scholarly journals Use of thermonuclease testing to identify Staphylococcus aureus by direct examination of blood cultures

2003 ◽  
Vol 9 (1-2) ◽  
pp. 185-190
Author(s):  
N. M. Kaplan
Keyword(s):  
Staphylococcus Aureus ◽  
Blood Culture ◽  
Direct Detection ◽  
Blood Cultures ◽  
Military Hospital ◽  
Clinical Microbiology Laboratory ◽  
Microbiology Laboratory ◽  
Direct Examination ◽  
Gram Positive ◽  
Gram Positive Cocci

Blood cultures submitted to the Clinical Microbiology Laboratory, Queen Alia Military Hospital, Amman during 1999-2001 were examined to evaluate thermonuclease testing for identifying Staphylococcus aureus in blood culture broths growing gram-positive cocci. Of 170 cultures studied, 129 yielded gram-positive staphylococci and 41 yielded other gram-positive cocci. Toluidine blue-deoxynucleic acid agar plates were used to test for thermonuclease activity. St and ard tube coagulase tests were performed on the isolates. Direct detection of thermonuclease activity in 76 blood culture broths containing gram-positive staphylococci showed 100% correlation with subsequent tube coagulase tests. The thermonuclease test provides a fast, specific and reliable confirmation of S. aureus bacteraemia by direct examination of blood culture broths that contain gram-positive cocci. This allows for timely, optimal antibiotic therapy

scholarly journals Nosocomial blood stream infections in Imam Khomeini Hospital, Urmia, Islamic Republic of Iran, 1999-2001

2005 ◽  
Vol 11 (3) ◽  
pp. 478-484
Author(s):  
M. Rahbar
Keyword(s):  
Blood Stream ◽  
Blood Cultures ◽  
Microbiology Laboratory ◽  
Islamic Republic ◽  
Coagulase Negative Staphylococci ◽  
Gram Positive ◽  
Blood Stream Infections ◽  
Skin Contamination ◽  
Islamic Republic Of Iran ◽  
Gram Positive Cocci

Ina 2-year retrospective study, the database of the microbiology laboratory of the Imam Khomeini Hospital was reviewed to identify patients who had nosocomial bacteraemia between 1 May 1999 and 31 May 2001 and identify the pathogen responsible and its resisitance to antibiotics. Of 6492 patients in various wards, 593 [9.1%] had positive blood cultures; 85 of those [14.3%] had signs of potential skin contamination. Gram-positive cocci, including coagulase-negative staphylococci, Staphylococcus aureus, Streptococcus pneumoniae and other Gram-positive cocci, accounted for 42.3% of isolates. Gram-negative bacilli were responsible for another 42.3% of isolates; Pseudomonas aeruginosa was the predominant isolate. Patterns of drug resistance varied according to species of bacteria but were generally quite high

scholarly journals Clinical Evaluation of the iCubate iC-GPC Assay for Detection of Gram-Positive Bacteria and Resistance Markers from Positive Blood Cultures

2018 ◽  
Vol 56 (9) ◽  
Author(s):  
Paul A. Granato ◽  
Melissa M. Unz ◽  
Raymond H. Widen ◽  
Suzane Silbert ◽  
Stephen Young ◽  
...  
Keyword(s):  
Blood Culture ◽  
Staphylococcus Epidermidis ◽  
Bloodstream Infections ◽  
Blood Cultures ◽  
Gram Positive ◽  
Content Type ◽  
Gram Positive Bacteria ◽  
Sequencing Method ◽  
Resistance Markers ◽  
Gram Positive Cocci

ABSTRACT The iC-GPC Assay (iCubate, Huntsville, AL) is a qualitative multiplex test for the detection of five of the most common Gram-positive bacteria (Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumoniae, Enterococcus faecalis, and Enterococcus faecium) responsible for bacterial bloodstream infections, performed directly from positive blood cultures. The assay also detects the presence of the mecA, vanA, and vanB resistance determinants. This study comparatively evaluated the performance of the iC-GPC Assay against the Verigene Gram-positive blood culture (BC-GP) assay (Luminex Corp., Austin, TX) for 1,134 patient blood culture specimens positive for Gram-positive cocci. The iC-GPC Assay had an overall percent agreement with the BC-GP assay of 95.5%. Discordant specimens were further analyzed by PCR and a bidirectional sequencing method. The results indicate that the iC-GPC Assay together with the iCubate system is an accurate and reliable tool for the detection of the five most common Gram-positive bacteria and their resistance markers responsible for bloodstream infections.

scholarly journals Automated Interpretation of Blood Culture Gram Stains by Use of a Deep Convolutional Neural Network

2017 ◽  
Vol 56 (3) ◽  
Author(s):  
Kenneth P. Smith ◽  
Anthony D. Kang ◽  
James E. Kirby
Keyword(s):  
Neural Network ◽  
Blood Culture ◽  
Convolutional Neural Network ◽  
Clinical Laboratory ◽  
Clinical Microbiology Laboratory ◽  
Proof Of Concept ◽  
Gram Stain ◽  
Gram Positive ◽  
Gram Negative ◽  
Gram Positive Cocci

ABSTRACTMicroscopic interpretation of stained smears is one of the most operator-dependent and time-intensive activities in the clinical microbiology laboratory. Here, we investigated application of an automated image acquisition and convolutional neural network (CNN)-based approach for automated Gram stain classification. Using an automated microscopy platform, uncoverslipped slides were scanned with a 40× dry objective, generating images of sufficient resolution for interpretation. We collected 25,488 images from positive blood culture Gram stains prepared during routine clinical workup. These images were used to generate 100,213 crops containing Gram-positive cocci in clusters, Gram-positive cocci in chains/pairs, Gram-negative rods, or background (no cells). These categories were targeted for proof-of-concept development as they are associated with the majority of bloodstream infections. Our CNN model achieved a classification accuracy of 94.9% on a test set of image crops. Receiver operating characteristic (ROC) curve analysis indicated a robust ability to differentiate between categories with an area under the curve of >0.98 for each. After training and validation, we applied the classification algorithm to new images collected from 189 whole slides without human intervention. Sensitivity and specificity were 98.4% and 75.0% for Gram-positive cocci in chains and pairs, 93.2% and 97.2% for Gram-positive cocci in clusters, and 96.3% and 98.1% for Gram-negative rods. Taken together, our data support a proof of concept for a fully automated classification methodology for blood-culture Gram stains. Importantly, the algorithm was highly adept at identifying image crops with organisms and could be used to present prescreened, classified crops to technologists to accelerate smear review. This concept could potentially be extended to all Gram stain interpretive activities in the clinical laboratory.

scholarly journals Evaluation of Four Methods for Rapid Identification of Staphylococcus aureus from Blood Cultures

1998 ◽  
Vol 36 (4) ◽  
pp. 1032-1034 ◽  
Author(s):  
David J. Speers ◽  
Thomas R. Olma ◽  
Gwendolyn L. Gilbert
Keyword(s):  
Staphylococcus Aureus ◽  
Blood Culture ◽  
Culture System ◽  
Rapid Identification ◽  
Culture Broth ◽  
Blood Cultures ◽  
Blood Culture System ◽  
Variable Sensitivity ◽  
Rapid Tests ◽  
Gram Positive Cocci

The identification of Staphylococcus aureus directly from blood cultures is clinically relevant, but it requires a test that is both rapid and reliable. Previously, biochemical, immunological, tube coagulase, and thermostable-endonuclease methods have shown variable sensitivity and specificity. Testing directly from blood culture broth has not been described for the latex kit Staphaurex Plus (Murex Diagnostics Ltd.), and the modified conventional tests have not been used with the newer, continuously monitored blood culture systems. In addition, the commercial RAPIDEC staph kit (bioMerieux Vitek, Inc.) has been used to detect S. aureus directly from the Vital blood culture system (bioMerieux, Marcy l’Etoile, France), but its performance has not been evaluated with other continuously monitored systems. A total of 201 clinical blood cultures (BACTEC 9240 culture system; Johnston Laboratories, Inc.) in which a Gram stain showed gram-positive cocci resembling staphylococci were evaluated prospectively. The Staphaurex Plus kit, the tube coagulase test, the thermostable-endonuclease test, and the RAPIDEC staph kit were compared. The sensitivities were 23, 92, 85, and 98% and the specificities were 99, 100, 93, and 100%, respectively. The RAPIDEC staph kit was the most reliable test, with a diagnostic accuracy comparable to that of the best published results for any of the rapid tests. However, it was the most expensive of the tests and relatively labor-intensive. The tube coagulase test was also sensitive, the simplest to perform, and inexpensive.

scholarly journals Direct inoculation procedure for the rapid classification of bacteria from blood culture

1975 ◽  
Vol 2 (6) ◽  
pp. 469-473
Author(s):  
S C Edberg ◽  
M Novak ◽  
H Slater ◽  
J M Singer
Keyword(s):  
Blood Culture ◽  
Blood Cultures ◽  
Blood Culture Bottle ◽  
Gram Positive ◽  
Culture Bottle ◽  
Direct Inoculation ◽  
Inoculation Procedure ◽  
Identification Of Bacteria ◽  
Gram Positive Cocci

A procedure was developed for 4-h identification of bacteria from blood culture. From a turbid blood culture bottle a 10- to 15-ml aliquot was drawn off and centrifuged. The pellet was utilized to inoculate a series of enzymatic and physiologic reactions. Three hundred eight positive blood cultures were tested including 222 strains of Enterobacteriaceae, 40 strains of facultative grampositive cocci, 26 strains of anaerobes, and 20 assorted strains. There was over 96.5% agreement between 4-h and conventional methods with the Enterobacteriaceae, 98% with facultative gram-positive cocci, 100% with anaerobes, and 99% with the assorted strains.

scholarly journals Oxacillin Susceptibility Testing of Staphylococci Directly from Bactec Plus Blood Cultures by the BBL Crystal MRSA ID System

1999 ◽  
Vol 37 (6) ◽  
pp. 2034-2036 ◽  
Author(s):  
M. Kubina ◽  
B. Jaulhac ◽  
X. Delabranche ◽  
C. Lindenmann ◽  
Y. Piemont ◽  
...  
Keyword(s):  
Blood Culture ◽  
Reliable Method ◽  
Susceptibility Testing ◽  
Direct Detection ◽  
Methicillin Resistance ◽  
Rapid Identification ◽  
Blood Cultures ◽  
Becton Dickinson ◽  
Coagulase Negative Staphylococci ◽  
Gram Positive Cocci

The BBL Crystal MRSA ID test (Becton Dickinson) was applied directly to blood culture vials containing clusters of gram-positive cocci. The sensitivity and specificity of the test were 84 and 100% and 54 and 100% for vials containing Staphylococcus aureusand coagulase-negative staphylococci, respectively. This test is a reliable method for direct detection of methicillin resistance in positive blood culture vials when S. aureus is identified in parallel by rapid identification procedures.

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