Rifampicin/imipenem combination in the treatment of carbapenem-resistant Acinetobacter baumannii infections.
BACKGROUND
In the setting of a large endemic of Acinetobacter baumannii infections, treatment of those due to carbapenem-resistant strains, susceptible only to colistin, has become a major problem in our hospital during the past years. Successful results have been reported using colistin, but clinical experience with this antibiotic is limited. In our experimental studies using these strains in a mouse pneumonia model, the best results were observed with a combination of rifampicin and imipenem.


METHODS
From July 2000 to September 2001, we performed a pilot study with patients suffering from serious infections due to carbapenem-resistant A. baumannii. Patients were treated with a rifampicin/imipenem combination and followed up prospectively. Cultures were repeated during and after treatment, and in vitro activity of rifampicin was monitored. Genotyping of these strains was performed by means of PFGE.


RESULTS
Ten patients were selected: four with ventilator-associated pneumonia, and six with other infections (one catheter-related bacteraemia, five surgical infections). Three patients died, two of whom were considered therapeutic failures. In five of the seven patients who were cured, other procedures were also performed such as surgical drainage or catheter removal. In vitro development of high resistance to rifampicin was shown in seven (70%). PFGE demonstrated that initial isolates and high-resistant strains belonged to the same clones.


CONCLUSIONS
The results of our study argue against the use of a rifampicin/imipenem combination for the treatment of carbapenem-resistant A. baumannii infections. However, combinations of rifampicin with other antibiotics merit further studies.
Saballs
Mireia
M
Infectious Disease Service, Hospital de Bellvitge, University of Barcelona C/Feixa Llarga s/n 08907, L'Hospitalet de Llobregat, Barcelona, Spain. msaballs@csub.scs.es
Pujol
Miquel
M
Tubau
Fe
F
Peña
Carmen
C
Montero
Abelardo
A
Domínguez
M Angeles
MA
Gudiol
Francesc
F
Ariza
Javier
J
D000151:Acinetobacter Infections / Q000188:drug therapy* / Q000382:microbiology; D040981:Acinetobacter baumannii / Q000187:drug effects* / Q000302:isolation & purification; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D015780:Carbapenems / Q000494:pharmacology*; D004334:Drug Administration Schedule; D024901:Drug Resistance, Multiple, Bacterial / Q000187:drug effects; D004359:Drug Therapy, Combination; D005260:Female; D006801:Humans; D015378:Imipenem / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D007262:Infusions, Intravenous; D007275:Injections, Intravenous; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D012293:Rifampin / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D016896:Treatment Outcome
D000900:Anti-Bacterial Agents; D015780:Carbapenems; D015378:Imipenem; D012293:Rifampin