Aerobic gram-neg coccobacilli or rods, often mistaken for Neisseria or Moraxella on Gram stain.
Common in environment (water, soil) and hospital (catheters, lotions, ventilation equipment).
Grows on standard agar media.
A. baumannii is the major species of Acinetobacter. Others occasional human pathogens include A. calcoaceticus, A. lwoffi, A. junii, A. johnsonii and A. baylyi.
A. baumannii is low grade pathogen affecting compromised hosts (immunosuppression, post-surgical, ventilator-associated pneumonia, burn wounds, ICU pts, device-associated infections and malnutrition).
Emerging as important global, pan-resistant GNB nosocomial pathogen.
Clearly pathogenic when recovered from blood and normally sterile body sites.
Risks: hospitalization, ICU, surgery, antibiotic exposure and catheters.
May cause nosocomial epidemics from contaminated common sources, e.g., ventilation equipment, catheters, etc.
Diagnosis by standard aerobic bacterial culture.
Lab isolations often meaningless (representing colonization) unless from
- normally sterile site
- found as a dominant pathogen and moderate or heavy growth from potentially contaminated sites
- outbreak and/or
- good clinical correlation.
- Usually a cause of nosocomial infections.
- Pneumonia: nosocomial, especially ventilator-associated.
- Septicemia: often catheter-associated, or consequence of HAP or VAP.Wounds: burns, war wounds acquired in Iraq, natural disasters--hurricanes/earthquakes.
- Rare: meningitis (post-neurosurgical), liver abscess, endocarditis, urinary tract infections, brain abscess.
- Community-acquired: reports from Iraqi war theater, one major report from New Zealand.
Antibiotic selection guided by in vitro sensitivity tests--most active: imipenem, ampicillin/sulbactam, colistin, tigecycline and amikacin.
- Imipenem:0.5-1gm IV q6h,
- meropenem：0.5-1gm IV q 8h,
- doripenem：500 mg IV q 8h.
Ampicillin/sulbactam: 3 gm ampicillin/1.5 gm sulbactam IV q 6h (sulbactam is the active component).
Other agents with variable activities: aminoglycosides, cephalosporins, minocycline, rifampin.