Genotypic and phenotypic antimicrobial resistance of Irish Clostridioides difficile isolates, 2022.

OBJECTIVES: Infection with Clostridioides difficile usually occurs after antibiotic treatment for other infections and can cause gastro-intestinal disorders of variable severity. C. difficile can be resistant to a wide spectrum of antimicrobials. Detection of antimicrobial resistance (AMR) is important to direct optimal treatment and surveillance of AMR patterns in the overall population. Correlation between genotypic markers and phenotypic AMR is not yet well defined. The aim for this study is to assess whether and to what extent genotypic determinants of AMR correlate with phenotypic resistance. METHODS: C. difficile isolates (n = 99) were phenotypically characterized for resistance to eight antibiotics using Sensititre plates or E-tests. Their genomes were screened for genetic markers of resistance. Accuracy, sensitivity, specificity, positive and negative predictive values were calculated. RESULTS: We found high rates of resistance (>50 %) to cefoxitin and clindamycin, intermediate rates of resistance (10 %-50 %) to moxifloxacin and tetracycline and low rates of resistance (<10 %) to imipenem, metronidazole, vancomycin, and rifampicin. For moxifloxacin, tetracycline, and clindamycin, we found a good correlation between genotypic and phenotypic AMR, with an overall accuracy of 98 % (95 % CI 93%-100 %), 78 % (95 % CI 68%-86 %) and 86 % (95 % CI 77%-92 %) respectively. For the other five antibiotics, accurate estimates on the correlation could not be made. CONCLUSION: Our results suggest that for moxifloxacin, tetracycline and clindamycin, phenotypic resistance in C. difficile can be predicted by genetic indicators and used for public health purposes. However, for the other five antibiotics, the model is not accurate and further development is necessary.

Neurological involvement in children with hemolytic uremic syndrome.

Our objective was to establish the rate of neurological involvement in Shiga toxin-producing Escherichia coli-hemolytic uremic syndrome (STEC-HUS) and describe the clinical presentation, management and outcome. A retrospective chart review of children aged ≤ 16 years with STEC-HUS in Children's Health Ireland from 2005 to 2018 was conducted. Laboratory confirmation of STEC infection was required for inclusion. Neurological involvement was defined as encephalopathy, focal neurological deficit, and/or seizure activity. Data on clinical presentation, management, and outcome were collected. We identified 240 children with HUS; 202 had confirmed STEC infection. Neurological involvement occurred in 22 (11%). The most common presentation was seizures (73%). In the neurological group, 19 (86%) were treated with plasma exchange and/or eculizumab. Of the 21 surviving children with neurological involvement, 19 (91%) achieved a complete neurological recovery. A higher proportion of children in the neurological group had renal sequelae (27% vs. 12%, P = .031). One patient died from multi-organ failure.Conclusion: We have identified the rate of neurological involvement in a large cohort of children with STEC-HUS as 11%. Neurological involvement in STEC-HUS is associated with good long-term outcome (complete neurological recovery in 91%) and a low case-fatality rate (4.5%) in our cohort. What is Known: • HUS is associated with neurological involvement in up to 30% of cases. • Neurological involvement has been reported as predictor of poor outcome, with associated increased morbidity and mortality. What is New: • The incidence of neurological involvement in STEC-HUS is 11%. • Neurological involvement is associated with predominantly good long-term outcome (90%) and a reduced case-fatality rate (4.5%) compared to older reports.

Comparison and correlation of commercial SARS-CoV-2 real-time-PCR assays, Ireland, June 2020.

We report the performance of a variety of commercially available SARS-CoV-2 PCR kits, used in several different sites across Ireland to determine if Ct values across platforms are comparable. We also investigate whether a Ct value, a surrogate for calculated viral loads in the absence of viral culture of > 34 can be used to exclude SARS-CoV-2 infection and its complications. We found a variation in Ct values from different assays for the same calculated viral load; this should be taken into consideration for result interpretation.

Vasopressin V1a receptors mediate the hypertensive effects of [Pyr1 ]apelin-13 in the rat rostral ventrolateral medulla.

KEY POINTS: Dysfunctions in CNS regulation of arterial blood pressure lead to an increase in sympathetic nerve activity that participates in the pathogenesis of hypertension. The apelin-apelin receptor system affects arterial blood pressure homeostasis; however, the central mechanisms underlying apelin-mediated changes in sympathetic nerve activity and blood pressure have not been clarified. We explored the mechanisms involved in the regulation of [Pyr1 ]apelin-13-mediated cardiovascular control within the rostral ventrolateral medulla (RVLM) using selective receptor antagonists. We show that [Pyr1 ]apelin-13 acts as a modulating neurotransmitter in the normotensive RVLM to affect vascular tone through interaction with the vasopressin V1a receptor but that [Pyr1 ]apelin-13-induced sympathoexcitation is independent of angiotensin II receptor type 1, oxytocin, ionotropic glutamate and GABAA receptors. Our data confirm a role for the apelin peptide system in cardiovascular regulation at the level of the RVLM and highlight that this system is a possible potential therapeutic target for the treatment of hypertension. ABSTRACT: Apelin is a ubiquitous peptide that can elevate arterial blood pressure (ABP) yet understanding of the mechanisms involved remain incomplete. Bilateral microinjection of [Pyr1 ]apelin-13 into the rostral ventrolateral medulla (RVLM), a major source of sympathoexcitatory neurones, increases ABP and sympathetic nerve activity. We aimed to investigate the potential involvement of neurotransmitter systems through which the apelin pressor response may occur within the RVLM. Adult male Wistar rats were anaesthetized and ABP was monitored via a femoral arterial catheter. Bilateral RVLM microinjection of [Pyr1 ]apelin-13 significantly increased ABP (9 ± 1 mmHg) compared to saline (-1 ± 2mmHg; P < 0.001), which was blocked by pretreatment with the apelin receptor antagonist, F13A (0 ± 1 mmHg; P < 0.01). The rise in ABP was associated with an increase in the low frequency spectra of systolic BP (13.9 ± 4.3% total power; P < 0.001), indicative of sympathetic vasomotor activation. The [Pyr1 ]apelin-13-mediated pressor response and the increased low frequency spectra of systolic BP response were fully maintained despite RVLM pretreatment with the angiotensin II type 1 receptor antagonist losartan, the oxytocin receptor antagonist desGly-NH2 , d(CH2 )5 [D-Tyr2 ,Thr4 ]OVT, the ionotropic glutamate receptor antagonist kynurenate or the GABAA antagonist bicuculline (P > 0.05). By contrast, the [Pyr1 ]apelin-13 induced pressor and sympathoexcitatory effects were abolished by pretreatment of the RVLM with the vasopressin V1a receptor antagonist, SR 49059 (-1 ± 1 mmHg; 1.1 ± 1.1% total power, respectively; P < 0.001). These findings suggest that the pressor action of [Pyr1 ]apelin-13 in the RVLM of normotensive rats is not mediated via angiotensin II type 1 receptor, oxytocin, ionotropic glutamate or GABAA receptors but instead involves a close relationship with the neuropeptide modulator vasopressin.

Evolutionary Context of Non-Sorbitol-Fermenting Shiga Toxin-Producing Escherichia coli O55:H7.

In July 2014, an outbreak of Shiga toxin-producing Escherichia coli (STEC) O55:H7 in England involved 31 patients, 13 (42%) of whom had hemolytic uremic syndrome. Isolates were sequenced, and the sequences were compared with publicly available sequences of E. coli O55:H7 and O157:H7. A core-genome phylogeny of the evolutionary history of the STEC O55:H7 outbreak strain revealed that the most parsimonious model was a progenitor enteropathogenic O55:H7 sorbitol-fermenting strain, lysogenized by a Shiga toxin (Stx) 2a-encoding phage, followed by loss of the ability to ferment sorbitol because of a non-sense mutation in srlA. The parallel, convergent evolutionary histories of STEC O157:H7 and STEC O55:H7 may indicate a common driver in the evolutionary process. Because emergence of STEC O157:H7 as a clinically significant pathogen was associated with acquisition of the Stx2a-encoding phage, the emergence of STEC O55:H7 harboring the stx2a gene is of public health concern.

Evidence-based Practice of Radiology.

Current health care reform in the United States is producing a shift in radiology practice from the traditional volume-based role of performing and interpreting a large number of examinations to providing a more affordable and higher-quality service centered on patient outcomes, which is described as a value-based approach to the provision of health care services. In the 1990 s, evidence-based medicine was defined as the integration of current best evidence with clinical expertise and patient values. When these methods are applied outside internal medicine, the process is called evidence-based practice (EBP). EBP facilitates understanding, interpretation, and application of the best current evidence into radiology practice, which optimizes patient care. It has been incorporated into "Practice-based Learning and Improvement" and "Systems-based Practice," which are two of the six core resident competencies of the Accreditation Council for Graduate Medical Education and two of the 12 American Board of Radiology milestones for diagnostic radiology. Noninterpretive skills, such as systems-based practice, are also formally assessed in the "Quality and Safety" section of the American Board of Radiology Core and Certifying examinations. This article describes (a) the EBP framework, with particular focus on its relevance to the American Board of Radiology certification and maintenance of certification curricula; (b) how EBP can be integrated into a residency program; and (c) the current value and likely place of EBP in the radiology information technology infrastructure. Online supplemental material is available for this article.

CD141⁺ myeloid dendritic cells are enriched in healthy human liver.

BACKGROUND & AIMS: Extensive populations of liver immune cells detect and respond to homeostatic perturbation caused by damage, infection or malignancy. Dendritic cells (DCs) are central to these activities, governing the balance between tolerance and immunity. Most of our knowledge about human liver DCs is derived from studies on peritumoral tissue. Little is known about the phenotype and function of DCs, in particular the recently described CD141(+) subset, in healthy human liver and how this profile is altered in liver disease. METHODS: During liver transplantation, healthy donor and diseased explant livers were perfused and hepatic mononuclear cells isolated. Dendritic cell subset frequency and phenotype were characterised in liver perfusates by flow cytometry and the function of CD141(+) DCs was evaluated by mixed lymphocyte reactions (MLRs) and measuring cytokine secretion. RESULTS: Almost one third of liver CD11c(+) myeloid DCs (mDCs) expressed CD141 compared to <5% of circulating mDCs. Hepatic CD141(+) DCs demonstrated pro-inflammatory function in allogeneic MLRs, inducing T cell production of interferon gamma (IFN-γ) and interleukin (IL)-17. While CD123(+) plasmacytoid DCs (pDCs) and CD1c(+) mDCs were expanded in diseased liver perfusates, CD141(+) DCs were significantly depleted. Despite their depletion, CD141(+) DCs from explant livers produced markedly increased poly(I:C)-induced IFN lambda (IFN-λ) compared with donor DCs. CONCLUSIONS: Accumulation of CD141(+) DCs in healthy liver, which are significantly depleted in liver disease, suggests differential involvement of mDC subsets in liver immunity.

G protein-coupled receptors in the hypothalamic paraventricular and supraoptic nuclei--serpentine gateways to neuroendocrine homeostasis.

G protein-coupled receptors (GPCRs) are the largest family of transmembrane receptors in the mammalian genome. They are activated by a multitude of different ligands that elicit rapid intracellular responses to regulate cell function. Unsurprisingly, a large proportion of therapeutic agents target these receptors. The paraventricular nucleus (PVN) and supraoptic nucleus (SON) of the hypothalamus are important mediators in homeostatic control. Many modulators of PVN/SON activity, including neurotransmitters and hormones act via GPCRs--in fact over 100 non-chemosensory GPCRs have been detected in either the PVN or SON. This review provides a comprehensive summary of the expression of GPCRs within the PVN/SON, including data from recent transcriptomic studies that potentially expand the repertoire of GPCRs that may have functional roles in these hypothalamic nuclei. We also present some aspects of the regulation and known roles of GPCRs in PVN/SON, which are likely complemented by the activity of 'orphan' GPCRs.

Characterization of farm, food, and clinical Shiga toxin-producing Escherichia coli (STEC) O113.

Thirty-nine Shiga toxin-producing Escherichia coli (STEC) O113 Irish farm, abattoir, and clinical isolates were analyzed in conjunction with eight Australian, New Zealand, and Norwegian strains for H (flagellar) antigens, virulence gene profile (eaeA, hlyA, tir, espA, espB katP, espP, etpD, saa, sab, toxB, iha, lpfA(O157/OI-141,) lpfA(O113,) and lpfA(O157/OI-154)), Shiga toxin gene variants (stx(1c), stx(1d), stx(2), stx(2c), stx(2dact), stx(2e), stx(2f,) and stx(2g)) and were genotyped using pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). All of the Irish strains were O113:H4, regardless of source, while all non-Irish isolates carried the H21 flagellar antigen. The stx(1) gene was present in 30 O113:H4 strains only, whereas the stx(2d) gene was common to all isolates regardless of source. In contrast, eaeA was absent, while hlyA was found in the Australian, New Zealand, Norwegian, and two of the Irish human clinical isolates. saa was present in the O113:H21 but not in the O113:H4 serotype. To the best of the author's knowledge, this is the first report of clinically significant STEC lacking both the eaeA and saa genes. PFGE analysis was inconclusive; however, MLST grouped the strains into three sequence types (ST): ST10, ST56, and ST223. Based on our findings, it was concluded that the stx(2d) gene is common in STEC O113, which are generally eaeA negative. Furthermore, STEC O113:H4 is a new, emerging bovine serotype of human clinical significance.

Genetic mechanism, baseline sensitivity and risk of resistance to oxathiapiprolin in oomycetes.

BACKGROUND: Oxathiapiprolin is a piperidinyl thiazole isoxazoline fungicide discovered by DuPont and commercialized by Corteva Agriscience. It acts by inhibiting a novel fungal target, an oxysterol binding protein (OSBP), and is intrinsically highly active against oomycetes including grape downy mildew (Plasmopara viticola) and potato late blight (Phytophthora infestans). Because the fungicide acts at a single site there is a need to determine the risk of resistance development. RESULTS: Oxathiapiprolin controlled European Plasmopara viticola and Phytophthora infestans isolates at very low concentrations with half maximal effective concentration (EC50 ) values ranging from 0.001 to 0.0264 mg L-1 and 0.001 to 0.03 mg L-1 , respectively. Laboratory mutagenesis studies performed with Phytophthora capsici using ultraviolet (UV) irradiation generated mutants with reduced sensitivity to oxathiapiprolin. All resistant mutants had a base pair change in the OSBP gene that resulted in an amino acid change. Most common substitutions were S768Y, G770V, G839W and L863W. Isolates of Plasmopara viticola and Phytophthora infestans with reduced sensitivity were also detected in field trial sites where oxathiapiprolin had been applied repeatedly each season over several consecutive years. CONCLUSIONS: The risk of oxathiapiprolin resistance development in Plasmopara viticola and Phytophthora infestans is medium to high and strict resistance management measures are required. Over-exposure of target populations to single-site fungicides during product development should be avoided.