Bloodstream Infections Caused by Extended-Spectrum-ß-Lactamase-Producing Klebsiella pneumoniae: Risk Factors, Molecular Epidemiology, and Clinical Outcome

January 26, 2006 at 11:06 am Leave a comment

Source: Antimicrobial Agents and Chemotherapy Feb 2006 vol.50 N.2 p. 498-504

Mario Tumbarello,1* Teresa Spanu,2 Maurizio Sanguinetti,2 Rita Citton,1 Eva Montuori,1 Fiammetta Leone,2 Giovanni Fadda,2 and Roberto Cauda1

Departments of Infectious Diseases,1 Microbiology, Catholic University, Largo A. Gemelli 8, 00168 Rome, Italy2

Bloodstream infections caused by extended-spectrum-ß-lactamase (ESBL)-producing Klebsiella pneumoniae isolates are a major concern for clinicians, since they markedly increase the rates of treatment failure and death. One hundred forty-seven patients with K. pneumoniae bloodstream infections were identified over a 5-year period (January 1999 to December 2003). The production of ESBLs in bloodstream isolates was evaluated by molecular methods. A retrospective case-case-control study was conducted to identify risk factors for the isolation of ESBL-producing K. pneumoniae or non-ESBL-producing K. pneumoniae isolates in blood cultures. Forty-eight cases infected with ESBL-producing K. pneumoniae isolates and 99 cases infected with non-ESBL-producing K. pneumoniae isolates were compared to controls.

Risk factors for isolation of ESBL-producing K. pneumoniae isolates were exposure to antibiotic therapy (odds ratio [OR], 11.81; 95% confidence interval [CI], 2.72 to 51.08), age (OR, 1.14; 95% CI, 1.08 to 1.21), and length of hospitalization (OR, 1.10; 95% CI, 1.04 to 1.16). Independent determinants for isolation of non-ESBL-producing K. pneumoniae were previous urinary tract infection (OR, 8.50; 95% CI, 3.69 to 19.54) and length of hospitalization (OR, 1.07; 95% CI, 1.04 to 1.10). When the initial response was assessed at 72 h after antimicrobial therapy, the treatment failure rate for the ESBL-producing K. pneumoniae-infected group was almost twice as high as that of the non-ESBL-producing K. pneumoniae-infected group (31% versus 17%; OR, 2.19; 95% CI, 0.98 to 4.89). The 21-day mortality rate for all patients was 37% (54 of 147); it was 52% (25 of 48) for patients with ESBL-producing K. pneumoniae bloodstream infections and 29% (29 of 99) for patients with non-ESBL-producing K. pneumoniae bloodstream infections (OR, 2.62; 95% CI, 1.28 to 5.35). In summary, this investigation identifies epidemiological characteristics that distinguish ESBL-producing K. pneumoniae infections from non-ESBL-producing K. pneumoniae ESBL bloodstream infections.

* Corresponding author. Mailing address: Istituto Malattie Infettive, Università Cattolica del Sacro Cuore, Largo A. Gemelli 8, 00168 Rome, Italy. Phone: 39-06-30155373. Fax: 39-06-3054519. E-mail:

Entry filed under: Bacterias, Bacteriemias, Epidemiología, Resistencia bacteriana.

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