The Impact of Transit Times on the Detection of Bacterial Pathogens in Blood Cultures: A College of American Pathologists Q-Probes Study of 36 Institutions.

CONTEXT.­: Consolidation of clinical microbiology laboratory services has resulted in extended transit time for blood cultures from service points distant from the laboratory. Sepsis is critical; delays in identification of etiologic agents of diseases could adversely impact patient care. OBJECTIVE.­: To examine the effect of total preanalytic time and blood culture volume on the instrument time-to-detection for bacterial pathogens in blood cultures. A secondary objective was to obtain relevant blood culture information by questionnaire. DESIGN.­: Participants in this Q-Probes study recorded date, time, and volume information for the first 50 positive blood cultures collected during the 12-week study period. Additional information regarding blood culture collection practices was obtained through questionnaire. RESULTS.­: Prolonged overall time-to-detection was secondary to prolonged preanalytic time, particularly prolonged transit time, rather than slower organism growth once bottles were placed on the instrument. Among 1578 blood cultures, the overall time from collection to positive result was significantly less for blood cultures collected on-site than for off-site locations. Most institutions lack sufficient training programs and do not monitor preanalytic time metrics associated with blood cultures. Four hundred fifty-six of the 1580 blood cultures with blood volume adequacy reported (28.9%) were inadequately filled. CONCLUSIONS.­: Overall process time (specimen collection to positive blood culture detection) is predicted to be higher for blood cultures collected off-site. Transit time is a variable that can be reduced to decrease overall time to detection. Thus, improved training and closer attention to preanalytic metrics associated with blood cultures could decrease hospital stays and mortality rates.

A test of lens opacity as an indicator of preclinical Alzheimer Disease.

Previous studies reported that characteristic lens opacities were present in Alzheimer Disease (AD) patients postmortem. We therefore determined whether cataract grade or lens opacity is related to the risk of Alzheimer dementia in participants who have biomarkers that predict a high risk of developing the disease. AD biomarker status was determined by positron emission tomography-Pittsburgh compound B (PET-PiB) imaging and cerebrospinal fluid (CSF) levels of Aß42. Cognitively normal participants with a clinical dementia rating of zero (CDR = 0; N = 40) or with slight evidence of dementia (CDR = 0.5; N = 2) were recruited from longitudinal studies of memory and aging at the Washington University Knight Alzheimer's Disease Research Center. The age, sex, race, cataract type and cataract grade of all participants were recorded and an objective measure of lens light scattering was obtained for each eye using a Scheimpflug camera. Twenty-seven participants had no biomarkers of Alzheimer dementia and were CDR = 0. Fifteen participants had biomarkers indicating increased risk of AD, two of which were CDR = 0.5. Participants who were biomarker positive were older than those who were biomarker negative. Biomarker positive participants had more advanced cataracts and increased cortical light scattering, none of which reached statistical significance after adjustment for age. We conclude that cataract grade or lens opacity is unlikely to provide a non-invasive measure of the risk of developing Alzheimer dementia.