scholarly journals 1287. Double Disk Diffusion Study to Evaluate the Synergistic Effect Between Cefiderocol and Ceftazidime-Avibactam Against Cefiderocol-Non-susceptible Acinetobacter baumannii

2021 ◽  
Vol 8 (Supplement_1) ◽  
pp. S732-S733
Author(s):  
Yoshinori Yamano ◽  
Miki Takemura ◽  
Naomi Anan ◽  
Roger Echols ◽  
Christopher Longshaw
Keyword(s):  
Synergistic Effect ◽  
Acinetobacter Baumannii ◽  
Disk Diffusion ◽  
Bacterial Suspension ◽  
Gram Negative Bacteria ◽  
Surveillance Studies ◽  
Mueller Hinton ◽  
Diffusion Studies ◽  
Mueller Hinton Agar ◽  
Mueller Hinton Broth

Abstract Background Cefiderocol (CFDC), a siderophore cephalosporin, has broad coverage of Gram-negative bacteria and has been approved for clinical use in USA and Europe. The SIDERO-WT surveillance studies showed that CFDC shows >95% susceptibility against Acinetobacter baumannii. Against many of CFDC non-susceptible isolates, most of which had blaPER gene, the combination use of avibactam significantly decreased the MIC by broth microdilution (BMD). In this study, we evaluated the appropriate methodology to evaluate the synergistic effect by disk diffusion studies. Methods The susceptibility testing was conducted as recommended by the CLSI using CFDC non-susceptible isolates (MIC of >4 µg/mL based on CLSI breakpoint). The MIC by BMD was determined using iron-depleted cation-adjusted Mueller-Hinton broth, in the presence or absence of 4 µg/mL of avibactam. The disk diffusion was evaluated using Mueller-Hinton agar, and the synergy was evaluated by using disk stacking methods. For disk stacking methods, CFDC disk was placed on agar on which bacterial suspension of 0.5 McFarland units was spread, then the ceftazidime-avibactam (CZA) disks was stacked on the top, followed by adding a drop (30 µL) of saline on the stacked disks. As an alternative method, CZA was immersed in saline for 1 second instead of adding a drop of saline, followed by the stacking on the top. The disk zone size was determined after 24-hour incubation at 37°C. Results Against blaPER-positive A. baumannii which showed >64 µg/mL MIC of CFDC and CZA, CFDC MIC decreased to 0.25 µg/mL in the presence of avibactam. The disk diffusion methods also showed isolates resistant to CFDC and CZA and showed susceptiblilty disk zone to CFDC by stacking both disks. On the other hand, against blaNDM-positive A. baumannii which showed 64 µg/mL MIC of CFDC and CZA, the disk diffusion methods showed resistance even when stacking both disks. Against multiple isolates, the MIC of CFDC without or with avibactam was correlated well with the disk zone produced by CFDC disk alone or stacked with CZA disks, respectively (Figure). Conclusion The synergistic effect between CFDC and avibactam by BMD methods could be detected by disk stacking methodology using CFDC and CZA disks. Disclosures Yoshinori Yamano, PhD, Shionogi (Employee) Miki Takemura, MS, SHIONOGI & CO., LTD. (Employee) Roger Echols, MD, Shionogi (Consultant) Christopher Longshaw, PhD, Shionogi (Employee)

scholarly journals Evaluation of cefiderocol activity for Gram-negative bacteria and performance of cefiderocol disk diffusion testing using multiple brands of Mueller Hinton Agar

2021 ◽  
Vol 156 (Supplement_1) ◽  
pp. S5-S5
Author(s):  
Robert Potter ◽  
Meghan Wallace ◽  
Carey-Ann Burnham
Keyword(s):  
Susceptibility Testing ◽  
Disk Diffusion ◽  
Resistant Bacteria ◽  
Clinical Microbiology Laboratory ◽  
Gram Negative Bacteria ◽  
Broth Microdilution ◽  
Gram Negative ◽  
Mueller Hinton ◽  
Significant Difference ◽  
Mueller Hinton Agar

Abstract Cefidericol is a cephalosporin-siderophore antibiotic for the treatment of multidrug resistant Gram-negative bacteria. Similar to other cephalosporin antibiotics, the lethal mechanism of action is due to inhibition of penicillin binding proteins leading to lysis of the bacteria. However, unlike previously developed antibiotics, the siderophore portion of cefidericol is able to bind iron and then be actively transported into the periplasmic space. To ascertain the feasibility of cefidericol antibiotic susceptibility testing in the Barnes-Jewish Clinical Microbiology Laboratory, we collected a cohort of multidrug Enterobacteriacae (5 Enterobacter cloace, 8 Escherichia coli, 12 Klebsiella pneumoniae), Pseudomonas aeruginosa (n=23), Stenotrophomonas maltophila (n=24), and Acinetobacter baumannii (n=25). We evaluated activity of cefidericol on these strains, and the performance of disk diffusion using three different brands of Mueller-Hinton Agar (BD, Hardy, and Remel). The reference method for comparison was an FDA-cleared broth microdilution panel containing cefidericol (ThermoFisher Scientific). Using CLSI breakpoints, we found that disk diffusion with BD agar had 96% categorical agreement for Enterobacterales, 100% for P. aeruginosa, 92% for A. baumannii, 96% for S. maltophila. We found that Hardy had 96% categorical agreement for Enterobacterales, 92% for P. aeruginosa, 92% for A. baumannii, 96% for S. maltophila. Finally, we found that Hardy had 96% categorical agreement for Enterobacterales, 92% for P. aeruginosa, 92% for A. baumannii, 96% for S. maltophila. Minor errors on any media never exceed 4% and there were no very major errors. Resistance to cefidericol within our cohort of selected antibiotic resistant bacteria was rare, one E. coli isolate and two P. aeruginosa isolates had minimal inhibitory concentrations (MICs) > 32 μg/mL. The highest MICs for one isolate of A. baumannii and one isolate S. maltophila was 8 μg/mL and 4 μg/mL, respectively, both of which were intermediate. There was no difference in the distribution of zone disk diffusion diameter for A. baumannii or Enterobacterales. However, there was a significant difference in the distribution of zone disk diffusion diameters for P. aeruginosa and S. maltophila on BD vs Hardy agar. The median for P. aeruginosa on BD is 25 mm while it is 29 mm on Hardy. The trend for S. maltophila is the opposite as the median for BD was 31.5 mm and 28.5 mm for Hardy. Use of FDA vs CLSI vs EUCAST breakpoints significantly changes outcome of susceptibility testing for broth microdilution and disk diffusion. As one example for broth microdilution of A. baumannii, we had one isolate intermediate using CLSI breakpoints, 4 resistant using EUCAST breakpoints, and 4 resistant and 3 intermediate isolates using FDA breakpoints. Our work demonstrates that cefedericol testing can be performed in a routine format, with certain organismal differences on Mueller-Hinton agar, and that different interpretative criteria significantly change outcomes.

scholarly journals ARGONAUT-I: Activity of Cefiderocol (S-649266), a Siderophore Cephalosporin, against Gram-Negative Bacteria, Including Carbapenem-Resistant Nonfermenters and Enterobacteriaceae with Defined Extended-Spectrum β-Lactamases and Carbapenemases

2018 ◽  
Vol 63 (1) ◽  
Author(s):  
Michael R. Jacobs ◽  
Ayman M. Abdelhamed ◽  
Caryn E. Good ◽  
Daniel D. Rhoads ◽  
Kristine M. Hujer ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Acinetobacter Baumannii ◽  
Stenotrophomonas Maltophilia ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Content Type ◽  
Carbapenem Resistant ◽  
Extended Spectrum ◽  
Mueller Hinton ◽  
Mueller Hinton Broth

ABSTRACT The activity of the siderophore cephalosporin cefiderocol is targeted against carbapenem-resistant Gram-negative bacteria. In this study, the activity of cefiderocol against characterized carbapenem-resistant Acinetobacter baumannii complex, Stenotrophomonas maltophilia, Pseudomonas aeruginosa, and Enterobacteriaceae strains was determined by microdilution in iron-depleted Mueller-Hinton broth. The MIC90s against A. baumannii, S. maltophilia, and P. aeruginosa were 1, 0.25, and 0.5 mg/liter, respectively. Against Enterobacteriaceae, the MIC90 was 1 mg/liter for the group harboring OXA-48-like, 2 mg/liter for the group harboring KPC-3, and 8 mg/liter for the group harboring TEM/SHV ESBL, NDM, and KPC-2.

scholarly journals Disk Diffusion-Based Methods for Determining Candida parapsilosis Susceptibility to Anidulafungin

2003 ◽  
Vol 47 (9) ◽  
pp. 3018-3020 ◽  
Author(s):  
Zekaver Odabasi ◽  
Victor Paetznick ◽  
Beth P. Goldstein ◽  
John H. Rex ◽  
Luis Ostrosky-Zeichner
Keyword(s):  
Methylene Blue ◽  
Dimethyl Sulfoxide ◽  
Candida Parapsilosis ◽  
Tween 80 ◽  
Disk Diffusion ◽  
Broth Microdilution ◽  
Mueller Hinton ◽  
Mueller Hinton Agar

ABSTRACT Zone diameters for anidulafungin by disk diffusion for 139 isolates of C. parapsilosis were compared with MICs by NCCLS M27-A2 broth microdilution. The comparison was poor unless the disks were prepared by dissolving anidulafungin in 1% dimethyl sulfoxide plus 0.1% Tween 80 and testing on Mueller-Hinton agar flooded with glucose and methylene blue.

scholarly journals Synthesis and Antimicrobial Assessment of Fe3+ Inclusion Complex of p-tert-Butylcalix[4]arene Diamide Derivative

2019 ◽  
Vol 2019 ◽  
pp. 1-8 ◽  
Author(s):  
Anwar Ali Chandio ◽  
Ayaz Ali Memon ◽  
Shahabuddin Memon ◽  
Fakhar N. Memon ◽  
Qadeer Khan Panhwar ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Diffusion Method ◽  
Gram Negative Bacteria ◽  
Disc Diffusion ◽  
Disc Diffusion Method ◽  
Gram Negative ◽  
Mueller Hinton ◽  
Mueller Hinton Agar ◽  
Ft Ir ◽  
Bacteria And Fungi

Present study deals with the synthesis of the p-tert-butylcalix[4]arene diamide derivative as ligand (L) and its Fe3+ complex, followed by its characterization using TLC and FT-IR, while UV-Vis and Job’s plot study were performed for complex formation. Antimicrobial activity of the derivative (L) and its metal complex was carried out by the disc diffusion method against bacteria (Escherichia coli and Staphylococcus albus) and fungi (R. stolonifer). Different concentrations of the derivative (L) (6, 3, 1.5, 0.75, and 0.37 μg/mL) and its Fe3+ complex were prepared, and Mueller–Hinton agar was used as the medium for the growth of microorganisms. Six successive dilutions of the derivative (L) and Fe3+ complex were used against microorganisms. Two successive dilutions (6 and 3 μg/mL) of the derivative (L) showed antibacterial action against both Gram-positive and Gram-negative bacteria. In addition, three successive dilutions (6, 3, and 1.5 μg/mL) of the derivative (L) showed antifungal activity. However, all of six dilutions of the Fe3+ complex showed antimicrobial activity. Derivative (L) showed 3 and 1.5 μg/mL minimum inhibitory concentrations (MIC) against bacteria and fungi, respectively. On the contrary, its Fe3+ complex showed 0.37 μg/mL value of MIC against bacteria and fungi. Hence, Fe3+ complex of the derivative (L) was found to be a more effective antimicrobial agent against selected bacteria and fungi than the diamide derivative (L).

scholarly journals Disk diffusion Method in Enriched Mueller Hinton agar for determining susceptibility of Candida isolates from various clinical specimens

2020 ◽  
Vol 28 (1) ◽  
pp. 28-33
Author(s):  
Nabeela Mahboob ◽  
Hasina Iqbal ◽  
Mushtaque Ahmed ◽  
Md Mehedi Hasan Magnet ◽  
Kazi Zulfiquer Mamun
Keyword(s):  
Methylene Blue ◽  
Amphotericin B ◽  
Candida Species ◽  
Susceptibility Testing ◽  
Antifungal Susceptibility ◽  
Antifungal Susceptibility Testing ◽  
Disk Diffusion ◽  
Clinical Specimens ◽  
Mueller Hinton ◽  
Mueller Hinton Agar

Background: Candida species are responsible for various clinical infections ranging from mucocutaneous infection to life threatening invasive diseases. Recently there is a serious concern with increased resistance of antifungal drugs and its consequences. Thus, identification of Candida and its antifungal susceptibility testing has a paramount significance in the management of Candidal infections. The aim of the study was to determine antifungal susceptibility pattern of Candida by Mueller-Hinton agar media supplemented with glucose and methylene blue for disk diffusion testing of fluconazole, miconazole, clotrimazole, amphotericin B and nystatin. Methods: A total of 35 Candida species was isolated from 2000 clinical specimens over 6 month’s period from July 2016 to December 2016. Growths on Blood agar and chromogenic agar were evaluated for colony appearance and microscopic examination. Antifungal susceptibility testing was performed by disk diffusion using Mueller-Hinton agar supplemented with glucose and methylene blue. Results: Candida species were more sensitive to clotrimazole (88.58%) and amphotericin B (88.58%) followed by nystatin ((77.14%), miconazole (74.29%) whereas fluconazole showed the highest level of resistance (60%). Conclusions: The increase in resistance to fluconazole is of serious concern as it is the most commonly used azole for candidiasis. The sensitivity profile of Candida isolates will be helpful to choose appropriate antifungal agents, thus decreasing patient’s morbidity and mortality. J Dhaka Medical College, Vol. 28, No.1, April, 2019, Page 28-33

scholarly journals Comparison of Automated and Traditional Minimum Inhibitory Concentration Procedures for Microbiological Cosmetic Preservatives

1996 ◽  
Vol 79 (6) ◽  
pp. 1294-1299 ◽  
Author(s):  
Melissa E Lenczewski ◽  
Sean T McGavin ◽  
Karl Vandyke
Keyword(s):  
Minimum Inhibitory Concentration ◽  
Inhibitory Concentration ◽  
Color Change ◽  
Gram Negative Bacteria ◽  
Cosmetic Products ◽  
Mueller Hinton ◽  
Visual Color ◽  
Redox Indicator ◽  
Tetrazolium Violet ◽  
Mueller Hinton Broth

Abstract Minimum inhibitory concentration (MIC) is used to test resistance of microorganisms against antibiotics and to test cosmetic preservatives. This research expanded traditional MIC with automation and application of colorimetric endpoint MIC. All experiments included common cosmetic preservatives and microorganisms used in testing preservative efficacy. An autodilutor using three 96-well microliter plates processed 6 preservatives against 1 microorganism in 15 min. The unique tip design made it possible to accurately deliver viscous test materials that cannot be dispensed accurately with vacuum or fluid-filled systems. Tetrazolium violet, a redox indicator, provided a visual color change from clear to purple at the MIC. Optimum concentration of tetrazolium violet was 0.01 % with addition of 0.2% glucose to Mueller-Hinton broth for both gram-positive and gram-negative bacteria. The colorimetric endpoint was evident after 24 h from previously cryogenically stored organisms that were thawed before use and after 4 h for 18–24 h broth cultures subcultured from agar plates. The autodilutor accurately pipetted viscous cosmetic products such as hand lotion and shampoo, which cannot be pipetted with a traditional micropipetter.

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