Incidence Rate and Outcome of Gram-Negative Bloodstream Infection in Solid Organ Transplant Recipients

M. N. Al-Hasan; R. R. Razonable; J. E. Eckel-Passow; L. M. Baddour

Disclosures

American Journal of Transplantation. 2009;9(4):835-843. 

In This Article

Abstract and Introduction

Abstract

Bacterial infections are common complications of solid organ transplantation (SOT). In this study, we defined the incidence, mortality and in vitro antimicrobial resistance rates of Gram-negative bloodstream infection (BSI) in SOT recipients. We identified 223 patients who developed Gram-negative BSI among a cohort of 3367 SOT recipients who were prospectively followed at the Mayo Clinic (Rochester, MN) from January 1, 1996 to December 31, 2007. The highest incidence rate (IR) of Gram-negative BSI was observed within the first month following SOT (210.3/1000 person-years [95% confidence interval (CI): 159.3-268.3]), with a sharp decline to 25.7 (95% CI: 20.1-32.1) and 8.2 (95% CI: 6.7-10.0) per 1000 person-years between 2 and 12 months and more than 12 months following SOT, respectively. Kidney recipients were more likely to develop Gram-negative BSI after 12 months following transplantation than were liver recipients (10.3 [95% CI: 7.9-13.1] vs. 5.2 [95% CI: 3.1-7.8] per 1000 person-years). The overall unadjusted 28-day all-cause mortality of Gram-negative BSI was 4.9% and was lower in kidney than in liver recipients (1.6% vs. 13.2%, p < 0.001). We observed a linear trend of increasing resistance among Escherichia coli isolates to fluoroquinolone antibiotics from 0% to 44% (p = 0.002) throughout the study period. This increase in antimicrobial resistance may influence the choice of empiric therapy.

Introduction

Bacterial infections constitute the majority of infectious disease complications during the first month after solid organ transplantation (SOT),[1,2] with many of these manifesting as bloodstream infections (BSI).[3] Recent reports have demonstrated a shift in the distribution of BSI toward Gram-negative bacteria as the predominant pathogens.[4,5,6] Notably, mortality was higher among SOT recipients who developed Gram-negative compared to Gram-positive BSI.[5,6,7] Several studies characterized the impact of bacterial infections on SOT during the early era of transplantation medicine.[3,7] Because SOT has evolved, in part, due to the availability of newer immunosuppressive therapies and revised paradigms of antimicrobial prophylaxis, we hypothesized that the incidence rate (IR) of Gram-negative BSI in SOT recipients has changed.

The primary aim of this study was to determine the IR of Gram-negative BSI in SOT recipients at the Mayo Clinic (Rochester, MN) from January 1, 1996 to December 31, 2007. We compared the IR of Gram-negative BSI in SOT recipients within the first month, between 2 and 12 months and more than 12 months following SOT. We also compared the IR of Gram-negative BSI during these three-time periods after kidney and liver transplantation; the two most commonly transplanted solid organs at Mayo Clinic, Rochester, MN. We examined for a temporal change in IR over the 12-year study period. Furthermore, we determined the 28-day all-cause mortality among SOT patients who developed Gram-negative BSI and the impact of gram-negative BSI on long-term outcome following SOT. Last, we examined trends in in vitro antibiotic susceptibility of Gram-negative bloodstream isolates to the most commonly used antibiotics.

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