skin and soft tissue infections Flashcards

Question

what are predisposing factors of septic bursitis?

Answer 1

Infection is often from adjacent skin infection Other predisposing factors include Rheumatoid arthritis Alcoholism Diabetes mellitus Intravenous drug abuse Immunosuppression Renal insufficiency

Answer 2

Peribursal cellulitis, swelling and warmth are common Fever and pain on movement also seen

Answer 3

Diagnosis is based on aspiration of the fluid Most common cause is Staph aureus Rarer organisms include Gram negatives Mycobacteria Brucella

Answer 4

Infection of the synovial sheats that surround tendons Flexor muscle-associated tendons and tendon sheats of the hand most commonly involved Penetrating trauma most common inciting event Most common cause Staph aureus and streptococci Chronic infections due to mycobacteria, fungi Possibility of disseminated gonococcal infection

Answer 5

Present with erythematous fusiform swelling of finger Held in a semiflexed position Tenderness over the length of the tendon sheat and pain with extension of finger are classical

Answer 6

Empiric antibiotics Hand surgeon to review ASAP

Answer 7

Often due to superantigens Group of pyrogenic exotoxins Do not activate immune system via normal contact between APC and T cells Superantigens bypass this and attach directly to the T cell receptors activating up to 20% of the total pool of T cells instead of the normal 1/10,000 Massive burst in cytokine release Leads to endothelial leakage, haemodynamic shock, multi-organ failure and ?death

Answer 8

Mostly due to some strains of Staphylococcus aureus and Streptococcus pyogenes Staph aureus: TSST1 ETA and ETB Strep pyogenes: TSST1

Answer 9

Fever Hypotension Diffuse macular rash Three of the following organs involved Liver, blood, renal, gatrointestinal, CNS, muscular Isolation of Staph aureus from mucosal or normally sterile sites Production of TSST1 by isolate Development of antibody to toxin during convalescence

Answer 10

Almost always associated with presence of Streptococci in deep seated infections such as erysipelas or necrotising fasciitis Mortality rate is much higher than Staphylococcal (50% vs 5%) Treatment necessitates urgent surgical debridement of the infected tissues

Answer 11

Remove offending agent (ex tampon) Intravenous fluids Inotropes Antibiotics Intravenous immunoglobulins

Answer 12

Infection due to a particular strain of Staph aureus producing the exfoliative toxin A or B Characterised by widespread bullae and skin exfoliation Usually occurs in children but rarely in adults as well Treatment with intravenous fluids and antimicrobials Mortality 3% in children but higher in adults who often are immunosuppressed

Answer 13

It is a gamma haemolysin Can be transferred from one strain of Staph aureus to another, including MRSA Can cause SSTI and haemorrhagic pneumonia Tends to affect children and young adults Patients present with recurrent boils which are difficult to treat Treat with antibiotics that reduce toxin production

Answer 14

Nosocomial infection Normally starts as local SST inflammation progressing to cellulitis and even tissue necrosis Common to have an associated bacteraemia Risk factors for infections Continuous infusion >24 hours Cannula in situ >72 hours Cannula in lower limb Patients with neurological/neurosurgical problems Most common organism is Staph aureus (MSSA and MRSA) Commonly forms a biofilm which then spills into bloodstream Can seed into other places (ex endocarditis, osteomyelitis) Diagnosis made clinically or by positive blood cultures

Answer 15

Treatment is to remove cannula Express any pus from the thrombophlebitis Antibiotics for 14 days Echocardiogram Prevention more important Do not leave unused cannula Do not insert cannulae unless you are using them Change cannulae every 72 hours Monitor for thrombophlebitis Use aseptic technique when inserting cannulae

Answer 16

Classification of surgical wounds 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 the gastrointestinal tract) Class IV: Infected wound (existing clinical infection, infection present before the operation)

Answer 17

Staph aureus (incl MSSA and MRSA) Coagulase negative Staphylococci Enterococcus Escherichia coli Pseudomonas aeruginosa Enterobacter Streptococci Fungi Anaerobes

Answer 18

Patient associated Diabetes Smoking Obesity Malnutrition Concurrent steroid use Colonisation with Staph aureus Procedural factors Shaving of site the night prior to procedure Improper preoperative skin preparation Improper antimicrobial prophylaxis Break in sterile technique Inadequate theatre ventilation Perioperative hypoxia

Answer 19

Importance of sending pus/infected tissue for cultures especially with clean wound infections Avoid superficial swabs – aim for deep structures Consider an unlikely pathogen as a cause if obtained from a sterile site (ex bone infection) Antibiotics to target likely organisms