Susceptibility of extended-spectrum b-lactamase-producing Escherichia coli strains causing nosocomially- and community-acquired bacteraemia

Abstract number: 1733_1148

Picon E., Rodriguez-Bano J., Gijon P., Hernandez J.R., Ruiz M., Pena C., Almirante B., Almela M., Canton R., Guerrero A., Gimenez M., Oliver A., Horcajada J., Navarro G., Coloma A., Pascual on behalf of the Red Española de Investigacion en Patologia Infecciosa A.

Background: Community and nosocomially acquired bacteraemias caused by extended-spectrum b-lactamase-producing Escherichia coli (ESBL-Ec) are increasing in Spain. Therapeutic options for these infections are scarce.

Methods: Prospective cohort study including all episodes of bacteraemia due to ESBL-Ec from October/04 to January/06 in 13 hospitals from 6 areas in Spain. E. coli isolates were identified with API20E and ESBL production was confirmed according to CLSI guidelines. Susceptibility to 18 antimicrobial agents including ceftazidime, cefotaxime, cefepime, piperacillin-tazobactam, amoxicillin-clavulanate, ticarcillin-clavulanate, imipenem, meropenem, ertapenem, ciprofloxacin, nalidixic acid, amikacin, gentamicin, tobramycin, trimethoprim-sulfamethoxazole, fosfomycin, and tigecycline was determined by broth microdilution following CLSI recommendations. For tigecycline EUCAST guidelines were followed.

Results: We included 190 episodes of bacteraemia; 49.5% were nosocomially-acquired and 50.5% were community-acquired. No differences were found in the MIC and clinical category distribution between community and nosocomial isolates. All the strains were susceptible to the three carbapenems studied (imipenem, meropenem and ertapenem) and tigecycline. The MIC50 and MIC90 of tygecycline were 0.06 mg/L. Among b-lactam/b-lactamase inhibitor combinations piperacillin-tazobactam was the most active agent with 92% susceptible strains, followed by amoxicillin-clavulanate and ticarcillin-clavulanate (61% and 18% respectively). Aminoglycosides activity was as follows: amikacin 98%, tobramycin 82% and gentamicin 80% of susceptible strains, respectively. Ciprofloxacin and trimethoprim-sulfamethoxazole were the less active agents with 33% and 39% of susceptible strains, respectively.

Conclusions: ESBL-Ec is a relevant cause of community and nosocomially acquired bacteraemia in Spain. The most active agents against ESBL-Ec were carbapenems and tigecycline with 100% of susceptible strains. No difference in susceptibility to antimicrobial agents were found between nosocomial or community acquired isolates.

Session Details

Date: 31/03/2007
Time: 00:00-00:00
Session name: European Society of Clinical Microbiology and Infectious Diseases
Location: ICC, Munich, Germany
Presentation type:
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