Rapid Detection and Characterization of Carbapenemases in Enterobacterales with a New Modified Carbapenem Inactivation Method, mCIMplus.

The worldwide emergence and spread of antimicrobial resistance in Gram-negative bacteria are severely limiting therapeutic options and thus constitute a major public health threat. The timely accurate detection of carbapenemase producers and the determination of carbapenemase class according to the Ambler classification can guide antimicrobial therapy and facilitate infection control measures. A modified version of the carbapenemase inactivation method (CIM), mCIM, was described and approved by the CLSI in 2017. We evaluated the performance of a faster new mCIM-based assay, mCIMplus, which can detect carbapenemase activity within 8 h and characterize the carbapenemase according to the Ambler classification in 20 h. A panel of 137 isolates producing carbapenemases (GES, IMP, KPC, NDM, OXA-48, OXA-48-like, and VIM enzymes) and 22 non-carbapenemase-producing isolates was used to evaluate the performance of mCIMplus. We evaluated the detection of carbapenemase activity at 8 and 20 h. Carbapenemase class was determined, with specific inhibitors, at 20 h. The sensitivities of mCIMplus were 99.3% at 8 h and 98.5% at 20 h. Its specificity was 100% regardless of culture time. Based on a decision algorithm, this test successfully identified the carbapenemase class for 98.4% of the tested isolates (127/129). Characterization was correct for 100, 95, and 100% of Ambler class A, B, and D isolates, respectively. This test can, therefore, be used to detect carbapenemase activity within 8 h and to determine carbapenemase class within 20 h. It constitutes a very affordable (<€1 per isolate) and reliable technique requiring only basic laboratory equipment.

[Determination of procalcitonin (PCT) in micro-method on AQT90 FLEX® analyzer and in vitro stability study]. / Dosage de la procalcitonine (PCT) en microméthode sur analyseur AQT90 FLEX® et étude de la stabilité in vitro.

Radiometer® has developed a point-of-care test for fast PCT measurement on whole blood in micromethod on a AQT90 FLEX® instrument. We have verified the analytical performances of the AQT90 FLEX® PCT assay in heparinized macrotube and EDTA microtube for pediatric use, according to modified French Society of Clinical Biology (SFBC) protocol to the requirements of the standard NF EN ISO 15189: 2012. The samples (n=61, 30 macrotubes, 31 microtubes) were analyzed by the Brahms Kryptor Compact Plus® reference method vs the AQT90 FLEX®. In a second step, we studied the stability of the PCT at room temperature for 24 h. A good correlation between the two methods on macro- or microtubes is observed (respectively r=0.990 and 0.993). The Bland-Altmann representations confirm the excellent correlation with a deviant, above the acceptable limit, which was calculated according to ISO 5725-6, for each type of tube and for the two concentration ranges (lower and greater than 1 ng/mL). The biases observed do not affect the clinical decision. No degradation of PCT after 24 h was demonstrated by the Mann and Whitney test on macro- and microtubes (p=0.50 and 0.34, respectively). The determination of PCT on AQT90 FLEX® has satisfactory analytical characteristics and can be used as point-of-care testing device on whole blood without pre-analytical treatment. In heparinized macrotube and EDTA microtube, the PCT is stable at room temperature up to 24 h.

Variation in Recombination Rate and Its Genetic Determinism in Sheep Populations.

Recombination is a complex biological process that results from a cascade of multiple events during meiosis. Understanding the genetic determinism of recombination can help to understand if and how these events are interacting. To tackle this question, we studied the patterns of recombination in sheep, using multiple approaches and data sets. We constructed male recombination maps in a dairy breed from the south of France (the Lacaune breed) at a fine scale by combining meiotic recombination rates from a large pedigree genotyped with a 50K SNP array and historical recombination rates from a sample of unrelated individuals genotyped with a 600K SNP array. This analysis revealed recombination patterns in sheep similar to other mammals but also genome regions that have likely been affected by directional and diversifying selection. We estimated the average recombination rate of Lacaune sheep at 1.5 cM/Mb, identified ∼50,000 crossover hotspots on the genome, and found a high correlation between historical and meiotic recombination rate estimates. A genome-wide association study revealed two major loci affecting interindividual variation in recombination rate in Lacaune, including the RNF212 and HEI10 genes and possibly two other loci of smaller effects including the KCNJ15 and FSHR genes. The comparison of these new results to those obtained previously in a distantly related population of domestic sheep (the Soay) revealed that Soay and Lacaune males have a very similar distribution of recombination along the genome. The two data sets were thus combined to create more precise male meiotic recombination maps in Sheep. However, despite their similar recombination maps, Soay and Lacaune males were found to exhibit different heritabilities and QTL effects for interindividual variation in genome-wide recombination rates. This highlights the robustness of recombination patterns to underlying variation in their genetic determinism.

Quinoline-Derived Two-Photon-Sensitive Octupolar Probes.

A systematic study on quinoline-derived light sensitive probes, having third-order rotational symmetry is presented. The electronically linked octupolar structures show considerably improved linear and nonlinear photophysical properties under one- and two-photon irradiation conditions compared to the corresponding monomers. Photolysis of the three acetate derivatives shows strong structure dependency: whereas irradiation of the 6- and 7-aminoquinoline derivatives resulted in fast intramolecular cyclization and only trace amounts of fragmentation products, the 8-aminoquinoline derivative afforded clean and selective photolysis, with a sequential release of their acetate groups (δu[730]=0.67 GM).

Preanalytical influence of pneumatic tube delivery system on results of routine biochemistry and haematology analysis.

Pneumatic tube delivery system (PTS) enables to reduce considerably turnaround times. The aim of the study was to assess the influence of the PTS on the quality of routine biochemical and hematological tests in our laboratory. Blood samples from 6 hospitalized patients and 8 healthy volunteers were analyzed. Blood samples were delivered to the laboratory by a PTS and by a human courier. We performed the following analysis: ionized calcium, sodium, potassium, lactate deshydrogenase (LDH), aspartate aminotransferase (ASAT), arterial blood gas, complete blood count and coagulation test as prothrombin time, activated partial thromboplastin time, factors V and VIII. Results were compared between the both method of transport according to the recommendation of the Société française de biologie clinique and the French committee for accreditation (SH-GTA01, norme NF ISO 5275-6). The hemolysis index of plasma was similar between the groups and no morphological differences were found on blood cells. For three samples, when delivered by PTS, LDH levels (two samples) and neutrophil polynuclear count (one sample) were above the recommended guidelines compared to those delivered by courier. Conversely, LDH levels and FVIII were below in two samples delivered by PTS. LDH levels, PNN count or factor VIII can be affected by PTS without the clinical interpretation being modified. We concluded that the PTS can be used to transport blood samples for routine biochemical and hematological analysis in our hospital.

Is a pre-analytical process for urinalysis required?

For the reliable urinary measurement of calcium, phosphate and uric acid, a pre-analytical process by adding acid or base to urine samples at laboratory is recommended in order to dissolve precipitated solutes. Several studies on different kind of samples and analysers have previously shown that a such pre-analytical treatment is useless. The objective was to study the necessity of pre-analytical treatment of urine on samples collected using the V-Monovette® (Sarstedt) system and measured on the analyser Architect C16000 (Abbott Diagnostics). Sixty urinary samples of hospitalized patients were selected (n=30 for calcium and phosphate, and n=30 for uric acid). After acidification of urine samples for measurement of calcium and phosphate, and alkalinisation for measurement of uric acid respectively, differences between results before and after the pre-analytical treatment were compared to acceptable limits recommended by the French society of clinical biology (SFBC). No difference in concentration between before and after pre-analytical treatment of urine samples exceeded acceptable limits from SFBC for measurement of calcium and uric acid. For phosphate, only one sample exceeded these acceptable limits, showing a result paradoxically lower after acidification. In conclusion, in agreement with previous study, our results show that acidification or alkalinisation of urine samples from 24 h urines or from urination is not a pre-analytical necessity for measurement of calcium, phosphate and uric acid.

Two-photon "caging" groups: effect of position isomery on the photorelease properties of aminoquinoline-derived photolabile protecting groups.

High two-photon photolysis cross sections and water solubility of probes are important to avoid toxicity in biomedical applications of photolysis. Systematic variation of the position of a carboxyl electron-withdrawing group (EWG) on photolysis of 8-dimethylaminoquinoline protecting groups identified the C5-substituted isomer as a privileged dipole. The 5-benzoyl-8-DMAQ substitution yields a caging group with an enhanced two-photon uncaging cross section (δu = 2.0 GM) and good water solubility (c ≤ 50 mM, pH 7.4).

Substitution effect on the one- and two-photon sensitivity of DMAQ "caging" groups.

The systematic SAR study of a "caging" group showed a strong influence of the position of the donor dimethylamino group on the efficiency of photolysis of the DMAQ (2-hydroxymethylene-(N,N-dimethylamino)quinoline) caged acetate under one-photon near-UV or two-photon near-IR excitation. Photorelease of l-glutamate by the most efficient 8-DMAQ derivative strongly and efficiently activated glutamate receptors, generating large, fast rising responses similar to those elicited by glutamate photoreleased from the widely used MNI-caged glutamate.