1222. Fosfomycin Susceptibility Testing using the new ETEST®FO

Abstract Background Fosfomycin (FO) is a bactericidal antibiotic with a broad spectrum of activity against a wide range of Gram-positive and Gram-negative bacteria. Oral FO is mainly used in the treatment of urinary tract infections, particularly those caused by E. coli and E. faecalis. In order to determine MICs to FO, the ETEST® FM is already available but the reading can be difficult especially with E. coli. To resolve this issue, a new ETEST® with FO, called ETEST® FO, has been developed (not FDA cleared, yet). The purpose of this study is to compare this new strip to the agar dilution reference method (AD) on a panel of E. coli and E. faecalis. Methods A total of 39 isolates comprising 20 E. coli (ESBL or CPE) and 19 E. faecalis (VRE or VSE) were tested by ETEST® FO and Agar dilution. The isolates were sub-cultured on Columbia agar plates supplemented with 5% sheep blood before testing. After incubation, suspensions of the isolates were prepared in 0.85% saline. These suspensions were used to inoculate both AD and ETEST® plates. Results were read after 16-20 hours incubation at 35°C +2°C in ambient air. Following CLSI QC guideline, 4 QC organisms were tested. Results were analyzed using the FDA/CLSI breakpoints for FO (S < 64µg/mL, I=128 µg/mL, R> 256 µg/mL). Performance was evaluated using FDA performance criteria, essential agreement (EA, ≥ 90%), category agreement (CA, ≥ 90%), major error rate (ME, ≤3.0%) and very major error rate (VME, ≤2.0%). Results All the QC strains MICs were within the CLSI ranges. For the panel results, see the table below: Performance for ETEST® FO on E. coli and E. faecalis Conclusion This first and preliminary study shows that ETEST® FO can potentially meet the FDA acceptance criteria and could be a valuable tool for determining FO MIC for E. coli harboring various resistance mechanisms and E. faecalis including VRE. Moreover, in comparison with the current ETEST FM strip, this new strip brings a real reading improvement and resolve the issue for E. coli. The clinical study phase will determine the product’s performance. Disclosures Marion Pompilio, BioMérieux (Employee) Gilles Zambardi, biomerieux (Employee)

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1227. Plazomicin Susceptibility Testing using ETEST® MIC for Enterobacterales

Open Forum Infectious Diseases ◽

10.1093/ofid/ofaa439.1412 ◽

2020 ◽

Vol 7 (Supplement_1) ◽

pp. S634-S634

Author(s):

Yun Ying ◽

Tom Armstrong ◽

Laurine Blanchard ◽

Michael Kresken ◽

Gilles Zambardi ◽

...

Keyword(s):

Error Rate ◽

Clinical Performance ◽

Treatment Options ◽

Klebsiella Oxytoca ◽

Reference Method ◽

Ambient Air ◽

Performance Criteria ◽

Major Error ◽

High Level ◽

Tract Infections

Abstract Background Plazomicin (PLZ) approved by FDA in June of 2018, is an aminoglycoside class antibacterial indicated for the treatment of adults with complicated urinary tract infections (cUTI) including pyelonephritis caused by Enterobacterales. It is used in patients who have limited or no alternative treatment options, e.g. CRE and MDRO patients. The drug has bactericidal activity, it is active against organisms producing ESBL, Carbapenemase and aminoglycoside-modifying enzymes. The purpose of this study was to compare ETEST® PLZ bioMérieux to the broth microdilution reference method (BMD) for Citrobacter freundii, Enterobacter cloacae, Escherichia coli, Klebsiella oxytoca and pneumoniae, Morganella morganii, Providencia stuartii, Proteus mirabilis and vulgaris and Serratia marcescens isolates. Methods A total of 598 isolates were tested by ETEST® (PLZ) and BMD at four clinical trial sites. Isolates were subcultured on tryptic soy or Columbia agar plates supplemented with 5% sheep blood. Suspensions of the isolates were prepared in 0.85% saline, which were used to inoculate BMD and Mueller Hinton agar for ETEST®. Results were read after 16-20 hours incubation at 35°C +2°C in ambient air. QC organisms were tested with each run following CLSI QC guidelines. Results were analyzed using FDA breakpoints for PLZ (Susceptible <2 µg/mL, Intermediate 4 µg/mL, Resistant >8 µg/mL). Performance was evaluated using FDA performance criteria, EA and CA (≥ 90%), major error rate (≤3.0%) and very major error rate (≤2.0%). Results Conclusion ETEST® PLZ clinical performance met the FDA acceptance criteria and was found useful for determining Plazomicin MIC of Enterobacterales, including ESBL, CRE (MBL, KPC, Oxa-48), high level AmpC and aminoglycoside resistant strains. Percent susceptibility of Plazomicin is at 80% among the 598 isolates tested, the mode MIC is 0.5 ug/ml as Susceptible. Disclosures Tom Armstrong, BS, bioMérieux (Employee) Laurine Blanchard, PhD, bioMérieux (Employee) Michael Kresken, PhD, bioMérieux (Scientific Research Study Investigator, Research Grant or Support) Gilles Zambardi, biomerieux (Employee) Marion Pompilio, BioMérieux (Employee)

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Multicenter Evaluation of Ceftazidime-Avibactam Susceptibility Testing of Enterobacterales and Pseudomonas aeruginosa on the VITEK® 2 System

Journal of Clinical Microbiology ◽

10.1128/jcm.01870-20 ◽

2020 ◽

Author(s):

Romney Humphries ◽

Shelley Campeau ◽

Thomas E. Davis ◽

Kristin J. Nagaro ◽

Vincent J. LaBombardi ◽

...

Keyword(s):

Pseudomonas Aeruginosa ◽

Error Rate ◽

Susceptibility Testing ◽

Reference Method ◽

Error Rates ◽

Performance Criteria ◽

Test Results ◽

Major Error ◽

Overall Performance ◽

Vitek 2

In this multisite study, VITEK® 2 AST-Gram-Negative Ceftazidime-Avibactam (CZA) test results for 1073 isolates (866 Enterobacterales and 207 Pseudomonas aeruginosa) were compared to the Clinical & Laboratory Standards Institute (CLSI) broth microdilution (BMD) reference method. The results were analyzed for essential agreement (EA), category agreement (CA), major error rates, and very major error rates following FDA/ISO performance criteria using the FDA-recognized CLSI/EUCAST breakpoints (S ≤8/4 μg/ml and R ≥16/4 μg/ml). The overall EA was 94.5% (1014/1073) and CA was 98.7% (1059/1073). No very major errors were reported. The major error rate was 1.4% (14/998). Out of 14 major errors, 9 were within EA. Based on the EA and lack of an intermediate category for CZA, the adjusted major error rate for FDA criteria was 0.5% (5/998). The performance for ISO criteria after error resolutions included EA 94.5% (1014/1073), CA 98.9% (1061/1073), major error 1.2% (12/998), and no very major error. Vitek 2 met the ISO and FDA criteria of ≥95% reproducibility and ≥95% quality control (QC) results within acceptable ranges for QC organisms. Vitek 2 overall performance for Enterobacterales and P. aeruginosa met or exceeded the FDA and ISO performance criteria and thus is a reliable alternative to BMD reference method for routine CZA susceptibility testing.

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Development of Broth Microdilution MIC and Disk Diffusion Antimicrobial Susceptibility Test Quality Control Ranges for the Combination of Cefepime and the Novel β-Lactamase Inhibitor Enmetazobactam

Journal of Clinical Microbiology ◽

10.1128/jcm.00607-19 ◽

2019 ◽

Vol 57 (8) ◽

Cited By ~ 4

Author(s):

Adam Belley ◽

Michael D. Huband ◽

Kelley A. Fedler ◽

Amy A. Watters ◽

Robert K. Flamm ◽

...

Keyword(s):

Quality Control ◽

Performance Criteria ◽

Disk Diffusion ◽

Broth Microdilution ◽

Content Type ◽

E Coli ◽

Wide Range ◽

Tract Infections ◽

Reference Strains ◽

Lactamase Inhibitor

ABSTRACTThird-generation cephalosporin resistance amongEnterobacteriaceae, mediated by the spread of extended-spectrum β-lactamases (ESBLs), is a very serious medical concern with limited therapeutic options. Enmetazobactam (formerly AAI101) is a novel penicillanic sulfone β-lactamase inhibitor active against a wide range of ESBLs. The combination of enmetazobactam and cefepime has entered phase 3 development in patients with complicated urinary tract infections. Using the Clinical and Laboratory Standards Institute (CLSI) M23 tier 2 study design, broth microdilution MIC and disk diffusion quality control (QC) ranges were determined for cefepime-enmetazobactam. Enmetazobactam was tested at a fixed concentration of 8 μg/ml in the MIC assay, and a cefepime-enmetazobactam disk mass of 30/20 μg was used in the disk diffusion assay.Escherichia coliATCC 25922,E. coliATCC 35218,E. coliNCTC 13353,Klebsiella pneumoniaeATCC 700603, andPseudomonas aeruginosaATCC 27853 were chosen as reference strains. The CTX-M-15-producingE. coliNCTC 13353 isolate is recommended for routine testing to control for inhibition of ESBL activity by enmetazobactam. Broth microdilution MIC QC ranges spanned 3 to 4 doubling dilutions and contained 99.6% to 100.0% of obtained MIC values for the five reference strains. Disk diffusion yielded inhibition zone diameter QC ranges that spanned 7 mm and encompassed 97.1% to 100.0% of the obtained values. Quality control ranges were approved by the CLSI in 2017 (broth microdilution MIC) and 2019 (disk diffusion). The established QC ranges will ensure that appropriate assay performance criteria are attained using CLSI reference methodology when determining the susceptibility of clinical isolates to cefepime-enmetazobactam.

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Urinary Excretion and Bactericidal Activities of a Single Oral Dose of 400 Milligrams of Fleroxacin versus a Single Oral Dose of 800 Milligrams of Pefloxacin in Healthy Volunteers

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.42.7.1659 ◽

1998 ◽

Vol 42 (7) ◽

pp. 1659-1665 ◽

Cited By ~ 15

Author(s):

Kurt G. Naber ◽

Ursula Theuretzbacher ◽

Martina Kinzig ◽

Orlin Savov ◽

Fritz Sörgel

Keyword(s):

Oral Dose ◽

Healthy Volunteers ◽

Single Oral Dose ◽

E Coli ◽

Wide Range ◽

The Mean ◽

Bactericidal Activities ◽

Tract Infections ◽

Time Kill ◽

Randomized Crossover Study

ABSTRACT Twelve healthy volunteers participated in this randomized crossover study to compare the concentrations and recovery levels of fleroxacin and pefloxacin in urine and to assess their bactericidal activities against 12 strains of urinary pathogens with different susceptibilities over a wide range of MICs. The volunteers received a single oral dose of 400 mg of fleroxacin or 800 mg of pefloxacin. The mean cumulative renal excretion of unchanged fleroxacin,N-demethyl-fleroxacin, and N-oxide-fleroxacin accounted for 67, 7, and 6% of the total dose, respectively. The total urinary recovery of pefloxacin and the active metabolite norfloxacin was 34%. In the time-kill and the urinary bactericidal titer (UBT) studies, only the subjects’ urine not supplemented with broth was used. With most tested organisms and both quinolones it took more than 8 h to achieve a reduction in CFU of 99.9% (3 log units). Overall, there was a good correlation between UBTs and MICs for the strains. Against Escherichia coli ATCC 25922 the median UBTs were similar for both antibiotics and at least 1:8 for 96 h; against the E. coli strain for which the MIC was 0.5 μg/ml the UBT was at least 1:4 for 48 h. The UBTs of both drugs against Klebsiella pneumoniae were at least 1:16 for 72 h. The UBTs for Staphylococcus aureus (the MIC for which was 16 μg/ml) of both antibiotics were low, and in some of the samples, no bactericidal titers were observed. UBTs for Proteus mirabilis of pefloxacin are significantly higher than those of fleroxacin. For Pseudomonas aeruginosa the median UBTs were present for the 24-to-48-h interval. The same is true forEnterococcus faecalis. Against Staphylococcus saprophyticus, UBTs were present for at least 48 h with both quinolones. Overall, a single oral dose of 400 mg of fleroxacin exhibits UBTs comparable to those of 800 mg of pefloxacin. Therefore, it may be expected that half of the dose of fleroxacin gives comparable results in the treatment of urinary tract infections; this should be substantiated in comparative clinical trials.

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The Repeat-In-Toxin Family Member TosA Mediates Adherence of Uropathogenic Escherichia coli and Survival during Bacteremia

Infection and Immunity ◽

10.1128/iai.05713-11 ◽

2011 ◽

Vol 80 (2) ◽

pp. 493-505 ◽

Cited By ~ 31

Author(s):

Patrick D. Vigil ◽

Travis J. Wiles ◽

Michael D. Engstrom ◽

Lev Prasov ◽

Matthew A. Mulvey ◽

...

Keyword(s):

Escherichia Coli ◽

Urinary Tract ◽

Virulence Factors ◽

Upper Urinary Tract ◽

Host Cells ◽

Content Type ◽

E Coli ◽

Wide Range ◽

Novel Target ◽

Tract Infections

ABSTRACTUropathogenicEscherichia coli(UPEC) is responsible for the majority of uncomplicated urinary tract infections (UTI) and represents the most common bacterial infection in adults. UPEC utilizes a wide range of virulence factors to colonize the host, including the novel repeat-in-toxin (RTX) protein TosA, which is specifically expressed in the host urinary tract and contributes significantly to the virulence and survival of UPEC.tosA, found in strains within the B2 phylogenetic subgroup ofE. coli, serves as a marker for strains that also contain a large number of well-characterized UPEC virulence factors. The presence oftosAin anE. coliisolate predicts successful colonization of the murine model of ascending UTI, regardless of the source of the isolate. Here, a detailed analysis of the function oftosArevealed that this gene is transcriptionally linked to genes encoding a conserved type 1 secretion system similar to other RTX family members. TosA localized to the cell surface and was found to mediate (i) adherence to host cells derived from the upper urinary tract and (ii) survival in disseminated infections and (iii) to enhance lethality during sepsis (as assessed in two different animal models of infection). An experimental vaccine, using purified TosA, protected vaccinated animals against urosepsis. From this work, it was concluded that TosA belongs to a novel group of RTX proteins that mediate adherence and host damage during UTI and urosepsis and could be a novel target for the development of therapeutics to treat ascending UTIs.

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Correlation of cefpodoxime susceptibility with cephalothin and cefuroxime for urinary tract isolates

Journal of Medical Microbiology ◽

10.1099/jmm.0.063040-0 ◽

2014 ◽

Vol 63 (2) ◽

pp. 218-221 ◽

Cited By ~ 3

Author(s):

David A. Bookstaver ◽

Christopher M. Bland ◽

Mitchell W. Woodberry ◽

Karon B. Mansell

Keyword(s):

Escherichia Coli ◽

Urinary Tract ◽

Error Rate ◽

Surrogate Marker ◽

Error Rates ◽

The Other ◽

Colony Count ◽

Major Error ◽

E Coli ◽

Microscan System

This study attempted to determine whether cefuroxime was superior to cephalothin as a surrogate marker for cefpodoxime among urinary tract isolates. The MicroScan system (Siemens) was used to determine susceptibility for cephalothin and cefuroxime on consecutive cultures with a colony count of ≥50 000 organisms. Simultaneously, an Etest (bioMérieux) for cefpodoxime was conducted. The cefpodoxime interpretation was compared to that of the other two agents, and the categorical agreement was calculated, defined as the percentage of identical susceptibility interpretations. Cefuroxime (83 %) had a significantly higher categorical agreement than cephalothin (63 %) among 300 isolates (P<0.01). The major error rate was 16 % for cephalothin and 3 % for cefuroxime. The very major error rate was 7 % for cephalothin and 14 % for cefuroxime among the 14 cefpodoxime-resistant isolates. For Escherichia coli, the major error rates were 15 % and 1 % for cephalothin and cefuroxime, respectively. Very major error rates were 9 % for both agents. Cefuroxime was a better predictor of cefpodoxime susceptibility than cephalothin, and appears to be the preferred surrogate agent for the MicroScan system, particularly for E. coli.

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In Vitro and In Vivo Antibacterial Activities of SM-216601, a New Broad-Spectrum Parenteral Carbapenem

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.49.10.4185-4196.2005 ◽

2005 ◽

Vol 49 (10) ◽

pp. 4185-4196 ◽

Cited By ~ 27

Author(s):

Yutaka Ueda ◽

Katsunori Kanazawa ◽

Ken Eguchi ◽

Koji Takemoto ◽

Yoshiro Eriguchi ◽

...

Keyword(s):

Bacterial Infections ◽

Antibacterial Activities ◽

Multiresistant Pathogens ◽

E Coli ◽

Wide Range ◽

Agar Dilution ◽

Resistant Strains ◽

Mrsa Strains

ABSTRACT SM-216601 is a novel parenteral 1β-methylcarbapenem. In agar dilution susceptibility testing, the MIC of SM-216601 for 90% of the methicillin-resistant Staphylococcus aureus (MRSA) strains tested (MIC90) was 2 μg/ml, which was comparable to those of vancomycin and linezolid. SM-216601 was also very potent against Enterococcus faecium, including vancomycin-resistant strains (MIC90 = 8 μg/ml). SM-216601 exhibited potent activity against penicillin-resistant Streptococcus pneumoniae, ampicillin-resistant Haemophilus influenzae, Moraxella catarrhalis, Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis, with MIC90s of less than 0.5 μg/ml, and intermediate activity against Citrobacter freundii, Enterobacter cloacae, Serratia marcescens, and Pseudomonas aeruginosa. The therapeutic efficacy of SM-216601 against experimentally induced infections in mice caused by S. aureus, E. faecium, E. coli, and P. aeruginosa reflected its in vitro activity and plasma level. Thus, SM-216601 is a promising candidate for nosocomial bacterial infections caused by a wide range of gram-positive and gram-negative bacteria, including multiresistant pathogens.

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Novel Flow Cytometric Immunoassay for Detection of Proinsulin Autoantibodies in Diabetes Mellitus Employing a Recombinant Autoantigen Expressed in E. coli

Frontiers in Immunology ◽

10.3389/fimmu.2021.648021 ◽

2021 ◽

Vol 12 ◽

Author(s):

Adriana Victoria Sabljic ◽

Silvina Sonia Bombicino ◽

Juan Ignacio Marfía ◽

Luciano Lucas Guerra ◽

Alberto Penas Steinhardt ◽

...

Keyword(s):

Diabetes Mellitus ◽

Dynamic Range ◽

Geometric Mean ◽

Reference Method ◽

Diabetic Patients ◽

Analytical Sensitivity ◽

E Coli ◽

Flow Cytometric ◽

Wide Range

IntroductionInsulin and proinsulin autoantibodies (IAA/PAA) are usually the first markers to appear in patients with type 1 Diabetes Mellitus (T1DM) and their prevalence ranges from 10 to 60% in the child-adolescent population. The reference method for IAA/PAA detection is the Radioligand Binding Assay (RBA), a highly specific and sensitive technique, but expensive and polluting. The aim of this work was to develop a novel flow cytometric microsphere-based immunoassay (FloCMIA) for PAA detection, employing recombinant human proinsulin (PI), as an alternative method to RBA, less expensive and harmful to the environment.Materials and MethodsHuman PI was expressed as Thioredoxin fusion protein (TrxPI) in E. coli and a fraction was biotinylated. A double paratope model was used in which samples were incubated with TrxPI–biotin and microspheres adsorbed with TrxPI. The immune complexes were revealed using Streptavidin–Phycoerythrin. The geometric mean of the signals was analyzed, and the results were expressed as Standard Deviation scores (SDs). Sera from 100 normal human control and from 111 type 1 diabetic patients were evaluated by FloCMIA. To correlate the novel assay with RBA, 51 diabetic patients were selected, spanning a wide range of PAA reactivity by RBA.ResultsThe study of ROC curves allowed choosing a cut-off value of 3.0 SDs and the AUC was 0.705, indicating that FloCMIA has fair ability to distinguish between samples from each group. A prevalence of 50% for PAA was obtained in the population of diabetic patients studied. The specificity was 96% and the analytical sensitivity (percentage of patients RBA positive, also positive by FloCMIA) was 69%. There was a substantial agreement between methods (kappa statistic=0.700).ConclusionsA novel immunoassay based on flow cytometry that uses easy-to produce recombinant PI was developed. This assay constitutes an innovative and cost-effective alternative to RBA for the determination of PAA in patients’ sera. The method developed here, presents good performance and a wide dynamic range together with a small required sample volume. Furthermore, these results make it possible to develop multiplex immunoassays that allow the combined detection of autoantibodies present in T1DM and other related autoimmune diseases.

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Susceptibility of Clinical Isolates of Escherichia coli to Fosfomycin as Measured by Four In Vitro Testing Methods

Journal of Clinical Microbiology ◽

10.1128/jcm.01306-20 ◽

2020 ◽

Vol 58 (10) ◽

Author(s):

James A. Karlowsky ◽

Philippe R. S. Lagacé-Wiens ◽

Nancy M. Laing ◽

Melanie R. Baxter ◽

Heather J. Adam ◽

...

Keyword(s):

Escherichia Coli ◽

Reference Method ◽

Clinical Isolates ◽

Disk Diffusion ◽

Content Type ◽

E Coli ◽

Agar Dilution ◽

Vitek 2 ◽

Urinary Isolates

ABSTRACT Clinical isolates of Escherichia coli (n = 554) were tested against fosfomycin using agar dilution, disk diffusion, and Etest. Agar dilution (reference method) identified few isolates with fosfomycin MICs of 64 (n = 3), 128 (n = 4), and ≥256 μg/ml (n = 2). Applying CLSI (M100, 2020) and EUCAST (v. 10.0, 2020) breakpoints, 98.9% and 98.4% (agar dilution), 99.3% and 99.1% (disk diffusion), and 99.1% and 98.9% (Etest) of isolates were fosfomycin susceptible, respectively. Essential agreement (agar dilution versus Etest) was low (40.8%); 59.3% (131/221) of isolates with agar dilution MICs of 2 to 128 μg/ml tested 2 to 4 doubling dilutions lower by Etest. Applying CLSI breakpoints, categorical agreement was >99% for both disk diffusion and Etest; no major errors (MEs) or very major errors (VMEs) were identified, and rates of minor errors (mEs) were <1%. EUCAST breakpoints yielded categorical agreements of >99% and no MEs for both disk diffusion and Etest; however, VMEs occurred at unacceptable rates of 44.4% (disk diffusion) and 33.3% (Etest). All isolates with agar dilution MICs of ≥32 μg/ml (n = 12) and a subset of isolates with MICs of ≤16 μg/ml (n = 49) were also tested using the Vitek 2 AST-N391 card and generated fosfomycin MICs 1 to ≥3 doubling dilutions lower than agar dilution for 11/12 isolates with agar dilution MICs of ≥32 μg/ml. We conclude that performing fosfomycin disk diffusion or Etest on urinary isolates of E. coli and interpreting results using CLSI breakpoints reliably identified fosfomycin-susceptible isolates regardless of differences in endpoint reading criteria. EUCAST breakpoints generated excessive rates of VMEs for our isolate collection of high fosfomycin susceptibility.

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701. Comparison of MIC Results for Gepotidacin by Agar Dilution and Broth Microdilution Methods

Open Forum Infectious Diseases ◽

10.1093/ofid/ofz360.769 ◽

2019 ◽

Vol 6 (Supplement_2) ◽

pp. S317-S317

Author(s):

S J Ryan Arends ◽

Michele A Canino ◽

Brieanna M Roth ◽

Paul R Rhomberg ◽

Robert K Flamm ◽

...

Keyword(s):

Susceptibility Testing ◽

Reference Method ◽

Broth Microdilution ◽

Topoisomerase Iv ◽

Acute Cystitis ◽

Minimal Inhibitory Concentrations ◽

E Coli ◽

Agar Dilution ◽

Gram Negative Organisms

Abstract Background Gepotidacin (GSK2140944) is a novel triazaacenaphthylene bacterial type II topoisomerase inhibitor in clinical development for the treatment of gonorrhea and uncomplicated UTI (acute cystitis). Gepotidacin selectively inhibits bacterial DNA gyrase and topoisomerase IV by a unique mechanism not utilized by any currently approved therapeutic agent and demonstrates in vitro activity against most target pathogens resistant to established antibacterials, including fluoroquinolones. This study tested the equivalency of minimal inhibitory concentrations (MICs) obtained by 2 reference susceptibility testing methods, agar dilution (AD) and broth microdilution (BMD), for gepotidacin against Gram-positive and Gram-negative organisms. Methods Susceptibility testing for both methods was performed on a total of 733 clinical isolates recovered largely in 2016 from over 120 medical centers worldwide. For N. gonorrhoeae, only the AD method is recommended by CLSI, therefore BMD was performed using Fastidious Broth for comparison purposes. Essential agreement (EA) based on evaluable results was calculated as the number of isolates with MICs within one 2-fold dilution of the reference method divided by the total number of results. Equivalency was defined using the 95% criteria from the FDA’s class II controls document. Results The EA observed for gepotidacin with these 2 methods was 85.8% overall and 98.3% when H. influenzae and N. gonorrhoeae isolates were excluded. Slightly higher gepotidacin MICs were observed when tested by BMD for each of these species/groups; this trend was especially prominent for E. coli and S. pyogenes. Gepotidacin tested against H. influenzae (73.1%) or N. gonorrhoeae (28.6%) species had much lower EAs. Conclusion Equivalency (EA >95%) was established between AD and BMD methods for determining gepotidacin susceptibility results against Staphylococcus spp., Streptococcus spp. and E. coli. However, for N. gonorrhoeae and H. influenzae, equivalency between the 2 methods was not established; therefore, future antimicrobial susceptibility testing for gepotidacin against these organisms should adhere to the methods for which quality control ranges and breakpoints are approved. Disclosures All authors: No reported disclosures.

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