Determinants and impact of multidrug antibiotic resistance in pathogens causing ventilator-associated-pneumonia.

Pieter O Depuydt,Stijn I Blot,Dominique D Benoit,Dirk P Vogelaers,Johan M Decruyenaere,Maarten A Bekaert,Dominique M Vandijck

doi:10.1186/cc7119

Pieter O Depuydt, Stijn I Blot + Show 5 more

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https://doi.org/10.1186/cc7119

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Journal: Critical Care	Publication Date: Jan 1, 2008
Citations: 129	License type: cc-by

Affiliation: Ghent University Hospital, Ghent University

Abstract

IntroductionThe idea that multidrug resistance (MDR) to antibiotics in pathogens causing ventilator-associated pneumonia (VAP) is an independent risk factor for adverse outcome is still debated. We aimed to identify the determinants of MDR versus non-MDR microbial aetiology in VAP and assessed whether MDR versus non-MDR VAP was independently associated with increased 30-day mortality.MethodsWe performed a retrospective analysis of a prospectively registered cohort of adult patients with microbiologically confirmed VAP, diagnosed at a university hospital intensive care unit during a three-year period. Determinants of MDR as compared with non-MDR microbial aetiology and impact of MDR versus non-MDR aetiology on mortality were investigated using multivariate logistic and competing risk regression analysis.ResultsMDR pathogens were involved in 52 of 192 episodes of VAP (27%): methicillin-resistant Staphylococcus aureus in 12 (6%), extended-spectrum β-lactamase producing Enterobacteriaceae in 28 (15%), MDR Pseudomonas aeruginosa and other non-fermenting pathogens in 12 (6%). Multivariable logistic regression identified the Charlson index of comorbidity (odds ratio (OR) = 1.38, 95% confidence interval (CI) = 1.08 to 1.75, p = 0.01) and previous exposure to more than two different antibiotic classes (OR = 5.11, 95% CI = 1.38 to 18.89, p = 0.01) as predictors of MDR aetiology. Thirty-day mortality after VAP diagnosis caused by MDR versus non-MDR was 37% and 20% (p = 0.02), respectively. A multivariate competing risk regression analysis showed that renal replacement therapy before VAP (standardised hazard ratio (SHR) = 2.69, 95% CI = 1.47 to 4.94, p = 0.01), the Charlson index of comorbidity (SHR = 1.21, 95% CI = 1.03 to 1.41, p = 0.03) and septic shock on admission to the intensive care unit (SHR = 1.86, 95% CI = 1.03 to 3.35, p = 0.03), but not MDR aetiology of VAP, were independent predictors of mortality.ConclusionsThe risk of MDR pathogens causing VAP was mainly determined by comorbidity and prior exposure to more than two antibiotics. The increased mortality of VAP caused by MDR as compared with non-MDR pathogens was explained by more severe comorbidity and organ failure before VAP.

Highlights

The idea that multidrug resistance (MDR) to antibiotics in pathogens causing ventilator-associated pneumonia (VAP) is an independent risk factor for adverse outcome is still debated
Multivariable logistic regression identified the Charlson index of comorbidity (odds ratio (OR) = 1.38, 95% confidence interval (CI) = 1.08 to 1.75, p = 0.01) and previous exposure to more than two different antibiotic classes (OR = 5.11, 95% confidence intervals (CI) = 1.38 to 18.89, p = 0.01) as predictors of MDR aetiology
A multivariate competing risk regression analysis showed that renal replacement therapy before VAP (standardised hazard ratio (SHR) = 2.69, 95% CI = 1.47 to 4.94, p = 0.01), the Charlson index of comorbidity (SHR = 1.21, 95% CI = 1.03 to 1.41, p = 0.03) and septic shock on admission to the intensive care unit (SHR = 1.86, 95% CI = 1.03 to 3.35, p = 0.03), but not MDR aetiology of VAP, were independent predictors of mortality

Summary

Introduction

The idea that multidrug resistance (MDR) to antibiotics in pathogens causing ventilator-associated pneumonia (VAP) is an independent risk factor for adverse outcome is still debated. Estimates of attributable mortality of VAP range from 0% to as high as 50% [6], and this variability is thought to depend on several factors such as admission diagnosis of patients in the study, severity of illness at the time of VAP, type of microbial pathogen and APACHE: Acute Physiology and Chronic Health Evaluation; ARDS: Acute Respiratory Distress Syndrome; CFU: colony forming units; CI: confidence interval; CPIS: Clinical Pulmonary Infections Score; ESBL: extended spectrum β-lactamase producing Enterobacteriaceae; ICU: intensive care unit; MDR: multidrug antbiotic resistant; MRSA: methicillin-resistant Staphylococcus aureus; OR: odds ratio; SHR: standardised hazard ratio; SOFA: sequential organ failure assessment; VAP: ventilator-associated pneumonia; WBC: white blood cell count. Others have taken the alternative view that increased mortality in MDR VAP is largely due to confounding [16,17,18,19] by the preferential occurrence of MDR infection in a subset of ICU patients with a priori decreased odds for survival, that is, those patients with a prolonged duration of mechanical ventilation and previous antibiotic treatment [20]

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