Surgery - Surgical Infection & Antibiotics Flashcards
What general factors contribute to wound infection following a surgical procedure?
Age Malnutrition Immunosuppression Malignancy Obesity Hypoxia Anaemia
What local factors contribute to wound infection following a surgical procedure?
Type of surgery (clean vs contaminated) Length of procedure Residual local malignancy Foreign body insertion Ischaemia
What microbiological factors contribute to wound infection following a surgical procedure?
Lack of a/b prophylaxis
Virulence of organism
What are the four types of operative procedure, in reference to their potential for infectious complications?
Clean
Potentially-contaminated
Contaminated
Dirty
Describe a clean operative procedure
Operation does not enter colonised viscus or lumen of body
SSI risk from contaminants from environment (2-5%)
-S. aureus most common
Describe a potentially-contaminated procedure
Operation enters colonised viscus or body cavity but under elective & controlled conditions
SSI risk from endogenous bacteria (10%)
Describe a contaminated procedure
Contamination present at surgical site w/o obvious infection
SSI risk from endogenous bacteria (20%)
Describe a dirty procedure
Surgery performed where active infection already present
SSI risk from established pathogens (30%)
What are the three types of surgical site infection?
Superficial Incisional
Deep Incisional
Organ/space
What is a Superficial Incisional SSI?
Infection of skin & s.c. tissue of incision
What is a Deep Incisional SSI?
Infection of deep tissues (muscle/fascial) and includes organ/space SSIs draining through the incision
What is an Organ/Space SSI?
Infection of any site involved in the operation other than the incision
Which patients should be given prophylactic infection?
Pts at high risk of infection
Pts where an infection would be serious, even if risk is low
What determines choice of antibiotic in surgical pts?
Likely infecting organisms
Hospital guidelines
-cefuroxime & metronidazole
What is impetigo?
Superficial purulent infection caused by staph/strep w/ golden crust on erythematous base
How should impetigo be managed?
Swab to confirm organism
Treat w/ topical mupirocin/fusidic acid
What is ecthyma?
Purulent skin infection caused by staph/strep. Ulceration under a crust
How should ecthyma be managed?
Associated w/ poor hygiene & malnutrition
Treat by guidelines
What is erythrasma?
Mildly itchy eruption b/w toes/flexures caused by corynebacterium
How should erythrasma be managed?
Topical miconazole OR
Oral erythromycin
What is Folliculitis?
Pustular infection caused by staph
-can be deep or superficial
How should folliculitis be managed?
Oral flucloxacillin (if superficial) Tetracycline/erythromycin (if deep)
What is Staphylococcal Scalded Skin Syndrome?
Fever, irritability & skin tenderness THEN
Erythema & blistering (after 24-48hrs)
How should SSSS be managed?
Bacterial swab from nose/throat
IV flucloxacillin
What is Cellulitis?
Infection of s.c. tissue due to staph
What is Erysipelas?
Infection of dermis due to staph
Raised erythematous edge
Often on face
What are Viral Warts?
Smooth, skin coloured papules w/ irregular hyperkeratotic surface
-resolve spontaneously
What is Molluscum Contagiosum?
Poxvirus causing umbilicated papules
-resolve spontaneously over months
What is Ringworm?
Erythematous annular lesions w/ central clearing
How should Ringworm be managed?
Topical terbinafine/ketoconazole
-may be systemic in widespread disease
What is Scabies?
Scabietic burrows on edges of fingers/sides of hands/feet
How should Scabies be managed?
Topical permethrin/malathion
-give to all physical contacts
What are the two broad types of gangrene?
Anaerobic
Synergistic (necrotising fasciitis)
What causes anaerobic gangrene?
Clostridium perfringens in soil/faeces
- arises from trivial injury
- often in immunocompromised pts
How does anaerobic gangrene present?
Gas in tissues & skm (crepitus)
Oedema
Spreading gangrene w/ systemic upset
How should anaerobic gangrene be managed?
Resuscitation
Aggressive debridement
IV penicillin + metronidazole
What causes synergistic gangrene?
Aerobes & synergistic anaerobes infect wound/surgical site
How does synergistic gangrene present?
Severe wound pain
Gas in tissues
Extensive subdermal gangrene
How should synergistic gangrene be managed?
Debridement
Antibiotics
Systemic support
What are the causes of post-op fever?
Mild pyrexia common post-op (response to tissue injury/stress) Severe pyrexia (infection)
What general steps should be taken when reviewing a patient with post-op fever?
Review general obs, urine output etc.
Inspect wound for SSI/haematoma
Inspect cannula sites for thrombophlebitis/infection
Examine chest for infection/infarction/acute heart failure
Examine legs for DVT
Consider other sources of infection
When is a routine isolation unit used?
Protect other pts/staff from pts infection
When are reverse isolation units used?
Protect pts from infections carried by staff/visitors/pts
-used when pts have decreased immunity
What are the common locations of an intra-abdominal abscesses?
Alongside organ of origin
Pelvic
Subphrenic
What are the clinical features of an intra-abdominal abscesses?
Malaise Anorexia Swinging pyrexia Tachycardia Possible mass
How are intra-abdominal abscesses investigated?
CT abdo/pelvis
How are intra-abdominal abscesses managed?
IV empirical a/b
Radiologically guided drainage
-surgical drainage as last line
How should a superficial s.c. abscess be drained?
Performed under GA
Fluctuance incised
Blunt probing ensures all loculi drained
