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Background: Cefiderocol is generally active against carbapenem-resistant Klebsiella spp. (CRK) with higher MICs against metallo-beta-lactamase producers. There is a variation in cefiderocol interpretive criteria determined by EUCAST and CLSI. Our objective was to test CRK isolates against cefiderocol and compare cefiderocol susceptibilities using EUCAST and CLSI interpretive criteria., Methods: A unique collection ( n  = 254) of mainly OXA-48-like- or NDM-producing CRK bloodstream isolates were tested against cefiderocol with disc diffusion (Mast Diagnostics, UK). Beta-lactam resistance genes and multilocus sequence types were identified using bioinformatics analyses on complete bacterial genomes., Results: Median cefiderocol inhibition zone diameter was 24 mm (interquartile range [IQR] 24-26 mm) for all isolates and 18 mm (IQR 15-21 mm) for NDM producers. We observed significant variability between cefiderocol susceptibilities using EUCAST and CLSI breakpoints, such that 26% and 2% of all isolates, and 81% and 12% of the NDM producers were resistant to cefiderocol using EUCAST and CLSI interpretive criteria, respectively., Conclusions: Cefiderocol resistance rates among NDM producers are high using EUCAST criteria. Breakpoint variability may have significant implications on patient outcomes. Until more clinical outcome data are available, we suggest using EUCAST interpretive criteria for cefiderocol susceptibility testing.

Ceftazidime-avibactam exhibits good in vitro activity against carbapenem resistant Klebsiella carrying OXA-48-like enzymes. We tested two hundred unique carbapenem resistant Klebsiella blood stream isolates (71% with single OXA-48-like carbapenemases, including OXA-48, n = 62; OXA-232, n = 57; OXA-244, n = 17; OXA-181, n = 5) that were collected as part of a multicentre study against ceftazidime-avibactam using Etest (bioMérieux, Marcyl'Étoile, France), 10/4 μg disc (Thermo Fisher) and Sensititre Gram Negative EURGNCOL Plates (Lyophilized panels, Sensititre, Thermo Fisher) with the aim of comparing the performances of the Etest and disc to that of Sensititre. Ceftazidime-avibactam MIC 50/90 was 2/>16 mg/L for the entire collection and was 2/4 mg/L for single OXA-48-like producers. Categorical and essential agreements between the Etest and Sensititre were 100% and 97%, respectively. Categorical agreement between the disc and Sensititre was 100%. Etest and 10/4 μg discs are suitable alternatives to Sensititre for ceftazidime-avibactam sensitivity testing for OXA-48-like producers., Competing Interests: Declaration of competing interest Dr. Paterson reports research grants from Merck, Pfizer and Shionogi. David Paterson has received honoraria for advisory board membership from Merck, Pfizer, Shionogi, GSK, QPex, Entasis, VenatoRx, BioMerieux, and Accelerate. Dr Harris has received research grants from Sandoz, Merck/MSD and Shionogi, speaker's fees from Pfizer and honoraria for advisory board membership from Merck and Sandoz, paid to the University of Queensland. All others have no conflict of interest to declare., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Background: Increased antimicrobial resistance is a problem in managing urinary tract infections (UTI). With this study we assessed the resistance patterns of urinary isolates in children with UTI between January 2017 and January 2018., Methods: A retrospective cohort study was conducted. Among 5,443 isolates, a total of 776 UTI episodes in 698 patients were included. Patients' gender, age, voiding dysfunction, UTI history, prophylaxis status, and presence of vesicoureteral reflux were noted. Patients were divided into three age groups: group 1 for ages ≤12 months; group 2 for ages 13-60 months; and group 3 for ages >60 months. The susceptibilities of etiologic agents to different antimicrobials were explored., Results: Median age was 54 months (range 1 month-21 years); male to female ratio was 1:5. The most common causative agent was Escherichia coli (83% of the cases), followed by Klebsiella pneumoniae (7.5%). Resistance to ampicillin (62.6%) and co-trimoxazole (39.8%) were remarkable in all isolates. Overall extended-spectrum beta-lactamase (ESBL) positivity was 23.5%. The highest resistance rates, higher ESBL positivity (28.6%), and K. pneumoniae frequency (13.5%) were observed in group 1. Ceftriaxone resistance was significantly low (0.5%) in the ESBL (-) group, which constituted the majority of the isolates. Higher resistance rates were observed among the patients on prophylaxis compared to those off prophylaxis (P < 0.001)., Conclusion: Ceftriaxone can still be used for empirical treatment; however, initial urine culture results are crucial due to high ESBL positivity. Special consideration must be taken for patients under 1 year of age. Periodical surveillance studies are needed to explore the changing resistance patterns of uropathogens and modify treatment plans., (© 2020 Japan Pediatric Society.)

A set of new aziridinyl phosphonates (4a-g) were synthesized by using the Gabriel-Cromwell reaction and its modified version developed in this study and their structures confirmed by HRMS, IR, and NMR spectra. All the compounds were screened for their antibacterial activity. They all showed comparable moderate to good growth inhibitory activity in reference to ampicillin and streptomycin., (Copyright © 2011 Elsevier Masson SAS. All rights reserved.)