alimentary, genital or urinary system not been entered
What is a class 2 (clean contaminated wound) surgical infection?
Respiratory, alimentary, genital or urinary system entered, but no unusual contamination
What is a class 3 (contaminated wound) surgical infection?
Open, fresh accidental wounds or gross spillage from intestinal tract
What is a class 4 (infected wound) surgical infection?
Exisitng clinical infection (before operation)
What are the main causes of a surgical site infection?
Staph A Coagulase negative staphylococci Enterococcus E coli Pseudomonas Aeruginosa Enterobacter Streptococci Fungi Anaerobes
What are the risk factors of surgical site infections? (patient associated)
Diabetes Smoking Obesity Malnutrition Steroid use Colonisation of staph A
What are the procederal risk factors for a surgical site infection?
Site shaved night before operation Improper preop skin prep Improper antimicrobial prphylaxis/sterile technique Insufficient theatre ventillation Perioperative hypoxia
How do you diagnose surgical site infections?
Avoid superficial swabs - aim deep
Antibiotics
Send pus/tissue for cultures!
