What is Burkholderia cepacia?

Burkholderia cepacia: An Opportunistic Pathogen with Significant Clinical Implications

Burkholderia cepacia is an opportunistic gram-negative bacterial pathogen that poses minimal risk to healthy individuals but can cause severe, life-threatening infections in vulnerable populations, particularly those with cystic fibrosis or immunocompromised conditions. 1

Microbiology and Classification

• B. cepacia is part of the Burkholderia cepacia complex (Bcc), which comprises at least 24 distinct species that were originally thought to be a single species 2
• It is a gram-negative, aerobic bacterium that can survive in various environments
• The bacterium can form biofilms that significantly reduce antibiotic effectiveness 1
• It is commonly identified in respiratory specimens but can cause infections at various body sites

Clinical Significance

High-Risk Populations

• Cystic fibrosis patients: B. cepacia can cause:

  • Chronic asymptomatic colonization
  • Progressive respiratory decline
  • Cepacia syndrome (acute necrotizing pneumonia, respiratory distress, and bacteremia) with mortality rates up to 75% 3
  • Significantly elevated IgG antibody responses against B. cepacia antigens are diagnostic for biofilm infections in CF patients 4

• Immunocompromised patients:

  • Patients with chronic granulomatous disorder
  • Diabetic patients, even without other immunocompromising conditions 1
  • Transplant recipients

Sites of Infection

• Respiratory tract (most common, especially in CF patients)
• Bloodstream (bacteremia)
• Skin and soft tissues
• Bone (including vertebral osteomyelitis)
• Can be associated with contaminated medical products and devices 5, 2

Antimicrobial Resistance

B. cepacia presents significant treatment challenges due to:

• Intrinsic resistance to multiple antibiotics, including:

  • Aminoglycosides
  • Polymyxins
  • Many antipseudomonal penicillins 1, 5

• Resistance mechanisms include:

  • Efflux pump activity
  • Biofilm formation
  • Multiple virulence determinants 6

Diagnostic Approaches

• Phenotypic methods often lack sensitivity for accurate identification 5
• Molecular testing is critical for species identification within the Bcc 5
• Antimicrobial susceptibility testing:
  • Broth microdilution is the recommended method
  • Disk diffusion, agar dilution, and gradient diffusion (ETEST) perform poorly 7
  • Recent evidence suggests routine antimicrobial susceptibility testing should not be performed for Bcc isolates due to poor method performance 7

Treatment Approaches

Antibiotic Options

• First-line treatment: Ceftazidime (alone or in combination) 1
• Other potentially effective antibiotics based on susceptibility testing:
  • Trimethoprim-sulfamethoxazole
  • Meropenem or doripenem
  • Doxycycline or minocycline 5

Complex Cases

• For severe infections or cepacia syndrome:
  • Multimechanistic approach with combination therapy may be necessary
  • Example combination: nebulized tobramycin, IV sulfamethoxazole-trimethoprim, ceftazidime, and enteral minocycline 3
  • Systemic corticosteroids may be beneficial in cepacia syndrome 3

Infection Control Measures

For hospitalized patients with B. cepacia, implement:

• Hand hygiene with alcohol-based hand rub or soap and water
• Contact precautions for all colonized patient encounters
• Cohorting patients with B. cepacia in designated areas
• Environmental cleaning with appropriate disinfectants
• Dedicated patient-care equipment for infected/colonized patients 1

Clinical Pitfalls and Considerations

• B. cepacia should be considered in any patient with chronic sinusitis at an early age or in children with nasal polyps 4
• The mucoid phenotype of B. cepacia in clinical samples indicates biofilm infection and should be reported to clinicians 4
• B. cepacia exclusion is critical before lung transplantation in CF patients 7
• Hospital-acquired infections are common, representing approximately 59% of non-respiratory B. cepacia infections 2

By understanding the complex nature of B. cepacia infections and implementing appropriate diagnostic, treatment, and infection control measures, clinicians can improve outcomes for affected patients, particularly those in high-risk groups.