Metallo-β-lactamases (MBLs) are a growing clinical threat because they inactivate nearly all β-lactam-containing antibiotics, and there are no clinically available inhibitors. A significant number of ...variants have already emerged for each MBL subfamily. To understand the evolution of imipenemase (IMP) genes (
) and their clinical impact, 20 clinically derived IMP-1 like variants were obtained using site-directed mutagenesis and expressed in a uniform genetic background in
strain DH10B. Strains of IMP-1-like variants harboring S262G or V67F substitutions exhibited increased resistance toward carbapenems and decreased resistance toward ampicillin. Strains expressing IMP-78 (S262G/V67F) exhibited the largest changes in MIC values compared to IMP-1. In order to understand the molecular mechanisms of increased resistance, biochemical, biophysical, and molecular modeling studies were conducted to compare IMP-1, IMP-6 (S262G), IMP-10 (V67F), and IMP-78 (S262G/V67F). Finally, unlike most New Delhi metallo-β-lactamase (NDM) and Verona integron-encoded metallo-β-lactamase (VIM) variants, the IMP-1-like variants do not confer any additional survival advantage if zinc availability is limited. Therefore, the evolution of MBL subfamilies (i.e., IMP-6, -10, and -78) appears to be driven by different selective pressures.
IntroductionPeople with lived expertise in managing mental health challenges can be an important source of knowledge and support for other people facing similar challenges, and for carers to learn ...how best to help. However, opportunities for sharing lived expertise are limited. Living libraries support people with lived expertise to be ‘living books’, sharing their experiences in dialogue with ‘readers’ who can ask questions. Living libraries have been piloted worldwide in health-related contexts but without a clear model of how they work or rigorous evaluation of their impacts. We aim to develop a programme theory about how a living library could be used to improve mental health outcomes, using this theory to codesign an implementation guide that can be evaluated across different contexts.Methods and analysisWe will use a novel integration of realist synthesis and experience-based codesign (EBCD) to produce a programme theory about how living libraries work and a theory and experience informed guide to establishing a library of lived experience for mental health (LoLEM). Two workstreams will run concurrently: (1) a realist synthesis of literature on living libraries, combined with stakeholder interviews, will produce several programme theories; theories will be developed collaboratively with an expert advisory group of stakeholders who have hosted or taken part in a living library and will form our initial analysis framework; a systematic search will identify literature about living libraries; data will be coded into our analysis framework, and we will use retroductive reasoning to explain living libraries’ impacts across multiple contexts. Individual stakeholder interviews will help refine and test theories; (2) data from workstream 1 will inform 10 EBCD workshops with people with experience of managing mental health difficulties and health professionals to produce a LoLEM implementation guide; data from this process will also inform the theory in workstream 1.Ethics and disseminationEthical approval was granted by Coventry and Warwick National Health Service Research Ethics Committee on 29 December 2021 (reference number 305975). The programme theory and implementation guide will be published as open access and shared widely through a knowledge exchange event, a study website, mental health provider and peer support networks, peer reviewed journals and a funders report.PROSPERO registration detailsCRD42022312789.
Carbapenem-resistant Acinetobacter baumannii (CRAb) is 1 of the most problematic antimicrobial-resistant bacteria. We sought to elucidate the international epidemiology and clinical impact of CRAb.
...In a prospective observational cohort study, 842 hospitalized patients with a clinical CRAb culture were enrolled at 46 hospitals in five global regions between 2017 and 2019. The primary outcome was all-cause mortality at 30 days from the index culture. The strains underwent whole-genome analysis.
Of 842 cases, 536 (64%) represented infection. By 30 days, 128 (24%) of the infected patients died, ranging from 1 (6%) of 18 in Australia-Singapore to 54 (25%) of 216 in the United States and 24 (49%) of 49 in South-Central America, whereas 42 (14%) of non-infected patients died. Bacteremia was associated with a higher risk of death compared with other types of infection (40 42% of 96 vs 88 20% of 440). In a multivariable logistic regression analysis, bloodstream infection and higher age-adjusted Charlson comorbidity index were independently associated with 30-day mortality. Clonal group 2 (CG2) strains predominated except in South-Central America, ranging from 216 (59%) of 369 in the United States to 282 (97%) of 291 in China. Acquired carbapenemase genes were carried by 769 (91%) of the 842 isolates. CG2 strains were significantly associated with higher levels of meropenem resistance, yet non-CG2 cases were over-represented among the deaths compared with CG2 cases.
CRAb infection types and clinical outcomes differed significantly across regions. Although CG2 strains remained predominant, non-CG2 strains were associated with higher mortality. Clinical Trials Registration. NCT03646227.
Serious infections caused by multidrug-resistant (MDR) organisms (Klebsiella pneumoniae, Pseudomonas aeruginosa, Acinetobacter baumannii) present a critical need for innovative drug development. ...Herein, we describe the preclinical evaluation of YU253911, 2, a novel γ-lactam siderophore antibiotic with potent antimicrobial activity against MDR Gram-negative pathogens. Penicillin-binding protein (PBP) 3 was shown to be a target of 2 using a binding assay with purified P. aeruginosa PBP3. The specific binding interactions with P. aeruginosa were further characterized with a high-resolution (2.0 Å) X-ray structure of the compound’s acylation product in P. aeruginosa PBP3. Compound 2 was shown to have a concentration >1 μg/ml at the 6 h time point when administered intravenously or subcutaneously in mice. Employing a meropenem resistant strain of P. aeruginosa, 2 was shown to have dose-dependent efficacy at 50 and 100 mg/kg q6h dosing in a mouse thigh infection model. Lastly, we showed that a novel γ-lactam and β-lactamase inhibitor (BLI) combination can effectively lower minimum inhibitory concentrations (MICs) against carbapenem resistant Acinetobacter spp. that demonstrated decreased susceptibility to 2 alone.
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•Multidrug resistance to antibiotics is a challenging global health threat.•A γ-Lactam antibiotic was designed active vs. Pseudomonas aeruginosa and Klebsiella spp.•YU253911 and sulbactam are active against carbapenem resistant Acinetobacter spp.•YU253911 formed an acylation complex to PBP3 of P. aeruginosa (2 Å).•In a murine infection model, YU253911 demonstrated efficacy at 50 and 100 mg/kg.
Genome sequencing of carbapenem-resistant Klebsiella pneumoniae isolates from regional U.S. hospitals was used to characterize strain diversity and the bla(KPC) genetic context. A phylogeny based on ...core single-nucleotide variants (SNVs) supports a division of sequence type 258 (ST258) into two distinct groups. The primary differences between the groups are in the capsular polysaccharide locus (cps) and their plasmid contents. A strict association between clade and KPC variant was found. The bla(KPC) gene was found on variants of two plasmid backbones. This study indicates that highly similar K. pneumoniae subpopulations coexist within the same hospitals over time.
Multidrug-resistant (MDR) Pseudomonas aeruginosa infections are a major clinical challenge. Many isolates are carbapenem resistant, which severely limits treatment options; thus, novel therapeutic ...combinations, such as imipenem-relebactam (IMI/REL), ceftazidime-avibactam (CAZ/AVI), ceftolozane-tazobactam (TOL/TAZO), and meropenem-vaborbactam (MEM/VAB) were developed. Here, we studied two extensively drug-resistant (XDR) P. aeruginosa isolates, collected in the United States and Mexico, that demonstrated resistance to IMI/REL. Whole-genome sequencing (WGS) showed that both isolates contained acquired GES β-lactamases, intrinsic PDC and OXA β-lactamases, and disruptions in the genes encoding the OprD porin, thereby inhibiting uptake of carbapenems. In one isolate (ST17), the entire C terminus of OprD deviated from the expected amino acid sequence after amino acid G388. In the other (ST309), the entire
gene was interrupted by an IS
1328 insertion element after amino acid D43, rendering this porin nonfunctional. The poor inhibition by REL of the GES β-lactamases (GES-2, -19, and -20; apparent
of 19 ± 2 μM, 23 ± 2 μM, and 21 ± 2 μM, respectively) within the isolates also contributed to the observed IMI/REL-resistant phenotype. Modeling of REL binding to the active site of GES-20 suggested that the acylated REL is positioned in an unstable conformation as a result of a constrained Ω-loop.
Fluoroquinolones (FQs) are not commonly prescribed in children, yet the increasing incidence of multidrug-resistant (MDR) Enterobacterales (Ent) infections in this population often reveals FQ ...resistance. We sought to define the role of FQ resistance in the epidemiology of MDR Ent in children, with an overall goal to devise treatment and prevention strategies.
A case-control study of children (0-18 years) at three Chicago hospitals was performed. Cases had infections by FQ-susceptible, β-lactamase-producing (
) Ent harboring a non- or low-level expression of PMFQR genes (PMFQS Ent). Controls had FQR infections due to
Ent with expressed PMFQR genes (PMFQR Ent). We sought
genes by PCR or DNA (BD Max Check-Points assay
) and PMFQR genes by PCR. We performed rep-PCR, MLST, and
phylogenetic grouping. Whole genome sequencing was additionally performed on PMFQS Ent positive isolates. Demographics, comorbidities, and device, antibiotic, and healthcare exposures were evaluated. Predictors of infection were assessed.
Of 170 β-lactamase-producing Ent isolates, 85 (50%) were FQS; 23 (27%) had PMFQR genes (PMFQS cases). Eighty-five (50%) were FQR; 53 (62%) had PMFQR genes (PMFQR controls). The median age for children with PMFQS Ent and PMFQR Ent was 4.3 and 6.2 years, respectively (
= NS). Of 23 PMFQS Ent, 56% were
spp., and of 53 PMFQR Ent, 76% were
. The most common
and PMFQR genes detected in PMFQS Ent were
(44%) and
(57%), and the corresponding genes detected in PMFQR Ent were
(79%) and
(83%). Whole genome sequencing of PMFQS Ent revealed the additional presence of
, a transferable polymyxin resistance gene, in 47% of isolates, along with multiple plasmids and mobile genetic elements propagating drug resistance. Multivariable regression analysis showed that children with PMFQS Ent infections were more likely to have hospital onset infection (OR 5.7, 95% CI 1.6-22) and isolates containing multiple
genes (OR 3.8, 95% CI 1.1-14.5). The presence of invasive devices mediated the effects of healthcare setting in the final model. Differences in demographics, comorbidities, or antibiotic use were not found.
Paradoxically, PMFQS Ent infections were often hospital onset and PMFQR Ent infections were community onset. PMFQS Ent commonly co-harbored multiple
and PMFQR genes, and additional silent, yet transferrable antibiotic resistance genes such as
, affecting therapeutic options and suggesting the need to address infection prevention strategies to control spread. Control of PMFQS Ent infections will require validating community and healthcare-based sources and risk factors associated with acquisition.
Peer online mental health forums are commonly used and offer accessible support. Positive and negative impacts have been reported by forum members and moderators, but it is unclear why these impacts ...occur, for whom and in which forums. This multiple method realist study explores underlying mechanisms to understand how forums work for different people. The findings will inform codesign of best practice guidance and policy tools to enhance the uptake and effectiveness of peer online mental health forums.
In workstream 1, we will conduct a realist synthesis, based on existing literature and interviews with approximately 20 stakeholders, to generate initial programme theories about the impacts of forums on members and moderators and mechanisms driving these. Initial theories that are relevant for forum design and implementation will be prioritised for testing in workstream 2.Workstream 2 is a multiple case study design with mixed methods with several online mental health forums differing in contextual features. Quantitative surveys of forum members, qualitative interviews and Corpus-based Discourse Analysis and Natural Language Processing of forum posts will be used to test and refine programme theories. Final programme theories will be developed through novel triangulation of the data.Workstream 3 will run alongside workstreams 1 and 2. Key stakeholders from participating forums, including members and moderators, will be recruited to a Codesign group. They will inform the study design and materials, refine and prioritise theories, and codesign best policy and practice guidance.
Ethical approval was granted by Solihull Research Ethics Committee (IRAS 314029). Findings will be reported in accordance with RAMESES (Realist And MEta-narrative Evidence Syntheses: Evolving Standards) guidelines, published as open access and shared widely, along with codesigned tools.
ISRCTN 62469166; the protocol for the realist synthesis in workstream one is prospectively registered at PROSPERO CRD42022352528.
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