Acinetobacter baumannii complex: Difference between revisions

Latest revision as of 10:06, 5 May 2023

Background

Microbiology

Contains Acinetobacter baumannii, Acinetobacter nosocomialis, and Acinetobacter pittii
Non-motile, non-fermenting Gram-negative bacillus

Antimicrobial Resistance

A number of mechanisms
Carbapenem resistance is usually mediated by acquisition of OXA-type class D carbapenemase
- Less common mechanisms include acquisition of class B (VIM, IMP, and NDM) carbapenemases, loss of outer membrane CarO protein, and modification of AdeABC efflux pump

Management

Choice of antibiotic depends on susceptibility testing
Possible options include:
- Cefepime, ceftriaxone, and cefotaxime
- Cefiderocol
- Carbapenems
- Tigecycline
- Colistin and polymyxin B (though Acinetobacter junii has inherent resistance)
Aminoglycosides may not penetrate well into lungs and brain, so are usually avoided
Bacteriophages are promising

Carbapenem-Resistant Acinetobacter baumannii

Infection must be distinguished from colonization of the airway or wound
Resistance may be mediated by a number of β-lactamases, including OXA-24/40-like carbapenemases, OCA-23-like carbapenemases, and metallo-β-lactamases, and often has sulbactam resistance
Often have concurrent aminoglycoside-modifying enzymes or 16S rRNA methyltransferases, which confer resistance to aminoglycosides including plazomicin
Single-agent treatment may be sufficient for mild infections
- High-dose ampicillin-sulbactam is preferred, at a dose of either 9 g IV q8h infused over 4 hours, or 27 g IV q24h continuous infusion
Combination treatment with at least two agents that have in vitro activity for most other infections
- Options include ampicillin-sulbactam (preferred), minocycline, tigecycline, polymyxin B, and cefidercocol
- Ampicillin-sulbactam may remain effective in non-susceptible isolates when used at high doses
- Fosfomycin and rifampin are not recommended
- After clinical improvement, step down to single-agent therapy

@@ Line 4: / Line 4: @@
 *Contains ''Acinetobacter baumannii'', ''[[Acinetobacter nosocomialis]]'', and ''[[Acinetobacter pittii]]''
-*Non-motile, non-fermenting [[Stain::Gram-negative]] [[Cellular shape::bacillus]]
+*Non-motile, non-fermenting [[Stain::Gram-negative]] [[Shape::bacillus]]
+=== Antimicrobial Resistance ===
+* A number of mechanisms
+* Carbapenem resistance is usually mediated by acquisition of OXA-type class D [[Carbapenemases|carbapenemase]]
+** Less common mechanisms include acquisition of class B (VIM, IMP, and NDM) [[carbapenemases]], loss of outer membrane CarO protein, and modification of AdeABC efflux pump
 == Management ==
@@ Line 17: / Line 23: @@
 * [[Aminoglycosides]] may not penetrate well into lungs and brain, so are usually avoided
 * [[Bacteriophages]] are promising
+=== Carbapenem-Resistant ''Acinetobacter baumannii'' ===
+* Infection must be distinguished from colonization of the airway or wound
+* Resistance may be mediated by a number of [[β-lactamases]], including OXA-24/40-like carbapenemases, OCA-23-like carbapenemases, and metallo-β-lactamases, and often has [[sulbactam]] resistance
+* Often have concurrent aminoglycoside-modifying enzymes or 16S rRNA methyltransferases, which confer resistance to [[aminoglycosides]] including [[plazomicin]]
+* Single-agent treatment may be sufficient for mild infections
+** High-dose [[ampicillin-sulbactam]] is preferred, at a dose of either 9 g IV q8h infused over 4 hours, or 27 g IV q24h continuous infusion
+* Combination treatment with at least two agents that have ''in vitro'' activity for most other infections
+** Options include [[ampicillin-sulbactam]] (preferred), [[minocycline]], [[tigecycline]], [[polymyxin B]], and [[cefidercocol]]
+** [[Ampicillin-sulbactam]] may remain effective in non-susceptible isolates when used at high doses
+** [[Fosfomycin]] and [[rifampin]] are not recommended
+** After clinical improvement, step down to single-agent therapy
 {{DISPLAYTITLE:''Acinetobacter baumannii'' complex}}
 [[Category:Gram-negative bacilli]]