Blood Culture Metrics Are Human Metrics: The Missed Opportunity for Clinical Laboratory Quality Measures to Improve the Overall Blood Culture Process

Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) can accurately identify bloodstream pathogens directly from positive blood culture bottles without the need to wait for agar plate growth. In this study, 2% sodium dodecyl sulfate (SDS) detergent was assessed to determine its benefit in the removal of interfering cellular components for testing on the Bruker Microflex LT MALDI-TOF MS instrument with the Biotyper® CA system. Additionally, the use of a heat-drying step was evaluated for performance improvement over conventional air-drying of samples on the MALDI steel target plate. The modified method with 2% SDS outperformed the in-house protocol in overall success with percentage scores of 91% and 55% ( respectively). The data results support the potential of applying a simple lysing step to an existing in-house extraction method and the use of modified drying methods. The modified techniques evaluated in this study proved beneficial for identifying most blood culture pathogens encountered in the clinical laboratory, and they can allow for reduced turnaround times and more appropriate antibiotic treatments.

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2559. Incidence and Clinical Impact of Discordant Genotypic and Phenotypic Categorization of Methicillin Susceptibility in Staphylococcus aureus Bacteremia

Open Forum Infectious Diseases ◽

10.1093/ofid/ofy209.167 ◽

2018 ◽

Vol 5 (suppl_1) ◽

pp. S70-S70

Author(s):

Jessica Gulliver ◽

Brittney Jung-Hynes ◽

Derrick Chen

Keyword(s):

Staphylococcus Aureus ◽

Blood Culture ◽

Positive Blood Culture ◽

Clinical Laboratory ◽

Laboratory Data ◽

Rapid Identification ◽

Clinical Impact ◽

Staphylococcus Aureus Bacteremia ◽

Oxacillin Resistance ◽

Initial Hospitalization

Abstract Background Methicillin-susceptible/methicillin-resistant Staphylococcus aureus (MSSA/MRSA) can be directly identified from positive blood culture bottles using molecular methods. This provides faster results than traditional phenotypic testing, but discrepancies between the two are occasionally found. We sought to determine the incidence and clinical impact of such discrepancies. Methods Positive blood culture bottles are routinely tested in the hospital clinical laboratory for mecA via Xpert MRSA/SA BC (PCR), and antimicrobial susceptibility testing (AST) via MicroScan PC33 is performed on recovered S. aureus isolates; discrepancies between PCR and AST are resolved by repeat and supplemental (Kirby-Bauer) testing. A retrospective review of medical and laboratory data from January 2015 to December 2017 was performed on all patients that had discordant PCR and AST results. Results Approximately 1,200 PCR assays were performed from January 2015 to December 2017, and there were 5 (0.4%) cases with discordant AST Results. Four cases were classified as MSSA by PCR but MRSA by AST, and 1 case was classified as MRSA by PCR but MSSA by AST. For the former group, antimicrobial therapy was changed in 2 patients to cover MRSA and 1 patient was readmitted, while the remaining 2 patients were already being treated for MRSA; for the latter case, this patient was treated for MRSA during the initial hospitalization, but was readmitted with disseminated MSSA and subsequently deceased. Based on genetic targets identified by PCR and cefoxitin and oxacillin AST, discrepancies were likely due to borderline oxacillin resistance (BORSA) (n = 1), presence of an SCCmec variant not detected by PCR (n = 1), or undetermined (n = 3). Conclusion Rapid identification of MRSA bacteremia via PCR provides actionable information to direct empiric treatment. While highly accurate, PCR results are infrequently not corroborated by AST. This rare possibility should be considered when modifying therapy based on initial PCR results, and there should be close communication between the clinical team and laboratory for these challenging cases. Disclosures All authors: No reported disclosures.

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

Journal of Clinical Microbiology ◽

10.1128/jcm.01521-17 ◽

2017 ◽

Vol 56 (3) ◽

Cited By ~ 17

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.

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Direct-from-Blood-Culture Disk Diffusion To Determine Antimicrobial Susceptibility of Gram-Negative Bacteria: Preliminary Report from the Clinical and Laboratory Standards Institute Methods Development and Standardization Working Group

Journal of Clinical Microbiology ◽

10.1128/jcm.01678-17 ◽

2018 ◽

Vol 56 (3) ◽

Cited By ~ 27

Author(s):

Sukantha Chandrasekaran ◽

April Abbott ◽

Shelley Campeau ◽

Barbara L. Zimmer ◽

Melvin Weinstein ◽

...

Keyword(s):

Blood Culture ◽

Clinical Laboratory ◽

Blood Cultures ◽

Disk Diffusion ◽

Random Errors ◽

Disk Diffusion Test ◽

Potential Accuracy ◽

Content Type ◽

Methods Development ◽

Zones Of Inhibition

ABSTRACTThe performance of a disk diffusion test using broth from positive blood cultures as inoculum (direct disk diffusion [dDD]) was evaluated for a collection of 20 challenge isolates ofEnterobacteriaceae,Acinetobacter baumannii, andPseudomonas aeruginosa. Isolates seeded into human blood were inoculated into Bactec Plus Aerobic/F, VersaTREK Redox 1, and BacT/Alert FA Plus bottles and incubated in the respective automated blood culture systems. Disk diffusion results were compared to reference disk diffusion results. Categorical agreement (CA) values for dDD, after removal of random errors due to natural MIC variation, were 87.8%, 88.4%, and 92.2% for the BacT/Alert, Bactec, and VersaTREK systems, respectively. No very major errors (VME) were observed, and major error (ME) rates were 3.0%, 2.3%, and 1.7%, respectively. Incubation of the dDD test samples for 6 h compared to incubation for 16 to 18 h resulted in 19.9% of tests having too light of growth to allow reading of zones of inhibition. Among the evaluable dDD tests, CA values were 58.9%, 76.6%, and 73.2% for the isolates seeded into the BacT/Alert, Bactec, and VersaTREK systems, respectively. VME rates for isolates seeded into these systems were 2.2%, 1.8%, and 3.0%, respectively, and ME rates were 25.4%, 6.1%, and 2.8%, respectively, at the 6-h reading. The best performance of dDD was found for blood cultures with bacterial concentrations in the range of 7.6 × 107to 5.0 × 108CFU/ml; CA values ranged from 94.7 to 96.2% for these concentrations after 18 h of incubation and from 76.9 to 84.1% after 6 h of incubation. These preliminary data demonstrate the potential accuracy of dDD testing by the clinical laboratory.

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Effect of Clinical Variables on the Volume of Blood Collected for Blood Cultures in an Adult Patient Population

Infection Control and Hospital Epidemiology ◽

10.1017/ice.2017.230 ◽

2017 ◽

Vol 38 (12) ◽

pp. 1493-1497 ◽

Cited By ~ 9

Author(s):

R. Logan Jones ◽

Harlan R. Sayles ◽

Paul D. Fey ◽

Mark E. Rupp

Keyword(s):

Blood Culture ◽

Clinical Laboratory ◽

Statistical Significance ◽

Academic Medical Center ◽

Blood Cultures ◽

Charlson Comorbidity Index Score ◽

Central Venous ◽

Culture Volume ◽

Clinical Variables ◽

Volume Recovery

OBJECTIVETo identify clinical variables that influence blood culture volume recoveryDESIGNRetrospective chart review and linear model analysisSETTINGA 621-bed Academic Medical Center with a Clinical Laboratory that processes 20,000+ blood cultures annually and dedicated phlebotomy staff for venipuncturePATIENTSConsecutive patients requiring blood cultureMETHODSOver a 6-day period, blood volume was determined in 568 culture bottles from 128 unique adult patients, and clinical data from the time of phlebotomy were extracted from hospital electronic medical records. Conditional hierarchical linear models with random effects for patient and phlebotomy occasion were utilized to analyze correlations between values collected from the same patient and during the same phlebotomy occasion.RESULTSBlood samples obtained from a central venous catheter yielded, on average, 2.53 mL more blood (95% CI, 1.63–3.44 mL;P<.001) than those from peripheral venipuncture, and aerobic bottles contained 0.38 mL more blood (95% CI, 0.1–0.67 mL;P=.009) than the anaerobic bottles. The remaining clinical variables (eg, hospital department, patient age, body mass index, gender, mean arterial pressure, concomitant systemic antibiotic use, and Charlson comorbidity index score) failed to reach statistical significance (P<.05) in relation to volume.CONCLUSIONSBlood cultures obtained from central venous catheters contain significantly greater volume than those obtained via peripheral venipuncture. These data highlight the clinically significant issue of low culture volume recovery, indicate that diagnostic and prognostic tools that rely on volume-dependent phenomena (ie, time to positivity) may require further validation under usual clinical practice circumstances, and suggest goals for future institutional performance improvement.Infect Control Hosp Epidemiol2017;38:1493–1497

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Clinical laboratory comparison of the 10-ml isolator blood culture system with BACTEC radiometric blood culture media.

Journal of Clinical Microbiology ◽

10.1128/jcm.20.4.618-623.1984 ◽

1984 ◽

Vol 20 (4) ◽

pp. 618-623 ◽

Cited By ~ 32

Author(s):

J A Kellogg ◽

J P Manzella ◽

J H McConville

Keyword(s):

Blood Culture ◽

Culture System ◽

Clinical Laboratory ◽

Culture Media ◽

Blood Culture System

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Can BacT/Alert FA and FN blood culture bottles increase the recovery of microorganisms in the clinical laboratory?

Journal of Infection and Chemotherapy ◽

10.1007/s10156-004-0349-8 ◽

2004 ◽

Vol 10 (6) ◽

pp. 343-347 ◽

Cited By ~ 3

Author(s):

Takashi Saito ◽

Yoshitsugu Iinuma ◽

Shunji Takakura ◽

Naoko Fujihara ◽

Toyoichiro Kudo ◽

...

Keyword(s):

Blood Culture ◽

Clinical Laboratory

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1217. Clinical and Microbiological Characteristics of Patients with Bacteremia and Normal Procalcitonin at Single Tertiary Care Medical Center

Open Forum Infectious Diseases ◽

10.1093/ofid/ofaa439.1402 ◽

2020 ◽

Vol 7 (Supplement_1) ◽

pp. S630-S630

Author(s):

Leora Boussi ◽

Tarun Popli ◽

Nicholas Feola ◽

Rajat Nog

Keyword(s):

Blood Culture ◽

Bacterial Infections ◽

Clinical Laboratory ◽

Medical Center ◽

Tertiary Care ◽

High Sensitivity ◽

Culture Collection ◽

Contributing Factors ◽

Tertiary Care Medical Center ◽

Microbiological Characteristics

Abstract Background Procalcitonin (PCT) is a serum biomarker used to diagnose bacterial infections and guide antibiotic therapy. Many studies highlight its high sensitivity, specificity, and negative predictive value for bacteremia. PCT > 2ng/mL has been reported to be strongly indicative of systemic bacterial infection, with values of .5-2ng/mL suggesting localized infection and < .5ng/mL strongly suggesting absence of infection. However, emerging reports have raised concerns about PCT in bacteremia, demonstrating low sensitivity. Few studies have characterized patients with bacteremia and low PCT. We aimed to analyze the clinical and microbiological characteristics of patients with bacteremia and PCT < 2ng/mL. Methods Adult patients admitted at Westchester Medical Center with bacteremia and associated PCT level within 24 hours (hrs) prior to 48 hrs post blood culture collection from 1/1/2014-9/30/2019 were included. Demographic, clinical, laboratory, and microbiological data were retrospectively collected and analyzed. Results There were 414 total cases of bacteremia with an associated PCT level within 24 hrs prior to 48 hrs post blood culture collection. 209 of 414 (50.5%) patients had PCT < 2ng/mL. Of these, 86 were excluded (73 contaminants, defined as bacteremia not causing systemic inflammation and not treated, 10 fungal cultures, and 3 lacking data). Of the remaining 123 (37.5%) patients with PCT < 2ng/mL, 66 (53.7%) had PCT<. 5ng/mL. The leading infection source was endovascular/line-related at 31.7%, followed by intraabdominal/gastrointestinal and urinary. 30.9% of bloodstream organisms were gram negative. Among these 123 patients with PCT < 2ng/mL, in-hospital mortality with bacteremia clinically contributing to death was 13%. Characteristics of patients with bacteremia and procalcitonin < 2ng/mL Conclusion Despite literature supporting the use of PCT algorithms in initiation and de-escalation of antibiotics in patients with suspected bacterial infections, a substantial percentage of bacteremic patients can have low PCT but significant infection-related mortality. Therefore, PCT should not be the only factor utilized by clinicians in the management of such patients, including initiating or deescalating antibiotics. Further studies are needed to characterize patient characteristics as contributing factors for bacteremia with low PCT. Disclosures All Authors: No reported disclosures

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Clinical Laboratory Profile of Blood Culture Proven Enteric Fever in Children

Journal of Nepal Paediatric Society ◽

10.3126/jnps.v38i3.27512 ◽

2018 ◽

Vol 38 (3) ◽

pp. 153-156

Author(s):

Subhash Chandra Shah ◽

Prashank Shree Neupane ◽

Anusmriti Guragain ◽

Ajaya Kumar Dhakal

Keyword(s):

Blood Culture ◽

Enteric Fever ◽

Clinical Laboratory ◽

Salmonella Typhi ◽

Total Leucocyte Count ◽

Laboratory Findings ◽

Clinical Presentations ◽

Associated Symptoms ◽

Laboratory Profile ◽

The Mean

Introduction: Enteric fever has diverse clinical presentations and laboratory findings and blood culture is gold standard for diagnosis in the children. This study was done to analyse clinical profile and laboratory findings in culture proven enteric fever. Material and Methods: The study was descriptive observational study carried out in the patient aged 14 years of age or less admitted with culture proven enteric fever admitted in a Paediatric ward of a tertiary medical centre in Lalitpur, Nepal from April 2009 to February 2018. Results: Forty children with blood culture proven were enrolled in the study. All children had fever with the mean duration of 5.3 days (1-14). The most common associated symptoms were gastrointestinal which included anorexia (47.5%), pain abdomen (37.5%), vomiting (37.5%), diarrhoea (15%) and constipation (5 %). Splenomegaly (25%) and hepatomegaly (17.5%) were the commonest signs. The majority of children (80%) had normal total leucocyte count and 32.5% of them had anaemia. There were no children with thrombocytopenia. Salmonella typhi and Salmonella paratyphi A were isolated in 70% and 30% of children respectively. None of the isolates showed drug resistance against ceftriaxone, chloramphenicol, cotrimoxazole, gentamicin, norfloxacin and ofloxacin. There was no mortality. Conclusions: Enteric fever should be suspected in all the children with fever for more than five days along with anorexia, gastrointestinal associated symptoms and normal white blood counts.

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