Inter-phylum circulation of a beta-lactamase-encoding gene: a rare but observable event.

Beta-lactamase-mediated degradation of beta-lactams is the most common mechanism of beta-lactam resistance in Gram-negative bacteria. Beta-lactamase-encoding genes can be transferred between closely related bacteria, but spontaneous inter-phylum transfers (between distantly related bacteria) have never been reported. Here, we describe an extended-spectrum beta-lactamase (ESBL)-encoding gene (blaMUN-1) shared between the Pseudomonadota and Bacteroidota phyla. An Escherichia coli strain was isolated from a patient in Münster (Germany). Its genome was sequenced. The ESBL-encoding gene (named blaMUN-1) was cloned, and the corresponding enzyme was characterized. The distribution of the gene among bacteria was investigated using the RefSeq Genomes database. The frequency and relative abundance of its closest homolog in the global microbial gene catalog (GMGC) were analyzed. The E. coli strain exhibited two distinct morphotypes. Each morphotype possessed two chromosomal copies of the blaMUN-1 gene, with one morphotype having two additional copies located on a phage-plasmid p0111. Each copy was located within a 7.6-kb genomic island associated with mobility. blaMUN-1 encoded for an extended-spectrum Ambler subclass A2 beta-lactamase with 43.0% amino acid identity to TLA-1. blaMUN-1 was found in species among the Bacteroidales order and in Sutterella wadsworthensis (Pseudomonadota). Its closest homolog in GMGC was detected frequently in human fecal samples. This is, to our knowledge, the first reported instance of inter-phylum transfer of an ESBL-encoding gene, between the Bacteroidota and Pseudomonadota phyla. Although the gene was frequently detected in the human gut, inter-phylum transfer was rare, indicating that inter-phylum barriers are effective in impeding the spread of ESBL-encoding genes, but not entirely impenetrable.

Perturbation and resilience of the gut microbiome up to 3 months after ß-lactams exposure in healthy volunteers suggest an important role of microbial ß-lactamases.

BACKGROUND: Antibiotics notoriously perturb the gut microbiota. We treated healthy volunteers either with cefotaxime or ceftriaxone for 3 days, and collected in each subject 12 faecal samples up to day 90. Using untargeted and targeted phenotypic and genotypic approaches, we studied the changes in the bacterial, phage and fungal components of the microbiota as well as the metabolome and the ß-lactamase activity of the stools. This allowed assessing their degrees of perturbation and resilience. RESULTS: While only two subjects had detectable concentrations of antibiotics in their faeces, suggesting important antibiotic degradation in the gut, the intravenous treatment perturbed very significantly the bacterial and phage microbiota, as well as the composition of the metabolome. In contrast, treatment impact was relatively low on the fungal microbiota. At the end of the surveillance period, we found evidence of resilience across the gut system since most components returned to a state like the initial one, even if the structure of the bacterial microbiota changed and the dynamics of the different components over time were rarely correlated. The observed richness of the antibiotic resistance genes repertoire was significantly reduced up to day 30, while a significant increase in the relative abundance of ß-lactamase encoding genes was observed up to day 10, consistent with a concomitant increase in the ß-lactamase activity of the microbiota. The level of ß-lactamase activity at baseline was positively associated with the resilience of the metabolome content of the stools. CONCLUSIONS: In healthy adults, antibiotics perturb many components of the microbiota, which return close to the baseline state within 30 days. These data suggest an important role of endogenous ß-lactamase-producing anaerobes in protecting the functions of the microbiota by de-activating the antibiotics reaching the colon. Video Abstract.

Lessons from a global antimicrobial resistance surveillance network.

The World Health Organization developed the Tricycle surveillance programme to obtain a global picture of antimicrobial resistance, especially in countries with limited surveillance capacity. The programme was developed within a One Health perspective. Tricycle provides a framework for applying a standardized technical protocol to determining the prevalence of extended-spectrum ß-lactamase (ESBL)-producing Escherichia coli in three sectors: the human, animal and environment sectors. Regular use of the protocol would enable information to be obtained on time trends and on inter- and intraregional variations, thereby generating dynamic data on antibacterial resistance for decision-makers. To date, 19 countries have begun implementing the Tricycle protocol, while other countries will start implementation in the coming years. The Network for Enhancing Tricycle ESBL Surveillance Efficiency (NETESE) was established to support countries implementing the Tricycle protocol. Currently, NETESE includes representatives from 15 institutions in eight low- or middle-income countries at different stages of Tricycle protocol implementation, and from four European countries involved in devising the protocol. This paper describes the Tricycle protocol, reports the initial experiences of NETESE participants with its implementation and discusses future challenges and opportunities.

L'Organisation mondiale de la Santé a développé le programme de surveillance Tricycle afin d'avoir une vue globale de la résistance aux antimicrobiens, en particulier dans les pays où les capacités de surveillance sont limitées. Ce programme a été mis au point selon l'approche «One Health¼. Tricycle établit le cadre d'application d'un protocole technique standardisé qui vise à mesurer la prévalence de souches d'Escherichia coli productrices de ß-lactamase à spectre étendu (BLSE) dans trois secteurs: humain, animal et environnemental. L'usage régulier du protocole permettrait d'obtenir des informations sur l'évolution dans le temps et les variations inter- et intrarégionales, ce qui générerait des données dynamiques sur la résistance aux antimicrobiens pour les décideurs. À ce jour, 19 pays se sont lancés dans la mise en place du protocole Tricycle, tandis que d'autres prévoient de le faire dans les années à venir. Le réseau NETESE (Network for Enhancing Tricycle ESBL Surveillance Efficiency) a été créé pour les aider à appliquer ce protocole. Actuellement, le réseau NETESE réunit des représentants de 15 institutions dans huit pays à revenu faible ou intermédiaire à différents stades de mise en œuvre du protocole Tricycle, ainsi que quatre pays européens impliqués dans sa conception. Le présent document décrit le protocole Tricycle, partage les premières expériences des participants au réseau NETESE en matière de déploiement, et aborde les futurs défis et opportunités qui y sont liés.

La Organización Mundial de la Salud desarrolló el programa de vigilancia Tricycle para obtener un panorama global de la resistencia a los antimicrobianos, especialmente en países con una capacidad de vigilancia limitada. El programa se creó desde la perspectiva One Health. Tricycle proporciona un marco que permite aplicar un protocolo técnico estandarizado con el fin de determinar la prevalencia de Escherichia coli productora de ß-lactamasa de espectro extendido (ESBL) en tres sectores: el humano, el animal y el medio ambiente. El uso habitual del protocolo permitiría obtener información sobre las tendencias temporales y las variaciones inter e intrarregionales, generando así datos dinámicos sobre la resistencia a los antibacterianos que resultarían útiles para los responsables de la toma de decisiones. Hasta la fecha, 19 países han comenzado a implementar el protocolo Tricycle, mientras que otros países comenzarán a aplicarlo en los próximos años. La red NETESE (Network for Enhancing Tricycle ESBL Surveillance Efficiency), se creó para apoyar a los países que implementan el protocolo Tricycle. Actualmente, NETESE está formada por representantes de 15 instituciones de ocho países con ingresos medios o bajos, que se encuentran en diferentes etapas de implementación del protocolo Tricycle. También incluye a representantes de cuatro países europeos que intervienen en el diseño del protocolo. El presente documento describe el protocolo Tricycle, recoge las primeras experiencias de los participantes de NETESE durante la implementación de dicho protocolo, y aborda tanto los retos como las oportunidades futuras.

Faecal Viral Excretion and Gastrointestinal Co-Infection Do Not Explain Digestive Presentation in COVID-19 Patients.

The physiopathological mechanisms responsible for digestive symptoms in COVID-19 patients are still unclear. The aim of this study was to determine the influence of faecal viral shedding on digestive symptoms and propose differential diagnoses in order to understand the gastrointestinal clinical spectrum in acute cases of COVID-19. All patients managed between March and May 2020, from whom stool samples were collected for microbiological investigations, were included. Microbiological analysis consisted of syndromic PCR screening and microscopic parasitological examination supplemented with microsporidia and multiplex protozoa PCR. SARS-CoV-2 infection was diagnosed via viral detection in respiratory and frozen stool samples, completed via serological test when necessary. Epidemiological, clinical, radiological, and biological data and clinical courses were compared according to COVID-19 status and faecal SARS-CoV-2 shedding and enteric co-infection status. The sample included 50 COVID+ and 67 COVID- patients. Faecal viral shedding was detected in 50% of stool samples and was associated with a higher viral load in the upper respiratory tract. Detected enteric pathogens were not different between subjects with different COVID-19 statuses or faecal SARS-CoV-2 shedding and had no impact on the clinical course for COVID-19 patients. The connection between SARS-CoV-2 shedding and enteric pathogen co-infection involvement in gastrointestinal presentation and clinical course is still unclear, suggesting other processes are involved in digestive disorders in COVID-19 patients.

Towards monitoring of antimicrobial resistance in the environment: For what reasons, how to implement it, and what are the data needs?

Antimicrobial resistance (AMR) is a global threat to human and animal health and well-being. To understand AMR dynamics, it is important to monitor resistant bacteria and resistance genes in all relevant settings. However, while monitoring of AMR has been implemented in clinical and veterinary settings, comprehensive monitoring of AMR in the environment is almost completely lacking. Yet, the environmental dimension of AMR is critical for understanding the dissemination routes and selection of resistant microorganisms, as well as the human health risks related to environmental AMR. Here, we outline important knowledge gaps that impede implementation of environmental AMR monitoring. These include lack of knowledge of the 'normal' background levels of environmental AMR, definition of high-risk environments for transmission, and a poor understanding of the concentrations of antibiotics and other chemical agents that promote resistance selection. Furthermore, there is a lack of methods to detect resistance genes that are not already circulating among pathogens. We conclude that these knowledge gaps need to be addressed before routine monitoring for AMR in the environment can be implemented on a large scale. Yet, AMR monitoring data bridging different sectors is needed in order to fill these knowledge gaps, which means that some level of national, regional and global AMR surveillance in the environment must happen even without all scientific questions answered. With the possibilities opened up by rapidly advancing technologies, it is time to fill these knowledge gaps. Doing so will allow for specific actions against environmental AMR development and spread to pathogens and thereby safeguard the health and wellbeing of humans and animals.

ResFinderFG v2.0: a database of antibiotic resistance genes obtained by functional metagenomics.

Metagenomics can be used to monitor the spread of antibiotic resistance genes (ARGs). ARGs found in databases such as ResFinder and CARD primarily originate from culturable and pathogenic bacteria, while ARGs from non-culturable and non-pathogenic bacteria remain understudied. Functional metagenomics is based on phenotypic gene selection and can identify ARGs from non-culturable bacteria with a potentially low identity shared with known ARGs. In 2016, the ResFinderFG v1.0 database was created to collect ARGs from functional metagenomics studies. Here, we present the second version of the database, ResFinderFG v2.0, which is available on the Center of Genomic Epidemiology web server (https://cge.food.dtu.dk/services/ResFinderFG/). It comprises 3913 ARGs identified by functional metagenomics from 50 carefully curated datasets. We assessed its potential to detect ARGs in comparison to other popular databases in gut, soil and water (marine + freshwater) Global Microbial Gene Catalogues (https://gmgc.embl.de). ResFinderFG v2.0 allowed for the detection of ARGs that were not detected using other databases. These included ARGs conferring resistance to beta-lactams, cycline, phenicol, glycopeptide/cycloserine and trimethoprim/sulfonamide. Thus, ResFinderFG v2.0 can be used to identify ARGs differing from those found in conventional databases and therefore improve the description of resistomes.

Genes mcr improve the intestinal fitness of pathogenic E. coli and balance their lifestyle to commensalism.

BACKGROUND: The plasmid-mediated resistance gene mcr-1 confers colistin resistance in Escherichia coli and paves the way for the evolution to pan-drug resistance. We investigated the impact of mcr-1 in gut colonization in the absence of antibiotics using isogenic E. coli strains transformed with a plasmid encoding or devoid of mcr-1. RESULTS: In gnotobiotic and conventional mice, mcr-1 significantly enhanced intestinal anchoring of E. coli but impaired their lethal effect. This improvement of intestinal fitness was associated with a downregulation of intestinal inflammatory markers and the preservation of intestinal microbiota composition. The mcr-1 gene mediated a cross-resistance to antimicrobial peptides secreted by the microbiota and intestinal epithelial cells (IECs), enhanced E. coli adhesion to IECs, and decreased the proinflammatory activity of both E. coli and its lipopolysaccharides. CONCLUSION: Overall, mcr-1 changed multiple facets of bacterial behaviour and appeared as a factor enhancing commensal lifestyle and persistence in the gut even in the absence of antibiotics. Video Abstract.

Acquisition of Enterobacterales carrying the colistin resistance gene mcr following travel to the tropics.

BACKGROUND: Colistin is an antibiotic of last resort in the management of highly drug-resistant Enterobacterales infections. Travel to some destinations presents a high risk of acquiring multidrug-resistant Enterobacterales, but little data are available on the risk of acquiring colistin-resistant strains. Here, we use the VOYAG-R sample collection (2012-2013) in order to evaluate the rate of acquisition of colistin-resistant Enterobacterales, excluding species with intrinsic resistance (CRE), following travel to tropical regions. METHODS: A total of 574 frozen stool samples of travellers returning from tropical regions were screened for colistin-resistant strains using ChromID Colistin R agar (bioMerieux®) after pre-enrichment culture with 1 mg/L of colistin. Genomes were obtained by Illumina sequencing and genetic determinants of colistin resistance (mutational events and mcr genes) were searched. RESULTS: A total of 22 travellers (3.8%) acquired colistin-resistant Enterobacterales carrying an mcr gene. Acquisition rates varied between visited regions: 9.2% (18/195) for Asia (southeast Asia: 17/18), 2.2% (4/184) for Latin America (Peru: 4/4) and 0% from Africa (0/195). Acquired strains were predominantly Escherichia coli (92%) and carried mostly the mcr-1 variant (83%). Escherichia coli strains belonged mainly to commensal phylogroups A and B1, and were genetically highly diverse (5 non-clonal sequence type (ST)10 and 17 ST singletons). Only four non mcr colistin-resistant strains (two E. coli and two Enterobacter cloacae complex) were identified. Among all the strains, two also carried extended-spectrum beta-lactamase genes. CONCLUSIONS: Travel to tropical regions, and particularly to Southeast Asia, is a risk factor for the acquisition of mcr-carrying Enterobacterales. This study highlights the community dissemination of mcr in humans as early as 2012, 4 years prior to its first published description.

Oropharyngeal and intestinal concentrations of opportunistic pathogens are independently associated with death of SARS-CoV-2 critically ill adults.

BACKGROUND: The composition of the digestive microbiota may be associated with outcome and infections in patients admitted to the intensive care unit (ICU). The dominance by opportunistic pathogens (such as Enterococcus) has been associated with death. However, whether this association remains all throughout the hospitalization are lacking. METHODS: We performed a single-center observational prospective cohort study in critically ill patients admitted with severe SARS-CoV-2 infection. Oropharyngeal and rectal swabs were collected at admission and then twice weekly until discharge or death. Quantitative cultures for opportunistic pathogens were performed on oropharyngeal and rectal swabs. The composition of the intestinal microbiota was assessed by 16S rDNA sequencing. Oropharyngeal and intestinal concentrations of opportunistic pathogens, intestinal richness and diversity were entered into a multivariable Cox model as time-dependent covariates. The primary outcome was death at day 90. RESULTS: From March to September 2020, 95 patients (765 samples) were included. The Simplified Acute Physiology Score 2 (SAPS 2) at admission was 33 [24; 50] and a Sequential Organ Failure Assessment score (SOFA score) at 6 [4; 8]. Day 90 all-cause mortality was 44.2% (42/95). We observed that the oropharyngeal and rectal concentrations of Enterococcus spp., Staphylococcus aureus and Candida spp. were associated with a higher risk of death. This association remained significant after adjustment for prognostic covariates (age, chronic disease, daily antimicrobial agent use and daily SOFA score). A one-log increase in Enterococcus spp., S. aureus and Candida spp. in oropharyngeal or rectal swabs was associated with a 17% or greater increase in the risk of death. CONCLUSION: We found that elevated oropharyngeal/intestinal Enterococcus spp. S. aureus and Candida spp. concentrations, assessed by culture, are associated with mortality, independent of age, organ failure, and antibiotic therapy, opening prospects for simple and inexpensive microbiota-based markers for the prognosis of critically ill SARS-CoV-2 patients.

Dissemination of carbapenemase-producing Enterobacterales in the community of Rawalpindi, Pakistan.

Carbapenems are considered last-line beta-lactams for the treatment of infections caused by multidrug-resistant Gram-negative bacteria. However, their activity is compromised by the rising prevalence of carbapenemase-producing Enterobacterales (CPE), which are especially marked in the Indian subcontinent. In Pakistan, previous reports have warned about the possible spread of CPE in the community, but data are still partial. This study was carried out to analyse the prevalence of CPE, the genetic characterisation, and phylogenetic links among the spreading CPE in the community. In this cohort study, we collected 306 rectal swabs from patients visiting Benazir Bhutto hospital, Rawalpindi. CPEs were screened by using ertapenem-supplemented MacConkey agar. Identification was performed by using conventional biochemical tests, and genomes were sequenced using Illumina chemistry. Antibiotic resistance genes, plasmid incompatibility groups, and Escherichia coli phylogroups were determined in silico. Sequence types were determined by using MLST tool. The prevalence of CPE carriage observed was 14.4% (44/306 samples). The most common carbapenemase-encoding gene was bla-NDM-5 (n = 58) followed by blaNDM-1 (n = 7), blaNDM (non-assigned variant, n = 4), blaOXA-181 (n = 3), blaOXA-232 (n = 3) and blaNDM-7 (n = 1). Most of the CPE were E. coli (55/64, 86%), and the genomic analysis revealed a pauciclonal diffusion of E. coli with ST167 (n = 14), 405 (n = 10), 940 (n = 8), 648 (n = 6) and 617 (n = 5). We obtained a second sample from 94 patients during their hospital stay in whom carriage was negative at admission and found that 7 (7.4%) acquired a CPE. Our results indicate that the prevalence of CPE carriage in the Pakistani urban community was high and driven by the dissemination of some E. coli clones, with ST167 being the most frequent. The high CPE carriage in the community poses a serious public health threat and calls for implementation of adequate preventive measures.

Deciphering polymorphism in 61,157 Escherichia coli genomes via epistatic sequence landscapes.

Characterizing the effect of mutations is key to understand the evolution of protein sequences and to separate neutral amino-acid changes from deleterious ones. Epistatic interactions between residues can lead to a context dependence of mutation effects. Context dependence constrains the amino-acid changes that can contribute to polymorphism in the short term, and the ones that can accumulate between species in the long term. We use computational approaches to accurately predict the polymorphisms segregating in a panel of 61,157 Escherichia coli genomes from the analysis of distant homologues. By comparing a context-aware Direct-Coupling Analysis modelling to a non-epistatic approach, we show that the genetic context strongly constrains the tolerable amino acids in 30% to 50% of amino-acid sites. The study of more distant species suggests the gradual build-up of genetic context over long evolutionary timescales by the accumulation of small epistatic contributions.

Contribution of Clinical Metagenomics to the Diagnosis of Bone and Joint Infections.

Bone and joint infections (BJIs) are complex infections that require precise microbiological documentation to optimize antibiotic therapy. Currently, diagnosis is based on microbiological culture, sometimes complemented by amplification and sequencing of the 16S rDNA gene. Clinical metagenomics (CMg), that is, the sequencing of the entire nucleic acids in a sample, was previously shown to identify bacteria not detected by conventional methods, but its actual contribution to the diagnosis remains to be assessed, especially with regard to 16S rDNA sequencing. In the present study, we tested the performance of CMg in 34 patients (94 samples) with suspected BJIs, as compared to culture and 16S rDNA sequencing. A total of 94 samples from 34 patients with suspicion of BJIs, recruited from two sites, were analyzed by (i) conventional culture, (ii) 16S rDNA sequencing (Sanger method), and (iii) CMg (Illumina Technology). Two negative controls were also sequenced by CMg for contamination assessment. Based on the sequencing results of negative controls, 414 out of 539 (76.7%) bacterial species detected by CMg were considered as contaminants and 125 (23.2%) as truly present. For monomicrobial infections (13 patients), the sensitivity of CMg was 83.3% as compared to culture, and 100% as compared to 16S rDNA. For polymicrobial infections (13 patients), the sensitivity of CMg was 50% compared to culture, and 100% compared to 16S rDNA. For samples negative in culture (8 patients, 21 samples), CMg detected 11 bacteria in 10 samples from 5 different patients. In 5/34 patients, CMg brought a microbiological diagnosis where conventional methods failed, and in 16/34 patients, CMg provided additional information. Finally, 99 antibiotic resistance genes were detected in 24 patients (56 samples). Provided sufficient genome coverage (87.5%), a correct inference of antibiotic susceptibility was achieved in 8/8 bacteria (100%). In conclusion, our study demonstrated that the CMg provides complementary and potentially valuable data to conventional methods of BJIs diagnosis.

Inferring antibiotic susceptibility from metagenomic data: dream or reality?

BACKGROUND: The diagnosis of bacterial infections continues to rely on culture, a slow process in which antibiotic susceptibility profiles of potential pathogens are made available to clinicians 48 hours after sampling, at best. Recently, clinical metagenomics, the metagenomic sequencing of samples with the purpose of identifying microorganisms and determining their susceptibility to antimicrobials, has emerged as a potential diagnostic tool that could prove faster than culture. Clinical metagenomics indeed has the potential to detect antibiotic resistance genes (ARGs) and mutations associated with resistance. Nevertheless, many challenges have yet to be overcome in order to make rapid phenotypic inference of antibiotic susceptibility from metagenomic data a reality. OBJECTIVES: The objective of this narrative review is to discuss the challenges underlying the phenotypic inference of antibiotic susceptibility from metagenomic data. SOURCES: We conducted a narrative review using published articles available in the National Center for Biotechnology Information PubMed database. CONTENT: We review the current ARG databases with a specific emphasis on those which now provide associations with phenotypic data. Next, we discuss the bioinformatic tools designed to identify ARGs in metagenomes. We then report on the performance of phenotypic inference from genomic data and the issue predicting the expression of ARGs. Finally, we address the challenge of linking an ARG to this host. IMPLICATIONS: Significant improvements have recently been made in associating ARG and phenotype, and the inference of susceptibility from genomic data has been demonstrated in pathogenic bacteria such as Staphylococci and Enterobacterales. Resistance involving gene expression is more challenging however, and inferring susceptibility from species such as Pseudomonas aeruginosa remains difficult. Future research directions include the consideration of gene expression via RNA sequencing and machine learning.

Modeling the bacterial dynamics in the gut microbiota following an antibiotic-induced perturbation.

Recent studies have highlighted the importance of ecological interactions in dysbiosis of gut microbiota, but few focused on their role in antibiotic-induced perturbations. We used the data from the CEREMI trial in which 22 healthy volunteers received a 3-day course of ceftriaxone or cefotaxime antibiotics. Fecal samples were analyzed by 16S rRNA gene profiling, and the total bacterial counts were determined in each sample by flux cytometry. As the gut exposure to antibiotics could not be experimentally measured despite a marked impact on the gut microbiota, it was reconstructed using the counts of susceptible Escherichia coli. The dynamics of absolute counts of bacterial families were analyzed using a generalized Lotka-Volterra equations and nonlinear mixed effect modeling. Bacterial interactions were studied using a stepwise approach. Two negative and three positive interactions were identified. Introducing bacterial interactions in the modeling approach better fitted the data, and provided different estimates of antibiotic effects on each bacterial family than a simple model without interaction. The time to return to 95% of the baseline counts was significantly longer in ceftriaxone-treated individuals than in cefotaxime-treated subjects for two bacterial families: Akkermansiaceae (median [range]: 11.3 days [0; 180.0] vs. 4.2 days [0; 25.6], p = 0.027) and Tannerellaceae (13.7 days [6.1; 180.0] vs. 6.2 days [5.4; 17.3], p = 0.003). Taking bacterial interaction as well as individual antibiotic exposure profile into account improves the analysis of antibiotic-induced dysbiosis.

Simultaneous Hospital Outbreaks of New Delhi Metallo-ß-Lactamase-Producing Enterobacterales Unraveled Using Whole-Genome Sequencing.

Multidrug-resistant Enterobacterales, including carbapenemase producers, are currently spreading in health care facilities and the community. The Bichat Claude Bernard hospital in Paris faced a prolonged NDM-producing Enterobacterales (NDM-CPE) outbreak. Whole-genome sequencing (WGS) was performed on all isolated NDM-CPE to evaluate its benefits for outbreak surveillance and comprehension. All NDM-CPE isolates collected during the outbreak period (August 2016 to January 2018) were sequenced using the Illumina NextSeq platform. Gene content and core genomes were compared. Genomics results underwent epidemiological analysis which classified NDM-CPE cases as imported (positive sample during the 48 h after admission), hospital acquired, or uncertain. Over the epidemic period, 61 patients were colonized or infected with 81 distinct NDM-CPE isolates. Klebsiella pneumoniae was the most common species (n = 52, 64%), followed by Escherichia coli (13.5%) and other species (22.5%). In all, 43/52 (83%) K. pneumoniae isolates were clonal (≤18 single nucleotide polymorphisms [SNPs] except for three isolates) and belonged to ST307. The IncFIIK [K2:A-/B-] plasmid carrying blaNDM-1 present in all ST307 K. pneumoniae isolates was also detected in 18 other NDM-CPE isolates. Additionally, eight clonal ST144 Klebsiella oxytoca (≤18 SNPs) isolates lacking the epidemic plasmid were observed. The WGS analyses confirmed the acquired and imported cases except for two patients and resolved uncertain cases, which all turned out to be hospital acquisitions. WGS coupled with epidemiological analysis unraveled three epidemic phenomena: mainly the spread of a clonal ST307 K. pneumoniae strain and its conjugative plasmid carrying blaNDM-1 but also the unexpected clonal spread of an ST144 K. oxytoca strain. IMPORTANCE Carbapenemase-producing Enterobacterales (CPE) can spread and cause outbreaks in health care facilities, resulting in increased lengths of stay and morbidity. Control of outbreaks requires epidemiological surveillance, usually based on microbiological screening and patient follow-up. These data are sometimes insufficient to identify the routes of dissemination. There is therefore a need for more accurate tools such as whole-genome sequencing (WGS), which allows comparison of isolates but also plasmids carrying resistance with a high definition. In this work, we retrospectively sequenced the genomes of all NDM-producing Enterobacterales isolated during a prolonged NDM outbreak in our hospital. We demonstrated the value of combining WGS with epidemiological data that unveiled the multiple mechanisms of dissemination involved in the outbreak and confirmed transmission cases. This work reinforces the potential of WGS in outbreak surveillance and suggests that it could improve outbreak control if used in real time by confirming transmission cases more rapidly.

Healthcare-associated infections in adult intensive care unit patients: Changes in epidemiology, diagnosis, prevention and contributions of new technologies.

Patients in intensive care units (ICUs) are at high risk for healthcare-acquired infections (HAI) due to the high prevalence of invasive procedures and devices, induced immunosuppression, comorbidity, frailty and increased age. Over the past decade we have seen a successful reduction in the incidence of HAI related to invasive procedures and devices. However, the rate of ICU-acquired infections remains high. Within this context, the ongoing emergence of new pathogens, further complicates treatment and threatens patient outcomes. Additionally, the SARS-CoV-2 (COVID-19) pandemic highlighted the challenge that an emerging pathogen provides in adapting prevention measures regarding both the risk of exposure to caregivers and the need to maintain quality of care. ICU nurses hold a special place in the prevention and management of HAI as they are involved in basic hygienic care, steering and implementing quality improvement initiatives, correct microbiological sampling, and aspects antibiotic stewardship. The emergence of more sensitive microbiological techniques and our increased knowledge about interactions between critically ill patients and their microbiota are leading us to rethink how we define HAIs and best strategies to diagnose, treat and prevent these infections in the ICU. This multidisciplinary expert review, focused on the ICU setting, will summarise the recent epidemiology of ICU-HAI, discuss the place of modern microbiological techniques in their diagnosis, review operational and epidemiological definitions and redefine the place of several controversial preventive measures including antimicrobial-impregnated medical devices, chlorhexidine-impregnated washcloths, catheter dressings and chlorhexidine-based mouthwashes. Finally, general guidance is suggested that may reduce HAI incidence and especially outbreaks in ICUs.

The role of the microbiota in the management of intensive care patients.

The composition of the gut microbiota is highly dynamic and changes according to various conditions. The gut microbiota mainly includes difficult-to-cultivate anaerobic bacteria, hence knowledge about its composition has significantly arisen from culture-independent methods based on next-generation sequencing (NGS) such as 16S profiling and shotgun metagenomics. The gut microbiota of patients hospitalized in intensive care units (ICU) undergoes many alterations because of critical illness, antibiotics, and other ICU-specific medications. It is then characterized by lower richness and diversity, and dominated by opportunistic pathogens such as Clostridioides difficile and multidrug-resistant bacteria. These alterations are associated with an increased risk of infectious complications or death. Specifically, at the time of writing, it appears possible to identify distinct microbiota patterns associated with severity or infectivity in COVID-19 patients, paving the way for the potential use of dysbiosis markers to predict patient outcomes. Correcting the microbiota disturbances to avoid their consequences is now possible. Fecal microbiota transplantation is recommended in recurrent C. difficile infections and microbiota-protecting treatments such as antibiotic inactivators are currently being developed. The growing interest in the microbiota and microbiota-associated therapies suggests that the control of the dysbiosis could be a key factor in the management of critically ill patients. The present narrative review aims to provide a synthetic overview of microbiota, from healthy individuals to critically ill patients. After an introduction to the different techniques used for studying the microbiota, we review the determinants involved in the alteration of the microbiota in ICU patients and the latter's consequences. Last, we assess the means to prevent or correct microbiota alteration.