Risk factors for infection/colonization caused by resistant Gram negative bacilli in critically ill patients (an observational study of 1633 critically ill patients).

OBJECTIVE: The objective of this study is to identify risk factors associated with multi-resistant Gram negative (RGNB) infection and colonization among critically ill patients. METHODS: A prospective cohort study of all patients aged 21-90 admitted for more than 24 hours in Medical and Surgical intensive care units (ICU) at a large teaching hospital in Singapore for the period of Aug '07-Dec '09 was conducted. Patient demographics, comorbidities, antibiotics, invasive devices, and culture results were collected. Forward stepwise logistic regression analyses were done to identify risk factors associated with RGNB infection and colonization. RESULTS: Of the 1373 patients included in the analysis, 13.5% developed RGNB infection. A logistic regression analysis including variables with a p value of <0.2 in the univariate analysis showed that recent surgery (OR 2.1, 95% CI 1.2-3.6), renal impairment (OR 2.9, 95% CI 1.5-5.4), liver disease (OR: 3.8, 95% CI 1.7-8.8), central line (OR 1.8, 95% CI 1.01-3.4) were independently associated with RGNB infection in the ICU. Surgery (OR 3.9, 95% CI 2.7-5.7), third-line antibiotics (carbapenem, vancomycin, linezolid) (OR 1.8, 95% CI 1.2-2.9) were independently associated with RGNB infection during their hospitalization. CONCLUSION: The major risk factors identified for RGNB infection and colonization in the ICU were mainly patient dependent. However, broad spectrum initial antibiotic treatment remains an important independent modifiable risk factor. Interventions aimed at reducing initial broad spectrum antibiotics are clearly needed to help control the spread of these difficult to treat infections.

Inappropriate empirical antimicrobial therapy for multidrug-resistant organisms in critically ill patients with pneumonia is not an independent risk factor for mortality: Results of a prospective observational study of 758 patients.

The benefits of broad-spectrum initial empirical antibiotic therapy for all patients in intensive care units (ICUs) with high rates of multidrug-resistant organisms (MDROs) have not been critically evaluated. In this study, 758 ICU patients with pneumonia were prospectively evaluated. Of 349 positive respiratory cultures, 119 (34.1%) were with MDRO isolates. These were associated with increased mortality [adjusted hazard ratio (HR)=1.65, 95% confidence interval (CI) 1.01-2.68; P=0.04] as was increasing age and Acute Physiology and Chronic Health Evaluation (APACHE) II score. Among the patients with MDRO-associated pneumonia, increasing age, APACHE II score and inappropriate definitive antimicrobial therapy (IDAT) were found to be significant risk factors for mortality (in-ICU mortality, adjusted HR=2.8, 95% CI 1.3-5.8; P=0.007), but inappropriate empirical antimicrobial therapy (IEAT) was not (in-ICU mortality, unadjusted HR=1.6, 95% CI 0.7-3.6; P=0.3). In conclusion, we found that among critically ill patients with MDRO-associated pneumonia, IEAT is not an independent risk factor for ICU mortality. Hence, we do not recommend the use of broad-spectrum initial empirical antimicrobial therapy for all patients, as its benefits may not outweigh the potential risks. Early microbiological diagnosis to facilitate implementation of early definitive antimicrobial therapy through use of novel technologies is likely to have a major impact.