Controversy exists regarding the clinical utility of pleural fluid pH,lactate dehydrogenase (LDH), and glucose for identifying complicated parapneumonic effusions that require drainage. In this report, we performed a meta-analysis of pertinent studies, using receiver operating characteristic (ROC) techniques, to assess the diagnostic accuracy of these tests, to determine appropriate decision thresholds, and to evaluate the quality of the primary studies. Seven primary studies reporting values for pleural fluid pH (n = 251), LDH (n = 114), or glucose (n = 135) in pneumonia patients were identified. We found that pleural fluid pH had the highest diagnostic accuracy for all patients with parapneumonic effusions as measured by the area under the ROC curve (AUC = 0.92) compared with pleural fluid glucose (AUC = 0.84) or LDH (AUC = 0.82). After excluding patients with purulent effusions, pH (AUC = 0.89) retained the highest diagnostic accuracy. Pleural fluid pH decision thresholds varied between 7.21 and 7.29 depending on cost-prevalence considerations. The quality of the primary studies was the major limitation in determining the value of pleural fluid chemical analysis. We conclude that meta-analysis of the available data refines the application of pleural fluid chemical analysis but a clearer understanding of the usefulness of these tests awaits more rigorous primary investigations. Heffner JE, Brown LK, Barbieri C, Deleo JM. Pleural fluid chemical analysis in parapneumonic effusions: a meta-analysis. Am J Resplr Crit Care Med 1995;151:1700-8.Parapneumonic effusions occur in 20% to 57% of patients hospitalized for community-acquired bacterial pneumonia (1-3). These effusions may either resolve with antibiotic therapy alone or folIowa complicated course requiring tube thoracostomy or thoracotomy. Because the progression from a free-flowing parapneumonic effusion to the formation of intrapleural pus may occur rapidly (4), most experts recommend prompt pleural drainage when a complicated course appears likely (5-7).No clinical or radiograph findings, however, offer sufficient diagnostic accuracy to establish the need for pleural drainage in patients with parapneumonic effusions (2,4,8,9). Consequently, thoracentesis with pleural fluid analysis is employed to select patients for chest tube placement. The detection by thoracentesis of intrapleural pus or nonpurulent fluid with a positive Gram stain for pathogens is an accepted indication for instituting immediate pleural fluid drainage. Because the diagnostic sensitivities of these findings are low (5), determinations of pleural fluid pH, glucose, and lactate dehydrogenase (LDH) are recommended by expert statements and standard textbooks to assist in the decision to drain parapneumonic effusions (5, 7, 10-13). No general consensus exists, however, regarding the clinical utility of these criteria (8, 14-16).It appears that this lack of consensus derives at least partially from the small sample sizes of the individual primary studies that examine pleural fluid chemical ana...

Signal amplifiers: Superparamagnetic particle–antibody conjugates were used to detect a cancer biomarker in serum by surface plasmon resonance (SPR) at an unprecedented low level of 10 fg mL−1 (ca. 300 aM). Ultrahigh sensitivity is facilitated by enhanced mass and refractive index from aggregates of 1 μm magnetic particles on the SPR chip.

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e Carbapenem-resistant Enterobacteriaceae (CRE) have spread globally and represent a serious and growing threat to public health. Rapid methods for tracking plasmids carrying carbapenemase genes could greatly benefit infection control efforts. Here, we demonstrate that real-time, direct tracking of a single plasmid in a bacterial strain responsible for an outbreak is possible using a commercial matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) system. In this case, we retrospectively tracked the bla KPC carbapenemase gene-bearing pKpQIL plasmid responsible for a CRE outbreak that occurred at the NIH Clinical Center in 2011. An ϳ11,109-Da MS peak corresponding to a gene product of the bla KPC pKpQIL plasmid was identified and characterized using a combination of proteomics and molecular techniques. This plasmid peak was present in spectra from retrospectively analyzed K. pneumoniae outbreak isolates, concordant with results from whole-genome sequencing, and absent from a diverse control set of bla KPC -negative clinical Enterobacteriaceae isolates. Notably, the gene characterized here is located adjacent to the bla KPC Tn4401 transposon on the pKpQIL plasmid. Sequence analysis demonstrates the presence of this gene in other bla KPC Tn4401-containing plasmids and suggests that this signature MS peak may be useful in tracking other plasmids conferring carbapenem resistance. Plasmid identification using this MALDI-TOF MS method was accomplished in as little as 10 min from isolated colonies and 30 min from positive (spiked) blood cultures, demonstrating the potential clinical utility for real-time plasmid tracking in an outbreak.