Clinical Outcomes and Cost of Gram Negative Bacteremia

Specific Aim 1: Define the clinical impact of gram negative bacterial (GNB) bloodstream
infections (BSI). In this objective, the investigators will describe the prevalence, source
of bacteremia, and location of acquisition (i.e., community-acquired, healthcare-associated,
hospital-acquired) of GNB BSI. The investigators will also examine the outcomes associated
with GNB BSI including length of hospital stay, length of ICU stay, in-house mortality, and
hospital costs.

Specific Aim 2: Describe antibiotic resistance patterns in GNB BSI, and explore associations
between antibiotic resistance and clinical and economic outcomes. In this objective, the
investigators will describe the prevalence and antibiotic susceptibility profiles of
multidrug resistant phenotypes including MDR bacteria, which are defined by resistance to
three or more drug classes, ESBL-producers, and CRE. The investigators will examine the
differences in mortality, resource use (length of hospital stay, length of ICU stay), and
direct medical costs between cases with and without antibiotic resistance.

Inclusion Criteria:

Since January 2002, one investigator (VGF) has received daily reports from the clinical
microbiology laboratory on all hospitalized patients at Duke University Medical Center
with one or more blood culture(s) positive for gram negative rods. Patients were then
evaluated within 36 hours of the detection of bacteremia for clinical evidence of
infection

Exclusion Criteria:

Patients were excluded from the study for the following reasons: age less than 18 years,
polymicrobial infection (blood culture positive for more than one pathogen), neutropenia
(white blood cell count less than 1.0 x 109/L), or death prior to the return of positive
blood cultures. In order to preserve the independence of observations, only the initial
episode of gram negative bacteremia was included in the analysis (e.g., patients were only
included once). The study was approved by the Duke University Medical Center Institutional
Review Board.