Infections

Risk factors for infection

• Host factors - bold are modifiable
  • Cortisol and corticosteroids (stress response depressed e.g. reduced pro-inflammatory cascade)
  • Older age (>65)
  • Hyperglycaemia
  • Malnutrition
  • Obesity
  • Prior irradiation
  • Hypothermia
  • Hypoxaemia
  • Another, separate, infection
  • Recent operation
  • Chronic inflammation
  • Hypocholesterolaemia
• Interactions between host and therapy
  • Blood transfusions predispose to infection - be conservative
  • BGL control - targets should be below 14-18
  • Nutritional support - early enteral feeding
  • Post-op hypoxia predisposes to infection

Infection control

• Be wary of C diff - need to wash hands with soap to remove spores
• Central catheters should be placed under appropriate sterile conditions, and if not, should be removed within 24 hours and replaced
• Chlorhex is preferred to povidone-iodine
  • If iodine is used, it must be allowed to dry

CLABSI

• Commonly staphylococcus or candida, consider enterococci
  • One sample of staph epidermidis is likely a contaminant, especially if patient has no indwelling hardware
  • Staph aureus requires two weeks of Abx at least
  • Treatment of fungal CLABSIs is controversial - maybe only removal of catheter - obviously not in transplant recipients though
• Suspect in patients with abrupt-onset sepsis
• Remove catheter and culture tip - only culture if there is strong clinical suspicion of CLABSI
• Probably not necessary to remove lines to evaluate a fever unless super-high-risk - can just culture the line

IDC-associated UTI

• Catheter-associated bacteriuria or candiduria probably represents colonisation and is rarely symptomatic, and is rarely a cause of fever or secondary bloodstream infection, even in immunocompromised patients
  • Consider it, though, in patients with urinary tract obstruction, urologic manipulation, injury, or surgery along with neutropaenia
• Can evaluate catheters by taking a sample from the port after disinfecting
  • Pyuria is not a reliable predictor of infection
  • Dipsticks are not helpful when used with catheters

Intra-abdominal Infection (IAI)

• Uncomplicated (contained within viscera) or complicated
• Community or hospital acquired
  • Hospital-acquired obviously more likely to have MDR involvement
• Any abscess is likely polymicrobial - frequently anaerobic gram negative bacilli (Bacteroides fragilis etc), also E. coli and Klebsiella. Enterococci and Pseudomonas are frequently isolated but do not require specific therapy if patient is responding to therapy as prescribed.
• Tertiary peritonitis - failure of two source control procedures to control persistent IAI
  • Complete failure of intra-abdominal host defences
  • Probably some element of incompetent host defences involved
  • Consider management with open abdomen and regular toilet at the bedside until local host defences recover
• Empiric antibiotics for abdominal infections - see separate topic under 'Antibiotics' in 'ID'

Complicated skin/soft tissue infections

• DFUs
  • Skin ulceration from ischaemia or trauma to a neuropathic foot
  • Portal of entry, poor blood supply, poor humoral immunity, impaired monocyte-macrophage function
  • Usually caused by gram positive cocci (S. aureus most common)
  • If chronic or complex wounds, can harbour other pathogens like Enterobacteriaceae and P. aeruginosa if the wound is macerated (don't necessarily need to cover these initially)
  • Treat mild infections for a week, serious infections need longer +/- debridement/amputation