ABSTRACT
We describe a method and apparatus for rapid visual detection of microorganisms in blood cultures. In the 30-min procedure, a lysing reagent for the preferential digestion of blood cells and a concentration device which causes 1 ml of lysed specimen to pass through a portion (3 mm2) of a membrane filter (pore size, 0.6 micron) were used. After the material remaining on the filter was Gram stained, the filter was mounted and examined microscopically. The ability to detect microorganisms in blood cultures was determined by spiking seven common blood pathogens into blood cultures prepared from the blood of healthy volunteers. Microorganism concentration in the cultures ranged from 1 to 1,000/ml. All of 34 cultures with at least 100 CFU/ml were detected, 34 of 64 cultures with less than 100 CFU/ml were detected, and 41 of 42 negative controls were correctly reported as negative.
Subject(s)
Bacteriological Techniques , Blood/microbiology , Bacteriological Techniques/instrumentation , Humans , In Vitro TechniquesABSTRACT
A fluorescent staining procedure based upon thioflavin T is described. This dye permits rapid, vital, nonprecipitative staining of human reticulocytes. Flow cytometric analysis of thioflavin T stained whole blood specimens results in reticulocyte counts that correlate well with new methylene blue reticulocyte counts and give coefficients of variation approaching the theoretical limit. The shape of the fluorescence histogram is qualitatively similar to the reticulocyte age profile. Paired new methylene blue and thioflavin T reticulocyte counts are presented with illustrative cases of reticulocyte maturity distributions.
Subject(s)
Flow Cytometry/methods , Fluorescent Dyes , Reticulocytes/cytology , Staining and Labeling/methods , Thiazoles , Benzothiazoles , Erythrocyte Count , HumansABSTRACT
The widely practiced method for performing a reticulocyte count includes counting 1000 normal erythrocytes while searching for a relatively small population of reticulocytes. A method is presented using a spinner reticulocyte preparation which avoids the need to count the normal erythrocytes, thereby eliminating most of the tedium from the test. The accuracy and reproducibility of this new method, as compared to the currently practiced method, is presented, along with the results of an on-line comparison.
Subject(s)
Erythrocyte Count/methods , Reticulocytes , HumansABSTRACT
As part of the installation procedure of the LARC leukocyte differential classifier in a clinical laboratory, a 100-slide protocol is carried out to establish the performance of the classifier in the laboratory. The detailed make-up of this protocol and its relationship to key performance parameters for the leukocyte differential are described in detail. Data from the first ten of these protocols are presented which establish the (a) normal ranges, (b) reproducibility, (c) accuracy, (d) false-positive/false-negative rates for the detection of left shifts and (e) false-positive/false-negative rates for the detection of bloods with abnormal cells.
