WCS28 Surgical Infection Flashcards
Infection and Pathogenesis during Surgery
Infection:
- Invasion + Multiplication of microorganism in body tissues
- Causing local cellular injury due to Competitive metabolism, Toxins, Intracellular multiplication, Ag-Ab response
Pathogenesis:
- Infectious agent
- Susceptible host
- Closed unperfused space
Systemic Inflammatory Response Syndrome (SIRS)
> =2 criteria met:
- Body temp >=38oC / <36oC
- HR >90
- RR >20 / PaCO2 <32
- WBC >12 (Leukocytosis) / <4 (Leukopenia)
Sepsis:
- SIRS + Infection
Severe Sepsis:
- Sepsis associated with Organ dysfunction, Systemic hypoperfusion, Hypotension
Septic shock
- Sepsis (SIRS + Infection) + Arterial hypotension
Clinical approach to Septic patients
- Recognise septic patients
- Changes in core temperature
- **Unexplained hypotension
- **Oliguria
- Confusion - Locate source of infection
- Abdomen
- Skin
- Joints
- Respiratory
- CVS
- CNS
- Haematological - Identify underlying cause of infection + Investigations
- Blood tests
- Radiological tests
- Microbiological tests - Management
Abdomen
- GI tract
- IBD, perforation, anastomotic leakage, abscess - Hepato-biliary and pancreatic system
- Cholecystitis, Cholangitis, Pancreatitis, Hepatitis, abscess - Genito-urinary
- UTI, Pyelonephritis
Skin and Joints
Skin:
- Surgical wound infection, Percutaneous line (IV access), Soft tissue infection
Joints:
- Septic arthritis, Prosthetic infection
Respiratory, CVS, CNS, Haematological
Respiratory:
- Pneumonia, Empyema
CVS:
- Endocarditis
CNS:
- Meningitis, Encephalitis, Abscess
Haematological:
- Recent travel (malaria)
Investigations
- Blood tests
- CBC: **leukocytosis (neutrophil + leukocyte)
- RFT
- LFT: ductal + parenchymal enzymes
- **Arterial blood gases: **metabolic acidosis (e.g. ischaemic bowel)
- Clotting screening: **DIC
- Inflammatory markers: ***CRP, ESR
- Others: fasting glucose, HbA1c - Radiological tests
- X-ray
- USG
- CT
- Cardiac ECHO (look for cardiac function, vegetation on valves) - Microbiological tests
- Wound swab
- Urine: msu, csu
- Stool: culture, C. difficile toxin
- Blood
- Sputum
Management principles
- Excise / Drain any septic foci amenable to surgical therapy
- abscess - Antibiotics
- Infections that are likely to spread / persist after surgical therapy
- Immunocompromised
- ***Empirical - Organ support
- Fluids / nutrition
Folliculitis / Furuncle / Carbuncle
Folliculitis:
- 1 mm perifollicular red papule / pustule
- areas of sweat / abrasion
Furuncle (Boil):
- 1 cm tender red papule / fluctuant nodule
- areas of sweat / abrasion
Carbuncle:
- several cm diameter red plaque
- nape of neck
- necrotising infection of skin + SC tissue composed of cluster of furuncles with **multiple draining sinuses (S. aureus)
—> poorly controlled DM
—> **Excision (Remove all necrotic sources / draining sinuses) + **Antibiotics + **DM control
Necrotising fasciitis
- Infection that spreads along ***fascial planes
- ***Polymicrobial
- Portal of entry via skin
- 30% mortality
Signs:
- Erythema
- SC edema
- Dermal gangrene
- Foul smelling (Dishwater) discharge
- ***Venous thrombosis
- ***Crepitus during palpation (∵ anaerobes)
- ***Fournier’s gangrene —> dermal gangrene of scrotum and penis
Management:
- Rapid aggressive ***resuscitation
- ***Debridement of necrotic tissue
- ***Broad-spectrum antibiotics (∵ polymicrobial)
- Colostomy (if perineum is involved, to prevent faecal soiling)
- Foley catheter (prevent urinary contamination of debrided wound)
- Nutritional support
Cholecystitis
Management:
- Cholecystectomy
- laparoscopic
- open - Cholecystostomy
- incise a hole to drain all pus - Antibiotics
Appendicitis
Management:
- Appendectomy
- laparoscopic
- open - Antibiotics
Pyelonephritis
Pus in calyces
Management:
1. Drainage using nephrostomy
Parapharyngeal space abscess
- Secondary to foreign body ingestion
- Concerns of airways
Post-op infection
Identify source
- ***Surgical site infection
- ***Respiratory infection
- UTI
- ***Line-associated infection
***Surgical site infection
- Clean
- operative incisional wounds through non-inflamed tissue
- skin commensals (S. epidermidis, S. aureus, S. enterobacteria)
- very low infection rate (< 2%) - Clean contaminated
- perforation of clean viscus, ***entry into hollow viscus other than colon, with minimal, controlled contamination
- e.g. Gastrostomy, Cystotomy (relatively sterile)
- infection rate (~8-10%) - Contaminated
- ***breaching of hollow viscus with more spillage (opening the colon, open fractures, penetrating bites)
- e.g. Perforated peptic ulcer (PPU)
- infection rate (~20%) - Dirty wounds
- gross pus, perforated viscus (e.g. faecal peritonitis), traumatic wounds unattended >4 hours
- e.g. Ruptured diverticulum, Leakage from colonic anastomosis
- infection rate (~25%)
Management:
- Wound swab
- Blood culture
- Empirical antibiotics
- Drainage
- Debridement
Extensive skin wound: Burn
Eschar: tough leathery tissue remaining after a full-thickness burn has been termed eschar
—> following a full-thickness burn, as the underlying tissues are rehydrated, they become constricted due to the eschar’s **loss of elasticity
—> leading to **impaired circulation distal to the wound
Management:
1. ***Eschartomy: incision through the eschar to expose the fatty tissue below. Due to the residual pressure, the incision will often widen substantially
- Skin graft on wound bed
Respiratory infection
Causes:
- General anaesthetics + Basal atelectasis
- Prolonged ventilation
- Immunosuppression
4 types:
- Community acquired
- Nosocomial (usually gram -ve: **Klebsiella, **E. coli due to long term ventilation)
- Empyema (usually ***S. pneumoniae)
- Lung abscess (aspiration pneumonia, TB)
UTI
Causes:
- Community acquired
- **E. coli
- **Proteus
- Klebsiella - Renal abnormalities
- ***Pseudomonas - Catheterisation
- ***S. epidermidis
- E. faecalis
Line sepsis
Incidence ↑ with duration
Common organisms:
- Staphylococcus
- Streptococci
- Enterococci
- Gram -ve species
Management:
- Re-site the line if infection documented
- Blood culture
- ***infected line
- distant peripheral site - Antibiotics
Prevention of infection
- Infection control
- Identify patients at risk
- Infection control teams + Hospital policy
—> multidisciplinary
—> audit
—> implement hospital policy
- Patient isolation + Ward discipline - Measures to reduce infection
- Environmental factors
- Patient factors
- Surgeon factors
- Surgical technique
- ***Prophylactic antibiotics
***Measures to reduce infection
- Pre-operation skin preparation
- Shower
- Clipping of hair immediately pre-operation
- Antiseptics
—> **Betadine
—> **Chlorhexadine
—> Alcoholic (flammable) - Preparation of theatre
- Cleaniness
- Personnel movements
- Airflow
—> **PPFV (positive pressure filtered ventilation)
—> **Laminar flow
—> Ultraclean air systems - Preparation of surgical team
- Scrub-up (↓ bacterial skin count)
- Clothing (bacteria-impermeable fabrics)
- Caps (S. aureus on scalp)
- Masks
- Gloves
- Shoes - Asepsis and Sterilisation
- Asepsis: Prevent introduction of bacteria
—> skin preparation
—> bowel preparation
—> **draping to surround sterile field
—> **scrub up
—> ***sterile instrumentation
—> no-touch technique
—> good operative technique
- Sterilisation: Complete destruction of all viable microorganisms by means of heat, chemicals, irradiation
—> ***Autoclave sterilisation
- Prophylactic antibiotics
- Reduce surgical site infection
- Given pre-operation
- High levels of systemic antibiotics at the time of procedure and throughout surgery
- Must be **Broad spectrum and appropriate to likely organisms
- Indications:
—> procedures which commonly lead to infection
—> reducing post-op infections from endogenous sources
—> if results of sepsis would be devastating
—> **NO value in clean procedures (e.g. sebaceous cyst, abscess)
Antibiotic control of infection
Principles:
- Indication
- Microorganism
- Type / Class of antibiotics
- Route of administration
- Dosage
- Duration
- Reassessment
Beware:
- Allergy
- SE
- Toxicity (e.g. Hepatotoxicity / Renal toxicity)
- Microbial resistance
- MRSA
- VRE
Microbial resistance
- Inappropriate prescription
- Failure to complete full course of antibiotics
- Addition of antibiotics to food chain
- Extensive use of antibiotics in sick patients with multiple organisms may promote resistance and transmission between individuals
- Natural evolution of bacteria
Prevention of MRSA transmission
- Hand hygiene
- Patient screening
- ***Isolation of carriers
- Removal of colonised catheters
- Eradication of carriage
