Journal Article

Antibiotic combinations for serious infections caused by carbapenem-resistant <i>Acinetobacter baumannii</i> in a mouse pneumonia model

Abelardo Montero, Javier Ariza, Xavier Corbella, Alejandro Doménech, Carmen Cabellos, Josefina Ayats, Fe Tubau, Carmen Borraz and Francesc Gudiol

in Journal of Antimicrobial Chemotherapy

Published on behalf of British Society for Antimicrobial Chemotherapy

Volume 54, issue 6, pages 1085-1091
Published in print December 2004 | ISSN: 0305-7453
Published online December 2004 | e-ISSN: 1460-2091 | DOI:
Antibiotic combinations for serious infections caused by carbapenem-resistant Acinetobacter baumannii in a mouse pneumonia model

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Objectives: Successful therapy of carbapenem-resistant Acinetobacter baumannii strains has been reported with colistin, but recently we argued against its use as monotherapy because of the poor results obtained in a mouse pneumonia model. Our aim was to identify antibiotic combinations that were valid therapeutic alternatives in the same model.

Methods: We used two carbapenem-resistant A. baumannii strains (D and E; MICs of imipenem, 8 and 512 mg/L, respectively). MICs of tobramycin, rifampicin and colistin for both strains were 8, 8 and 0.5 mg/L, respectively.

Results: In infections caused by strain D, lung bacterial counts (log10 cfu/g, mean ± s.d.) were: controls (10.86±0.25), imipenem (5.99±0.59, P < 0.05 versus controls), and colistin (10.43 ± 1.09); imipenem + tobramycin was the most active combination (5.46±0.62, P < 0.05 versus controls). In infections caused by strain E, results were: controls (10.82±0.33), rifampicin (5.62±0.26, P < 0.05 versus controls), colistin (8.38±1.22, P < 0.05 versus controls), and imipenem (11.01±0.2); rifampicin + imipenem (3.79±0.99) and rifampicin + tobramycin (3.96±0.30) were the most active combinations (P < 0.05); results with rifampicin + colistin (5.59±1.17) were similar to those with rifampicin alone.

Conclusions: Our data indicate that imipenem can still be the best alternative for carbapenem-resistant A. baumannii infections with moderate levels of imipenem resistance, preferably combined with aminoglycosides. For strains highly resistant to imipenem, a combination of rifampicin with imipenem, tobramycin or colistin may be useful, if resistance to rifampicin is only moderate.

Keywords: multiresistant; A. baumannii; experimental; animals

Journal Article.  5314 words.  Illustrated.

Subjects: Medical Oncology ; Critical Care

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