scholarly journals Evaluation of MRSASelect™Chromogenic Medium for the Early Detection of Methicillin-ResistantStaphylococcus aureusfrom Blood Cultures

2013 ◽  
Vol 24 (4) ◽  
pp. e113-e116 ◽  
Author(s):  
Kanchana Manickam ◽  
Andrew Walkty ◽  
Philippe RS Lagacé-Wiens ◽  
Heather Adam ◽  
Barbara Swan ◽  
...  
Keyword(s):  
Early Detection ◽  
Antimicrobial Therapy ◽  
Predictive Value ◽  
Turnaround Time ◽  
Blood Cultures ◽  
Gram Stain ◽  
Chromogenic Medium ◽  
Gram Positive ◽  
Microbiological Methods ◽  
Gram Positive Cocci

INTRODUCTION:Staphylococcus aureusbacteremia is associated with considerable morbidity and mortality. In theory, reducing the turnaround time in reporting of methicillin-resistantS aureus(MRSA) among patients with bactermia could assist with the rapid optimization of antimicrobial therapy.OBJECTIVE: To evaluate the sensitivity and specificity of MRSASelect(Bio-Rad Laboratories, USA), a chromogenic medium, in the early detection of MRSA from blood cultures growing Gram-positive cocci in clusters, and to confirm that routine use of this medium would, in fact, reduce turnaround time for MRSA identification.METHODS: The present study was conducted at three microbiology laboratories in Manitoba. Between April 2010 and May 2011, positive blood cultures with Gram-positive cocci in clusters visualized on Gram stain were subcultured to both MRSASelectand routine media. MRSA isolates were identified using conventional microbiological methods from routine media and using growth with the typical colony morphology (pink colony) on MRSASelectmedium.RESULTS: A total of 490 blood cultures demonstrating Gram-positive cocci in clusters on Gram stain were evaluated.S aureuswas recovered from 274 blood cultures, with 51S aureusisolates (51 of 274 [18.6%]) identified as MRSA. MRSASelectmedium had a sensitivity of 98%, a specificity of 100%, a positive predictive value of 100% and a negative predictive value of 99.8% for the recovery and identification of MRSA directly from positive blood culture bottles. In addition, use of MRSASelectmedium was found to improve turnaround time in the detection of MRSA by almost 24 h relative to conventional methods.DISCUSSION: These data support the utility of MRSASelectmedium for the rapid identification of MRSA from positive blood cultures. Further clinical studies are warranted to determine whether the improvement in turnaround time will result in a measurable reduction in suboptimal antimicrobial therapy and/or improvement in patient outcome.

scholarly journals Efficacy of direct Gram stain in differentiating staphylococci from streptococci in blood cultures positive for gram-positive cocci

1978 ◽  
Vol 7 (2) ◽  
pp. 111-113
Author(s):  
W A Agger ◽  
D G Maki
Keyword(s):  
Antimicrobial Therapy ◽  
Blood Cultures ◽  
Gram Stain ◽  
Gram Positive ◽  
Staphylococcal Species ◽  
Presumptive Identification ◽  
Initial Antimicrobial Therapy ◽  
Microscopic Morphology ◽  
Gram Positive Cocci

A preponderance of clusters seen on direct Gram stain of blood cultures positive for gram-positive cocci was 98% sensitive and 100% specific for identification of staphylococcal species or of Peptococcus. A preponderance of chains, pairs, or both was 100% sensitive and 98% specific for identifying streptococci. Further presumptive identification of either staphylococci or streptococci based on microscopic morphology was unreliable. The direct Gram stain is highly reliable for differentiating staphylococci from streptococci and should be of considerable value to clinicians selecting initial antimicrobial therapy.

scholarly journals Rapid antimicrobial susceptibility testing on positive blood cultures through an innovative light scattering technology: performances and turnaround time evaluation

2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Lidvine Boland ◽  
Corentin Streel ◽  
Hélène De Wolf ◽  
Hector Rodriguez ◽  
Alexia Verroken
Keyword(s):  
Light Scattering ◽  
Antimicrobial Susceptibility ◽  
Susceptibility Testing ◽  
Turnaround Time ◽  
Blood Cultures ◽  
Antimicrobial Susceptibility Testing ◽  
Resistant Bacteria ◽  
Gram Positive ◽  
Gram Negative ◽  
Gram Positive Cocci

Abstract Background A bacteremia diagnosis with speeded-up identification and antimicrobial susceptibility testing (AST) is mandatory to adjust empirical broad-spectrum antibiotherapy and avoid the emergence of multi-resistant bacteria. Alfred 60AST (Alifax, Polverara, PD, Italy) is an innovative automated system based on light scattering measurements allowing direct AST from positive blood cultures with rapid results. In this study we aimed to evaluate the system’s performances and turnaround time (TAT) compared to routine AST. Methods The study was conducted during 2 non-consecutive 3-month periods at the microbiology laboratory of the Cliniques universitaires Saint-Luc. All blood cultures detected positive in the 0 AM–10 AM time frame with a pure Gram-positive cocci or Gram-negative bacilli stain were included for Alfred 60AST testing. Two customized EUCAST antibiotic panels were set up composed of 1) a “Gram-negative” panel including cefuroxime, ceftazidime Enterobacteriaceae, piperacillin-tazobactam Enterobacteriaceae, ciprofloxacine, and ceftazidime Pseudomonas 2) a “Gram-positive” panel including cefoxitin Staphylococcus aureus, cefoxitin coagulase-negative (CNS) Staphylococci and ampicillin Enterococci. Categorical agreement (CA), very major errors (VME), major errors (ME), minor errors (mE) and TAT to Alfred 60AST results were calculated in comparison with AST results obtained from direct testing on positive blood cultures with the Phoenix system (Becton Dickinson, Franklin Lakes, NJ, USA). Results Five hundred seventy and one hundred nine antibiotics were evaluated on respectively 166 Gram-negative bacilli and 109 Gram-positive cocci included in the studied population. During the first study period regarding Gram-negative strains a CA of 89.5% was obtained with a high rate of VME (19 and 15.4% respectively) for cefuroxime and piperacillin-tazobactam Enterobacteriaceae. Considering this, Alifax reviewed these antibiotics’ formulations improving Gram-negative bacilli total CA to 92.2% with no VME during the second study period. For Gram-positive cocci, total CA was 88.1% with 2.3% VME, 13.8% ME (mainly cefoxitin CNS) and 12% mE rates both study periods combined. Median TAT to AST results was 5 h with Alfred versus 12 h34 with Phoenix. Conclusion The Alfred 60AST system shows correct yet improvable microbiological performances and a major TAT reduction compared to direct automated AST testing. Clinical studies measuring the impact of the approach on antibiotic management of patients with bacteremia are recommended.

scholarly journals Time to First Culture Positivity Among Critically Ill Adults With Methicillin-Resistant Staphylococcus aureus Growth in Respiratory or Blood Cultures

2019 ◽  
Vol 54 (2) ◽  
pp. 131-137 ◽  
Author(s):  
Paige A. Melling ◽  
Michael J. Noto ◽  
Todd W. Rice ◽  
Matthew W. Semler ◽  
Joanna L. Stollings
Keyword(s):  
Staphylococcus Aureus ◽  
Critically Ill ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Blood Cultures ◽  
Gram Stain ◽  
Gram Positive ◽  
Patient Admissions ◽  
Critically Ill Adults ◽  
Ill Adults ◽  
Gram Positive Cocci

Background: For critically ill adults receiving empirical vancomycin, the duration of negative cultures after which vancomycin may be discontinued without risking subsequent growth of methicillin-resistant Staphylococcus aureus (MRSA) remains unknown. Objective: We hypothesized that if sputum cultures did not grow MRSA or blood cultures did not grow Gram-positive cocci on Gram stain by 48 hours, those cultures would not subsequently demonstrate MRSA. Methods: We conducted an ancillary analysis from patients enrolled in the Isotonic Solutions and Major Adverse Renal Events Trial (SMART). In this cohort of patients, we collected data on the time of either MRSA identification in culture or Gram-positive cocci identification on Gram stain and rate of vancomycin discontinuation. Results: Of the 15 802 patient admissions in the SMART study, 6553 (41.5%) received empirical intravenous vancomycin. Respiratory sputum cultures demonstrated MRSA during 178 patient admissions. Among respiratory cultures that would ultimately grow MRSA, 85% were positive within 48 hours, and 97% were positive within 72 hours. Cultures demonstrated MRSA bacteremia during 85 patient admissions. In 83 cases (97.6%) of MRSA bacteremia, Gram-positive cocci were identified within 48 hours after the culture was obtained. Conclusion and Relevance: This analysis of a large cohort of critically ill adults receiving empirical vancomycin found that Staphylococcus aureus was present in all but 15% of cases of MRSA-positive respiratory cultures after 48 hours, whereas Gram-positive cocci were identified within 48 hours during nearly all episodes of MRSA bacteremia. These findings may inform the timing of discontinuation of empirical vancomycin among critically ill adults.

The Diagnostic Value of Gram Stain for Initial Identification of the Etiologic Agent of Peritonitis in Capd Patients

1997 ◽  
Vol 17 (3) ◽  
pp. 269-272 ◽  
Author(s):  
Dinoráh A. Bezerra ◽  
Mario B. Silva ◽  
Jaqueline S.T. Caramori ◽  
Maria F. Sugizaki ◽  
Teruê Sadatsune ◽  
...  
Keyword(s):  
Predictive Value ◽  
Medical Center ◽  
Single Agent ◽  
Etiologic Agent ◽  
Initial Diagnosis ◽  
Gram Stain ◽  
Gram Positive ◽  
Dialysis Unit ◽  
Gram Negative ◽  
Gram Positive Cocci

Objective To evaluate the effectiveness of the Gram stain in the initial diagnosis of the etiologic agent of peritonitis in continuous ambulatory peritoneal dialysis (CAPD). Design Retrospective study analyzing the sensitivity (S), specificity (SS), positive predictive value (+PV), and negative predictive value (-PV) of the Gram stain relating to the results of cultures in 149 episodes of peritonitis in CAPD. The data were analyzed in two studies. In the first, only the cases with detection of a single agent by Gram stain were taken (Study 1). In the second, only the cases with two agents in Gram stain were evaluated (Study 2). Setting Dialysis Unit and Laboratory of Microbiology of a tertiary medical center. Patients Sixty-three patients on regular CAPD who presented one or more episodes of peritonitis from May 1992 to May 1995. Results The positivity of Gram stain was 93.2% and the sensitivity was 95.7%. The values of S, SS, +PV, and -PV were respectively: 94.9%, 53.5%, 68.3%, and 90.9% for gram -positive cocci and 83.3%, 98.8%, 95.2%, and 95.6% for gram-negative bacilli. The association of grampositive cocci plus gram -negative bacilli were predictive of growth of both in 6.8%, growth of gram -positive cocci in 13.7%, and growth of gram -negative bacilli in 72.5%. Conclusions The Gram stain is a method of great value in the initial diagnosis of the etiologic agent of peritonitis in CAPD, especially for gram-negative bacilli.

scholarly journals Evaluation of the LightCycler Staphylococcus MGRADE Kits on Positive Blood Cultures That Contained Gram-Positive Cocci in Clusters

2005 ◽  
Vol 43 (12) ◽  
pp. 6144-6146 ◽  
Author(s):  
N. K. Shrestha ◽  
M. J. Tuohy ◽  
R. A. Padmanabhan ◽  
G. S. Hall ◽  
G. W. Procop
Keyword(s):  
Blood Cultures ◽  
Gram Positive ◽  
Gram Positive Cocci

scholarly journals Comparing the Performance of the New Fully Automated Urine Particle Analyzer UF-5000 with UF-1000i and Gram Stain in Predicting Bacteria Growth Patterns in Women with Uncomplicated Urinary Tract Infections

2020 ◽  
Author(s):  
Stephen Shei-Dei Yang ◽  
Chun-Chun yang ◽  
Yi-Shen Chen ◽  
Shangjen chang
Keyword(s):  
Urinary Tract ◽  
Urine Analysis ◽  
Growth Patterns ◽  
Gram Stain ◽  
Gram Positive ◽  
Gram Negative ◽  
Bacterial Patterns ◽  
Tract Infections ◽  
Sensitivity Specificity ◽  
Gram Positive Cocci

Abstract BackgroudTo compare the performance of the new flow cytometer UF-5000 with UF-1000i (Sysmex, Kobe, Japan) and Gram stain in predicting the bacterial patterns in urine samples MethodsWomen with symptoms suggestive of urinary tract infection were enrolled. Mid-stream urine sample was collected for gram staining, urine analysis and urine culture. Bacterial patterns were classified though UF1000i (none, cocci bacteria or rods/mixed growth), UF-5000 (none, cocci, rods or mixed growth) and Gram stain. Results Among the 102 samples, there were 10 gram-positive cocci, 2 gram-positive bacilli, 66 gram-negative rods, and 24 mixed growth. The sensitivity/specificity of the UF-1000i was 81.8/91.1% for gram-negative rods and 23.5/96.9% for cocci/mixed. The sensitivity/specificity of the UF-5000 was 80.0/88.2% for gram negative rods and 70.0/86.5% for gram-positive cocci.ConclusionsThe UF-5000 demonstrated the good sensitivity and specificity for Gram-negative bacilli bacteria and demonstrated an improved sensitivity for detecting Gram-positive cocci.

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 Performance of a Semi-quantitative Multiplex Bacterial PCR Panel Compared with Standard Microbiological Laboratory Results: 396 Patients Studied with the BioFire® Pneumonia Panel

2020 ◽  
Author(s):  
Kenneth H Rand ◽  
Stacy G Beal ◽  
Kartikeya Cherabuddi ◽  
Brianne Couturier ◽  
Beth Lingenfelter ◽  
...  
Keyword(s):  
Respiratory Tract ◽  
Predictive Value ◽  
Copy Number ◽  
Clinical Laboratory ◽  
Bacterial Species ◽  
Turnaround Time ◽  
Gram Stain ◽  
Potential Pathogen ◽  
Microbiological Laboratory ◽  
Standard Culture

Abstract Background Microbiologic results are critical to optimal management of patients with lower respiratory tract infection, but standard methods may take several days. The multiplex PCR BioFire® Pneumonia (PN) panel detects 15 common bacterial species semi-quantitatively as copy number/mL, 8 viral species and 7 resistance genes in about an hour within the clinical laboratory. Methods We tested 396 unique endotracheal or bronchoalveolar lavage specimens with the BioFire® Pneumonia panel, and compared the bacterial detections to conventional gram stain and culture results. Results Of the 396 patients, 180 grew at least 1 bacteria that had a target on the PN panel and 177/180 (98.3%) were detected by the panel. A further 20% of patients had additional targets detected, but not found in standard culture (specificity 69%, positive predictive value 63%, and negative predictive value 98.9%). Copy number was strongly related to standard semi-quantitative growth on plates reported by the laboratory (e.g. 1+, 2+, 3+ growth), and was significantly higher in those specimens that grew a potential pathogen. Both higher copy number and bacterial detections found by the PN panel, but not found in culture, were strongly positively related to the level of WBC reported in the initial gram stain. Conclusions Higher copy number and bacterial detections per se by the PN panel are related to the host respiratory tract inflammatory response. If laboratories can achieve a rapid turnaround time, the PN panel should have a significant impact both to patient management and to antibiotic stewardship.

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