Acinetobacter lwoffii: Cause and Treatment
Causative Factors
Acinetobacter lwoffii is a commensal organism found on normal human skin and oropharynx in approximately 25% of healthy individuals, but acts as an opportunistic pathogen primarily in healthcare settings through catheter-related infections, though rare community-acquired cases occur after trauma with CSF leaks. 1, 2
Primary Risk Factors:
- Indwelling vascular catheters (peripheral or central venous lines), particularly with continuous heparin infusions 3
- Neonatal ICU admission, especially in premature and very low-birth weight infants 4
- Immunocompromised states and prolonged hospitalization 2
- Traumatic CSF leaks (otorrhea or rhinorrhea) enabling direct CNS access 1
Clinical Presentations:
- Catheter-related bloodstream infections (most common) 3
- Neonatal sepsis 4
- Community-acquired meningitis following head trauma with CSF leak 1
- Rarely: gastroenteritis-associated bacteremia 2
Treatment Approach
For A. lwoffii infections, treatment should be guided by antimicrobial susceptibility testing, with carbapenems (imipenem or meropenem) as first-line therapy for susceptible isolates, though many strains retain susceptibility to fluoroquinolones and cephalosporins unlike A. baumannii. 5, 4
Treatment Algorithm Based on Infection Site:
Catheter-Related Bloodstream Infections:
- Remove the offending catheter immediately - this alone often resolves infection even without antibiotics 3
- If antibiotics needed: Use susceptibility-guided therapy
- Clinical course is typically benign with catheter removal 3
Neonatal Sepsis:
- Imipenem is first-line with 57% susceptibility in neonatal isolates 4
- Alternative agents based on susceptibility:
- Avoid empiric broad-spectrum therapy without cultures due to emerging multidrug resistance 4
Community-Acquired Meningitis:
- Cephalosporin-based therapy (cefuroxime or third-generation cephalosporins) guided by sensitivity testing 1
- Obtain CSF cultures before initiating therapy 1
- Address underlying CSF leak surgically if present 1
Respiratory Tract Infections:
- Imipenem 0.5-1g IV every 6 hours for susceptible isolates 5
- A. lwoffii is FDA-approved indication for imipenem in lower respiratory tract infections 5
Key Antibiotic Susceptibility Patterns:
Unlike A. baumannii, A. lwoffii often remains susceptible to multiple antibiotic classes, though multidrug resistance is emerging particularly in neonatal ICU settings. 4
- Most reliable agents: Carbapenems (imipenem/meropenem) 5, 4
- Moderate activity: Fluoroquinolones, cotrimoxazole 4
- Variable activity: Third-generation cephalosporins, amoxicillin-clavulanate 1, 4
- Generally resistant: Aminoglycosides, first-generation cephalosporins 6
Critical Warnings and Pitfalls
Common Mistakes to Avoid:
- Do not assume A. lwoffii has the same resistance profile as A. baumannii - lwoffii is generally more susceptible to standard antibiotics 4, 3
- Do not treat catheter-related infections without removing the catheter - antibiotics alone are insufficient 3
- Do not use empiric polymyxin-based therapy as you would for carbapenem-resistant A. baumannii - obtain susceptibilities first 7, 4
- Do not delay antibiotics in critically ill patients while awaiting cultures, but narrow therapy once susceptibilities available 4
Infection Control Considerations:
- Implement strict catheter care protocols in ICU settings to prevent transmission 3
- Practice judicious antibiotic stewardship in NICUs to prevent emergence of multidrug-resistant strains 4
- Monitor for outbreaks in neonatal units where A. lwoffii can spread between vulnerable patients 4