Evaluation of Metallo-β-Lactamase Susceptibility Testing in a Physiologic Medium

Studies assessing antibiotic susceptibility profiles in nonconventional media are lacking. MBL-mediated resistance has come under scrutiny due to the dependence on extracellular zinc concentrations, which makes the choice of testing medium influential for β-lactam MICs. This study explores human urine as a physiologically relevant matrix with which susceptibility profiles of MBL-harboring isolates can be assessed, relative to conventional broth.

DC-Link Capacitor Voltage Balancing Control of a Five-Level Regenerative AC Electronic Load Using One-Cycle Control

High voltage electric power equipment requires rigorous regulation testing to specific standards which ensure proper and safe operation in the grid. Manufacturers conduct these tests in order to prove standard compliance and product liability. Variable linear or nonlinear loads are necessary for testing medium voltage (MV) high power AC power converters. Generally, those AC power converters or power supplies require performance validation, burn-in and/or lifetime testing under different load conditions, defined by the end-user or standards for the given applications. For flexible and efficient MV verification testing, this paper presents a five-level multilevel converter-based MV regenerative AC electronic load with one-cycle control (OCC), which is based on five-level diode-clamped multilevel converters with back-to-back structure and can emulate any impedance load. In this paper, especially the dc-link capacitor voltage balance of the proposed multilevel MV regenerative AC load is deeply analyzed. Simulation and experimental results are presented to verify the dc-link voltage balance performance of the proposed multilevel MV regenerative AC electronic load.

Chromatographic Analysis of Aflatoxigenic Aspergillus flavus Isolated from Malaysian Sweet Corn

High-performance liquid chromatography (HPLC) provides a quick and efficient tool for accurately characterizing aflatoxigenic and non-aflatoxigenic isolates of Aspergillus flavus. This method also provides a quantitative analysis of AFs in Aspergillus flavus. The method’s recovery was assessed by spiking a mixture of AF at different concentrations to the testing medium. The validity of the method was confirmed using aflatoxigenic and non-aflatoxigenic strains of A. flavus. The HPLC system, coupled with a fluorescence detector and post-column photochemical reactor, showed high sensitivity in detecting spiked AFs or AFs produced by A. flavus isolates. Recovery from medium spiked with 10, 20, 60, and 80 ppb of AFs was found to be 73–86% using this approach. For AFB1 and AFB2, the limit of detection was 0.072 and 0.062 ppb, while the limit of quantification was 0.220 and 0.189 ppb, respectively. The AFB1 concentrations ranged from 0.09 to 50.68 ppb, while the AFB2 concentrations ranged between 0.33 and 9.23 ppb. The findings showed that six isolates produced more AFB1 and AFB2 than the acceptable limit of 5 ppb. The incidence of aflatoxigenic isolates of A. flavus in sweet corn and higher concentrations of AFB1 and AFB2 emphasize the need for field trials to explore their real potential for AF production in corn.

The qualitative parameters of potato tubers in dependence on variety and duration of storage

The qualitative parameters of the potatoes tubers may be significantly changed depending on the variety, group of ripening, way, regime, and duration of storage. So, these researches aimed to define the influence of the variety characteristics and duration storage on qualitative parameters of tuber potatoes. Five potato varieties of two ripening groups were used for testing: medium-early (Satina, Red Lady, Mozart) and medium-ripe (Aroza, Sifra). The chemical properties such as dry matters (DM), starch, sugars (total and reducing), crude protein (CP), ascorbic acid (AA), and nitrates content were determined before and after 2, 4, and 6 months of storage. DM lost during the storage of potato tubers, especially during the period from 4 to 6 months. The group of ripening did not influence this index. Potato tubers of all varieties had high starch content and the duration of storage had a light effect on the level of its losses. In the medium-early group, maximum changes of starch were 1% but in the medium-ripe – 1.9%. A strong effect on the quantities of total sugars (TS) had varietal characteristics of the potato but a group of ripening had light influence. The highest content of sugars was Satin (0.65%) and the smallest Sifra (0.22%) and Mozart (0.23%). After 6 months of storage content of TS depending on the variety increased from 2 till 5 times, while the reducing sugars (RS) increased at least five times and at the end of storage were 0.4% to 0.65%. The amount of AA and its losses during storage depended on the variety. The relative losses during the total storage period were 21.9% in the medium-early group and 28.1% in the medium-ripe. Influence ripening group on level changing AA was not detected. Nitrates' content did not exceed the maximum permissible level (250 mg.kg-1). Their quantities after 6 months were 47 – 61 mg.kg-1.

The paradoxical in vivo activity of β-lactams against metallo-β-lactamase-producing Enterobacterales is not restricted to carbapenems

Background Using murine models of infection, we previously reported the potent in vivo activity of carbapenems against MBL-producing Enterobacterales despite the observed resistance in vitro. In the current study, we examined the in vivo activity of a cefepime human-simulated regimen against MBL-producing Enterobacterales in a murine thigh infection model. Methods A population of clinical isolates and isogenic engineered MBL-producing Enterobacterales transformants expressing MBLs but no detectable cefepime-hydrolysing serine β-lactamases were utilized. KPC-producing isolates were included as positive controls. Cefepime, piperacillin/tazobactam and meropenem MICs were determined using broth microdilution in conventional CAMHB and EDTA-supplemented (zinc-limited) broth. In vivo efficacy of a cefepime human-simulated regimen (2 g q8h as a 2 h infusion) was determined in the neutropenic murine thigh infection model against the test strains. Efficacy was measured as the change in log10 cfu/thigh at 24 h compared with 0 h controls. Results MBL-producing Enterobacterales strains were found to be cefepime, piperacillin/tazobactam and meropenem non-susceptible in conventional broth. Supplementation with EDTA at a concentration of 300 mg/L resulted in multi-fold reduction in the MICs and restoration of susceptibility. In accordance with the MICs generated in zinc-limited broth, administration of a cefepime human-simulated regimen was associated with substantial bacterial reductions among mice infected with MBL-producing Enterobacterales. Absence of MIC reduction in zinc-limited broth and lack of efficacy among mice infected with KPC-producing isolates were observed. Conclusions For MBL-producing Enterobacterales, susceptibility testing with Mueller–Hinton broth, a zinc-rich testing medium, is flawed since it does not recapitulate the host environment, in which zinc concentrations are low.

1299. In Vitro-In Vivo Discordance with β-lactams against Metallo-β-lactamase-Producing Enterobacterales: Implications for Susceptibility Testing

Background Using murine models of thigh and lung infection, we previously reported the potent in vivo activity of carbapenem human-simulated regimens against metallo-β-lactamase-producing Enterobacterales despite the observed resistance in vitro (JAC 2020 Apr 1;75(4):997-1005, AAC 2014;58(3):1671-7). In the current study, we examined the in vivo activity of cefepime human-simulated regimen against metallo-β-lactamase-producing Enterobacterales in a murine thigh infection model. Methods A population of clinical (n=21) and isogenic engineered (n=5) metallo-β-lactamase-producing Enterobacterales isolates expressing VIM, IMP or NDM but not co-expressing ESBLs or serine carbapenemases were utilized. KPC-producing strains (n=3) were included as positive controls. MICs of cefepime, piperacillin-tazobactam and meropenem were determined using broth microdilution in conventional cation-adjusted Muller Hinton and EDTA-supplemented broth at EDTA concentration of 300 mg/L (zinc-limited). The in vivo efficacy of a cefepime human-simulated regimen (2 g q8h as 2 h infusion) was determined in the neutropenic murine thigh infection model against the test isolates. Efficacy was measured as the change in log10cfu/thigh at 24 h compared with 0 h controls. Results Metallo-β-lactamase-producing Enterobacterales were found to be cefepime, piperacillin-tazobactam and meropenem non-susceptible in conventional broth. Supplementation with EDTA resulted in multi-fold reduction in the MICs and restoration of susceptibility. In accordance with the MICs generated in the zinc-limited broth, the administration of cefepime human-simulated regimen was associated with substantial bacterial reductions among mice infected with the clinical as well as the isogenic engineered metallo-β-lactamase-producing isolates. As anticipated with serine-based resistance, absence of MIC reduction in zinc-limited broth and lack of in vivo activity against KPC-producers were observed. Conclusion For metallo-β-lactamase-producing Enterobacterales, in vitro susceptibility testing to β-lactams with conventional media such as cation-adjusted Muller Hinton broth, a zinc-rich testing medium, is flawed since it does not recapitulate the host environment in which zinc concentrations are low. Disclosures David P. Nicolau, PharmD, Cepheid (Other Financial or Material Support, Consultant, speaker bureau member or has received research support.)Merck & Co., Inc. (Consultant, Grant/Research Support, Speaker’s Bureau)Wockhardt (Grant/Research Support)

Sports Education, Graduate Program, University PGRI Adi Buana Surabaya , Surabaya, East Jawa, Indonesia

This study aims to develop a module for the development of freestyle swimming teaching materials using trial and error methods as a medium for learning implementation, a module for developing learning or free style swimming training to facilitate swimming trainers and as an alternative method that can be used by trainers or teachers in learning freestyle swimming. This research is a type of development research with reference to the opinion of Kaufman, (1979) which researchers have developed with the current situation, the product developed is a freestyle swimming learning or training method with a trial and error method that contains learning sequences and learning with a psychological approach to swimming students. Product development through several stages began testing learning design experts and swimming material experts, then making questionnaires validated by swimming material experts and also sports psychologists, then in field trials, testing small groups and students, testing medium groups and students and large group trials. The place for testing in the swimming pool is insan cendekia krian, the data collection technique uses a questionnaire by assessing the responses of swimming students and in analysis using descriptive statistics that are presented in percentage form. The results of this study indicate that, the product validation test by learner design experts with a percentage of 88.4% was very good, a pool material expert with a percentage of 95% was very good, in swimming student trials with a small group trial with a percentage of 84.8% very good , moderate group students with a percentage of 87.9% were very good, and large group tests with a percentage of 91.7% were very good. Thus the module for developing swimming learning using the trial and error method is feasible to be used by trainers or swimming teachers.

Scope and Predictive Genetic/Phenotypic Signatures of Bicarbonate (NaHCO3) Responsiveness and β-Lactam Sensitization in Methicillin-Resistant Staphylococcus aureus

ABSTRACT Addition of sodium bicarbonate (NaHCO3) to standard antimicrobial susceptibility testing medium reveals certain methicillin-resistant Staphylococcus aureus (MRSA) strains to be highly susceptible to β-lactams. We investigated the prevalence of this phenotype (NaHCO3 responsiveness) to two β-lactams among 58 clinical MRSA bloodstream isolates. Of note, ∼75% and ∼36% of isolates displayed the NaHCO3 responsiveness phenotype to cefazolin (CFZ) and oxacillin (OXA), respectively. Neither intrinsic β-lactam MICs in standard Mueller-Hinton broth (MHB) nor population analysis profiles were predictive of this phenotype. Several genotypic markers (clonal complex 8 [CC8]; agr I and spa t008) were associated with NaHCO3 responsiveness for OXA.

Validity of Teleneuropsychological Assessment in Older Patients with Cognitive Disorders

Objective The feasibility and reliability of neuropsychological assessment at a distance have been demonstrated, but the validity of this testing medium has not been adequately demonstrated. The purpose of this study was to determine the ability of video teleconferencing administration of neuropsychological measures (teleneuropsychology) in discriminating cognitively impaired from non-impaired groups of older adults. It was predicted that measures administered via video teleconference would distinguish groups and that the magnitude of differences between impaired and non-impaired groups would be similar to group differences achieved in traditional administration. Methods The sample consisted of 197 older subjects, separated into two groups, with and without cognitive impairment. The cognitive impairment group included 78 individuals with clinical diagnoses of mild cognitive impairment or Alzheimer’s disease. All participants completed counterbalanced neuropsychological testing using alternate test forms in both a teleneuropsychology and a traditional face-to-face (FTF) administration condition. Tests were selected based upon their common use in dementia evaluations, brevity, and assessment of multiple cognitive domains. Results from FTF and teleneuropsychology test conditions were compared using individual repeated measures ANCOVA, controlling for age, education, gender, and depression scores. Results All ANCOVA models revealed significant main effects of group and a non-significant interaction between group and administration condition. All ANCOVA models revealed non-significant main effects for administration condition, except category fluency. Conclusions Results derived from teleneuropsychologically administered tests can distinguish between cognitively impaired and non-impaired individuals similar to traditional FTF assessment. This adds to the growing teleneuropsychology literature by supporting the validity of remote assessments in aging populations.