What are the causes of infective phlebitis?

Causes of Infective Phlebitis

Infective phlebitis is primarily caused by Staphylococcus aureus and coagulase-negative staphylococci, followed by streptococcal species, gram-negative bacilli, and Candida species. 1

Microbiology of Infective Phlebitis

Bacterial Causes

• Staphylococcal species

  • Staphylococcus aureus (41% of cases) 2
  • Coagulase-negative staphylococci (especially with intravascular devices) 1
  • Staphylococcus lugdunensis (particularly aggressive) 1

• Streptococcal species

  • Group A streptococci (20% of cases) 2
  • Viridans group streptococci 1
  • Group B, C, F, and G streptococci 1
  • Streptococcus pneumoniae 1

• Enterococci (increasingly common in healthcare settings) 1

• Gram-negative organisms

  • Pseudomonas aeruginosa (most common gram-negative cause, ~10% of cases) 1
  • Escherichia coli 1
  • Enterobacter species 1
  • Klebsiella pneumoniae 1
  • HACEK group organisms (in rare cases) 1

Fungal Causes

• Candida species (particularly C. albicans) 1
• Aspergillus species (rare) 1

Pathogenesis and Risk Factors

Mechanisms of Infection

1. Extraluminal colonization - Microorganisms migrate from the skin at the insertion site along the external surface of the catheter 1
2. Intraluminal colonization - Contamination of the catheter hub and internal lumen 1
3. Hematogenous seeding - Less common; occurs from distant infection sites 1
4. Contaminated infusate - Rarely, direct contamination of the infusion fluid 1

Risk Factors

• Catheter-related factors

  • Prolonged catheter dwell time (>72-96 hours) 3
  • Poor aseptic technique during insertion 1, 3
  • Inappropriate catheter site selection 3
  • Steel needles (higher risk than flexible catheters) 3
  • Emergency placement 1

• Infusate-related factors

  • Irritating medications (particularly dicloxacillin and erythromycin) 4
  • Hypertonic solutions 3
  • Acidic or alkaline solutions 5

• Patient-related factors

  • Immunocompromised status 1
  • Advanced age 4
  • Underlying vascular disease 1
  • Intravenous drug use 2

Clinical Differentiation Between Infectious and Non-Infectious Phlebitis

Infectious Phlebitis

• Appears later (mean 4.1 days after catheter insertion) 6
• Associated with fever (40% of cases) 6
• May present with purulent drainage at insertion site 1, 6
• Can lead to serious complications including bacteremia, endocarditis, and septic shock 6
• Responds to intervention programs aimed at improving sterile technique 6

Non-Infectious Phlebitis

• Appears earlier (mean 2.4 days after catheter insertion) 6
• Rarely associated with fever (5.9% of cases) 6
• Strongly associated with irritating compounds (OR 6.1) 6
• Typically resolves without serious complications 6

Specific Clinical Scenarios

Peripheral Venous Catheter-Related Phlebitis

• Most common form of infective phlebitis in healthcare settings 1
• Presents with pain, erythema, induration, and tenderness at insertion site 1, 3
• May progress to a palpable venous cord if untreated 3
• Requires immediate catheter removal and site rotation 3

Suppurative Thrombophlebitis

• Severe form of infective phlebitis with intravascular abscess formation 1
• Characterized by persistent bacteremia or fungemia despite appropriate antimicrobial therapy and catheter removal 1
• Diagnosis requires demonstration of thrombus by imaging studies 1
• May require surgical intervention if conservative management fails 1, 2

Septic Phlebitis in Intravenous Drug Users

• Accounts for approximately 46% of septic phlebitis cases 2
• Primarily affects veins in the arms or neck (80% of cases) 2
• Predominantly caused by gram-positive organisms (80% of cases) 2
• Lower complication rate compared to healthcare-associated septic phlebitis 2

Prevention and Management

Prevention

• Proper aseptic technique during catheter insertion 3
• Regular site assessment (at least daily) 3
• Replacement of peripheral catheters every 72-96 hours 3
• Selection of appropriate catheter type and insertion site 3
• Use of sutureless securement devices 3

Management

• Immediate removal of the affected catheter 1, 3
• Application of warm compresses to the affected area 3
• Collection of blood cultures if systemic infection is suspected 3
• Antimicrobial therapy only if documented infection is present 3
• Surgical intervention for suppurative thrombophlebitis that fails to respond to conservative management 1, 2

By understanding the causes and mechanisms of infective phlebitis, healthcare providers can implement appropriate preventive measures and promptly identify and manage this potentially serious complication of intravenous therapy.