Objective: The objective of this study was to analyze risk factors and outcomes of BSI due to MDR-AB.
Methods: A case-control study was conducted at Detroit Medical Center from January 2006 to April 2009 .Patients with positive blood cultures for AB were identified from laboratory data. Cases were patients with MDR-AB BSI defined as: patients with one or more blood cultures positive for AB strains resistant to ampicillin/sulbactam and one or more of the type 2 carbapenems.Controls were patients with non–MDR-AB BSI defined as: patients with one or more positive blood cultures with AB strains, sensitive to a type 2 carbapenem and/or ampicillin/sulbactam. Patient variables collected included demographics, comorbid conditions, functional status and hospital mortality. Logistic regression was used to identify independent predictors of MDR-AB BSI and in-hospital mortality.
Results: 74 MDR-AB BSI cases and 200 non-MDR-AB BSI controls were analyzed. The mean age of the cases was 62 years and controls was 52 years (p value<0.001). 59.4% of the cases and 44.5% of the controls were males (p value=0.03). 74.5% of the cohort was African-American.55 (74.3 %) of cases and 122 (61%) of controls had a Charlson score greater than 3 (p=0.04). A rapidly fatal condition at the time of admission was present in 17(23%) of cases and 17(8.5%) of controls (pvalue=0.003).Independent predictors of MDR-AB BSI on multivariate analysis included: presence of a rapidly fatal condition at admission (OR=2.33, 95% CI=1.07~5.08) and admission to an intensive care unit (OR=2.39, 95% CI=1.34~4.25); other variables did not reach statistical significance but were retained in the model [Charlson score > 3 (OR=1.33, 95% CI=0.69~2.56), and age > 60 (OR=1.76, 95% CI=0.97~3.19)]. 31 (42%) cases and 40 (20 %) controls died during hospitalization (OR=2.88, 95% CI 1.62~5.14)). Independent predictors of in-hospital mortality included: admission to an intensive care unit (OR=8.30, 95% CI=4.24~16.24) and Charlson score>3 (OR=2.35, 95% CI=1.10~5.01). MDR-AB BSI was associated with mortality but did not reach statistical significance (OR=1.75, 95% CI=0.90~3.39). Conclusions: Critically ill patients were at increased risk for BSI due to MDR-AB. BSI due to MDR-AB was associated with an almost 2-fold increase in in-hospital mortality, compared to BSI due to more susceptible strains of AB.
Conclusions: Critically ill patients were at increased risk for BSI due to MDR-AB. BSI due to MDR-AB was associated with an almost 2-fold increase in in-hospital mortality, compared to BSI due to more susceptible strains of AB.