In vitro activity of tigecycline against 313 Gram-positive and Gram-negative clinical isolates

Abstract Background In the era of antibiotic resistance, alternative anti-infectives must be explored. The National Action Plan for Combating Antibiotic-Resistant Bacteria calls for developing nontraditional therapeutics, including natural compounds such as essential oils (EOs) (Goal 4.4). A pilot study previously showed in vitro activity of EOs against CRE and warranted further study of their antibacterial activity. We studied cinnamon bark, clove, lavender, lemongrass, eucalyptus, oregano, rosemary, thyme, tea tree, manuka, and Thieves® blend (Young Living Essential Oils, Lehi UT) against an expanded panel of Gram-positive and Gram-negative isolates. Methods 30 Gram-positive and 70 Gram-negative clinical isolates, including CRE, were tested using CLSI methods. Isolates were grown overnight on TSA; 0.5 McFarland suspensions in sterile water were swabbed over Mueller–Hinton agar using the Kirby–Bauer method. 20 μl of full-strength oils were pipetted onto blank paper disks in a sterile dish. Disks were placed aseptically onto the plates immediately after inoculating disks. Vancomycin was tested with Gram-positives and meropenem with Gram-negatives. Median zone diameters are shown. Results EOs oregano, thyme, cinnamon bark, and lemongrass had the largest zones of inhibition against Gram-positive organisms and were larger than those of vancomycin for MRSA/MSSA. Cinnamon bark had the largest zone of inhibition against P. aeruginosa and was larger than that of meropenem. Oregano, thyme, cinnamon bark had the largest zones of inhibition against Enterobacteriaceae and were larger than those of meropenem against K. pneumoniae and E. cloacae. Conclusion Essential oils showed significant in vitro activity against clinical isolates, including CRE. Further study of the clinical activity of essential oils is warranted. Disclosures J. E. Patterson, Young Living Essential Oils: Independent Contractor, Salary

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724. The In Vitro Activity of Gepotidacin and Comparator Agents Against Anaerobic Bacterial Isolates

Open Forum Infectious Diseases ◽

10.1093/ofid/ofz360.792 ◽

2019 ◽

Vol 6 (Supplement_2) ◽

pp. S325-S325

Author(s):

Meredith Hackel ◽

Michele A Canino ◽

Daniel F Sahm ◽

Nicole Scangarella-Oman

Keyword(s):

Vitro Activity ◽

Clinical Isolates ◽

In Vitro Activity ◽

Topoisomerase Iv ◽

Gram Positive ◽

Acute Cystitis ◽

Gram Negative ◽

Agar Dilution ◽

Clinically Significant

Abstract Background Gepotidacin (GSK2140944) is a first in class 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 assessed the in vitro activity of gepotidacin and comparators against a collection of 649 Gram-positive and Gram-negative anaerobic bacterial clinical isolates. Methods A total of 649 clinically significant Gram-negative (333) and Gram-positive (316) anaerobic clinical isolates previously collected and frozen at −70°C were tested. Isolates came from North America (315/48.5%) and Europe (334/51.5%) and were collected between 2000 and 2017. Minimum inhibitory concentrations (MICs) for gepotidacin and 6 comparators were determined by agar dilution (AD) for all isolates, and by both AD and broth microdilution (BMD) for Bacteroides spp. according to CLSI guidelines (CLSI M11-A8). Most Lactobacillus spp. tested in this study require anaerobic conditions for growth and were tested by anaerobic AD. Results The in vitro activity results of gepotidacin and comparators are shown in the table below. The gepotidacin MIC90 for all Gram-negative anaerobic isolates tested in this study was 4 µg/mL and for the comparators tested was as follows: ceftriaxone 512 μg/mL, clindamycin >8 μg/mL, imipenem 0.5 μg/mL, metronidazole 2 μg/mL, moxifloxacin 8 μg/mL and piperacillin–tazobactam 16 μg/mL. Gepotidacin had the lowest MIC90 (2 μg/mL) for the Gram-positive anaerobic isolates compared with the other antibiotics tested, with the exception of metronidazole (MIC90 = 0.5 µg/mL). Conclusion Gepotidacin showed in vitro activity against a collection of 649 anaerobic Gram-negative and Gram-positive clinical isolates, with an MIC90 value against all Gram-negative anaerobic isolates of 4 µg/mL, and against all Gram-positive anaerobic isolates of 2 µg/mL. Disclosures All authors: No reported disclosures.

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