The argument against using quantitative cultures in clinical trials and for the management of ventilator-associated pneumonia.
Summary of "The argument against using quantitative cultures in clinical trials and for the management of ventilator-associated pneumonia."
Quantitative cultures have been proposed as the most accurate way to both establish the presence of ventilator-associated pneumonia (VAP) and define the etiologic pathogen. Although the clinical diagnosis of VAP has been much maligned, it may be very accurate, particularly if it is objectively defined by calculating the Clinical Pulmonary Infection Score and if the score incorporates a Gram stain of a lower respiratory tract sample. After the clinical diagnosis of VAP is made, a culture is needed to identify the etiologic pathogen, but this culture does not need to be quantitative or bronchoscopic. Quantitative culture-based diagnosis may not be more accurate than clinical diagnosis, and quantitative cultures have a number of methodologic limitations that can cause both false-positive and false-negative results. Finally, a number of studies have suggested that clinical management without quantitative cultures may be accurate and that outcomes, such as mortality and change in antibiotics to a focused regimen, are not improved by the use of quantitative cultures. In clinical trials, management using nonquantitative cultures of a tracheal aspirate specimen may be preferable. Reliance on quantitative cultures can complicate enrollment and will ensure that only a subset of patients with VAP is studied because of the relatively high false-negative rate of quantitative culture results, particularly among patients treated with antibiotics before samples are obtained.
Affiliation
Department of Medicine, Winthrop-University Hospital, Mineola, New York, USA. mniederman@winthrop.org
Journal Details
This article was published in the following journal.
Name: Clinical infectious diseases : an official publication of the Infectious Diseases Society of America
ISSN: 1537-6591
Pages: S93-9
Links
- PubMed Source: http://www.ncbi.nlm.nih.gov/pubmed/20597678
- DOI: http://dx.doi.org/10.1086/653055
Medical and Biotech [MESH] Definitions
Clinical Trial
Work that is the report of a pre-planned clinical study of the safety, efficacy, or optimum dosage schedule of one or more diagnostic, therapeutic, or prophylactic drugs, devices, or techniques in humans selected according to predetermined criteria of eligibility and observed for predefined evidence of favorable and unfavorable effects. While most clinical trials concern humans, this publication type may be used for clinical veterinary articles meeting the requisites for humans. Specific headings for specific types and phases of clinical trials are also available.
Early Termination Of Clinical Trials
Earlier than planned termination of clinical trials.
Clinical Trials As Topic
Pre-planned studies of the safety, efficacy, or optimum dosage schedule (if appropriate) of one or more diagnostic, therapeutic, or prophylactic drugs, devices, or techniques selected according to predetermined criteria of eligibility and observed for predefined evidence of favorable and unfavorable effects. This concept includes clinical trials conducted both in the U.S. and in other countries.
Controlled Clinical Trials As Topic
Clinical trials involving one or more test treatments, at least one control treatment, specified outcome measures for evaluating the studied intervention, and a bias-free method for assigning patients to the test treatment. The treatment may be drugs, devices, or procedures studied for diagnostic, therapeutic, or prophylactic effectiveness. Control measures include placebos, active medicines, no-treatment, dosage forms and regimens, historical comparisons, etc. When randomization using mathematical techniques, such as the use of a random numbers table, is employed to assign patients to test or control treatments, the trials are characterized as RANDOMIZED CONTROLLED TRIALS AS TOPIC.
Clinical Trials Data Monitoring Committees
Committees established to review interim data and efficacy outcomes in clinical trials. The findings of these committees are used in deciding whether a trial should be continued as designed, changed, or terminated. Government regulations regarding federally-funded research involving human subjects (the "Common Rule") require (45 CFR 46.111) that research ethics committees reviewing large-scale clinical trials monitor the data collected using a mechanism such as a data monitoring committee. FDA regulations (21 CFR 50.24) require that such committees be established to monitor studies conducted in emergency settings.
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