Factors Predicting Bacterial Involvement in Severe Acute Exacerbations of Chronic Obstructive Pulmonary Disease

Abstract

Background: Strategies aiming at reducing antibiotic use are required in the intensive care unit (ICU). Although antibiotic treatment is recommended in patients with severe exacerbation of chronic obstructive pulmonary disease (COPD), a bacterial etiology is found in only a half of these patients. Objectives: The aim of this study was to determine factors predicting bacterial isolation in severe acute exacerbations of COPD. Methods: All patients with severe acute exacerbation of COPD requiring intubation and mechanical ventilation were included in this prospective observational cohort study. At ICU admission, information on endotracheal aspirate purulence and hyperthermia was collected. In all patients, Gram stain and quantitative endotracheal aspirate culture (positive at 10⁶ cfu/ml) were performed. In addition, leukocyte count, C-reactive protein and procalcitonin (PCT) levels were measured. Results: Ninety-eight severe acute exacerbations of COPD requiring intubation and mechanical ventilation were studied. Forty-nine bacteria were isolated at significant threshold in 40 exacerbations. Streptococcus pneumoniae (16%), methicillin-sensitive Staphylococcus aureus (16%) and Hemophilus influenzae (14%) were the most frequently isolated bacteria. PCT >0.5 ng/ml and positive Gram stain of endotracheal aspirate were independently associated with bacterial isolation in severe acute exacerbation of COPD. Positive Gram stain and PCT >0.5 ng/ml had a negative predictive value >95%. Similar results were found after excluding patients with prior antibiotic treatment. Conclusion: Positive Gram stain of endotracheal aspirate and PCT >0.5 ng/ml are independently associated with bacterial isolation in severe acute exacerbation of COPD. These results could be helpful for future interventional studies aiming at reducing antibiotic use in these patients.

Serum Procalcitonin as a Biomarker for the Prediction of Bacterial Exacerbation and Mortality in Severe COPD Exacerbations Requiring Mechanical Ventilation

“…In a study done in hospitalized COPDE patients, 76% had antibiotic therapy, but if the threshold of PCT <0.25 ng/ml had been used, treatment would have been given to only 7% of them [28]. Nseir et al [44] reported that PCT >0.5 ng/ml with a positive Gram stain for endotracheal aspirate was associated with bacterial exacerbations. In a multicenter randomized controlled study from Italy, the authors compared 10 days of antibiotic treatment with discontinuation of antibiotics within 3 days plus PCT guidance in patients hospitalized for COPDE [20].…”

Acute Exacerbation of Chronic Obstructive Lung Disease: Etiology and Treatment.

“…[17][18] From studies evaluating the parameters associated with bacterial colonization, a significant relationship was found between the frequency of exacerbations and increased colonization. 14,19 There are studies showing correlation between the decrease in FEV1 and the colonization. 16 As a result, in patients with frequent exacerbation, bacterial colonization seems to be more common.…”

Is It Possible to Reduce the Use of Antibiotics in Severe Exacerbations of Chronic Obstructive Pulmonary Disease?

“…The positive predictive value of the combination of a positive Gram stain and PCT 1 0.5 ng/ ml drops from 93.1 to 58% in the frequent situation of a previous intake of antibiotics [6] . Another aspect is the Increasing resistance of respiratory pathogens to the usual treatments is caused by the abuse of antibiotics.…”