spp. are members of the Enterobacteriaceae family and are Gram-negative, rod-shaped bacteria known to mainly cause urinary tract infections (UTIs) in humans. However, even though scarce evidence ...exists suggesting their potential to cause infective endocarditis (IE), a study summarizing the existing evidence is lacking. The purpose of this study was to systemically review all published cases of IE by
species in the literature. A systematic review of PubMed, Scopus and Cochrane Library (through 5
May 2020) for studies providing epidemiological, clinical and microbiological data as well as data on treatment and outcomes of IE by
species was performed. A total of 16 studies, containing data of 16 patients, were included. A prosthetic valve was present in 25%, while the most common causative pathogen was
. Aortic valve was the most common infected site in 33.3%, followed by mitral valve in 26.7%. Diagnosis was set with transesophageal echocardiography in 37.5%, and transthoracic echocardiography in 25%, while the diagnosis was set at autopsy in 25%. Fever and sepsis were present in 100% and 84.6%, respectively. Aminoglycosides and cephalosporins were the most common antimicrobials used for treatment. Clinical cure was noted in 62.5%, while overall mortality was 43.8%. This systematic review describes IE by
species in detail and provides information on epidemiology, clinical presentation, treatment and outcomes.
Purpose
Pending approval of new antimicrobials, synergistic combinations are the only treatment option against pandrug-resistant
A. baumannii
(PDRAB). Considering the lack of a standardized ...methodology, the aim of this manuscript is to systematically review the methodology and discuss unique considerations for assessing antimicrobial combinations against PDRAB.
Methods
Post-hoc analysis of a systematic review (conducted in PubMed and Scopus from inception to April 2021) of studies evaluating antimicrobial combination against
A. baumannii
, based on antimicrobials that are inactive in vitro alone.
Results
Eighty-four publications were reviewed, using a variety of synergy testing methods, including; gradient-based methods (
n
= 11), disk-based methods (
n
= 6), agar dilution (
n
= 2), checkerboard assay (
n
= 44), time-kill assay (
n
= 50), dynamic in vitro PK/PD models (
n
= 6), semi-mechanistic PK/PD models (
n
= 5), and in vivo animal models (
n
= 11). Several variations in definitions of synergy and interpretation of each method were observed and are discussed. Challenges related to testing combinations of antimicrobials that are inactive alone (with regards to concentrations at which the combinations are assessed), as well as other considerations (assessment of stasis vs killing, clinical relevance of re-growth in vitro after initial killing, role of in vitro vs in vivo conditions, challenges of clinical testing of antimicrobial combinations against PDRAB infections) are discussed.
Conclusion
This review demonstrates the need for consensus on a standardized methodology and clinically relevant definitions for synergy. Modifications in the methodology and definitions of synergy as well as a roadmap for further development of antimicrobial combinations against PDRAB are proposed.
Abstract
Stochastic structural stability theory (S3T) provides analytical methods for understanding the emergence and equilibration of jets from the turbulence in planetary atmospheres based on the ...dynamics of the statistical mean state of the turbulence closed at second order. Predictions for formation and equilibration of turbulent jets made using S3T are critically compared with results of simulations made using the associated quasi-linear and nonlinear models. S3T predicts the observed bifurcation behavior associated with the emergence of jets, their equilibration, and their breakdown as a function of parameters. Quantitative differences in bifurcation parameter values between predictions of S3T and results of nonlinear simulations are traced to modification of the eddy spectrum which results from two processes: nonlinear eddy–eddy interactions and formation of discrete nonzonal structures. Remarkably, these nonzonal structures, which substantially modify the turbulence spectrum, are found to arise from S3T instability. Formation as linear instabilities and equilibration at finite amplitude of multiple equilibria for identical parameter values in the form of jets with distinct meridional wavenumbers is verified, as is the existence at equilibrium of finite-amplitude nonzonal structures in the form of nonlinearly modified Rossby waves. When zonal jets and nonlinearly modified Rossby waves coexist at finite amplitude, the jet structure is generally found to dominate even if it is linearly less unstable. The physical reality of the manifold of S3T jets and nonzonal structures is underscored by the existence in nonlinear simulations of jet structure at subcritical S3T parameter values that are identified with stable S3T jet modes excited by turbulent fluctuations.
Abstract
Turbulent flows are often observed to be organized into large-spatial-scale jets such as the familiar zonal jets in the upper levels of the Jovian atmosphere. These relatively steady ...large-scale jets are not forced coherently but are maintained by the much smaller spatial- and temporal-scale turbulence with which they coexist. The turbulence maintaining the jets may arise from exogenous sources such as small-scale convection or from endogenous sources such as eddy generation associated with baroclinic development processes within the jet itself. Recently a comprehensive theory for the interaction of jets with turbulence has been developed called stochastic structural stability theory (SSST). In this work SSST is used to study the formation of multiple jets in barotropic turbulence in order to understand the physical mechanism producing and maintaining these jets and, specifically, to predict the jet amplitude, structure, and spacing. These jets are shown to be maintained by the continuous spectrum of shear waves and to be organized into stable attracting states in the mutually adjusted mean flow and turbulence fields. The jet structure, amplitude, and spacing and the turbulence level required for emergence of jets can be inferred from these equilibria. For weak but supercritical turbulence levels the jet scale is determined by the most unstable mode of the SSST system and the amplitude of the jets at equilibrium is determined by the balance between eddy forcing and mean flow dissipation. At stronger turbulence levels the jet amplitude saturates with jet spacing and amplitude satisfying the Rayleigh–Kuo stability condition that implies the Rhines scale. Equilibrium jets obtained with the SSST system are in remarkable agreement with equilibrium jets obtained in simulations of fully developed β-plane turbulence.
Abstract
Jets coexist with planetary-scale waves in the turbulence of planetary atmospheres. The coherent component of these structures arises from cooperative interaction between the coherent ...structures and the incoherent small-scale turbulence in which they are embedded. It follows that theoretical understanding of the dynamics of jets and planetary-scale waves requires adopting the perspective of statistical state dynamics (SSD), which comprises the dynamics of the interaction between coherent and incoherent components in the turbulent state. In this work, the stochastic structural stability theory (S3T) implementation of SSD for barotropic beta-plane turbulence is used to develop a theory for the jet–wave coexistence regime by separating the coherent motions consisting of the zonal jets together with a selection of large-scale waves from the smaller-scale motions that constitute the incoherent component. It is found that mean flow–turbulence interaction gives rise to jets that coexist with large-scale coherent waves in a synergistic manner. Large-scale waves that would exist only as damped modes in the laminar jet are found to be transformed into exponentially growing waves by interaction with the incoherent small-scale turbulence, which results in a change in the mode structure, allowing the mode to tap the energy of the mean jet. This mechanism of destabilization differs fundamentally and serves to augment the more familiar S3T instabilities in which jets and waves arise from homogeneous turbulence with the energy source exclusively from the incoherent eddy field and provides further insight into the cooperative dynamics of the jet–wave coexistence regime in planetary turbulence.
A 29-year old man with a history of hypertrophic cardiomyopathy with an implanted cardiac defibrillator due to previous ventricular tachycardia and a family history of sudden cardiac death presented ...to the Emergency Department because of severe left sided abdominal pain that was non-colicky and was not associated with food. The patient denied urinary frequency, hematuria, vomiting or diarrhea and had normal bowel movements. At clinical examination he was afebrile, with a normal blood pressure, a heart rate of about 100bpm while he had left upper quadrant tenderness at the examination of the abdomen, without rebound tenderness, while the abdominal sounds were normal. Complete blood count revealed leukocytosis with a white blood cell count of 13.800 cells, while transaminases, bilirubin, amylase and urine chemistry were normal. An electrocardiogram showed sinus tachycardia. A computed tomography of the thorax and the abdomen with intravenous contrast was performed and revealed an infarct of the spleen as the cause for the left upper quadrant abdominal pain. A representative image is shown in (A). The patient was admitted and a heart ultrasound revealed the presence of a thrombus in the left ventricle. Splenic infarction is an unusual condition that has been described in almost any age, is mostly associated with hematologic disorders in patients less than 40 years old and with thromboembolic disease in older patients. Other causes are splenic vascular disease, collagen vascular disease, anatomic abnormalities, pancreatic disease and solid tumors.
Bacteria belonging to the genus
are thin, capnophilic, Gram-negative bacilli with tapered ends that include nine species that are isolated from the mouth of humans and animals and, from a ...phylogenetical perspective, they belong to the family
. Two more species, namely
and
have been recovered from a periapical abscess and human and animal infections, respectively.
spp. can cause serious and potentially life-threatening infections in humans, such as bacteremia and meningitis, most commonly in the context of penetrating trauma as a result of contact with animals, especially after animal bites. Other invasive diseases such as osteomyelitis, septic arthritis, and infective endocarditis (IE) may also occur more rarely. The aim of this study was to review all previously described cases of IE by
spp. and provide information about the epidemiology, microbiology, antimicrobial susceptibility, clinical characteristics, treatment, and outcomes of this infection. A narrative review based on a search in PubMed, the Cochrane Library, and Scopus was performed. Studies published until 11 September 2023 providing relevant data for IE caused by
spp. in humans were included. A total of 31 studies containing data from 31 patients were included. A history of dog bites was present in 10 out of 26 patients (38.5%). A prosthetic valve was present in 3 patients (9.7%). The most commonly infected valve was the aortic valve, followed by the tricuspid valve. Fever, embolic phenomena, paravalvular abscess, and sepsis were the most common clinical presentations. Beta-lactams and aminoglycosides were the antimicrobials most commonly used. Surgery was performed in 20 patients (64.5%). Overall mortality reached 16.1%.
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