Infectious Disease Compendium

Acinetobacter

A few reviews: PubMed and PubMed.

Microbiology

Gram negative rods (when growing) and coccobacillus (when not) and includes A. baumannii, A. haemolyticus, A. junii, A. johnsenii, A. lwoffi, A. radioresistens and 15 others.

Epidemiologic Risks

Usually a complication of hospitalization or nursing homeization (my neologism, if you use it you owe me a dollar).There is a particularly resistant strain of A. baumannii found in soldiers from Iraq and Afghanistan (PubMed) for which imipenem is the most reliable agent; may want to consider colistin. As of today, however, there is little hope that our troops will be returning any time soon and bringing this bug home with them.

It is an increasing nosocomial/nursing home pathogen, often multi-drug resistant (PubMed).

Syndromes

Usually hospital acquired nosocomial infections of all types, all kinds of infections in our current veterans.

Treatment

CID Treatment review 2010

Often resistance emerges during therapy with third generation cephalosporins, know your local susceptibilities. Generally imipenem/meropenem,cefepime, and ciprofloxacin are the best bet. However, resistant A. baumannii are rapidly increasing, in some areas as of 2006 as high as 40% resistant to beta lactams.

For the MDR strains, consider tigecycline and colistin, amikacin, or minocycline (PubMed), which is not better or worse than tobramycin for efficacy or toxicity (Ref). Carbapenem resistant organisms may be treated best with ampicillin/sulbactam (oddly it is susceptible to the sulbactam component of Unisin) >colistin (PubMed). Resistance may develop resistance to tigecycline while on therapy (PubMed).

In vitro,colistin/meropenem, colistin/rifampicin, colistin/minocycline and minocycline/meropenem are synergistic (Ref).

For colistin resistant, perhaps the the best option is colistin, a carbapenem, and ampicillin-sulbactam (PubMed ).

Although in a randomized clinical trial, rifampin added nothing to colistin (PubMed).

Notes

Usually sensitive to third generation cephalosporins,carbapenems, and quinolones.