An agent-based model on antimicrobial de-escalation in intensive care units: Implications on clinical trial design.

Antimicrobial de-escalation refers to reducing the spectrum of antibiotics used in treating bacterial infections. This strategy is widely recommended in many antimicrobial stewardship programs and is believed to reduce patients' exposure to broad-spectrum antibiotics and prevent resistance. However, the ecological benefits of de-escalation have not been universally observed in clinical studies.

A stochastic dynamical model for nosocomial infections with co-circulation of sensitive and resistant bacterial strains.

Nosocomial infections (hospital-acquired) has been an important public health problem, which may make those patients with infections or involved visitors and hospital personnel at higher risk of worse clinical outcomes or infection, and then consume more healthcare resources. Taking into account the stochasticity of the death and discharge rate of patients staying in hospitals, in this paper, we propose a stochastic dynamical model describing the transmission of nosocomial pathogens among patients admitted for hospital stays. The stochastic terms of the model are incorporated to capture the randomness arising from death and discharge processes of patients.

Linking mathematical models and trap data to infer the proliferation, abundance, and control of Aedes aegypti.

Aedes aegypti is one of the most dominant mosquito species in the urban areas of Miami-Dade County, Florida, and is responsible for the local arbovirus transmissions. Since August 2016, mosquito traps have been placed throughout the county to improve surveillance and guide mosquito control and arbovirus outbreak response. In this paper, we develop a deterministic mosquito population model, estimate model parameters by using local entomological and temperature data, and use the model to calibrate the mosquito trap data from 2017 to 2019.

A novel method based on Ag-Au nanorings with tunable plasmonic properties for the sensitive detection of amantadine.

To prevent the toxic effect of amantadine (AMD) on humans, a sensitive and direct detection method is required. The conventional enzyme-linked immunosorbent assay (ELISA) usually shows a monochromatic gradient color variation with the concentration of the target; hence, it is not a sensitive method for naked-eye detection. In this work, Ag-Au nanorings with highly tunable plasmon properties were synthesized as colorimetric nanosensors.

Estimating asymptomatic, undetected and total cases for the COVID-19 outbreak in Wuhan: a mathematical modeling study.

Background: The COVID-19 outbreak in Wuhan started in December 2019 and was under control by the end of March 2020 with a total of 50,006 confirmed cases by the implementation of a series of nonpharmaceutical interventions (NPIs) including unprecedented lockdown of the city. This study analyzes the complete outbreak data from Wuhan, assesses the impact of these public health interventions, and estimates the asymptomatic, undetected and total cases for the COVID-19 outbreak in Wuhan.

Methods: By taking different stages of the outbreak into account, we developed a time-dependent compartmental model to describe the dynamics of disease transmission and case detection and reporting.

Effectiveness and feasibility of convalescent blood transfusion to reduce COVID-19 fatality ratio.

As of December 2020, COVID-19 has spread all over the world with more than 81 million cases and more than 1.8 million deaths. The rapidly increasing number of patients mandates the consideration of potential treatments for patients under severe and critical conditions.

Modeling Antibiotic Use Strategies in Intensive Care Units: Comparing De-escalation and Continuation.

Antimicrobial de-escalation refers to the treatment mechanism of switching from empiric antibiotics with good coverage to alternatives based on laboratory susceptibility test results, with the aim of avoiding unnecessary use of broad-spectrum antibiotics. In a previous study, we have developed multi-strain and multi-drug models in an intensive care unit setting, to evaluate the benefits and trade-offs of de-escalation in comparison with the conventional strategy called antimicrobial continuation. Our simulation results indicated that for a large portion of credible parameter combinations, de-escalation reduces the use of the empiric antibiotic but increases the probabilities of colonization and infections.

H NMR combined with PLS for the rapid determination of squalene and sterols in vegetable oils.

Proton nuclear magnetic resonance (H NMR) combined with partial least squares (PLS) was developed for the rapid determination of squalene and sterols (brassicasterol, campesterol, stigmasterol and β-sitosterol) in 119 vegetable oils from 7 different species. The H NMR spectra of these oil samples were correlated to the reference value determined by gas chromatography-mass spectrometry (GC-MS) method by PLS regression, using outlier removal, selection of input X-variables and data pretreatments. Auto-scaling (UV) was chosen as the best pre-processing for the PLS models of stigmasterol, β-sitosterol, and squalene.

Optimal control of environmental cleaning and antibiotic prescription in an epidemiological model of methicillin-resistant Staphylococcus aureus infections in hospitals.

We consider a deterministic model of Methicillin-resistant Staphylococcus aureus infections in hospitals with seasonal oscillations of the antibiotic prescription rate. The model compartments consist of uncolonized patients with or without antibiotic exposure, colonized patients with or without antibiotic exposure, uncontaminated or contaminated healthcare workers, and free-living bacteria in the environment. We apply optimal control theory to this seven-compartment periodic system of ordinary differential equations to reduce the number of colonized patients and density of bacteria in the environment while minimizing the cost associated with environmental cleaning and antibiotic use in a particular time period.

Modelling and Analyzing Virus Mutation Dynamics of Chikungunya Outbreaks.

Chikungunya fever, caused by chikungunya virus (CHIKV) and transmitted to humans by infected Aedes mosquitoes, has posed a global threat in several countries in 2015. Recent outbreaks in La Réunion, Italy and China are related with a new variant of CHIKV with shorter extrinsic incubation period in contaminated mosquitoes, but the role of this new variant on the spread of chikungunya fever is unclear. We develop a mathematical model that incorporates the virus mutation dynamics in the transmission of CHIKV among mosquitoes and humans.

A conceptual model for optimizing vaccine coverage to reduce vector-borne infections in the presence of antibody-dependent enhancement.

Background: Many vector-borne diseases co-circulate, as the viruses from the same family are also transmitted by the same vector species. For example, Zika and dengue viruses belong to the same Flavivirus family and are primarily transmitted by a common mosquito species Aedes aegypti. Zika outbreaks have also commonly occurred in dengue-endemic areas, and co-circulation and co-infection of both viruses have been reported.

Two Cases of Multi-antibiotic Resistant Cronobacter spp. Infections of Infants in China.

Infections by Cronobacter spp. are hazardous to infants since they can lead to neonatal meningitis, bacteremia, and necrotizing enterocolitis. Cronobacter spp.

Benefits and unintended consequences of antimicrobial de-escalation: Implications for stewardship programs.

Sequential antimicrobial de-escalation aims to minimize resistance to high-value broad-spectrum empiric antimicrobials by switching to alternative drugs when testing confirms susceptibility. Though widely practiced, the effects de-escalation are not well understood. Definitions of interventions and outcomes differ among studies.

Treatment-donation-stockpile dynamics in ebola convalescent blood transfusion therapy.

The interim guidance issued by the World Health Organization during the West Africa 2014 Ebola outbreak provides guidelines on the use of convalescent blood from Ebola survivors for transfusion therapy. Here we develop a novel mathematical model, based on the interim guidance, to examine the nonlinear transmission-treatment-donation-stockpile dynamics during an Ebola outbreak and with a large scale use of the transfusion therapy in the population. We estimate the reduction of case fatality ratio by introducing convalescent blood transfusion as a therapy, and inform optimal treatment-donation-stockpile strategies to balance the treatment need for case fatality ratio reduction and the strategic need of maintaining a minimal blood bank stockpile for other control priorities.

A model of the 2014 ebola epidemic in west Africa with contact tracing.

A differential equations model is developed for the 2014 Ebola epidemics in Sierra Leone and Liberia. The model describes the dynamic interactions of the susceptible and infected populations of these countries. The model incorporates the principle features of contact tracing, namely, the number of contacts per identified infectious case, the likelihood that a traced contact is infectious, and the efficiency of the contact tracing process.