Assessment trial of the effect of enteral insulin on the preterm infant intestinal microbiota.

BACKGROUND: Insulin might be associated with changes in infant gastrointestinal microbiota. The objective of this randomized controlled trial was to assess the efficacy of two doses of recombinant human(rh) enteral insulin administration compared to placebo in intestinal microbiota. METHODS: 19 preterm patients were recruited at the NICU of La Paz University Hospital (Madrid, Spain). Subjects received 2000 µIU of rh enteral insulin/ml(n = 8), 400 µIU of rh enteral insulin/ml(n = 6) or placebo(n = 5) for 28 days administered once per day. Extracted DNA from fecal samples collected at the beginning and end of treatment were analyzed. The 16S rRNA V4 region was amplified and sequenced in a Miseq(Illumina®) sequencer using 2 × 250 bp paired end. Resulting reads were filtered and analyzed using Qiime2 software. Metabolic activity was assessed by GC. RESULTS: Gestational age and birth weight did not differ between groups. At the phylum level, both insulin treated groups increased the relative abundance of Bacillota, while Pseudomonadota decreased. No change was observed in infants receiving placebo. At the genus level, insulin at both doses showed enriching effects on Clostridium. We found a significant increase in concentrations of fecal propionate in both rh insulin treated groups. CONCLUSION: Rh insulin may modify neonatal intestinal microbiota and SCFAs in preterm infants. IMPACT STATEMENT: Decrease of Pseudomonadota (former Proteobacteria phylum) and increase of Bacillota (former Firmicutes phylum) obtained in this study are the changes observed previously in low-risk infants for NEC. The administration of recombinant enteral insulin may modify the microbiota of preterm new-borns and SCFAs. Modulation of the microbiota may be a mechanism whereby insulin contributes to neonatal intestinal maturation and/or protection.

Computational Modeling and Design of New Inhibitors of Carbapenemases: A Discussion from the EPIC Alliance Network.

The EPIC consortium brings together experts from a wide range of fields that include clinical, molecular and basic microbiology, infectious diseases, computational biology and chemistry, drug discovery and design, bioinformatics, biochemistry, biophysics, pharmacology, toxicology, veterinary sciences, environmental sciences, and epidemiology. The main question to be answered by the EPIC alliance is the following: "What is the best approach for data mining on carbapenemase inhibitors and how to translate this data into experiments?" From this forum, we propose that the scientific community think up new strategies to be followed for the discovery of new carbapenemase inhibitors, so that this process is efficient and capable of providing results in the shortest possible time and within acceptable time and economic costs.

A New Application of MALDI Biotyper for a Potential Use in Therapeutic Drug Monitoring of Voriconazole.

We present a proof-of-concept study on the use of MALDI Biotyper to detect and monitor the levels of voriconazole in human serum. A simple extraction-concentration method and a MALDI Biotyper protocol were developed, and a parent ion of voriconazole (1 H+) could be detected and quantified with good reproducibility. Our results point to a new application of MALDI Biotyper for therapeutic drug monitoring.

Characterization of an osteomyelitis case caused by dalbavancin, ceftaroline, and vancomycin non-susceptible methicillin-resistant Staphylococcus aureus.

We report a case of osteomyelitis due to methicillin-resistant Staphylococcus aureus (MRSA) that is also non-susceptible to vancomycin, dalbavancin, ceftaroline, and ceftobiprole, in the absence of exposure to the latter three antibiotics. It was isolated from a patient with a 26-year history of cranial surgeries and episodes of osteomyelitis. Whole-genome sequencing was performed. It was found to belong to ST247 and the mecA gene was detected within the SSCmec type I (1B) gene cassette that lacked the E447K mutation known to produce resistance to ceftobiprole and ceftaroline. However, mutations in other genes related to resistance to these antibiotics were found.

Epidemiology of bloodstream Candida species in a Spanish tertiary care hospital as a guide for implementation of T2MR (T2CANDIDA®) for rapid diagnosis of candidemia.

The aim of this work was to study the epidemiology of candidemia in our hospital in order to determine whether the T2MR system might be a useful tool for early diagnosis of candidemia in selected units. We perform a retrospective review of all candidemia episodes registered in the last 12 years in selected units of our hospital in adult and pediatric patients. Candida species and antifungal susceptibility patterns were registered. A total of 686 isolates were registered, of which 625 were infections due to the five most common species of Candida. C. albicans (45.6%) and C. parapsilosis (33.1%) were the predominant species found in our institution. In adults these species were closely followed by C. glabrata (12-21%) in all units. While in pediatric medical and intensive care units (PICU), these species were followed by other uncommon yeasts. Resistance rates to triazoles were low in C. albicans and C. parapsilosis. In C. glabrata and C. tropicalis the resistance rates to fluconazole ranged from 10.86 to 6.67%. Resistance rates for echinocandins were very low and all strains were susceptible to amphotericin B. T2Candida® might be useful to guide antifungal targeted treatment and discontinuation of antifungal empirical treatment in those units where the five most common Candida species represent more than the ninety percent of the isolates. The selection of medical and surgical units should be based on local epidemiology and antifungal susceptibility patterns. Incidence should be taken into account in order to make clinical decisions based on negative results. LAY ABSTRACT: T2Candida® might be useful selectively in clinical units according to their local epidemiology, antifungal resistance patterns, and incidence of candidemia. It optimizes the clinical value of positive results supporting decisions about targeted therapies or discontinuations based on negative results.

Candidemia Diagnosis With T2 Nuclear Magnetic Resonance in a PICU: A New Approach.

OBJECTIVES: Early diagnosis of invasive Candida infections is a challenge for pediatricians, intensivists, and microbiologists. To fill this gap, a new nanodiagnostic method has been developed using manual application of T2 nuclear magnetic resonance to detect Candida species. The aim of this study was to evaluate, prospectively, the usefulness as a tool diagnosis of the T2Candida panel in pediatric patients admitted at the PICU compared with blood culture. DESIGN: This is a prospective, observational, and unicentric study to compare T2Candida results with simultaneous blood cultures for candidemia diagnose. SETTING: This study was carried out in a 1,300-bed tertiary care hospital with a 16-bed medical-surgical PICU. PATIENTS: Sixty-three patients from 0 to 17 years old were enrolled in this study, including those undergoing solid organ transplantation (kidney, liver, pulmonary, multivisceral, intestinal, and heart) and hematopoietic stem cell transplantation. MEASUREMENTS AND MAIN RESULTS: Seven patients were positive by the T2Candida test. Only two of them had the simultaneous positive blood culture. T2Candida yielded more positive results than blood cultures. CONCLUSIONS: T2Candida might be useful for the diagnosis of candidemia in PICUs. The prevalence of candidemia might be underestimated in this pediatric population. The use of this diagnostic tool in these units may help clinicians to start adequate and timely antifungal treatments.

Evaluation of three immunochromatographic tests for rapid detection of antibodies against SARS-CoV-2.

Lateral flow immunoassays (LFIA) for rapid detection of specific antibodies (IgM and IgG) against SARS-CoV-2 in different human specimens have been developed in response to the pandemic. The aim of this study is to evaluate three immunocromathographic assays (Sienna®, Wondfo® and Prometheus®) for detection of antibodies against SARS-CoV-2 in serum samples, considering RT-qPCR as a reference. A total of 145 serum samples from 145 patients with clinical suspicion of COVID-19 were collected: all of the samples were tested with Sienna®, 117 with Wondfo® and 89 with Prometheus®. The overall results of sensitivity, specificity, positive predictive value and negative predictive value obtained were as follows: 64.4%, 75%, 85.5% and 47.8% with Sienna®; 45.2%, 81.8%, 80.5% and 47.4% with Wondfo® and 75.5%, 12.5%, 51.4% and 29.4% with Prometheus®. The accuracy of the test for Sienna®, Wondfo® and Prometheus® was 67.6%, 59% and 47.2%, with a prevalence of COVID-19 of 69.7%, 62.4% and 55.1% respectively. Sensitivity of the three tests (Sienna®, Wondfo® and Prometheus® respectively) along the three different stages was 36.6%, 18.8% and 68.6% in the early stage (first week); 81.3%, 74.1% and 90.9% in the intermediate stage (second week) and 100%, 83.3% and 100% in the late stage (third week). The results demonstrate that even though Prometheus® presented a high sensitivity, the specificity was notably lower than the other two tests. Sienna® showed the greatest contrast between sensitivity and specificity, achieving the best accuracy, followed by Wondfo®. The sensitivity of the three ICT assays was higher in late stages of the disease.

Emergence of NDM-producing Klebsiella pneumoniae and Escherichia coli in Spain: phylogeny, resistome, virulence and plasmids encoding blaNDM-like genes as determined by WGS.

OBJECTIVES: NDM carbapenemases have spread worldwide. However, little information exists about the impact of NDM-producing Enterobacteriaceae in Spain. By WGS, we sought to elucidate the population structure of NDM-like-producing Klebsiella pneumoniae and Escherichia coli in Spain and to determine the plasmids harbouring blaNDM-like genes. METHODS: High-resolution SNP typing, core-genome MLST and plasmid reconstruction (PlasmidID) were performed on 59 NDM-like-producing K. pneumoniae and 8 NDM-like-producing E. coli isolated over an 8 year period in Spain. RESULTS: Five major epidemic clones of NDM-producing K. pneumoniae caused five important nationwide outbreaks: ST437/NDM-7, ST437/NDM-1, ST147/NDM-1, ST11/NDM-1 and ST101/NDM-1; in contrast, the spread of NDM-producing E. coli was polyclonal. Three blaNDM types were identified: blaNDM-1, 61.2%; blaNDM-7, 32.8%; and blaNDM-5, 6%. Five K. pneumoniae isolates co-produced other carbapenemases (three blaOXA-48 and two blaVIM-1). The average number of acquired resistance genes was higher in K. pneumoniae than in E. coli. The plasmids encoding blaNDM-like genes belonged to IncFII, IncFIB, IncX3, IncR, IncN and IncC types, of which IncF, IncR and IncC were associated with MDR. The genetic surroundings of blaNDM-like genes showed a highly variable region upstream of ISAba125. CONCLUSIONS: In recent years NDM-producing K. pneumoniae and E. coli have emerged in Spain; the spread of a few high-risk K. pneumoniae clones such as ST437/NDM-7, ST437/NDM-1, ST147/NDM-1, ST11/NDM-1 and ST101/NDM-1 have caused several interregional outbreaks. In contrast, the spread of NDM-producing E. coli has been polyclonal. Plasmid types IncFII, IncFIB, IncX3, IncR, IncN and IncC carried blaNDM, and the same IncX3 plasmid was detected in K. pneumoniae and E. coli.

MALDI-TOF MS for rapid diagnosis of Anaerobiospirillum succiniciproducens, an unusual causative agent of bacteraemia in humans. Two case reports and literature review.

Anaerobiospirillum succiniciproducens is a gram-negative anaerobic spiral rod which is part of the normal flora of dogs and cats and can produce bacteraemia and diarrhoea in humans. In this report we describe two cases of bacteraemia caused by A. succiniciproducens which was successfully identified by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). We present a comprehensive literature review of 48 cases of A. succiniciproducens bacteraemia in which we describe previous underlying conditions, clinical presentations, identification methodology and antibiotic susceptibility data.

The challenge of molecular diagnosis of bloodstream infections.

Early detection and identification of pathogens in bloodstream infections (BSI) is important to initiate or adjust antibiotic therapy as soon as possible. The current gold standard for diagnostic of BSI infection is the blood culture, that has a turnaround time of one to few days. Molecular tests performed directly in blood samples have promised faster diagnostics, with response times of a few hours, but their implementation into the clinical routine has been hampered by critical technical and procedural problems. Assay integration into laboratory workflows with random-access loading mode and minimal hands-on time is essential to meet rapid response times. Decreasing assay costs will favor fair clinical evaluations and might increase the applicability of the assays. Control of background contamination with bacterial DNA is one of the most difficult problems and might be avoided with pathogen-specific real-time PCR designs oriented to particular patient groups, or perhaps by quantitative, next-generation sequencing approaches.

Direct Detection of OXA-48 Carbapenemase Gene in Lysate Samples through Changes in Mechanical Properties of DNA Monolayers upon Hybridization.

Carbapenem-resistant Enterobacteriaceae have recently become an important cause of morbidity and mortality due to healthcare-associated infections. Most commonly used diagnostic methods are incompatible with fast and accurate directed therapy. We report here the direct identification of the blaOXA48 gene, which codes for the carbapenemase OXA-48, in lysate samples from Klebsiella pneumoniae. The method is PCR-free and label-free. It is based on the measurement of changes in the stiffness of DNA self-assembled monolayers anchored to microcantilevers that occur as a consequence of the hybridization. The stiffness of the DNA layer is measured through changes of the sensor resonance frequency upon hybridization and at varying relative humidity.

The Cell Division Protein FtsZ from Streptococcus pneumoniae Exhibits a GTPase Activity Delay.

The cell division protein FtsZ assembles in vitro by a mechanism of cooperative association dependent on GTP, monovalent cations, and Mg(2+). We have analyzed the GTPase activity and assembly dynamics of Streptococcus pneumoniae FtsZ (SpnFtsZ). SpnFtsZ assembled in an apparently cooperative process, with a higher critical concentration than values reported for other FtsZ proteins. It sedimented in the presence of GTP as a high molecular mass polymer with a well defined size and tended to form double-stranded filaments in electron microscope preparations. GTPase activity depended on K(+) and Mg(2+) and was inhibited by Na(+). GTP hydrolysis exhibited a delay that included a lag phase followed by a GTP hydrolysis activation step, until reaction reached the GTPase rate. The lag phase was not found in polymer assembly, suggesting a transition from an initial non-GTP-hydrolyzing polymer that switches to a GTP-hydrolyzing polymer, supporting models that explain FtsZ polymer cooperativity.

[Historical perspective of mass spectrometry in microbiology]. / Perspectiva histórica de la espectrometría de masas en microbiología.

La espectrometría de masas (EM) es una técnica de análisis que permite caracterizar muestras midiendo las masas (estrictamente las razones masa-carga) de las moléculas componentes. Cuenta con más de un siglo de historia y evolución tecnológica y a lo largo de los años ha ampliado su alcance desde los isótopos a moléculas pequeñas, moléculas orgánicas más complejas y, en las últimas décadas, macromoléculas (ácidos nucleicos y proteínas). La EM MALDI-TOF (matrix-assisted laser desorption ionization time-of-flight) es una variante que permite el análisis de mezclas complejas de proteínas y que se ha aplicado recientemente a la identificación de microorganismos en cultivo, convirtiéndose en una herramienta rápida y eficaz para el diagnóstico microbiológico que ha conseguido entrar en poco tiempo en la rutina de muchos servicios de microbiología clínica. El gran impacto que ha tenido está impulsando el desarrollo de nuevas aplicaciones en el campo de la microbiología clínica.

Label-free DNA-based detection of Mycobacterium tuberculosis and rifampicin resistance through hydration induced stress in microcantilevers.

We have developed a label-free assay for the genomic detection of Mycobacterium tuberculosis and rifampicin resistance. The method relies on the quantification of the hydration induced stress on microcantilever biosensors functionalized with oligonucleotide probes, before and after hybridization with specific targets. We have found a limit of detection of 10 fg/mL for PCR amplified products of 122 bp. Furthermore, the technique can successfully target genomic DNA (gDNA) fragments of length >500 bp, and it can successfully discriminate single mismatches. We have used both loci IS6110 and rpoB as targets to detect the mycobacteria and the rifampicin resistance from gDNA directly extracted from bacterial culture and without PCR amplification. We have been able to detect 2 pg/mL target concentration in samples with an excess of interfering DNA and in a total analysis time of 1 h and 30 min. The detection limit found demonstrates the capability to develop direct assays without the need for long culture steps or PCR amplification. The methodology can be easily translated to different microbial targets, and it is suitable for further development of miniaturized devices and multiplexed detection.

Evaluation of cytomegalovirus infection in low-birth weight children by breast milk using a real-time polymerase chain reaction assay.

Human Cytomegalovirus (CMV) is the most common cause of intrauterine and perinatal infections worldwide. Postnatal CMV transmission has usually no consequences, but in some cases it may produce disease in preterm infants. Literature reports a broad range of breast milk-acquired CMV infections (5.7-58.6%), which depends on the study's design and the treatment of the milk. To evaluate CMV transmission via breast milk, a prospective study using a real-time PCR assay was performed. One hundred and thirty-one mothers (accounting for 160 children) accepted the participation in the study. Urine samples from the infants and breast milk samples from their mothers were collected at 3, 15, 30, 60, and 90 days after delivery. CMV-DNA in breast milk was analysed by quantitative real-time PCR assay Affigene® CMV Trender (Cepheid, Bromma, Sweden). The breast milk samples from 92 mothers (92 of 131, 70.2%) were positive for CMV by PCR. CMV infection was detected in thirteen children by PCR, and four of them (30.7%) had clinical symptoms. There were not significant differences in morbidity between symptomatic and non- symptomatic patients; nonetheless, the average length of hospitalization in symptomatic children was higher than that of non-symptomatic children (P < 0.05). The rtPCR technique is useful for detection of mothers with high viral loads of CMV-DNA in milk, and might be of help to decide whether to freeze the breast milk in preterm children less than 28 weeks.

Uncoupling between core genome and virulome in extraintestinal pathogenic Escherichia coli.

Extraintestinal pathogenic Escherichia coli (ExPEC) are among the most frequently isolated bacterial pathogens in hospitals. They are considered opportunistic pathogens and are found mostly in urinary and bloodstream infections. They are genetically diverse, and many studies have sought associations between genotypes or virulence genes and infection site, severity, or outcome, with varied, often contradictory, results. To understand these difficulties, we have analyzed the diversity patterns in the core genomes and virulomes of more than 500 ExPEC isolates from 5 different collections. The core genome was analyzed using a multilocus sequence type-based single-nucleotide polymorphism (SNP) pyrosequencing approach, while the virulence gene content (the virulome) was studied by polymerase chain reaction detection of 25 representative genes. SNP typing showed a similar population structure in the different collections: half of the isolates belong to a few sequence types (5 to 8), while the other half is composed of a large diversity of sequence types that are found once or twice. Sampling analysis by rarefaction plots of SNP profiles showed saturation curves indicative of a limited diversity. Contrary to this, the virulome shows an extremely high diversity, with almost as many gene profiles as isolates, and linear, nonsaturating, rarefaction plots, even within sequence types. These data show that genetic exchange rates are very heterogeneous along the chromosome, being much higher in the virulome fraction of the genome than in the core genome.

Control by potassium of the size distribution of Escherichia coli FtsZ polymers is independent of GTPase activity.

The influence of potassium content (at neutral pH and millimolar Mg(2+)) on the size distribution of FtsZ polymers formed in the presence of constantly replenished GTP under steady-state conditions was studied by a combination of biophysical methods. The size of the GTP-FtsZ polymers decreased with lower potassium concentration, in contrast with the increase in the mass of the GDP-FtsZ oligomers, whereas no effect was observed on FtsZ GTPase activity and critical concentration of polymerization. Remarkably, the concerted formation of a narrow size distribution of GTP-FtsZ polymers previously observed at high salt concentration was maintained in all KCl concentrations tested. Polymers induced with guanosine 5'-(α,ß-methylene)triphosphate, a slowly hydrolyzable analog of GTP, became larger and polydisperse as the potassium concentration was decreased. Our results suggest that the potassium dependence of the GTP-FtsZ polymer size may be related to changes in the subunit turnover rate that are independent of the GTP hydrolysis rate. The formation of a narrow size distribution of FtsZ polymers under very different solution conditions indicates that it is an inherent feature of FtsZ, not observed in other filament-forming proteins, with potential implications in the structural organization of the functional Z-ring.

Point-of-care system for detection of Mycobacterium tuberculosis and rifampin resistance in sputum samples.

Early detection of Mycobacterium tuberculosis complex (MTBC) and markers conveying drug resistance can have a beneficial impact on preventive public health actions. We describe here a new molecular point-of-care (POC) system, the Genedrive, which is based on simple sample preparation combined with PCR to detect MTBC and simultaneously detect mutation markers in the rpoB gene directly from raw sputum sample. Hybridization probes were used to detect the presence of the key mutations in codons 516, 526, and 531 of the rpoB gene. The sensitivities for MTBC and rpoB detection from sputum samples were assessed using model samples spiked with known numbers of bacteria prepared from liquid cultures of M. tuberculosis. The overall sensitivities were 90.8% (95% confidence interval [CI], 81, 96.5) for MTBC detection and 72.3% (95% CI, 59.8, 82.7) for rpoB detection. For samples containing ≥1,000 CFU/ml, the sensitivities were 100% for MTBC and 85.7% for rpoB detection, while for samples containing ≤100 CFU/ml, the sensitivities were 86.4% and 65.9% for MTBC and rpoB detection, respectively. The specificity was shown to be 100% (95% CI, 83.2, 100) for MTBC and rpoB. The clinical sputum samples were processed using the same protocol and showed good concordance with the data generated from the model. Tuberculosis-infected subjects with smear samples assessed as scanty or negative were detectable by the Genedrive system. In these paucibacillary patients, the performance of the Genedrive system was comparable to that of the GeneXpert assay. The characteristics of the Genedrive platform make it particularly useful for detecting MTBC and rifampin resistance in low-resource settings and for reducing the burden of tuberculosis disease.

Genomic analysis of the emergence and evolution of multidrug resistance during a Klebsiella pneumoniae outbreak including carbapenem and colistin resistance.

OBJECTIVES: To characterize at the genomic level the evolution of multiresistance during an outbreak of Klebsiella pneumoniae in a burns intensive care unit. The outbreak involved a DHA-1 ß-lactamase-producing strain that later acquired carbapenem and fosfomycin resistance, and in one case colistin resistance. METHODS: The genomes of two isolates were sequenced and compared with a previously sequenced genome. The role of hypermutability was investigated by measuring the mutation frequencies of the isolates and comparison with a collection of control strains. RESULTS: Sequence comparison identified four single-nucleotide variants and two transposon insertions. Analysis of the variants in the whole collection related carbapenem and fosfomycin resistance to a nonsense mutation in the ompK36 porin gene and colistin resistance to an IS1 insertion in the mgrB gene. The plasmid carrying the blaDHA-1 gene was unstable in the absence of antibiotics, and analysis of isolates that had lost the plasmid showed that the porin mutation alone was not sufficient to generate carbapenem resistance. The mutation frequencies were similar among all the strains analysed. CONCLUSIONS: Carbapenem resistance required production of the DHA-1 ß-lactamase and decreased permeability, but fosfomycin resistance depended only on permeability. Resistance to colistin might be related to an alteration in the regulation of the phoPQ system. Hypermutation is not related to the selection of porin mutants. Plasmid instability might be due to the high number of mobile elements and suggests a major role for antibiotic selection pressure in the emergence and evolution of this outbreak.

Intrinsic disorder of the bacterial cell division protein ZipA: coil-to-brush conformational transition.

The full-length ZipA protein from Escherichia coli, one of the essential elements of the cell division machinery, was studied in a surface model built as adsorbed monolayers. The interplay between lateral packing and molecular conformation was probed using a combined methodology based on the scaling analysis of the surface pressure isotherms and ellipsometry measurements of the monolayer thickness. The observed behavior is compatible with the one expected for an intrinsically disordered and highly flexible protein that is preferentially structured in a random coil conformation. At low grafting densities, ZipA coils organize in a mushroom-like regime, whereas a coil-to-brush transition occurs on increasing lateral packing. The structural results suggest a functional scenario in which ZipA acts as a flexible tether anchoring bacterial proto-ring elements to the membrane during the earlier stages of division.