Acinetobacter baumannii complex: Difference between revisions
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Acinetobacter baumannii complex
(Created page with "* Contains ''Acinetobacter baumannii'', ''Acinetobacter nosocomialis'', and ''Acinetobacter pittii'' {{DISPLAYTITLE:''Acinetobacter baumannii'' complex}} Category:Gram-...") |
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+ | == Background == |
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⚫ | |||
+ | === Microbiology === |
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+ | |||
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+ | *Non-motile, non-fermenting [[Stain::Gram-negative]] [[Shape::bacillus]] |
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+ | |||
+ | === Antimicrobial Resistance === |
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+ | |||
+ | * A number of mechanisms |
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+ | * Carbapenem resistance is usually mediated by acquisition of OXA-type class D [[Carbapenemases|carbapenemase]] |
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+ | ** 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 |
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+ | |||
+ | == Management == |
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+ | |||
+ | * Choice of antibiotic depends on susceptibility testing |
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+ | * Possible options include: |
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+ | ** [[Cefepime]], [[ceftriaxone]], and [[cefotaxime]] |
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+ | ** [[Cefiderocol]] |
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+ | ** [[Carbapenems]] |
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+ | ** [[Tigecycline]] |
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+ | ** [[Colistin]] and [[polymyxin B]] (though [[Acinetobacter junii]] has inherent resistance) |
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+ | * [[Aminoglycosides]] may not penetrate well into lungs and brain, so are usually avoided |
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+ | * [[Bacteriophages]] are promising |
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+ | |||
+ | === Carbapenem-Resistant ''Acinetobacter baumannii'' === |
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+ | |||
+ | * Infection must be distinguished from colonization of the airway or wound |
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+ | * 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 |
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+ | * Often have concurrent aminoglycoside-modifying enzymes or 16S rRNA methyltransferases, which confer resistance to [[aminoglycosides]] including [[plazomicin]] |
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+ | * Single-agent treatment may be sufficient for mild infections |
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+ | ** 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 |
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+ | * Combination treatment with at least two agents that have ''in vitro'' activity for most other infections |
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+ | ** Options include [[ampicillin-sulbactam]] (preferred), [[minocycline]], [[tigecycline]], [[polymyxin B]], and [[cefidercocol]] |
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+ | ** [[Ampicillin-sulbactam]] may remain effective in non-susceptible isolates when used at high doses |
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+ | ** [[Fosfomycin]] and [[rifampin]] are not recommended |
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+ | ** After clinical improvement, step down to single-agent therapy |
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{{DISPLAYTITLE:''Acinetobacter baumannii'' complex}} |
{{DISPLAYTITLE:''Acinetobacter baumannii'' complex}} |
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[[Category:Gram-negative bacilli]] |
[[Category:Gram-negative bacilli]] |
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