Preparation, Antibacterial and Antistatic Properties of PP/Ag-Ms/CB Composites

Polypropylene（PP） composites that contain silver micro-particles（MILLION KILLER, denoted as Ag-Ms） and conductive carbon black（CB） have both antibacterial and antistatic properties. In the present study, the antibacterial and antistatic PP/Ag-Ms/CB composites were prepared by melt blending. The results showed that when the content was 0.8 wt%, Ag-Ms could be uniformly dispersed in the PP matrix and the mechanical properties of the composites remained stable. And the reduction percentages of Staphylococcus aureus and Escherichia coli were more than 80% which showed the good antibacterial behavior. In addition, conductive carbon black had reinforcing and toughening effects on the mechanical properties of PP/Ag-Ms/CB composites. When the content of CB was beyond 30 wt%, the surface resistance of the composite was reduced to less than 108 Ω which showed a remarkable antistatic property. According to the different filling content of conductive carbon black, it can flexibly regulate the resistivity of PP, and the conductive effect is durable and stable. We thus can produce permanent antistatic materials.

Role of MexA-MexB-OprM Efflux Pump System in Chronic Pseudomonas Aeruginosa Pulmonary Infection in Mice

In order to investigate the role of the MexA-MexB-OprM efflux pump system in the pathogenesis of Pseudomonas aeruginosa(PA)-induced pulmonary infection,pulmonary infection models were established by intratracheal injection of K767(wild type),nalB(MexA-MexB-OprM up-regulated mutant),and △m exB(knockout) strains,separately.All mice were treated with Meropenem(intraperitoneal injection,100 mg/kg body weight,twice every day),and strain-related pathology,bacteria count,cytokine level,myeloperoxidase(MPO,indicator of neutrophil recruitment) activity,and macrophage inflammatory protein-2(MIP-2) expression were evaluated at early(3rd day post-infection) and late(7th and 14th day post-infection) stages of infection.E-test showed that △mexB was more significantly sensitive to panipenan(ETP),meropenem(MP) and imipenem(IP) than K767 and nalB strains.There was no significant difference in sensitivity to cefepime(TM) among the three stains.In contrast to the K767 and nalB groups,the △ mexB group showed decreased bacteria burden over time and less extensive pathological change.Additionally,MPO activity and levels of inflammatory cytokines(IL-1b,IL-12,and TNF-α) were increased at the early stage(day 3) and decreased at the later stage(day 14).Serum MIP-2 expression level was steadily increased in all three groups from early to late stages,but significantly higher in △m exB group than in K767 and nalB groups(P<0.05).In conclusion,the MexA-MexB-OprM efflux pump system might play an important role in PA-induced chronic pulmonary infection.High expression of the MexA-MexB-OprM efflux pump could increase antibacterial resistance and promote infection.

Mass drug administration of antibacterials: weighing the evidence regarding benefits and risks

Background: Mass drug administration(MDA)is a strategy to improve health at the population level through widespread delivery of medicine in a community.We surveyed the literature to summarize the benefits and potential risks associated with MDA of antibacterials,focusing predominantly on azithromycin as it has the greatest evidence base.Main body: High-quality evidence from randomized controlled trials(RCTs)indicate that MDA-azithromycin is effective in reducing the prevalence of infection due to yaws and trachoma.In addition,RCTs suggest that MDA-azithromycin reduces under-five mortality in certain low-resource settings that have high childhood mortality rates at baseline.This reduction in mortality appears to be sustained over time with twice-yearly MDA-azithromycin,with the greatest effect observed in children<1 year of age.In addition,observational data suggest that infections such as skin and soft tissue infections,rheumatic heart disease,acute respiratory illness,diarrheal illness,and malaria may all be treated by azithromycin and thus incidentally impacted by MDA-azithromycin.However,the mechanism by which MDA-azithromycin reduces childhood mortality remains unclear.Verbal autopsies performed in MDA-azithromycin childhood mortality studies have produced conflicting data and are underpowered to answer this question.In addition to benefits,there are several important risks associated with MDA-azithromycin.Direct adverse effects potentially resulting from MDA-azithromycin include gastrointestinal side effects,idiopathic hypertrophic pyloric stenosis,cardiovascular side effects,and increase in chronic diseases such as asthma and obesity.Antibacterial resistance is also a risk associated with MDA-azithromycin and has been reported for both gram-positive and enteric organisms.Further,there is the risk for cross-resistance with other antibacterial agents,especially clindamycin.Conclusions: Evidence shows that MDA-azithromycin programs may be beneficial for reducing trachoma,yaws,and mortality in children<5 years of age in certain under-resourced settings.However,there are significant potential risks that need to be considered when deciding how,when,and where to implement these programs.Robust systems to monitor benefits as well as adverse effects and antibacterial resistance are warranted in communities where MDA-azithromycin programs are implemented.

A review of global initiatives to fight antibiotic resistance and recent antibiotics' discovery

Data from across the world have shown an overall decline in the antibiotic pipeline and continually rising resistance to all first-line and last-resort antibiotics. The gaps in our knowledge of existing prevalence and mechanisms of antibiotic resistance(ABR) are all too well known. Several decades of antibiotic abuse in humans, animals, and agricultural practices have created health emergency situations and huge socio-economic impact. This paper discusses key findings of the studies conducted by several national and international collaborative organizations on the current state of affairs in ABR.Alongside, a brief overview of the antibacterial agents' discovery in recent years approved by the US FDA is discussed.