Is vitamin D deficiency important in the natural history of COPD?

cultures.Up to 22% of patients intubated for >48 h had evidence of virus recoverable from tracheobronchial secretions in one study.12 Whether viruses in VAP contribute to an actual pneumonic process remains unclear.Very interestingly, IL-1b and IL-8 concentrations were similar in the patients with VAP with typical pathogenic microbes and those with microbes usually considered to be less pathogenic, for example coagulase-negative staphylococci or Candida species.It is not clear how many of these patients had simultaneous positive cultures for other microbes.If these are the sole isolates, the cytokine data suggest that these microbes do in fact induce an inflammatory response: by extrapolation, therefore, they may require treatment.Isolated Candida cultures, for example, are not routinely treated in clinical practice.This article raises the possibility that such "non-pathogenic" microbes are in fact true pathogens in the setting of VAP.Finally, the use of a bronchoscopically derived biomarker for clinical practice presents certain practical considerations.BAL is labour intense, and cannot be performed safely in all ICU patients (and as in the methods described, the sicker patients with higher ventilatory support requirements were excluded).This study was carried out by one investigator across two clinical sites.Highly precise methods were used to perform BAL by the investigator, and it is unlikely that this methodological rigour could be easily reproduced by multiple clinicians in different ICUs in clinical practice.Although the authors have previously demonstrated that BAL-based microbiological techniques can improve the diagnosis of VAP 8 there remains widespread high variability in the use of bronchoscopic sampling across ICUs throughout Europe.19 Nevertheless this study adds significantly to the diagnosis and understanding of VAP.The utility of these biomarkers for VAP in BAL now requires further evaluation in larger multicentre studies.It will be particularly interesting to see if the application of biomarker-based decisions could safely reduce antibiotic prescription, and whether biomarker measurements help our understanding of the role of atypical or "non-pathogenic" microbes in VAP.Competing interests None.