Accuracy of Nanosphere Verigene Gram-Negative Blood Culture (BC-GN) Test for Rapid Detection of Extended-Spectrum Beta-Lactamases (ESBLs) From Positive Blood Cultures

2019 ◽  
Vol 152 (Supplement_1) ◽  
pp. S17-S18
Author(s):  
Dennise Otero ◽  
Clay Patros ◽  
Erin McElvania ◽  
Kamaljit Singh
Keyword(s):  
Primary Objective ◽  
Blood Cultures ◽  
Diffusion Method ◽  
M Gene ◽  
Disk Diffusion Method ◽  
Gram Negative ◽  
Extended Spectrum Beta Lactamases ◽  
Hospital Acquired ◽  
Community Onset ◽  
Esbl Producers

Abstract Background The rapid and accurate detection of ESBL production in Gram-negative rod (GNR) bacteremia is critical as recent data suggest that carbapenem treatment decreases mortality. At the same time, avoiding widespread empiric carbapenem prescribing is an important goal of antimicrobial stewardship teams. The aim of this retrospective review was to determine the accuracy of a nucleic acid–based test, Luminex Verigene BC-GN panel, to detect ESBL-positive GNRs direct from blood cultures. Methods The Verigene BC-GN was performed on all first positive GNR blood cultures. In addition, routine antibiotic susceptibility testing was performed on all isolates by the disk-diffusion method and included phenotypic ESBL testing using cefotaxime and ceftazidime with and without clavulanate. Escherichia coli, Klebsiella spp., and Proteus mirabilis–positive blood cultures were identified as ESBL producers through either Verigene or phenotypic disk testing. Positive GNR blood cultures from February 2016 to July 2017 were included for review. The primary objective was to determine the sensitivity and specificity of Verigene for detection of ESBLs. The secondary objective was assessing the percent of community-onset and hospital-acquired ESBL-positive blood cultures. Results There were 83 positive blood cultures with ESBL producing GNR included in the primary review. A total of 82 of 83 positive GNR blood cultures were CTX-M gene positive via Verigene (sensitivity 98.8%). All 83 cultures were confirmed as ESBL producers via phenotypic tests. There were no positive Verigene cases with negative phenotypic results. All 68 ESBL E coli–positive cultures were detected by Verigene (100%), 10 ESBL K pneumoniae (100%), and four of the five ESBL P mirabilis–positive cultures (80%). Of the 73 results available for review in the secondary objectives, 68 were community onset (93%) and five were hospital acquired (7%). Conclusion The majority of ESBL-positive blood cultures in a low-prevalence setting were due to CTX-M producers. The Luminex Verigene BC-GN was accurate in detecting ESBL-producing Enterobacteriaceae from blood cultures and can be reliably used to guide antimicrobial therapy.

scholarly journals The frequency of resistance to antibiotics of most frequently isolated bacteria from blood cultures during the period 1997-2002

2004 ◽  
Vol 61 (4) ◽  
pp. 391-397
Author(s):  
Veljko Mirovic ◽  
Branka Tomanovic ◽  
Sonja Konstantinovic
Keyword(s):  
Clinical Laboratory ◽  
Blood Cultures ◽  
Diffusion Method ◽  
National Committee ◽  
Disk Diffusion Method ◽  
Beta Lactamases ◽  
Resistance To Antibiotics ◽  
Extended Spectrum Beta Lactamases ◽  
High Level

The aim of this study was to determine the frequency of resistance to antibiotics of the most frequently isolated bacteria from blood cultures of hospitalized patients during the period 1997-2002. The resistance to antibiotics was determined by disk diffusion method according to National Committee for Clinical Laboratory Standards procedures. The majority of staphylococci isolates were resistant to methicillin, and the proportion of methicillin-resistant Staphylococcus aureus was stable (76.8-81.6%), during the follow-up period. None of the staphylococci isolates were resistant to vancomycin, but there was a very high incidence of high-level resistance of enterococci to aminoglycosides (47.2-72.2%). In 1998, only one strain among enterococci was resistant to vancomycin (Enterococcus faecium, VanA fenotype). Enterococcus spp isolates expressed variable frequency of resistance to ampicillin (15-40.1%) during the follow-up period. Among Enterobacteriaceae there were no isolates resistant to imipenem, but dramatic increase of the resistance to ceftriaxone was found from 35.9% in 1997 to 95.9% in 2002 (p<0.001). Extended spectrum beta-lactamases production was found in all the species of enterobacteria isolates. Resistance to imipenem was observed in Acinetobacter spp isolates in 2002 for the first time. Pseudomonas spp isolates expressed high and very variable resistance to all antibiotics tested during the follow-up period.

scholarly journals Detection of TEM and CTX-M Genes in Escherichia coli Isolated from Clinical Specimens at Tertiary Care Heart Hospital, Kathmandu, Nepal

Diseases ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 15
Author(s):  
Ram Shankar Prasad Sah ◽  
Binod Dhungel ◽  
Binod Kumar Yadav ◽  
Nabaraj Adhikari ◽  
Upendra Thapa Shrestha ◽  
...  
Keyword(s):  
Antimicrobial Resistance ◽  
Clinical Isolates ◽  
Diffusion Method ◽  
Gram Negative Bacteria ◽  
Bacterial Isolates ◽  
Disk Diffusion Method ◽  
Gram Negative ◽  
Clinical Specimens ◽  
E Coli ◽  
Esbl Producers

Background: Antimicrobial resistance (AMR) among Gram-negative pathogens, predominantly ESBL-producing clinical isolates, are increasing worldwide. The main aim of this study was to determine the prevalence of ESBL-producing clinical isolates, their antibiogram, and the frequency of ESBL genes (blaTEM and blaCTX-M) in the clinical samples from patients. Methods: A total of 1065 clinical specimens from patients suspected of heart infections were collected between February and August 2019. Bacterial isolates were identified on colony morphology and biochemical properties. Thus, obtained clinical isolates were screened for antimicrobial susceptibility testing (AST) using modified Kirby–Bauer disk diffusion method, while ESBL producers were identified by using a combination disk diffusion method. ESBL positive isolates were further assessed using conventional polymerase chain reaction (PCR) to detect the ESBL genes blaTEM and blaCTX-M. Results: Out of 1065 clinical specimens, 17.8% (190/1065) showed bacterial growth. Among 190 bacterial isolates, 57.4% (109/190) were Gram-negative bacteria. Among 109 Gram-negative bacteria, 40.3% (44/109) were E. coli, and 30.2% (33/109) were K. pneumoniae. In AST, 57.7% (n = 63) Gram-negative bacterial isolates were resistant to ampicillin and 47.7% (n = 52) were resistant to nalidixic acid. Over half of the isolates (51.3%; 56/109) were multidrug resistant (MDR). Of 44 E. coli, 27.3% (12/44) were ESBL producers. Among ESBL producer E. coli isolates, 58.4% (7/12) tested positive for the blaCTX-M gene and 41.6% (5/12) tested positive for the blaTEM gene. Conclusion: Half of the Gram-negative bacteria in our study were MDR. Routine identification of an infectious agent followed by AST is critical to optimize the treatment and prevent antimicrobial resistance.

scholarly journals Extended Spectrem Beta Lactamases among Multi Drug Resistant Gram Negetive Bacilli Causing Urinry Tract Infection

2019 ◽  
Vol 5 (1) ◽  
pp. 25-28
Author(s):  
Ganga Sagar Bhattarai ◽  
Dipendra , Shrestha ◽  
Bishnu Raj Tiwari
Keyword(s):  
Urinary Tract ◽  
Tract Infection ◽  
Diffusion Method ◽  
Gram Negative ◽  
Beta Lactamases ◽  
Extended Spectrum ◽  
The Status ◽  
Extended Spectrum Beta Lactamases ◽  
Tract Infections ◽  
Esbl Producers

Extended Spectrum Beta Lactamases (ESBL), the main cause of resistance to broad spectrum β-lactams, among uropathogenic bacteria have increased over time raising a global concern in the therapeutic management of infections caused by these organisms. The study was carried out in Janamaitri Hospital, Kathmandu between December 2012 to May 2013 with an objective to determine the status of ESBL producing Gram negative bacilli isolated from the urine sample, collected from patients suspected of urinary tract infection. Gram negative bacilli isolated were tested for the presence of ESBL by combined disk and antibiotic susceptibility by Kirby Bauer disc diffusion method following Clinical and Laboratory Standard Institute guidelines. Among the total 1105 mid-stream urine samples, 256 Gram negative bacilli were isolated. By screening test using third generation cephalosporins, 156 isolates were screened as ESBL producers and 91 isolates were positive for ESBL test by combined disk method. Among the 91 (35.55%) ESBL producers, 70 (39.32%) Escherichia coli, 16 (44.44%) Klebsiella pneumoniae, and 5 (33.33%) Pseudomonas aeruginosa were found to be ESBL producers. Majority of ESBL producer showed resistance to ampicillin, co-trimoxazole, norfloxacin followed by ofloxacin. imipenem, amikacin and nitrofurantoin seemed to be the agent of choice for urinary tract infections when ESBL producers are susceptible to it. ESBL production found in these Gram negative bacilli with resultant microbial resistance to available cephalosporins and other agents may pose difficulties with the choice of therapeutic options for the treatment of severe infections. Keywords: UTI, Extended Spectrum Beta Lactamases, Gram negative bacilli

scholarly journals 898. Prevalence of Extended Spectrum Beta-Lactamase Producing Escherichia coli, Klebsiella Pneumoniae and Pseudomonas Aeruginosa from Hospital Acquired Surgical Site Infections in Ghana

2020 ◽  
Vol 7 (Supplement_1) ◽  
pp. S483-S483
Author(s):  
Beverly Egyir ◽  
Noah Nkrumah-Obeng ◽  
Edward Nyarko ◽  
Anne Fox ◽  
Andrew Letizia ◽  
...  
Keyword(s):  
Antimicrobial Stewardship ◽  
Surgical Site Infections ◽  
Diffusion Method ◽  
Pcr Analysis ◽  
Bacterial Isolates ◽  
Esbl Production ◽  
M Gene ◽  
Disk Diffusion Method ◽  
E Coli ◽  
Hospital Acquired

Abstract Background Globally, ESBL-producing bacteria pose a great challenge for treating hospital acquired SSI. Currently, the prevalence of ESBL pathogens in Ghana hospitals is poorly understood. Determining the frequency ESBLs are encountered will, in turn, provide insight for antibiogram development and shape antimicrobial stewardship policies in Ghana. Methods Using U.S. CDC criteria for SSI, wound swabs or aspirates were collected from 112 participants who met study inclusion criteria. Specimens were plated on MacConkey and blood agar; then colonies were isolated and identified using MALDI-TOF. Antimicrobial susceptibility testing was performed using the Kirby-Bauer disk diffusion method and interpreted according to the 2018 Clinical and Laboratory Standards Institute (CLSI) guidelines. The combined disk method was used to screen for ESBLs among E.coli and K. pneumoniae isolates. Genes associated with ESBL production (SHV, TEM and CTX-M) were detected using PCR analysis. Results Thirty-eight percent of the bacterial isolates recovered were E. coli, K. pneumonia accounted for 32%, and P. aeruginosa accounted for 16% of the total isolates; remaining isolates were gram positive pathogens not discussed here. ESBL production was detected in 50% of E. coli isolates and 73% of K. pneumoniae isolates. ESBL-producing isolates were susceptible to meropenem but resistant to cefuroxime, cefotaxime, tetracycline, trimethoprim-sulfamethoxazole, gentamicin, ciprofloxacin and chloramphenicol. P. aeruginosa isolates were only sensitive to meropenem, gentamicin, and ciprofloxacin. In our study, CTX-M was the most frequently detected gene producing the ESBL-phenotype: 33% of E. coli isolates and 73% of K. pneumoniae isolates possessed the CTX-M gene. Conclusion Approximately 70% of total bacterial isolates recovered from our SSI study were ESBL producers. The presence of these multi-drug resistant organisms raises clinical concerns due to the absence of routine antimicrobial resistance (AMR) testing and lack of suitable first-line antimicrobials for ESBL pathogens. Improved laboratory capacity to more readily detect MDROs is essential for effective clinical management of patients, antibiogram development and refining antimicrobial stewardship practices in Ghana hospitals. Disclosures All Authors: No reported disclosures

scholarly journals Molecular detection of blaCTX-M gene to predict phenotypic cephalosporin resistance and clinical outcome of Escherichia coli bloodstream infections in Vietnam

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Trinh Van Son ◽  
Nguyen Dang Manh ◽  
Ngo Tat Trung ◽  
Dao Thanh Quyen ◽  
Christian G. Meyer ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Clinical Outcome ◽  
Bloodstream Infections ◽  
Diffusion Method ◽  
M Gene ◽  
Disk Diffusion Method ◽  
Phenotypic Resistance ◽  
E Coli ◽  
Multiplex Pcr Assay ◽  
Esbl Producers

Abstract Background Blood stream infections (BSI) caused by Extended Spectrum Beta-Lactamases (ESBLs) producing Enterobacteriaceae is a clinical challenge leading to high mortality, especially in developing countries. In this study, we sought to describe the epidemiology of ESBL-producing Escherichia coli strains isolated from Vietnamese individuals with BSI, to investigate the concordance of genotypic-phenotypic resistance, and clinical outcome of ESBL E. coli BSI. Methods A total of 459 hospitalized patients with BSI were screened between October 2014 and May 2016. 115 E. coli strains from 115 BSI patients were isolated and tested for antibiotic resistance using the VITEK®2 system. The ESBL phenotype was determined by double disk diffusion method following the guideline of Clinical and Laboratory Standards Institute. Screening for beta-lactamase (ESBL and carbapenemase) genes was performed using a multiplex-PCR assay. Results 58% (67/115) of the E. coli strains were ESBL-producers and all were susceptible to both imipenem and meropenem. Resistance to third-generation cephalosporin was common, 70% (81/115) were cefotaxime-resistant and 45% (52/115) were ceftazidime-resistant. blaCTX-M was the most common ESBL gene detected (70%; 80/115) The sensitivity and specificity of blaCTX-M-detection to predict the ESBL phenotype was 87% (76–93% 95% CI) and 54% (39–48% 95% CI), respectively. 28%% (22/80) of blaCTX-M were classified as non-ESBL producers by phenotypic testing for ESBL production. The detection of blaCTX-M in ESBL-negative E. coli BSI was associated with fatal clinical outcome (27%; 6/22 versus 8%; 2/26, p = 0.07). Conclusion A high prevalence of ESBL-producing E. coli isolates harbouring blaCTX-M was observed in BSI patients in Vietnam. The genotypic detection of blaCTX-M may have added benefit in optimizing and guiding empirical antibiotic therapy of E. coli BSI to improve clinical outcome.

scholarly journals Identification and Antibiotic Susceptibility Testing of ESBL producing Klebsiella strains by Phenotypic methods

2018 ◽  
Vol 9 (1) ◽  
pp. 8-13
Author(s):  
Malik Taqdees ◽  
Asma Naim ◽  
Asma Saeed
Keyword(s):  
Diffusion Method ◽  
Multi Drug Resistance ◽  
Beta Lactamase ◽  
Disk Diffusion Method ◽  
Klebsiella Species ◽  
Gram Negative ◽  
Extended Spectrum Beta Lactamase ◽  
Extended Spectrum ◽  
Klebsiella Spp ◽  
Esbl Producers

Multi drug resistance has now become a worldwide therapeutic challenge due to the widespread use of broad spectrum antibiotics. Klebsiella species have significant importance in clinical field as they cause various infections in human and are considered as potential pathogens that express antibiotic resistance through their strong enzymatic activity. Extended spectrum beta lactamases (ESBLs) are plasmid mediated enzymes produced mostly because of mutation and few other factors.  These enzymes confer resistance against various β-lactam drugs including cephalosporins and monobactams. Among the genus Klebsiella, ESBLs are highly prevalent in K. pneumoniae followed by K. oxytoca. This study was conducted in Pakistan to assess the distribution of ESBL producers among Klebsiella spp., an important member of the family Enterobacteriaceae. From January 2010 to January 2012, a total of 236 gram-negative isolates were collected from different renowned microbiological laboratories. Out of the 236 gram-negative isolates, 125 were found as Klebsiella spp. by using standard microbiological techniques. Antimicrobial susceptibility profiling of these strains was performed by using Kirby Bauer disk diffusion method. Phenotypic detection of the production of extended spectrum beta lactamase enzyme was performed using double disc synergy method and combination disc method. It has been identified that Klebsiella strains are highly resistant against Amoxicillin, Tetracycline, Nalidixic Acid, Cephradine, Gentamicin, co-amoxyclav with the percentage of 100%, 86%, 86%, 82%, 82% and 80% respectively. The most effective antibiotics for Klebsiella spp. were found to be Amikacin, Meropenem and Piperacillin-tazobactam, with highest sensitivities of 96%, 94% and 91%. Phenotypic detection of Extended spectrum beta lactamase production by double disc synergy test was able to identify 28% ESBL producers among Klebsiella isolates whereas 64% were detected by combination disc test.

scholarly journals Detection of Extended Spectrum Beta-Lactamases Among Gram Negative Bacilli Recovered from Cattle Feces In Benin City, Nigeria

2017 ◽  
Vol 9 (2) ◽  
pp. 177-181 ◽  
Author(s):  
Helen Oroboghae OGEFERE ◽  
Salome O. AGBE ◽  
Ephraim Ehidiamen IBADIN
Keyword(s):  
Diffusion Method ◽  
Gram Negative Bacteria ◽  
Bacterial Isolates ◽  
Disk Diffusion Method ◽  
Gram Negative ◽  
Extended Spectrum Beta Lactamase ◽  
Benin City ◽  
Cattle Feces ◽  
Extended Spectrum ◽  
Extended Spectrum Beta Lactamases

This study was carried out to determine the prevalence of extended spectrum beta-lactamase (ESBL) among Gram negative bacteria isolated from cattle feces in Benin City, Nigeria. A total of 250 Gram negative bacteria isolates were recovered from cattle feces and were processed microbiologically using standard techniques. Emergent colonies were identified and antibacterial susceptibility tests were determined using Kirby-Bauer disk diffusion method. All bacterial isolates were screened for the presence of ESBL using the double-disc synergy method. A total of 37 (14.8%) isolates were positive for ESBL, with 33 (13.2%) indicated by ceftazidime, while only 4 (1.6%) were indicated by both ceftazidime and cefotaxime (P < 0.0001). Of the Gram negative bacterial isolates recovered, Salmonella species was the most prevalent ESBL-producer with 55.0% prevalence (P = 0.0092), while no isolate of Pseudomonas aeruginosa produced ESBL. ESBL-positive isolates showed poor susceptibility to the tested antibacterial agents in comparison with non-ESBL-producers and imipenem was the most active antibiotic. The prevalence of ESBL among Gram negative bacilli recovered from cattle feces was 14.8%. The study advises prudent use of antibiotics in the treatment of cattle and harps on improved hygiene in managing cattle, as they are potential reservoirs of ESBL-producing organisms.

scholarly journals Direct Detection of Extended Spectrum β-Lactamases from Positive Blood Cultures by using Aztreonam and Clavulanate

2021 ◽  
Author(s):  
Renji Francis ◽  
Ambica Rangaiah ◽  
Kusuma Gowdra Rangappa ◽  
Shwetha Jinnahalli Venugopal
Keyword(s):  
Target Genes ◽  
Direct Detection ◽  
Blood Cultures ◽  
Diffusion Method ◽  
Disc Diffusion ◽  
Gram Stain ◽  
Esbl Production ◽  
Disc Diffusion Method ◽  
Gram Negative ◽  
Esbl Producers

Introduction: Bacterial Sepsis by Multidrug Resistant Gram Negative Bacilli (MDRGNB) producing Extended Spectrum β-Lactamases (ESBL) is one of the major causes of mortality and morbidity in hospitals. Early detection of ESBLs directly from positive blood cultures can reduce mortality. The phenotypic detection of ESBLs is difficult as they may be masked by the co-production of additional enzymes like AmpC. This can be overcome by using an Aztreonam Discs With and Without Clavulanate (AO/CL) method. Aim: To identify ESBLs directly from the positive blood cultures by using AO/CL disc diffusion method and to detect the genes coding for ESBL enzymes by conventional Polymerase Chain Reaction (PCR). Materials and Methods: A prospective study was conducted over a period of five months (October 2020-February 2021). A total of 100 positive blood cultures showing Gram-negative bacilli on Gram stain was subjected to direct detection of ESBLs by using Cefotaxime (CTX), Ceftazidime (CAZ) discs with and without clavulanate and AO/CL. Isolates from positive blood culture were identified to genus and species level by VITEK-2 compact. Isolates were tested for ESBL production by CAZ/CTX with and without clavulanate disc diffusion method as recommended by CLSI. PCR was carried out to detect target genes responsible for ESBL production such as CTX–M, TEM, SHV genes. Statistical analysis was done by using MS Excel sheet. Descriptive statistics like percentage calculation was done in the study. Results: Out of 100 positive blood cultures showing Gram Negative Bacteria (GNB) on Gram stain, 33 were positive for ESBL production by direct disc diffusion method. Out of these, 27 ESBL producers were detected by CAZ/CTX with and without clavulanate disc diffusion method and AO/CL method whereas six ESBL producers were detected by AO/CL disc diffusion method only. A 27 culture isolates were found positive for ESBL production by CAZ/CTX with and without clavulanate disc diffusion method as recommended by Clinical and Laboratory Standards Institute (CLSI). Out of 33, 28 (85%) isolates possessed one of the target genes for ESBL production such as 10TEM (36%), 10CTX-M (36%), 07TEM+CTX M (25%), 01SHV (3%). Conclusion: Direct detection of ESBLs plays a significant role in management of sepsis. It helps the clinician in escalation and de-escalation of antibiotics and prevents the development of antimicrobial resistance. It contributes towards antibiotic stewardship and better compliance to infection prevention and control protocols. AO/CL method is preferred to detect ESBL producers directly from positive blood culture bottles.

scholarly journals 114. Implementation of an Empiric Organism Specific Guidelines for Gram-negative Bacteremia in conjunction with Rapid Diagnostic Testing

2020 ◽  
Vol 7 (Supplement_1) ◽  
pp. S71-S71
Author(s):  
Fidelia Bernice ◽  
Edina Avdic ◽  
Kathryn Dzintars ◽  
Aliyah Cruz
Keyword(s):  
Clinical Status ◽  
Compliance Rate ◽  
Diagnostic Testing ◽  
Specific Treatment ◽  
Resistance Mechanisms ◽  
Primary Objective ◽  
Blood Cultures ◽  
Common Reason ◽  
Empiric Antibiotic Therapy ◽  
Gram Negative

Abstract Background The objective of this study was to confirm the validity of institution specific treatment recommendations targeting organisms identified by GenMark Dx® ePlex® blood cultures identification (BCID) Gram-negative panel prior to susceptibility results. Methods We developed and implemented institution specific guidelines for empiric antibiotic therapy for Gram-negative organisms targeted by GenMark Dx® ePlex® BCID. We utilized blood culture antibiograms, existing evidence for the most optimal agent for each pathogen, probable resistance mechanisms and patient clinical status to create these guidelines. From December 16, 2019 through May 31, 2020, infectious diseases pharmacists reviewed all positive blood cultures; assessed compliance with guidelines and intervened as needed. The primary objective was to determine how frequently guideline recommend agents would be ineffective against targeted pathogens based on susceptibilities. Secondary objectives were compliance with guidelines and frequency of therapy escalation or de-escalation. Results GenMark® testing was completed on 222 cultures positive for Gram-negative rods with target organisms identification in 195 (88%) blood cultures. Two hundred and five organisms were identified; most commonly E. coli (40%) and K. pneumoniae (21%).Resistance markers were detected in 30 aerobic blood cultures; 28 CTX-M, and 2 KPC. Our institutional guideline provided appropriate empiric coverage in 93% of bacteremia episodes. The most common reason for ineffective therapy was the presence of resistance mechanisms not detected by GenMark® test (e.g. non-CTX-M extended spectrum beta-lactamases). The compliance rate with the guidelines was 55%; the most common reason for non-compliance was the use of an anti-pseudmonal beta-lactams in neutropenic patients.. The system failed to identify panel organisms in only 5 (2%) of blood cultures. Conclusion The institution-specific guidelines providing empiric coverage for each organism identified by rapid diagnostic tests can aid antimicrobial stewardship efforts to de-escalate therapy while still providing effective coverage in &gt;90% of cases. Disclosures All Authors: No reported disclosures.

scholarly journals 660. Evaluation of Qvella’s FAST-Prep™ Liquid Colony™ for Early Antimicrobial Sensitivity Testing of Positive Blood Culture by Disk Diffusion Method

2020 ◽  
Vol 7 (Supplement_1) ◽  
pp. S386-S386
Author(s):  
Susan M Novak-Weekley ◽  
Aye Aye Khine ◽  
Tino Alavie ◽  
Namidha Fernandez ◽  
Laxman Pandey ◽  
...  
Keyword(s):  
Direct Method ◽  
Viable Cell ◽  
Turnaround Time ◽  
Disk Diffusion ◽  
Diffusion Method ◽  
Gram Negative Bacteria ◽  
Sensitivity Testing ◽  
Gram Positive ◽  
Disk Diffusion Method ◽  
Gram Negative

Abstract Background Conventional antimicrobial susceptibility testing (AST) of microorganisms from positive blood cultures (PBC) can take ≥ 2 days. In order to improve the turnaround time for AST on a PBC, CLSI and EUCAST have made efforts to standardize procedures for disk diffusion (DD) direct from a PBC. Qvella Corporation (Richmond Hill, ON, Canada) has recently developed FAST-Prep, an automated centrifugal sample preparation system that rapidly delivers a Liquid Colony consisting of a purified, concentrated, viable cell suspension directly from a PBC. This study was performed to investigate the feasibility of DD AST off of a PBC using a FAST-Prep Liquid Colony. Methods Contrived PBC samples were prepared by spiking 6 species of Gram-positive and 4 species of Gram-negative bacteria (3-5 strains per species) into FA® Plus bottles and incubating in the BACT/ALERT® VIRTUO® System (bioMerieux, Durham, NC). After positivity, 3 mL of PBC was added to the FAST-Prep cartridge. After 20 minutes of processing in the FAST-Prep instrument, the Liquid Colony was removed from the cartridge and a 0.5 McFarland sample was prepared for DD AST. In parallel, the DD AST from a PBC was performed using 4 drops of PBC (CLSI direct method). Both methods were compared to conventional colony-based DD AST. After 16-18 hours of incubation zone diameters and S/I/R interpretations were determined. Categorical agreement (CA) and errors for both DD AST methods were calculated. In addition, colony plate counting was performed on 0.5 McFarland suspensions of Liquid Colony and the plate colony to determine biomass recovery and sample purity. Results CA for a FAST-Prep DD AST for Gram-positive and Gram-negative bacteria was 95.6% and 98.6%, respectively, compared to CA for CLSI DD AST of 77.2% and 81.9%, respectively. Biomass in the Liquid Colony was 7.2x108 and 1.2x109 CFU for Gram-positive and Gram-negative bacteria, respectively. Cell concentration in the 0.5 McFarland suspension of the Liquid Colony was 3.7x107 and 5.9x107 CFU/mL for Gram-positive and Gram-negative bacteria, respectively, which was similar to the concentration for the reference colony suspension. Conclusion The results support the potential role of FAST-Prep in providing a Liquid Colony for use in rapid AST. Disclosures Susan M. Novak-Weekley, PhD, D(ABMM), Qvella (Employee, Shareholder) Aye Aye Khine, PhD, Qvella (Employee, Shareholder) Tino Alavie, PhD, Qvella (Employee) Namidha Fernandez, MS, Qvella (Employee) Laxman Pandey, MS, Qvella (Employee) Abdossamad Talebpour, PhD, Qvella (Employee, Shareholder)

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