Opportunistic Pneumonia: Acinetobacter baumannii Flashcards
1) Know that even though this bug has low virulence, it can be very hard to eradicate. 2) Abx resistance is very prevalent, and abx therapy should only be used during infection, not colonization.
Classify Acinetobacter baumannii
Gram negative bacilli
Pleomorphic
Aerobic
Water loving
Who gets infected with this bug most often?
Hospitalized (ICU) patients
–advanced age, very sick IC patients, trauma, burns; invasive procedures, indwelling catheters, ventilators, long stays, and prior abx treatment are risk factors
How infectious is this bug?
Not very. It has low virulence, therefore it is opportunistic..
Most A. baumannii recovered are representative of colonization, not infection
Is antibiotic resistance new to A. baumannii?
No. This bug is inherently resistance to multiple antibiotics.
How is A. baumannii virulent?
1) causes apoptosis via in laryngeal epithelium via OMP38 (releases cytochrome c and an apoptosis-inducing factor into cells)
2) Antibiotic resistance genes (acquired)
3) Efflux pumps (antibiotics can’t get into the bug)
4) Integrons with multiple resistance determinants
Where are places you can find A. baumannii
1) Environment: soil and foods such as vegetables, meat, and fish
2) Hospital: irrigating and IV solutions, ICU patients’ sputum, respiratory secretions, wounds, and urine
3) SE Asia and Australia as a CA pneumonia
What are some diseases that A. baumannii causes?
Think of the 4 W’s
1) Pneumonia (Wind = ventilators)
* *HA pneumonia > CA pneumonia
2) Blood infections/meningitis (Wire = blood/IV/shunts)
3) Urinary tract infections (Water = foley catheter)
4) Skin (Wounds = skin infections)
How do you diagnose A. baumannii infection?
1) Culture blood, urine, or tissue
2) CXR
3) Lumbar puncture
You find A. baumannii in a afebrile patient’s sputum. Should you treat them?
NO.
This is likely a colonization. Do not treat this. Only treat if it is infectious.
How do you treat a A. baumannii infection?
1) Meropenum (beta-lactamase-resistant inhibitor of PBPs)
2) Plymyxin B + Colistin (cationic detergents)
3) Amikacin (aminoglycoside, stops 30S ribosomes)
4) Rifampin (stops RNA polymerase)
5) Minocycline/Tigecycline (tetracyclines, stops 30S ribosomes)
Which antibiotics are most likely contributing to A. baumannii antibiotic resistance?
1) All the cephalosporins
2) Macrolides (azithromycin, erythromycin, clarithromycin; inhibit 50S ribosomes)
3) Penicillins
