Sulbactam-durlobactam: A Step Forward in Treating Carbapenem-Resistant Acinetobacter baumannii (CRAB) Infections.

Antimicrobial resistance in gram-negative pathogens, such as Acinetobacter baumannii, is a serious threat to human health. Sulbactam-durlobactam, a unique ß-lactam and a ß-lactamase inhibitor combination, is a novel agent targeted against carbapenem-resistant A. baumannii. This supplement provides a summary of the development of SUL-DUR, discussing its unique features and role in treating infections caused by CRAB pathogens.

Pathogen-Targeted Clinical Development to Address Unmet Medical Need: Design, Safety, and Efficacy of the ATTACK Trial.

There is a crucial need for novel antibiotics to stem the tide of antimicrobial resistance, particularly against difficult to treat gram-negative pathogens like Acinetobacter baumannii-calcoaceticus complex (ABC). An innovative approach to addressing antimicrobial resistance may be pathogen-targeted development programs. Sulbactam-durlobactam (SUL-DUR) is a ß-lactam/ß-lactamase inhibitor combination antibiotic that is being developed to specifically target drug-resistant ABC. The development of SUL-DUR culminated with the Acinetobacter Treatment Trial Against Colistin (ATTACK) trial, a global, randomized, active-controlled phase 3 clinical trial that compared SUL-DUR with colistin for treating serious infections due to carbapenem-resistant ABC. SUL-DUR met the primary noninferiority endpoint of 28-day all-cause mortality. Furthermore, SUL-DUR had a favorable safety profile with a statistically significant lower incidence of nephrotoxicity compared with colistin. If approved, SUL-DUR could be an important treatment option for infections caused by ABC, including carbapenem-resistant and multidrug-resistant strains. The development program and the ATTACK trial highlight the potential for pathogen-targeted development programs to address the challenge of antimicrobial resistance.

Gepotidacin: a novel, oral, 'first-in-class' triazaacenaphthylene antibiotic for the treatment of uncomplicated urinary tract infections and urogenital gonorrhoea.

The ongoing spread of antimicrobial resistance has made the treatment of uncomplicated urinary tract infections (UTIs) and urogenital gonorrhoea increasingly difficult. New oral treatment options are urgently needed. Gepotidacin (previously GSK2140944) is a novel, bactericidal, oral, 'first-in-class' triazaacenaphthylene antibiotic that inhibits bacterial DNA replication by blocking two essential topoisomerase enzymes. Mutations in both enzymes would likely be necessary for resistance to occur, thus raising hopes that the drug will be able to maintain long-term effectiveness. Data from Phase II clinical trials of gepotidacin in UTIs and urogenital gonorrhoea appear promising, and Phase III trials are underway. In this review we summarize the development of gepotidacin and discuss its potential role in clinical practice. If approved, gepotidacin will be the first new oral antibiotic for UTIs in more than 20 years.

High data-rate communication link supported through the exploitation of optical channels in a characterized turbulent underwater environment.

Underwater turbulence presents a myriad of challenges for underwater optical systems through wavefront distortion and beam deflection. In this work, an underwater turbulence emulator is developed and thoroughly characterized to experimentally test the proposed underwater turbulence mitigation technique. This technique applies a modified HOBBIT system introduced in atmospheric turbulence to the relatively unknown underwater turbulence domain. By varying a beam's spatial position and relative phase gradient, a volume of turbulence is rapidly probed to determine the beam state for optimal propagation. This probe and control method is applied in multiple facets, including improved optical power transmission as well as supporting a 25-Gbps communication link through a dynamic environment.

Imipenem/Relebactam Resistance in Clinical Isolates of Extensively Drug Resistant Pseudomonas aeruginosa: Inhibitor-Resistant ß-Lactamases and Their Increasing Importance.

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 ß-lactamases, intrinsic PDC and OXA ß-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 oprD gene was interrupted by an ISPa1328 insertion element after amino acid D43, rendering this porin nonfunctional. The poor inhibition by REL of the GES ß-lactamases (GES-2, -19, and -20; apparent Ki 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.

A Systems-Based Analysis of Mono- and Combination Therapy for Carbapenem-Resistant Klebsiella pneumoniae Bloodstream Infections.

Antimicrobial resistance is a global threat. As "proof-of-concept," we employed a system-based approach to identify patient, bacterial, and drug variables contributing to mortality in patients with carbapenem-resistant Klebsiella pneumoniae (CRKp) bloodstream infections exposed to colistin (COL) and ceftazidime-avibactam (CAZ/AVI) as mono- or combination therapies. Patients (n = 49) and CRKp isolates (n = 22) were part of the Consortium on Resistance Against Carbapenems in Klebsiella and other Enterobacteriaceae (CRACKLE-1), a multicenter, observational, prospective study of patients with carbapenem-resistant Enterobacterales (CRE) conducted between 2011 and 2016. Pharmacodynamic activity of mono- and combination drug concentrations was evaluated over 24 h using in vitro static time-kill assays. Bacterial growth and killing dynamics were estimated with a mechanism-based model. Random Forest was used to rank variables important for predicting 30-day mortality. Isolates exposed to COL+CAZ/AVI had enhanced early bacterial killing compared to CAZ/AVI alone and fewer incidences of regrowth compared to COL and CAZ/AVI. The mean coefficient of determination (R2) for the observed versus predicted bacterial counts was 0.86 (range: 0.75 - 0.95). Bacterial subpopulation susceptibilities and drug mechanistic synergy were essential to describe bacterial killing and growth dynamics. The combination of clinical (hypotension), bacterial (IncR plasmid, aadA2, and sul3) and drug (KC50) variables were most predictive of 30-day mortality. This proof-of-concept study combined clinical, bacterial, and drug variables in a unified model to evaluate clinical outcomes.

OAM-based optical wavelet using a single pixel detection system for probing dynamic environments with application to real-time measurements of strong atmospheric turbulence.

This paper presents a novel method for optical probing by generating optical fields with characteristics of wavelets. The optical wavelets form a basis of rotated asymmetric beams with scaled orbital angular momentum (OAM) and beam sizes. The probing method was used experimentally to measure the continuous wavelet transform of a turbulent propagation path, giving insight into the angular properties about a fixed radius. The wavelet transform of a three-dimensional turbulence distribution was measured; the measurements are much faster than the turbulence changes, allowing characterization of an instantaneous realization of turbulence over time. Results show highly localized regions of OAM in space through the turbulence and characteristics of the turbulence can be extracted from the wavelet transforms.

Sensing and coupling of optical channels in dynamic atmospheric turbulence using OAM beamlets for improved power and data transmission.

Propagation of laser light is distorted in the presence of atmospheric turbulence. This poses an issue for sensing, free-space optical communications, and transmission of power. The presented system offers a novel solution to mitigate the effects of turbulence. By rapidly probing a turbulent volume by varying a beam's spatial and phase characteristics, the best transmission mode can be determined and updated in real time. Unlike a traditional tip-tilt system, this scheme is fully electronic, and has a scalable architecture to leverage multiple optical transmission paths simultaneously. This optical control system greatly improves power efficiency and successful recovery of data through environments with strong turbulence.

The UK stand together trial: protocol for a multicentre cluster randomised controlled trial to evaluate the effectiveness and cost-effectiveness of KiVa to reduce bullying in primary schools.

BACKGROUND: Reducing bullying is a public health priority. KiVa, a school-based anti-bullying programme, is effective in reducing bullying in Finland and requires rigorous testing in other countries, including the UK. This trial aims to test the effectiveness and cost-effectiveness of KiVa in reducing child reported bullying in UK schools compared to usual practice. The trial is currently on-going. Recruitment commenced in October 2019, however due to COVID-19 pandemic and resulting school closures was re-started in October 2020. METHODS: Design: Two-arm pragmatic multicentre cluster randomised controlled trial with an embedded process and cost-effectiveness evaluation. PARTICIPANTS: 116 primary schools from four areas; North Wales, West Midlands, South East and South West England. Outcomes will be assessed at student level (ages 7-11 years; n = approximately 13,000 students). INTERVENTION: KiVa is a whole school programme with universal actions that places a strong emphasis on changing bystander behaviour alongside indicated actions that provide consistent strategies for dealing with incidents of bullying. KiVa will be implemented over one academic year. COMPARATOR: Usual practice. PRIMARY OUTCOME: Student-level bullying-victimisation assessed through self-report using the extensively used and validated Olweus Bully/Victim questionnaire at baseline and 12-month follow-up. SECONDARY OUTCOMES: student-level bullying-perpetration; student mental health and emotional well-being; student level of, and roles in, bullying; school related well-being; school attendance and academic attainment; and teachers' self-efficacy in dealing with bullying, mental well-being, and burnout. SAMPLE SIZE: 116 schools (58 per arm) with an assumed ICC of 0.02 will provide 90% power to identify a relative reduction of 22% with a 5% significance level. RANDOMISATION: recruited schools will be randomised on 1:1 basis stratified by Key-Stage 2 size and free school meal status. Process evaluation: assess implementation fidelity, identify influences on KiVa implementation, and examine intervention mechanisms. Economic evaluation: Self-reported victimisation, Child Health Utility 9D, Client Service Receipt Inventory, frequency of services used, and intervention costs. The health economic analysis will be conducted from a schools and societal perspective. DISCUSSION: This two-arm pragmatic multicentre cluster randomised controlled trial will evaluate the KiVa anti-bullying intervention to generate evidence of the effectiveness, cost-effectiveness and scalability of the programme in the UK. Our integrated process evaluation will assess implementation fidelity, identify influences on KiVa implementation across England and Wales and examine intervention mechanisms. The integrated health economic analysis will be conducted from a schools and societal perspective. Our trial will also provide evidence regarding the programme impact on inequalities by testing whether KiVa is effective across the socio-economic gradient. TRIAL REGISTRATION: Trials ISRCTN 12300853 Date assigned 11/02/2020.

Fractional orbital angular momentum conversion in second-harmonic generation with an asymmetric perfect vortex beam.

This Letter demonstrates the nonlinear conversion of asymmetric perfect vortex (APV) beams with fractional orbital angular momentum (OAM). By controlling the amplitude and phase of the fundamental light field, we create APVs whose global OAM demonstrates a one-to-one correspondence of the charge numbers for fractional OAM values. The results show that the OAM of the second-harmonic generation fields follow the OAM conservation law. The nonlinear interactions of multiple OAM beams with the APVs are also investigated as they relate to the nonlinear frequency conversion and are shown to exhibit unique frequencies as a result of the Doppler frequency tagged OAM values.

Lefamulin: A Novel Semisynthetic Pleuromutilin Antibiotic for Community-acquired Bacterial Pneumonia.

Community-acquired bacterial pneumonia (CABP) remains a significant cause of morbidity and mortality worldwide. Antimicrobial resistance, including in pathogens that cause CABP, continues to spread at an alarming rate. Because of these factors, the development of new antibiotic classes is urgently needed. Lefamulin, previously known as BC-3781, is a semisynthetic pleuromutilin antibiotic that was approved by the Food and Drug Administration for the treatment of CABP in adults. Available in both oral and intravenous formulations, lefamulin has potent in vitro activity against both typical and atypical CABP pathogens. The first pleuromutilin to be used systemically in humans, lefamulin has a unique mechanism of action that inhibits protein synthesis by preventing the binding of tRNA for peptide transfer. This review summarizes the available data on lefamulin, including recent evidence from 2 phase III clinical trials (LEAP 1 and LEAP 2), and discusses its potential role in the treatment of CABP.

The Pitt Bacteremia Score Predicts Mortality in Nonbacteremic Infections.

BACKGROUND: Predicting mortality risk in patients is important in research settings. The Pitt bacteremia score (PBS) is commonly used as a predictor of early mortality risk in patients with bloodstream infections (BSIs). We determined whether the PBS predicts 14-day inpatient mortality in nonbacteremia carbapenem-resistant Enterobacteriaceae (CRE) infections. METHODS: Patients were selected from the Consortium on Resistance Against Carbapenems in Klebsiella and Other Enterobacteriaceae, a prospective, multicenter, observational study. We estimated risk ratios to analyze the predictive ability of the PBS overall and each of its components individually. We analyzed each component of the PBS in the prediction of mortality, assessed the appropriate cutoff value for the dichotomized score, and compared the predictive ability of the qPitt score to that of the PBS. RESULTS: In a cohort of 475 patients with CRE infections, a PBS ≥4 was associated with mortality in patients with nonbacteremia infections (risk ratio [RR], 21.9; 95% confidence interval [CI], 7.0, 68.8) and with BSIs (RR, 6.0; 95% CI, 2.5, 14.4). In multivariable analysis, the hypotension, mechanical ventilation, mental status, and cardiac arrest parameters of the PBS were independent risk factors for 14-day all-cause inpatient mortality. The temperature parameter as originally calculated for the PBS was not independently associated with mortality. However, a temperature <36.0°C vs ≥36°C was independently associated with mortality. A qPitt score ≥2 had similar discrimination as a PBS ≥4 in nonbacteremia infections. CONCLUSIONS: Here, we validated that the PBS and qPitt score can be used as reliable predictors of mortality in nonbacteremia CRE infections.

Experimental probing of turbulence using a continuous spectrum of asymmetric OAM beams.

Propagation of a continuous spectrum of orbital angular momentum (OAM) states through a realistic and controlled 3-dimensional turbulent condition has not been studied to date to the authors' knowledge. Using the Higher Order Bessel-gauss Beams Integrated in Time (HOBBIT) system and a 60 meter optical path Variable Turbulence Generator (VTG), we demonstrate that by changing the OAM in a continuous scan, a spectrum of OAMs provide an opportunity to take advantage of additional propagation channels within the aperture of the transmitter and optical path to the receiver. Experimental results are provided illustrating the HOBBIT system's ability to position the beam in space and time to exploit eigenchannels in the turbulent medium. This technique can be used to probe the turbulence at time scales much faster than the Greenwood frequency.

Second-harmonic generation of asymmetric Bessel-Gaussian beams carrying orbital angular momentum.

Nonlinear processes of laser beams carrying orbital angular momentum (OAM) offer a means to generate new wavelengths and to manipulate OAM charge numbers. We demonstrate the second-harmonic generation (SHG) of asymmetric Bessel-Gaussian (BG) beams carrying OAM of both integer and fractional charge numbers. Experimental results show a good one-to-one correspondence of the charge numbers and compliance with the OAM conservation law. The SHG conversion process and efficiency with different combined charge numbers are also discussed.

A Multicenter Survey of House Staff Knowledge About Sepsis and the "Surviving Sepsis Campaign Guidelines for Management of Severe Sepsis and Septic Shock".

BACKGROUND: We aimed to assess the knowledge, attitudes, and perceptions of resident physicians regarding sepsis in general and the Surviving Sepsis Campaign Guidelines in particular. METHODS: After institutional review board approval, we surveyed internal medicine (IM) and emergency medicine (EM) house staff from 3 separate institutions. House staff were notified of the survey via e-mail from their residency director or chief resident. The survey was Internet-based (using http://www.surveymonkey.com ), voluntary, and anonymous. The Surviving Sepsis Campaign Guidelines were used to develop the survey. The survey was open between December 2015 and April 2016. No incentives for participation were given. Reminder e-mails were sent approximately every 3 to 4 weeks to all eligible participants. Comparisons of responses were evaluated using the N-1 2-proportion test. RESULTS: A total of 133 responses were received. These included 84 from IM house staff, 27 from EM house staff, and 22 who selected "other." Eighty (101/126) percent reported managing at least 1 patient with sepsis in the preceding 30 days, 85% (97/114) rated their knowledge of the Surviving Sepsis Guidelines as "very familiar" or at least "somewhat familiar," and 84% (91/108) believed their training in the diagnosis and management of sepsis was "excellent" or at least "good." However, 43% (47/108) reported not receiving any feedback on their treatment of patients with sepsis in the last 30 days, while 24% (26/108) received feedback once. Both IM and EM house staff received comparable rates of feedback (62% vs 48%, respectively; P = .21). For the 3 questions that directly tested knowledge of the guidelines, the scores of the IM and EM house staff were similar. Notably, <20% of both groups correctly identified diagnostic criteria for sepsis. CONCLUSION: Additional education of IM and EM house staff on the Surviving Sepsis Campaign Guidelines is warranted, along with more consistent feedback regarding their diagnosis and management of sepsis.

Omadacycline: A Novel Tetracycline Derivative With Oral and Intravenous Formulations.

Omadacycline, an aminomethylcycline, is a novel member of the tetracycline class of antibiotics. It has received approval by the US Food and Drug Administration for the treatment of community-acquired bacterial pneumonia and acute bacterial skin and skin structure infections, and is available in both oral and intravenous formulations. It is also being evaluated in clinical trials for the treatment of cystitis and pyelonephritis. The omadacycline molecule was designed to overcome tetracycline resistance and has broad-spectrum activity that includes gram-positive bacteria, gram-negative bacteria, anaerobes, atypicals, and other drug-resistant strains, like methicillin-resistant Staphylococcus aureus, as well as Yersinia pestis and Bacillus anthracis, organisms of biodefense interest. Omadacycline has minimal drug-drug pharmacokinetic interactions and a favorable safety profile, with the most common adverse events being gastrointestinal symptoms.

Antimicrobial resistance in methicillin-resistant Staphylococcus aureus to newer antimicrobial agents.

Infections caused by methicillin-resistant Staphylococcus aureus (MRSA) result in significant morbidity and mortality for patients in both community and health care settings. This is primarily due to the difficulty in treating MRSA, which is often resistant to multiple classes of antibiotics. Understanding the mechanisms of antimicrobial resistance (AMR) in MRSA provides insight into the optimal use of antimicrobial agents in clinical practice and also underpins critical aspects of antimicrobial stewardship programs. In this review we delineate the mechanisms, prevalence, and clinical importance of resistance to antibiotics licensed in the past 20 years that target MRSA, as well as new drugs in the pipeline which are likely to be licensed soon. Current gaps in scientific knowledge about MRSA resistance mechanisms are discussed, and topics in the epidemiology of AMR in S. aureus that require further investigation are highlighted.

Rapidly tunable orbital angular momentum (OAM) system for higher order Bessel beams integrated in time (HOBBIT).

Beams with fast and continuously-tunable orbital angular momentum (OAM) have potential applications in classical and quantum optical communications, sensing, and in the study of beam propagation through turbulence. An acousto-optical deflector (AOD) is a sophisticated, well-studied device that continuously and rapidly tunes the deflection angle of an output beam. The log-polar HOBBIT setup can generate beams with OAM by wrapping elliptically shaped Gaussian beams with linear phase tilt to a ring. By combining the linear tilted output from the AOD with the OAM generation capabilities of the HOBBIT system, the generated OAM modes become continuously tunable at high speeds measured on the order of 400 kHz.

Colistin Versus Ceftazidime-Avibactam in the Treatment of Infections Due to Carbapenem-Resistant Enterobacteriaceae.

Background: The efficacy of ceftazidime-avibactam-a cephalosporin-ß-lactamase inhibitor combination with in vitro activity against Klebsiella pneumoniae carbapenemase-producing carbapenem-resistant Enterobacteriaceae (CRE)-compared with colistin remains unknown. Methods: Patients initially treated with either ceftazidime-avibactam or colistin for CRE infections were selected from the Consortium on Resistance Against Carbapenems in Klebsiella and other Enterobacteriaceae (CRACKLE), a prospective, multicenter, observational study. Efficacy, safety, and benefit-risk analyses were performed using intent-to-treat analyses with partial credit and the desirability of outcome ranking approaches. The ordinal efficacy outcome was based on disposition at day 30 after starting treatment (home vs not home but not observed to die in the hospital vs hospital death). All analyses were adjusted for confounding using inverse probability of treatment weighting (IPTW). Results: Thirty-eight patients were treated first with ceftazidime-avibactam and 99 with colistin. Most patients received additional anti-CRE agents as part of their treatment. Bloodstream (n = 63; 46%) and respiratory (n = 30; 22%) infections were most common. In patients treated with ceftazidime-avibactam versus colistin, IPTW-adjusted all-cause hospital mortality 30 days after starting treatment was 9% versus 32%, respectively (difference, 23%; 95% bootstrap confidence interval, 9%-35%; P = .001). In an analysis of disposition at 30 days, patients treated with ceftazidime-avibactam, compared with those treated within colistin, had an IPTW-adjusted probability of a better outcome of 64% (95% confidence interval, 57%-71%). Partial credit analyses indicated uniform superiority of ceftazidime-avibactam to colistin. Conclusions: Ceftazidime-avibactam may be a reasonable alternative to colistin in the treatment of K. pneumoniae carbapenemase-producing CRE infections. These findings require confirmation in a randomized controlled trial.

Multilevel quadrature amplitude multiplexing using coherently coupled orbital angular momentum modes.

Information can be encoded onto transverse spatial light modes, providing a platform that can improve the spectral efficiency of a communications link. Switching speed between these spatial modes and detection methods limit the information capacity of such links. This work demonstrates high speed capabilities of such a link. Transverse modes are created and switched at high rates by coherently coupling twisted light modes using passive optical elements in line with electro-optical modulators. Here we demonstrate the encoding and detection of two coherently coupled modes encoded with 0.5 Gbaud quadrature amplitude modulated (16- and 32-QAM) signals, for a 4X and 5X increase in spectral efficiency by exploiting both phase and amplitude of the coherently coupled modes. The receiver is able to successfully recover the signal with error rates below the forward error correction limit using passive optical techniques. The data rate of the system used is only limited by hardware, but similar devices are available that are capable of multi-Gigahertz operation.