In vitro activity of cefepime-taniborbactam against carbapenemase producing Enterobacterales and Pseudomonas aeruginosa isolates recovered in Spain

2022 ◽  
Author(s):  
Marta Hernández-García ◽  
María García-Castillo ◽  
Patricia Ruiz-Garbajosa ◽  
Germán Bou ◽  
María Siller-Ruiz ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Pseudomonas Aeruginosa ◽  
Therapeutic Option ◽  
Active Agent ◽  
Enterobacter Cloacae ◽  
Clinical Use ◽  
In Vitro Activity ◽  
Carbapenem Resistant ◽  
Lactamase Inhibitor

Novel β-lactam-β-lactamase inhibitor combinations currently approved for clinical use are poorly active against metallo-β-lactamase (MBL)-producing strains. We evaluated the in vitro activity of cefepime-taniborbactam (FTB, formerly cefepime/VNRX-5133) and comparator agents against carbapenemase-producing Enterobacterales (n=247) and carbapenem-resistant Pseudomonas spp. (n=170) clinical isolates prospectively collected from different clinical origin in patients admitted to 8 Spanish hospitals. FTB was the most active agent in both Enterobacterales (97.6% MIC FTB ≤8/4 mg/L) and Pseudomonas populations (67.1% MIC FTB ≤8/4 mg/L). MIC FTB was >8 mg/L in 6/247 (2.4%) Enterobacterales isolates (3 KPC- Klebsiella pneumoniae , 1 VIM- Enterobacter cloacae , 1 IMP- E. cloacae and 1 NDM- Escherichia coli ) and in 56/170 (32.9%) Pseudomonas spp., 19 of them carbapenemase producers (15 VIM, 2 GES, 1 GES+VIM, 1 GES+KPC). Against the Enterobacterales isolates with meropenem MIC>2 mg/L (138/247), FTB was the most active agent against both serine-β-lactamases (107/138) and MBL producers (31/138) (97.2% and 93.5% MIC FTB ≤8/4 mg/L, respectively) whereas the activity of comparators was reduced, particularly against the MBL producers (ceftazidime-avibactam, 94.4% and 12.9%; meropenem-vaborbactam, 85.0% and 64.5%; imipenem-relebactam, 76.6% and 9.7%; ceftolozane-tazobactam, 1.9% and 0%; piperacillin-tazobactam, 0% and 0%, respectively). Among the meropenem-resistant Pseudomonas spp. isolates (163/170, MIC>2 mg/L), activity of FTB against serine-β-lactamase (35/163) and MBL producers (43/163) was 88.6% and 65.1%, respectively, whereas the susceptibility of comparators was: ceftazidime-avibactam, 88.5% and 16.0%; meropenem-vaborbactam, 8.5% and 7.0%; imipenem-relebactam, 2.9% and 2.3%; ceftolozane-tazobactam, 0% and 2.3%; and piperacillin-tazobactam, 0% and 0%, respectively. Microbiological results suggest FTB as a potential therapeutic option in patients infected with carbapenemase-producing Enterobacterales and carbapenem-resistant Pseudomonas isolates, including MBL producers.

scholarly journals The ERACE-PA Global Surveillance Program: Ceftolozane/tazobactam and Ceftazidime/avibactam in vitro Activity against a Global Collection of Carbapenem-resistant Pseudomonas aeruginosa

2021 ◽  
Author(s):  
Christian M. Gill ◽  
Elif Aktaþ ◽  
Wadha Alfouzan ◽  
Lori Bourassa ◽  
Adrian Brink ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Active Agent ◽  
Surveillance Program ◽  
In Vitro Activity ◽  
Broth Microdilution ◽  
Entire Cohort ◽  
Highly Active ◽  
Carbapenem Resistant ◽  
Lactamase Inhibitor

AbstractThe cephalosporin-β-lactamase-inhibitor-combinations, ceftolozane/tazobactam and ceftazidime/avibactam, have revolutionized treatment of carbapenem-resistant Pseudomonas aeruginosa (CR-PA). A contemporary assessment of their in vitro potency against a global CR-PA collection and an assessment of carbapenemase diversity are warranted. Isolates determined as CR-PA by the submitting site were collected from 2019–2021 (17 centers in 12 countries) during the ERACE-PA Global Surveillance Program. Broth microdilution MICs were assessed per CLSI standards for ceftolozane/tazobactam, ceftazidime/avibactam, ceftazidime, and cefepime. Phenotypic carbapenemase testing was conducted (modified carbapenem inactivation method (mCIM)). mCIM positive isolates underwent genotypic carbapenemase testing using the CarbaR, the CarbaR NxG, or whole genome sequencing. The MIC50/90 was reported as well as percent susceptible (CLSI and EUCAST interpretation). Of the 807 isolates, 265 (33%) tested carbapenemase-positive phenotypically. Of these, 228 (86%) were genotypically positive for a carbapenemase with the most common being VIM followed by GES. In the entire cohort of CR-PA, ceftolozane/tazobactam and ceftazidime/avibactam had MIC50/90 values of 2/ > 64 and 4/64 mg/L, respectively. Ceftazidime/avibactam was the most active agent with 72% susceptibility per CLSI compared with 63% for ceftolozane/tazobactam. For comparison, 46% of CR-PA were susceptible to ceftazidime and cefepime. Against carbapenemase-negative isolates, 88 and 91% of isolates were susceptible to ceftolozane/tazobactam and ceftazidime/avibactam, respectively. Ceftolozane/tazobactam and ceftazidime/avibactam remained highly active against carbapenem-resistant P. aeruginosa, particularly in the absence of carbapenemases. The contemporary ERACE-PA Global Program cohort with 33% carbapenemase positivity including diverse enzymology will be useful to assess therapeutic options in these clinically challenging organisms with limited therapies.

scholarly journals Activity of cefiderocol against high-risk clones of multidrug-resistant Enterobacterales, Acinetobacter baumannii, Pseudomonas aeruginosa and Stenotrophomonas maltophilia

2020 ◽  
Vol 75 (7) ◽  
pp. 1840-1849 ◽  
Author(s):  
Mercedes Delgado-Valverde ◽  
M del Carmen Conejo ◽  
Lara Serrano ◽  
Felipe Fernández-Cuenca ◽  
Álvaro Pascual
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Acinetobacter Baumannii ◽  
Stenotrophomonas Maltophilia ◽  
Enterobacter Cloacae ◽  
Multidrug Resistant ◽  
In Vitro Activity ◽  
Carbapenem Resistant ◽  
Excellent Activity ◽  
In Vitro Antibacterial Activity

Abstract Background Cefiderocol is a novel siderophore cephalosporin, developed for activity against MDR Gram-negative bacilli (MDR-GNB). Objectives To assess the in vitro antibacterial activity of cefiderocol against a collection of MDR-GNB clinical isolates from hospitals in southern Spain. Methods Two hundred and thirty-one isolates of successful clones were tested: 125 Enterobacterales (121 ESBL- and/or carbapenemase-producing Klebsiella pneumoniae and 4 carbapenemase-producing Enterobacter cloacae), 80 Acinetobacter baumannii, 6 Pseudomonas aeruginosa and 20 Stenotrophomonas maltophilia. Ceftolozane/tazobactam, ceftazidime, ceftazidime/avibactam, cefepime, aztreonam, meropenem, amikacin, ciprofloxacin, colistin and tigecycline were used as comparators against Enterobacterales, P. aeruginosa and A. baumannii. Minocycline, levofloxacin and trimethoprim/sulfamethoxazole were studied against S. maltophilia instead of aztreonam, ciprofloxacin and cefepime. MICs were determined by broth microdilution according to CLSI guidelines. MIC determination was performed in CAMHB for all antimicrobials except cefiderocol, where iron-depleted CAMHB was used. Results Cefiderocol showed potent in vitro activity against the isolates analysed. MIC50 and MIC90 values were in the ranges 0.125–8 mg/L and 0.5–8 mg/L, respectively, and 98% of isolates were inhibited at ≤4 mg/L. Only five isolates showed cefiderocol MICs of >4 mg/L: three ST2/OXA-24/40-producing A. baumannii, one ST114/VIM-1-producing E. cloacae and one ST114/VIM-1 + OXA-48-producing E. cloacae. All KPC-3-producing K. pneumoniae were susceptible to cefiderocol, even those resistant to ceftazidime/avibactam. P. aeruginosa isolates showed cefiderocol MICs of <4 mg/L, including those resistant to ceftolozane/tazobactam. S. maltophilia isolates displayed cefiderocol MICs of <4 mg/L, including those resistant to levofloxacin and/or trimethoprim/sulfamethoxazole. Conclusions Cefiderocol showed excellent activity against MDR-GNB, including carbapenem-resistant isolates, and was the most active antimicrobial tested against this collection.

scholarly journals In Vitro Activity Comparison of Ceftazidime–Avibactam and Aztreonam–Avibactam Against Bloodstream Infections With Carbapenem-Resistant Organisms in China

2021 ◽  
Vol 11 ◽  
Author(s):  
Wei Yu ◽  
Luying Xiong ◽  
Qixia Luo ◽  
Yunbo Chen ◽  
Jinru Ji ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Pseudomonas Aeruginosa ◽  
Bloodstream Infections ◽  
Polymyxin B ◽  
Resistance Rate ◽  
In Vitro Activity ◽  
Carbapenem Resistant ◽  
Resistance Rates ◽  
Activity Comparison

ObjectivesThe aim of this work was to investigate the activity of ceftazidime–avibactam (CZA) and aztreonam–avibactam (AZA) against bloodstream infections caused by carbapenem-resistant organisms (CROs).MethodsNon-duplicate CROs, including 56 carbapenem-resistant Escherichia coli (CR-Eco), 318 carbapenem-resistant Klebsiella pneumoniae (CR-Kpn), and 65 carbapenem-resistant Pseudomonas aeruginosa (CR-Pae), were collected using the Blood Bacterial Resistant Investigation Collaborative System (BRICS) program in China. The minimum inhibitory concentrations (MICs) of 24 antibiotics were tested. Carbapenemase genes were amplified for CZA-resistant CROs by PCR. The MICs of CZA and AZA were further determined with avibactam at 8 and 16 mg/L, respectively.ResultsThe resistance rate of polymyxin B against CROs was less than 5%. Only one CR-Kpn was resistant to tigecycline. The resistance rates of CZA against CR-Eco, CR-Kpn, and CR-Pae were 75.0%, 12.6%, and 18.5%, respectively. The MIC90 values of AZA against CR-Eco, CR-Kpn, and CR-Pae were 2/4, 1/4, and 64/4 mg/L, respectively. Among the CZA-resistant CROs, 42 (100%) CR-Eco, 24 (60%) CR-Kpn, and 1 (8.3%) CR-Pae isolates harbored metallo-β-lactamase genes. The increase of avibactam concentration enhanced the susceptibility of CZA and AZA against CROs, especially for CR-Eco and CR-Kpn.ConclusionsThe in vitro activity of AZA was superior to that of CZA against CR-Eco and CR-Kpn, whereas CZA showed better effect against CR-Pae.

scholarly journals 203. Activity of Cefepime in Combination with Taniborbactam (formerly VNRX-5133) Against Pseudomonas aeruginosa from a Global 2018-2020 Surveillance Collection

2021 ◽  
Vol 8 (Supplement_1) ◽  
pp. S124-S124
Author(s):  
Meredith Hackel ◽  
Mark G G Wise ◽  
Daniel F Sahm
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Efflux Pump ◽  
Active Agent ◽  
Multidrug Resistant ◽  
Vitro Activity ◽  
In Vitro Activity ◽  
Independent Contractor ◽  
Carbapenem Resistant ◽  
New Treatment

Abstract Background Taniborbactam is a novel cyclic boronate-based broad-spectrum β-lactamase inhibitor (BLI) with potent and selective inhibitory activity against both serine- and metallo-β-lactamases (MBLs). Taniborbactam restores the activity of cefepime (FEP) against many multidrug resistant organisms, including cephalosporin- and carbapenem-resistant Enterobacterales and Pseudomonas aeruginosa (PA). We evaluated the in vitro activity of the investigational combination cefepime-taniborbactam and comparators against clinical isolates of PA collected during a 2018-2020 surveillance. Methods MICs of FEP with taniborbactam fixed at 4 µg/mL (FTB) and comparators were determined against 3,219 PA collected from 221 sites in 52 countries in 2018-2020. Resistant phenotypes were based on 2021 CLSI breakpoints. Acquired β-lactamase (BL) genes were identified via PCR/Sanger sequencing or whole-genome sequencing (WGS) for 516 isolates with meropenem (MEM) MIC ≥8 µg/mL, and for 94 randomly selected isolates with FEP or ceftazidime MIC ≥16 µg/mL. 186 isolates with FTB MIC ≥16 µg/mL, 16 with FTB MIC=8 µg/mL and one with FTB MIC=4 µg/mL were subjected to WGS. Results Overall, 28.7%, 26.2% and 20.3% of PA isolates were nonsusceptible (NS) to piperacillin-tazobactam (TZP), MEM or FEP, respectively (Table). FTB demonstrated potent activity (MIC50/90, 2/8 µg/mL; 94.2% inhibited at ≤8 µg/mL) against PA overall and inhibited between 63.4% (ceftazidime-avibactam [CZA] NS) and 82.1% (TZP NS) of isolates in the NS subsets compared to 0% to 69.1% S for comparators. Against the 111 strains carrying VIM or NDM MBL genes, 67.6% had FTB MICs ≤8 µg/mL, with 11.7% having FTB MICs of 16 µg/mL. Plausible explanations for elevated FTB MICs included IMP MBL genes, penicillin binding protein 3 variations, and/or possible efflux pump up-regulation. Conclusion FTB demonstrated potent in vitro activity against PA with different resistance profiles, including NS to FEP, MEM, and TZP, and to the BL/BLI combinations CZA, ceftolozane-tazobactam, and meropenem-vaborbactam. FTB was the most active agent tested against PA harboring VIM and NDM MBLs. These findings support the continued development of FTB as a potential new treatment option for challenging infections due to MDR PA. Disclosures Meredith Hackel, PhD MPH, IHMA (Employee)Pfizer, Inc. (Independent Contractor) Mark G G. Wise, PhD, IHMA (Employee)Pfizer, Inc. (Independent Contractor) Daniel F. Sahm, PhD, IHMA (Employee)Pfizer, Inc. (Independent Contractor)

scholarly journals In Vitro Activity of a Novel Siderophore-Cephalosporin LCB10-0200 (GT-1), and LCB10-0200/Avibactam, against Carbapenem-Resistant Escherichia coli, Klebsiella pneumoniae, Acinetobacter baumannii, and Pseudomonas aeruginosa Strains at a Tertiary Hospital in Korea

2021 ◽  
Vol 14 (4) ◽  
pp. 370
Author(s):  
Le Phuong Nguyen ◽  
Chul Soon Park ◽  
Naina Adren Pinto ◽  
Hyunsook Lee ◽  
Hyun Soo Seo ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Pseudomonas Aeruginosa ◽  
Klebsiella Pneumoniae ◽  
Acinetobacter Baumannii ◽  
Vitro Activity ◽  
In Vitro Activity ◽  
Strong Activity ◽  
E Coli ◽  
Carbapenem Resistant

The siderophore–antibiotic conjugate LCB10-0200 (a.k.a. GT-1) has been developed to combat multidrug-resistant Gram-negative bacteria. In this study, the in vitro activity of LCB10-0200 and LCB10-0200/avibactam (AVI) has been investigated against carbapenem-resistant Escherichia coli, Klebsiella pneumoniae, Acinetobacter baumannii, and Pseudomonas aeruginosa. Minimal inhibitory concentrations (MICs) of LCB10-0200, LCB10-0200/AVI, aztreonam, aztreonam/AVI, ceftazidime, ceftazidime/AVI, and meropenem were measured using the agar dilution method. Whole genome sequencing was performed using Illumina and the resistome was analyzed. LCB10-0200 displayed stronger activity than the comparator drugs in meropenem-resistant E. coli and K. pneumoniae, and the addition of AVI enhanced the LCB10-0200 activity to MIC ≤ 0.12 mg/L for 90.5% of isolates. In contrast, whereas LCB10-0200 alone showed potent activity against meropenem-resistant A. baumannii and P. aeruginosa at MIC ≤ 4 mg/L for 84.3% of isolates, the combination with AVI did not improve its activity. LCB10-0200/AVI was active against CTX-M-, SHV-, CMY-, and KPC- producing E. coli and K. pneumoniae, while LCB10-0200 alone was active against ADC-, OXA-, and VIM- producing A. baumannii and P. aeruginosa. Both LCB10-0200 and LCB10-0200/AVI displayed low activity against IMP- and NDM- producing strains. LCB10-0200 alone exhibited strong activity against selected strains. The addition of AVI significantly increased LCB10-0200 activity against carbapenem-resistant E. coli, K. pneumoniae.

scholarly journals 681. In vitro Activity of the β-Lactamase Inhibitor QPX7728 in Combination with Several β-Lactams Against Acinetobacter baumannii (AB) and Pseudomonas aeruginosa (PSA)

2019 ◽  
Vol 6 (Supplement_2) ◽  
pp. S310-S311 ◽  
Author(s):  
Olga Lomovskaya ◽  
Jill Lindley ◽  
Debora Rubio-Aparicio ◽  
Kirk J Nelson ◽  
Mariana Castanheira
Keyword(s):  
Resistance Mechanisms ◽  
Vitro Activity ◽  
Clinical Isolates ◽  
In Vitro Activity ◽  
Microdilution Method ◽  
Carbapenem Resistant ◽  
Broth Microdilution Method ◽  
Data Representative ◽  
Lactamase Inhibitor

Abstract Background QPX7728 (QPX) is a novel broad-spectrum boron-containing inhibitor of serine- and metallo-β-lactamases (MBLs). We evaluated the in vitro activity of QPX combined with several β-lactams against carbapenem-resistant AB (CRAB) and PSA clinical isolates with varying β-lactam resistance mechanisms. Methods A total of 503 CRAB (meropenem [MEM] MIC ≥8 µg/mL) and 762 PSA clinical isolates were tested by the reference broth microdilution method against β-lactams alone and combined with QPX (4 µg/mL and 8 µg/mL). PSA isolates were selected to represent the normal distribution of MEM, ceftazidime–avibactam (CAZ-AVI), and ceftolozane-tazobactam (TOL-TAZ) resistance according to 2017 surveillance data (representative panel). Additionally, 262 PSA isolates that were either nonsusceptible (NS) to MEM (MIC, ≥4 µg/mL) or to TOL-TAZ (MIC, ≥8 µg/mL), or resistant (R) to CAZ-AVI (MIC, ≥16 µg/mL) (challenge panel) were also tested. Within this 262 strain challenge set, 56 strains carried MBLs and the majority also had nonfunctional OprD. Results Against CRAB, QPX at 4 and 8 µg/mL increased the potency of all β-lactams tested. MEM-QPX was the most potent combination (table) displaying MIC50/MIC90 at 1/8 and 0.5/4 µg/mL with QPX at fixed 4 and 8 µg/mL, respectively. Susceptibility (S) to MEM was restored in >95% of strains. Against the 500 PSA from the representative panel, S for all QPX combinations was >90%. For the challenge panel, TOL-QPX and piperacillin (PIP)-QPX were the most potent combinations, restoring S in 76–77% of strains. TOL-QPX and MEM-QPX or cefepime (FEP)-QPX restored the MIC values to S rates when applying the CLSI breakpoint for the compound alone (comparison purposes only) in ~90% and ~75% of non-MBL-producing strains, respectively, vs. 60–70% for TOL-TAZ and CAZ-AVI. PIP-QPX reduce the MIC values to S values for PIP-TAZ in ~60% of MBL-producing strains vs. 20–30% and 3–7% for other QPX combinations and non-QPX tested combinations, respectively. Conclusion Combinations of QPX with various β-lactam antibiotics displayed potent activity against CRAB and resistant PSA isolates and warrant further investigation. Disclosures All authors: No reported disclosures.

scholarly journals In Vitro Activity of a Novel Siderophore-Cephalosporin, GT-1 and Serine-Type β-Lactamase Inhibitor, GT-055, against Escherichia coli, Klebsiella pneumoniae and Acinetobacter spp. Panel Strains

Antibiotics ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 267 ◽  
Author(s):  
Le Phuong Nguyen ◽  
Naina Adren Pinto ◽  
Thao Nguyen Vu ◽  
Hyunsook Lee ◽  
Young Lag Cho ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Klebsiella Pneumoniae ◽  
Vitro Activity ◽  
Intrinsic Activity ◽  
In Vitro Activity ◽  
E Coli ◽  
Acinetobacter Spp ◽  
Resistant Strains ◽  
Lactamase Inhibitor

This study investigates GT-1 (also known as LCB10-0200), a novel-siderophore cephalosporin, inhibited multidrug-resistant (MDR) Gram-negative pathogen, via a Trojan horse strategy exploiting iron-uptake systems. We investigated GT-1 activity and the role of siderophore uptake systems, and the combination of GT-1 and a non-β-lactam β-lactamase inhibitor (BLI) of diazabicyclooctane, GT-055, (also referred to as LCB18-055) against molecularly characterised resistant Escherichia coli, Klebsiella pneumoniae and Acinetobacter spp. isolates. GT-1 and GT-1/GT-055 were tested in vitro against comparators among three different characterised panel strain sets. Bacterial resistome and siderophore uptake systems were characterised to elucidate the genetic basis for GT-1 minimum inhibitory concentrations (MICs). GT-1 exhibited in vitro activity (≤2 μg/mL MICs) against many MDR isolates, including extended-spectrum β-lactamase (ESBL)- and carbapenemase-producing E. coli and K. pneumoniae and oxacillinase (OXA)-producing Acinetobacter spp. GT-1 also inhibited strains with mutated siderophore transporters and porins. Although BLI GT-055 exhibited intrinsic activity (MIC 2–8 μg/mL) against most E. coli and K. pneumoniae isolates, GT-055 enhanced the activity of GT-1 against many GT-1–resistant strains. Compared with CAZ-AVI, GT-1/GT-055 exhibited lower MICs against E. coli and K. pneumoniae isolates. GT-1 demonstrated potent in vitro activity against clinical panel strains of E. coli, K. pneumoniae and Acinetobacter spp. GT-055 enhanced the in vitro activity of GT-1 against many GT-1–resistant strains.

scholarly journals 598. In Vitro Activity of Aztreonam in Combination with Ceftazidime–Avibactam, Amoxicillin–Clavulanate, and Piperacillin–Tazobactam vs. NDM-Producing Escherichia coli and Klebsiella pneumoniae Clinical Isolates

2019 ◽  
Vol 6 (Supplement_2) ◽  
pp. S281-S281
Author(s):  
Andrew Walkty ◽  
James Karlowsky
Keyword(s):  
Escherichia Coli ◽  
Klebsiella Pneumoniae ◽  
Vitro Activity ◽  
Clinical Isolates ◽  
Disk Diffusion ◽  
In Vitro Activity ◽  
Zone Diameter ◽  
Amoxicillin Clavulanate ◽  
Lactamase Inhibitor

Abstract Background There are limited options available for the treatment of infections caused by Enterobacteriaceae that produce an NDM metallo-β-lactamase. The purpose of this study was to compare the in vitro activity of aztreonam in combination with three different β-lactam/β-lactamase inhibitors (ceftazidime–avibactam, amoxicillin-clavulanate, piperacillin–tazobactam) vs. NDM-positive Enterobacteriaceae clinical isolates. Methods Seven Escherichia coli and three Klebsiella pneumoniae clinical isolates (all NDM-positive by PCR) were included in this study. The in vitro activities of ceftazidime–avibactam, amoxicillin-clavulanate, piperacillin–tazobactam, and aztreonam were determined by disk diffusion as described by CLSI. For synergy testing, disks containing a β-lactamase inhibitor (ceftazidime–avibactam, amoxicillin-clavulanate, piperacillin tazobactam) were applied to Mueller–Hinton agar plates inoculated with the test organisms, and the plates were incubated for 1 hour. The disks were then removed and aztreonam disks were dropped on the previous disk sites. The plates were then incubated as per standard CLSI recommendations for disk diffusion testing. Results All ten isolates demonstrated phenotypic resistance to aztreonam, amoxicillin-clavulanate, and piperacillin–tazobactam, and eight were resistant to ceftazidime–avibactam (CLSI breakpoints). The zone diameter observed for aztreonam in combination with ceftazidime–avibactam was greater than for either antimicrobial on its own for nine isolates. Seven isolates (70%) had susceptibility to aztreonam restored (zone diameter ≥21 mm) in the presence of avibactam. Aztreonam in combination with amoxicillin-clavulanate demonstrated in increase in zone diameter for all isolates relative to the zone for each antimicrobial alone, but only two (20%) had aztreonam susceptibility restored. Aztreonam susceptibility was not restored for any of the isolates in combination with piperacillin–tazobactam. Conclusion Of the three β-lactam/β-lactamase inhibitor-aztreonam combinations evaluated, ceftazidime–avibactam plus aztreonam demonstrated the greatest in vitro activity vs. NDM-producing Enterobacteriaceae. Disclosures All authors: No reported disclosures.

scholarly journals In Vitro Activity of Newer and Conventional Antimicrobial Agents, Including Fosfomycin and Colistin, against Selected Gram-Negative Bacilli in Kuwait

Pathogens ◽  
2018 ◽  
Vol 7 (3) ◽  
pp. 75 ◽  
Author(s):  
Wadha Alfouzan ◽  
Rita Dhar ◽  
David Nicolau
Keyword(s):  
Escherichia Coli ◽  
Pseudomonas Aeruginosa ◽  
Antimicrobial Agents ◽  
The Other ◽  
In Vitro Activity ◽  
Limited Data ◽  
Gram Negative ◽  
E Coli ◽  
Microbroth Dilution

Limited data are available on susceptibilities of these organisms to some of the recently made accessible antimicrobial agents. The in vitro activities of newer antibiotics, such as, ceftolozane/tazobactam (C/T) and ceftazidime/avibactam (CZA) along with some “older” antibiotics, for example fosfomycin (FOS) and colistin (CL) were determined against selected strains (resistant to ≥ 3 antimicrobial agents) of Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa. Minimum inhibitory concentrations (MIC) were determined by Clinical and Laboratory Standards Institute microbroth dilution. 133 isolates: 46 E. coli, 39 K. pneumoniae, and 48 P. aeruginosa were tested. Results showed that E. coli isolates with MIC50/90, 0.5/1 μ g / mL for CL; 4/32 μ g / mL for FOS; 0.25/32 μ g / mL for C/T; 0.25/8 μ g / mL for CZA, exhibited susceptibility rates of 95.7%, 97.8%, 76.1%, and 89.1%, respectively. On the other hand, K. pneumoniae strains with MIC50/90, 0.5/1 μ g / mL for CL; 256/512 μ g / mL for FOS; 2/128 μ g / mL for C/T; 0.5/128 μ g / mL for CZA showed susceptibility rates of 92.3%, 7.7%, 51.3%, and 64.1%, respectively. P. aeruginosa isolates with MIC50/90, 1/1 μ g / mL for CL; 128/128 μ g / mL for C/T; 32/64 μ g / mL for CZA presented susceptibility rates of 97.9%, 33.3%, and 39.6%, respectively. Higher MICs were demonstrated against most of the antibiotics. However, CL retained efficacy at low MICs against most of the isolates tested.

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