Inappropriate empirical therapy was the strongest independent factor that we could modify to improve mortality in E. coli bacteraemia and was more frequent in cases caused by fluoroquinolone-resistant or ESBL-producing strains. Nosocomial acquisition, urinary catheterization and previous therapy with a fluoroquinolone or beta-lactam were predictive factors for infection with an antibiotic-resistant strain.

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Evidence supporting the combination of aminoglycosides with ␤-lactams for Gram-negative bacteremia is inconclusive. We have explored the influence on survival of empirical therapy with a ␤-lactam alone versus that with a ␤-lactam-aminoglycoside combination by retrospectively analyzing a series of bacteremic episodes due to aerobic or facultative Gram-negative microorganisms treated with single or combination therapy. The outcome variable was a 30-day mortality. Prognostic factors were selected by regression logistic analysis. A total of 4,863 episodes were assessed, of which 678 (14%) received combination therapy and 467 (10%) were fatal. Factors independently associated with mortality included age greater than 65 (odds ratio [OR], 2; 95% confidence interval [CI], 1.6 to 2.6), hospital acquisition (OR, 1.5; 95% CI, 1.2 to 1.9), a rapidly or ultimately fatal underlying disease (OR, 2.5; 95% CI, 2 to 3.2), cirrhosis (OR, 1.9; 95% CI, 1.4 to 2.6), prior corticosteroids (OR, 1.5; 95% CI, 1.1 to 2), shock on presentation (OR, 8.8; 95% CI, 7 to 11), pneumonia (OR, 2.8; 95% CI, 1.9 to 4), and inappropriate empirical therapy (OR, 1.8; 95% CI, 1.3 to 2.5). Subgroup analysis revealed that combination therapy was an independent protective factor in episodes presenting shock (OR, 0.6; 95% CI, 0.4 to 0.9) or neutropenia (OR, 0.5; 95% CI, 0.3 to 0.9). Combination therapy improved the appropriateness of empirical therapy in episodes due to extended-spectrum ␤-lactamase (ESBL)-or AmpC-producing Enterobacteriaceae and Pseudomonas aeruginosa. In patients with Gram-negative bacteremia, we could not find an overall association between empirical ␤-lactam-aminoglycoside combination therapy and prognosis. However, a survival advantage cannot be discarded for episodes presenting shock or neutropenia, hence in these situations the use of combination therapy may still be justified. Combination therapy also should be considered for patients at risk of being infected with resistant organisms, if only to increase the appropriateness of empirical therapy.

This study was undertaken to describe the epidemiology and sensitivity pattern of pathogens causing community-acquired (CA) and nosocomial (N) bloodstream infection (BSI) in adult HIV-infected patients and to establish risk factors for mortality. The type of study was a retrospective analysis of BSI episodes prospectively collected through a blood culture surveillance program from January 1991 to December 2006. We used non-conditional logistic regression methods with death as a dependent variable. One thousand and seventy-seven episodes of BSI (6%) occurred in HIV-infected patients out of 16,946 episodes during the period of study. CA and N BSI were 634 (59%) and 443 (41%) respectively. S. pneumoniae and S. aureus were the most frequent pathogens (n = 279, 44%) in CA BSI. Coagulase-negative staphylococci and S. aureus were the most frequent micro-organisms isolated in N cases (n = 169, 38%). Cotrimoxazole resistance was common in CA and N BSI and was caused by gram-negative bacilli (50% and 61% respectively). However, resistance rates to ceftriaxone were low (3%). Crude mortality accounted for 140 cases (13%). The independent risk factors associated with mortality were: liver cirrhosis (OR: 2.90, p = 0.001), corticosteroids treatment (OR: 3.51, p < 0.001), neutropenia (OR: 2.21, p = 0.02), inappropriate empirical therapy (OR: 2.44, p = 0.006), and isolate of C. albicans (OR: 7.58, p = 0.010). BSI in adult HIV-infected patients was often caused by gram-positive pathogens in both CA and N settings. Inappropriate empirical therapy and the presence of other immunosuppressive factors were independent risk factors for mortality. Ceftriaxone could be used as the initial empiric therapy for HIV-infected patients with suspected CA BSI.