Acinetobacter lwoffii: A Clinical Overview
Acinetobacter lwoffii is a non-fermentative aerobic gram-negative bacillus that exists as normal flora on human skin and oropharynx in approximately 25% of healthy individuals but can act as an opportunistic pathogen causing various nosocomial infections, particularly in immunocompromised patients. 1
Microbiology and Classification
- A. lwoffii belongs to the Acinetobacter genus but is distinct from the more commonly known A. baumannii group
- Clinical microbiology laboratories should distinguish between Acinetobacter species of the A. baumannii group (i.e., A. baumannii, A. nosocomialis, and A. pittii) and Acinetobacter species outside the A. baumannii group, such as A. lwoffii 2
- Identification to genus level is straightforward, but species-level identification requires advanced techniques such as MALDI-TOF MS (matrix-assisted laser desorption/ionization time-of-flight mass spectrometry) 2
- The gram variability of Acinetobacter can lead to misidentification if relying solely on Gram stain morphology 3
Clinical Significance and Pathogenicity
A. lwoffii has emerged as a significant pathogen causing:
- Catheter-related bloodstream infections, particularly in immunocompromised patients 4
- Neonatal sepsis, especially in premature and very low birth weight infants 5
- Bacteremia associated with acute gastroenteritis (community-acquired) 1
- Nosocomial infections including pneumonia, meningitis, and urinary tract infections 1
Risk Factors for A. lwoffii Infections
- Immunocompromised status (cancer patients, systemic lupus erythematosus) 4
- Presence of indwelling catheters 4
- Prior broad-spectrum antibiotic use 3
- Prolonged hospitalization, particularly in intensive care units 3
- Premature birth and very low birth weight in neonates 5
Antimicrobial Susceptibility and Treatment
A. lwoffii isolates have shown variable susceptibility patterns:
- In neonatal ICU settings, A. lwoffii isolates were most commonly sensitive to imipenem (57%), cotrimoxazole (32%), and ciprofloxacin (21%) 5
- Multi-drug resistant strains are increasingly reported, particularly in neonatal settings 5
- A. lwoffii isolates have shown resistance to cephalothin, aminoglycosides, and β-lactams in some studies 6
- Sensitivity to fluoroquinolones and tetracyclines has been documented 6
Management of A. lwoffii Infections
- For catheter-related infections, removal of the catheter is often necessary along with appropriate antimicrobial therapy 4
- Antimicrobial selection should be based on susceptibility testing of the isolate
- For empiric therapy in severe infections, carbapenems or polymyxins may be considered based on local susceptibility patterns 7
- Judicious and timely antibiotic use is crucial in controlling multi-drug resistant A. lwoffii infections, particularly in neonatal ICUs 5
Prognosis
- Catheter-related A. lwoffii bacteremia in immunocompromised hosts appears to be associated with a relatively low risk of mortality when appropriately managed 4
- Infections typically improve after catheter removal and/or appropriate antimicrobial therapy 4
Prevention and Control
- Standard infection control measures are essential to prevent nosocomial spread
- Environmental decontamination is important as Acinetobacter species can contaminate hospital surfaces and equipment 3
- Limiting broad-spectrum antibiotic use may help prevent emergence of resistant strains 5
A. lwoffii, while less commonly discussed than A. baumannii, represents an important emerging pathogen, particularly in healthcare settings with vulnerable populations such as neonatal ICUs and immunocompromised patients.