The early identification of carbapenemase-producing Enterobacterales (CPE) is required to prevent their spread and initiate proper therapy. Accordingly, it is crucial to develop efficient algorithms ...using susceptibility testing results to discriminate non-carbapenemase producers (non-CPE) from those that require complementary tests. In 2022, to adapt its recommendations to the evolution of CPE epidemiology (increased prevalence of OXA-244 producers), the Antibiogram Committee of the French Society of Microbiology (CA-SFM) proposed a new algorithm for the screening of CPE. We compared this algorithm to the former algorithm (2015-2021).
From July 2022 to January 2023, all nonduplicate enterobacterial isolates referred to French National Reference Centre for carbapenemase detection (n = 518) were subjected to the former CA-SFM algorithm (2015 to 2021) using inhibition diameters of ertapenem, ticarcillin-clavulanate, temocillin and meropenem or imipenem, and the novel CA-SFM algorithm (since 2022) using inhibition diameters of ceftazidime-avibactam, temocillin, and meropenem or imipenem.
Sensitivity, specificity, negative predictive value, and positive predictive value were of 80.8% (CI95 76.3%–84.6%), 66.2% (58.1%–73.5%), 59.3% (51.5%–66.6%), and 85.0% (80.7% - 88.5%) for the old CA-SFM algorithm and 97.8% (95.5%–99.0%), 45.5% (37.5%–53.7%), 89.7% (80.3%–95.2%), and 80.9% (76.9%–84.4%) for the novel CA-SFM algorithm.
The novel CA-SFM algorithm possesses the best performance for the screening of CPE particularly in countries with a high prevalence of OXA-48-like producers.
The blaNDM-1 gene has been reported to be often located on broad-host-range plasmids of the IncA/C type in clinical but also environmental bacteria recovered from the New Delhi, India, area. ...IncA/C-type plasmids are the main vehicles for the spread of the cephalosporinase gene blaCMY-2, frequently identified in the United States, Canada, and Europe. In this study, we completed the sequence of IncA/C plasmid pNDM-KN carrying the blaNDM-1 gene, recovered from a Klebsiella pneumoniae isolate from Kenya. This sequence was compared with those of three IncA/C-type reference plasmids from Escherichia coli, Yersinia ruckeri, and Photobacterium damselae. Comparative analysis showed that the blaNDM-1 gene was located on a widely diffused plasmid scaffold known to be responsible for the spread of blaCMY-2-like genes and consequently for resistance to broad-spectrum cephalosporins. Considering that IncA/C plasmids possess a broad host range, this scaffold might support a large-scale diffusion of the blaNDM-1 gene among Gram-negative rods.
► Extended-spectrum β-lactamases (ESBLs) genes are very diverse in Gram negatives. ► Acquisition is linked to insertion sequences, transposons and class 1 integrons. ► We examine the genetics of ...expression of those genes. ► We highlight the diversity of genetic vehicles involved in their mobilization.
Genes encoding extended-spectrum β-lactamases (ESBLs) have been reported in a variety of Gram-negative species, mostly in Enterobacteriaceae, Pseudomonas aeruginosa and Acinetobacter baumannii. They are either TEM- or SHV-derivatives, CTX-M-like enzymes and less frequently of the GES, PER, or VEB types. The mechanisms at the origin of their acquisition are diverse, and mostly are related to insertion sequences, transposons and class 1 integrons. This diversity of genetic vehicles at the origin of these mobilization/acquisition processes may explain spread of ESBLs worldwide.
OXA-244 is a single-point-mutant derivative of OXA-48 displaying reduced carbapenemase activity. Here, we report the microbiological features of seven OXA-244-producing
isolates. Only one isolate ...grew on ChromID Carba Smart medium (bioMérieux), but six of the seven isolates grew on ChromID extended-spectrum-β-lactamase (ESBL) medium (bioMérieux), as they coproduced an ESBL and/or a plasmid-encoded cephalosporinase. The production of a carbapenemase was detected in 57.1%, 71.4%, 71.4%, and 100% of the
isolates using the Carba NP test, the Rapidec Carba NP test (bioMérieux), a matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) hydrolysis assay (Bruker), and the OXA-48 K-SeT assay (Coris BioConcept), respectively. Our results indicate that OXA-244-producing
isolates are difficult to detect, which may lead to their silent spread.
•Despite infection prevention and control (IPC) measures are updated in the context of COVID-19, eXDR outbreak could occur.•This eXDR outbreak might be related to the misuse of gloves and the ...multiple-bedroom configuration of the department.•As IPC measures were thought to be applied, contact patient were not screened.•Applying contact precaution for eXDR carriers and performing screening in contact patients must be the rule.
In the hospital department dedicated to COVID-19-patient, infection prevention and control measures were upgraded. Therefore, the cross-transmission of other micro-organisms was thought unlikely to occur. However, we report an outbreak of NDM-5-producing Escherichia. coli in a 12-beds ICU dedicated to COVID-19 patients. This outbreak involved 6 patients of which 5 were asymptomatic carriers and 1 was infected. Several findings might have contributed to cross-transmission including the multiple-bedroom configuration of the department, uncomplete compliance for standard and contact precautions, overwork due to the burden of the disease, lack of training of staff for the care of ICU-patients, and misuse of gloves. Furthermore, as infection prevention and control measures were thought to be applied, contact patients were not screened for eXDR carriage. Applying rigorously standard and contact precautions and performing screening in contact patients when indicated must be the rules in COVID-19 wards.
Acinetobacter baumannii, recognized as a serious threat in healthcare facilities, has the ability to develop resistance to antibiotics quite easily. This resistance is related to either gene ...acquisition (horizontal gene transfer) or mutations in the genome, leading to gene disruption, over- or down-expression of genes. The clinically relevant antibiotic resistances in A. baumannii include resistance to aminoglycosides, broad-spectrum cephalosporins, carbapenems, tigecycline and colistin, which are the last resort antibiotics. The intrinsic and acquired resistance mechanisms of A. baumannii are presented here, with special focus on β-lactam resistance. The most up-to-date techniques for identification, including phenotypical and molecular tests, and screening of those emerging resistance traits are also highlighted. The implementation of early detection and identification of multidrug-resistant A. baumannii is crucial to control their spread.
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The rate of emulsification in surfactant/oil/water systems is influenced by transport of chemicals and mixing of the fluid phases. In porous media applications, complex flow regimes ...are generated due to three-dimensional connectivity and irregular cross-sections of the pores facilitating the mixing for emulsification. The properties of the resulting emulsified phase depend on the interplay of flow, mixing and emulsification kinetics of the surfactant/oil/water system. Emulsification can be relatively quick. Direct visualization of the process and compositional gradients in three-dimensional pore space during flow requires imaging at few seconds time intervals.
In this study, a flow unit was integrated in a synchrotron beamline-based fast X-ray computed micro-tomography set-up. Non-destructive three-dimensional visualization of multi phase flow inside a porous rock at flow conditions became viable. An oil saturated rock sample was first flooded with water, followed by surfactant solution to mobilize the remaining oil by miscible displacement. The sample was continuously imaged during injection; the scans were made at time intervals of 7–60 s.
The presence of an emulsified phase in addition to the oil and the aqueous phases required a more advanced image processing workflow compared to the workflows used for the immiscible fluid systems. A newly developed image processing technique was adopted; the grey levels in the images were correlated with the local oil content in the emulsified fluid regions. The visual extractions of the pore space showed that the emulsification occurred within seconds. Compositional gradients were observed in the emulsified phase as the injected surfactant solution reached the remote locations in the pore space. While a significant fraction of the oil was displaced within few seconds, the compositional gradients persisted over several millimeter length for several minutes, illustrating a sequence of mobilization and solubilization of the oil phase. The ability to interpret such compositional gradients in real time in porous space brings capability to study interfacial phenomena in applications where in situ emulsification occurs under flow.
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