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Clinical Microbiology Reviews Sep 2022Class C β-lactamases or cephalosporinases can be classified into two functional groups (1, 1e) with considerable molecular variability (≤20% sequence identity). These... (Review)
Review
Class C β-lactamases or cephalosporinases can be classified into two functional groups (1, 1e) with considerable molecular variability (≤20% sequence identity). These enzymes are mostly encoded by chromosomal and inducible genes and are widespread among bacteria, including Proteobacteria in particular. Molecular identification is based principally on three catalytic motifs (SXSK, YXN, KTG), but more than 70 conserved amino-acid residues (≥90%) have been identified, many close to these catalytic motifs. Nevertheless, the identification of a tiny, phylogenetically distant cluster (including enzymes from the genera , , and ) has raised questions about the possible existence of a C2 subclass of β-lactamases, previously identified as serine hydrolases. In a context of the clinical emergence of extended-spectrum AmpC β-lactamases (ESACs), the genetic modifications observed and (point mutations, insertions, or deletions) during the evolution of these enzymes have mostly involved the Ω- and H-10/R2-loops, which vary considerably between genera, and, in some cases, the conserved triplet YXN. Furthermore, the conserved deletion of several amino-acid residues in opportunistic pathogenic species of Acinetobacter, such as A. baumannii, A. calcoaceticus, A. pittii and A. nosocomialis (deletion of residues 304-306), and in Hafnia alvei and H. paralvei (deletion of residues 289-290), provides support for the notion of natural ESACs. The emergence of higher levels of resistance to β-lactams, including carbapenems, and to inhibitors such as avibactam is a reality, as the enzymes responsible are subject to complex regulation encompassing several other genes (R, D, G, etc.). Combinations of resistance mechanisms may therefore be at work, including overproduction or change in permeability, with the loss of porins and/or activation of efflux systems.
Topics: Anti-Bacterial Agents; Bacterial Proteins; Carbapenems; Microbial Sensitivity Tests; Porins; Serine; beta-Lactamases; beta-Lactams
PubMed: 35435729
DOI: 10.1128/cmr.00150-21 -
Current Rheumatology Reports Jul 2021This article presents a comprehensive narrative review of reactive arthritis (ReA) with focus on articles published between 2018 and 2020. We discuss the entire spectrum... (Review)
Review
PURPOSE OF REVIEW
This article presents a comprehensive narrative review of reactive arthritis (ReA) with focus on articles published between 2018 and 2020. We discuss the entire spectrum of microbial agents known to be the main causative agents of ReA, those reported to be rare infective agents, and those reported to be new candidates causing the disease. The discussion is set within the context of changing disease terminology, definition, and classification over time. Further, we include reports that present at least a hint of effective antimicrobial therapy for ReA as documented in case reports or in double-blind controlled studies. Additional information is included on microbial products detected in the joint, as well as on the positivity of HLA-B27.
RECENT FINDINGS
Recent reports of ReA cover several rare causative microorganism such as Neisseria meningitides, Clostridium difficile, Escherichia coli, Hafnia alvei, Blastocytosis, Giardia lamblia, Cryptosporidium, Cyclospora cayetanensis, Entamoeba histolytica/dispar, Strongyloides stercoralis, β-haemolytic Streptococci, Mycobacterium tuberculosis, Mycoplasma pneumoniae, Mycobacterium bovis bacillus Calmette-Guerin, and Rickettsia rickettsii. The most prominent new infectious agents implicated as causative in ReA are Staphylococcus lugdunensis, placenta- and umbilical cord-derived Wharton's jelly, Rothia mucilaginosa, and most importantly the SARS-CoV-2 virus. In view of the increasingly large spectrum of causative agents, diagnostic consideration for the disease must include the entire panel of post-infectious arthritides termed ReA. Diagnostic procedures cannot be restricted to the well-known HLA-B27-associated group of ReA, but must also cover the large number of rare forms of arthritis following infections and vaccinations, as well as those elicited by the newly identified members of the ReA group summarized herein. Inclusion of these newly identified etiologic agents must necessitate increased research into the pathogenic mechanisms variously involved, which will engender important insights for treatment and management of ReA.
Topics: Arthritis, Reactive; Blastocystis Infections; COVID-19; Clostridium Infections; Cryptosporidiosis; Cyclosporiasis; Entamoebiasis; Enterobacteriaceae Infections; Escherichia coli Infections; Giardiasis; HLA-B27 Antigen; Humans; Meningococcal Infections; Pneumonia, Mycoplasma; Prohibitins; Rocky Mountain Spotted Fever; SARS-CoV-2; Staphylococcal Infections; Streptococcal Infections; Strongyloidiasis; Tuberculosis
PubMed: 34196842
DOI: 10.1007/s11926-021-01018-6 -
International Journal of Molecular... Apr 2023Obesity and obesity-associated disorders pose a major public health issue worldwide. Apart from conventional weight loss drugs, next-generation probiotics (NGPs) seem to... (Review)
Review
Obesity and obesity-associated disorders pose a major public health issue worldwide. Apart from conventional weight loss drugs, next-generation probiotics (NGPs) seem to be very promising as potential preventive and therapeutic agents against obesity. Candidate NGPs such as , , and have shown promise in preclinical models of obesity and obesity-associated disorders. Proposed mechanisms include the modulation of gut flora and amelioration of intestinal dysbiosis, improvement of intestinal barrier function, reduction in chronic low-grade inflammation and modulation of gut peptide secretion. and have already been administered in overweight/obese patients with encouraging results. However, safety issues and strict regulations should be constantly implemented and updated. In this review, we aim to explore (1) current knowledge regarding NGPs; (2) their utility in obesity and obesity-associated disorders; (3) their safety profile; and (4) their therapeutic potential in individuals with overweight/obesity. More large-scale, multicentric and longitudinal studies are mandatory to explore their preventive and therapeutic potential against obesity and its related disorders.
Topics: Humans; Overweight; Obesity; Probiotics; Gastrointestinal Microbiome; Inflammation
PubMed: 37047729
DOI: 10.3390/ijms24076755 -
Nature Communications Dec 2021Because of its compatibility with semiconductor-based technologies, hafnia (HfO) is today's most promising ferroelectric material for applications in electronics. Yet,...
Because of its compatibility with semiconductor-based technologies, hafnia (HfO) is today's most promising ferroelectric material for applications in electronics. Yet, knowledge on the ferroic and electromechanical response properties of this all-important compound is still lacking. Interestingly, HfO has recently been predicted to display a negative longitudinal piezoelectric effect, which sets it apart from classic ferroelectrics (e.g., perovskite oxides like PbTiO) and is reminiscent of the behavior of some organic compounds. The present work corroborates this behavior, by first-principles calculations and an experimental investigation of HfO thin films using piezoresponse force microscopy. Further, the simulations show how the chemical coordination of the active oxygen atoms is responsible for the negative longitudinal piezoelectric effect. Building on these insights, it is predicted that, by controlling the environment of such active oxygens (e.g., by means of an epitaxial strain), it is possible to change the sign of the piezoelectric response of the material.
PubMed: 34911930
DOI: 10.1038/s41467-021-27480-5 -
Nanomaterials (Basel, Switzerland) Dec 2023Hafnia-based nanostructures and other high-k dielectrics are promising wide-gap materials for developing new opto- and nanoelectronic devices. They possess a unique...
Hafnia-based nanostructures and other high-k dielectrics are promising wide-gap materials for developing new opto- and nanoelectronic devices. They possess a unique combination of physical and chemical properties, such as insensitivity to electrical and optical degradation, radiation damage stability, a high specific surface area, and an increased concentration of the appropriate active electron-hole centers. The present paper aims to investigate the structural, optical, and luminescent properties of anodized non-stoichiometric HfO nanotubes. As-grown amorphous hafnia nanotubes and nanotubes annealed at 700 °C with a monoclinic crystal lattice served as samples. It has been shown that the bandgap for direct allowed transitions amounts to 5.65 ± 0.05 eV for amorphous and 5.51 ± 0.05 eV for monoclinic nanotubes. For the first time, we have studied the features of intrinsic cathodoluminescence and photoluminescence in the obtained nanotubular HfO structures with an atomic deficiency in the anion sublattice at temperatures of 10 and 300 K. A broad emission band with a maximum of 2.3-2.4 eV has been revealed. We have also conducted an analysis of the kinetic dependencies of the observed photoluminescence for synthesized HfO samples in the millisecond range at room temperature. It showed that there are several types of optically active capture and emission centers based on vacancy states in the O and O positions with different coordination numbers and a varied number of localized charge carriers (V, V, and V). The uncovered regularities can be used to optimize the functional characteristics of developed-surface luminescent media based on nanotubular and nanoporous modifications of hafnia.
PubMed: 38133006
DOI: 10.3390/nano13243109 -
International Journal of Environmental... Feb 2022The opportunistic infections with Gram-negative bacilli are frequently reported. The clinical studies are focused on the course of human infectious and very often the... (Review)
Review
The opportunistic infections with Gram-negative bacilli are frequently reported. The clinical studies are focused on the course of human infectious and very often the source of infection remain unclear. We aim to see if the Gram-negative bacilli isolated from a non-contaminated environment-the caves-are reported in human infections. Eleven samples were collected from six Romanian caves. We used the standard procedure used in our clinical laboratory for bacterial identification and for antibiotic susceptibility testing of the cave isolates. Out of the 14 bacterial strains, three isolates are Gram-negative bacilli-one isolate belong to and two strains belong to . We screened for the published studies-full-text original articles or review articles-that reported human infections with and Data sources-PubMed and Cochrane library. We retrieved 447 cases from 49 references-262 cases (58.61%) are infections and 185 cases (41.39%) are infections. The types of infections are diverse but there are some infections more frequent; there are 116 cases (44.27%) and many infections of the bloodstream with (116 cases) and 121 cases (65.41%) are urinary tract infections with . The acquired source of the bloodstream infections is reported for 93 of bloodstream infections-50 cases (43%) are hospital-acquired, and 40 cases (37%) are community-acquired. Most of the infections are reported in patients with different underlying conditions. There are 80 cases (17.9%) are reported of previously healthy persons. Out of the 72 cases of pediatric infections, 62 cases (86.11%) are caused by . There are ten death casualties-three are infections, and seven are infections.
Topics: Caves; Child; Gram-Negative Bacterial Infections; Hafnia alvei; Humans; Sphingomonas
PubMed: 35206510
DOI: 10.3390/ijerph19042324 -
Cureus Dec 2019Hafnia alvei, belonging to the Enterobacteriaceae family, is a gram-negative, facultative anaerobe. The organism predominantly colonizes the gastrointestinal tract and,...
Hafnia alvei, belonging to the Enterobacteriaceae family, is a gram-negative, facultative anaerobe. The organism predominantly colonizes the gastrointestinal tract and, less often, the tissues, urine, and catheters. A 75-year-old male presented with a dry cough, fatigue, decreased appetite, intermittent disorientation, and difficulty ambulating. He had a history of self-catheterization due to urinary retention. He was scheduled to undergo transcatheter aortic valve replacement for enterococcal endocarditis. Physical examination was not significant for any changes. Urine analysis revealed positive leukocyte esterase, the presence of red and white blood cells, urine bacteria, and hyaline casts. The patient was started on empiric intravenous ceftriaxone. Urine culture grew Hafnia alvei and he was switched over to cefepime due to greater susceptibility. On day four, he started deteriorating clinically and was treated with four pressors but remained hypotensive and eventually became anuric. The patient developed septic shock with multiple organ dysfunction syndromes. Despite all measures, his clinical condition failed to improve, and he was continued with comfort measures only. The literature on Hafnia alvei-induced urosepsis is poor and fragmentary. Our patient showed resistance to most beta-lactam antibiotics, including cefuroxime, ceftriaxone, and ceftazidime, along with intermediate susceptibility to piperacillin/tazobactam and was managed with intravenous cefepime based on the sensitivity report. Inducible Bush group 1 beta-lactamase produced by Hafnia alvei is postulated to be responsible for antibiotic resistance. Physicians should remain vigilant of Hafnia alvei-induced urosepsis in patients with long-term catheterization initiating appropriate treatment.
PubMed: 32025398
DOI: 10.7759/cureus.6471 -
Microorganisms Apr 2022, a close relative of , is an emerging zoonotic foodborne pathogen associated with watery diarrhea mainly in children and immunocompromised individuals. was initially... (Review)
Review
, a close relative of , is an emerging zoonotic foodborne pathogen associated with watery diarrhea mainly in children and immunocompromised individuals. was initially classified as -positive , however, as more genetic and biochemical information became available it was reassigned to its current novel taxonomy. Its infections are common under conditions of poor hygiene with confirmed transmission via contaminated water and food, mainly poultry-based products. This pathogen has been isolated from various domestic and wild animals, with most isolates being derived from birds, implying that birds among other wild animals might act as its reservoir. Due to the absence of standardized isolation and identification protocols, can be misidentified as other . Exploiting phenotypes such as its inability to ferment rhamnose and xylose and PCR assays targeting -specific genes such as the cytolethal distending toxin and the DNA-binding transcriptional activator of cysteine biosynthesis encoding genes can be used to accurately identify this pathogen. Several gaps exist in our knowledge of and need to be bridged. A deeper understanding of epidemiology and physiology is required to allow the development of effective measures to control its transmission and infections. Overall, current data suggest that might play a more significant role in global infectious diarrhea cases than previously assumed and is often overlooked or misidentified. Therefore, simple, and efficient diagnostic tools that cover biodiversity are required for effective isolation and identification of this elusive agent of diarrhea.
PubMed: 35630320
DOI: 10.3390/microorganisms10050875 -
Scientific Reports Jun 2022Honey bees are important pollinators for the conservation of the ecosystem and agricultural products and provide a variety of products important for human use, such as...
Honey bees are important pollinators for the conservation of the ecosystem and agricultural products and provide a variety of products important for human use, such as honey, pollen, and royal jelly. Sacbrood disease (SD) is a devastating viral disease in Apis cerana; an effective preventive measure for SD is urgently needed. In this study, the relationship between the gut microbiome of honey bees and SD was investigated by pyrosequencing. Results revealed that sacbrood virus (SBV)-resistant A. cerana strains harbour a unique acetic acid bacterium, Bombella intestini, and the lactic acid bacteria (LAB) Lactobacillus (unclassified)_uc, Bifidobacterium longum, B. catenulatum, Lactococcus lactis, and Leuconostoc mesenteroides in larvae and Hafnia alvei, B. indicum, and the LAB L. mellifer and Lactobacillus HM215046_s in adult bees. Changes in the gut microbiome due to SBV infection resulted in loss of bacteria that could affect host nutrients and inhibit honey bee pathogens, such as Gilliamella JFON_s, Gilliamella_uc, Pseudomonas putida, and L. kunkeei in A. cerana larvae and Frischella_uc, Pantoea agglomerans, Snodgrassella_uc, and B. asteroides in adult bees. These findings provide important information for the selection of probiotics for A. cerana larvae and adults to prevent pathogenic infections and keep honey bees healthy.
Topics: Animals; Bacteria; Bees; Disease Susceptibility; Ecosystem; Gastrointestinal Microbiome; Larva; RNA Viruses; Virus Diseases
PubMed: 35705585
DOI: 10.1038/s41598-022-13535-0 -
Journal of Clinical Microbiology May 2023A bacterial species is considered to be intrinsically resistant to an antimicrobial when nearly all of the wild-type isolates (i.e., those without acquired resistance)...
A bacterial species is considered to be intrinsically resistant to an antimicrobial when nearly all of the wild-type isolates (i.e., those without acquired resistance) exhibit minimum inhibitory concentration (MIC) values that are sufficiently high such that susceptibility testing is unnecessary, and that the antimicrobial should not be considered for therapy. Accordingly, knowledge of intrinsic resistance influences both the selection of treatment regimens and the approach to susceptibility testing in the clinical laboratory, where unexpected results also facilitate the recognition of microbial identification or susceptibility testing errors. Previously, limited data have suggested that spp. may be intrinsically resistant to colistin. We evaluated the activity of colistin against 119 that were isolated from human samples: 75 (63%) from routine clinical cultures and 44 (37%) from stool samples of travelers undergoing screening for antimicrobial resistant organisms. Broth microdilution colistin MICs were ≥4 μg/mL for 117 of 119 (98%) isolates. Whole-genome sequencing of 96 of the isolates demonstrated that the colistin-resistant phenotype was not lineage-specific. 2 of the 96 (2%) isolates harbored mobile colistin resistance genes. Compared to whole-genome sequencing, VITEK MS matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and VITEK 2 GN ID failed to consistently distinguish between Hafnia alvei, Hafnia paralvei, and Obesumbacterium proteus. In conclusion, using a reference antimicrobial susceptibility testing method and a genetically diverse collection of isolates, we found spp. to be intrinsically resistant to colistin. The recognition of this phenotype will help inform rational approaches by which to perform antimicrobial susceptibility testing and therapy for patients with infections that are caused by spp.
Topics: Humans; Colistin; Enterobacteriaceae; Hafnia; Anti-Infective Agents; Microbial Sensitivity Tests; Anti-Bacterial Agents
PubMed: 37022168
DOI: 10.1128/jcm.01326-22