Polymyxin B antagonizing biological activity of lipopolysaccharide

Objective ： To investigate the mechanism of polymyxin B （ PMB ） antagonizing the biological activity of Hipopolysaccharide （LPS）. Methods： The affinity of PMB for LPS and lipid A was assayed by biosensor, and the neutralization of PMB for LPS （2 ng/ml ） was detected by kinetic turbidimetric limnins test. The releases of TNF-α and IL-6 in murine peritoneal macrophages （PMφ） after exposure to LPS （ 100 ng/ml） were detected, and the expression levels of TLR4, TNF-α and IL-6 mRNA in PMφ induced by LPS （100 ng/ml） were measured by RT-PCR. Results： PMB had high-affinity to LPS and lipid A with dissociation equilibrium constants of 18.9 nmol/L and 11.1 nmol/L, respectively, and neutralized LPS in a dosedependent manner. Furthermore, PMB could markedly inhibit the expressions of TLR4, TNF-α and IL-6 mRNA and the release of cycokines in LPS-stimniated murine PMφ. Conclusions： PMB neutralizes LPS and inhibites the expression and release of cycokines in macrophages, in which the affinity of PMB for lipid A plays an important role.     

Polymyxin B,a selective inhibitor of protein kinase C,diminishes the release of noradrenaline and the enhancement of release caused by phorbol 12,13-dibutyrate

Summary Slices of the rabbit hippocampus were labelled with ³H-noradrenaline, superfused continuously with a modified Krebs-Henseleit medium containing the uptake inhibitor cocaine and stimulated electrically (2 ms, 3 Hz, 24 mA, 5 V/cm). Phorbol 12,13-dibutyrate (PDB), a potent activator of protein kinase C (PKC), strongly enhanced the electrically-evoked overflow of tritium. In contrast, polymyxin B, a relatively selective inhibitor of PKC, diminished the evoked tritium overflow in a time-and concentration-dependent manner. The enhancement of the evoked overflow of tritium caused by PDB was strongly reduced in the presence of polymyxin B (100 mol/l). These results suggest 1. that PKC may be involved in the physiological mechanism of action-potential-induced noradrenaline release from noradrenergic nerve terminals and 2. that the PDB-induced enhancement of noradrenaline release may be due to a direct activation of PKC.Abbreviations PKC protein kinase C - PDB phorbol 12,13-dibutyrate - TPA 12-O-tetradecanoyl 13-acetate     

Using machine learning to optimize antibiotic combinations: dosing strategies for meropenem and polymyxin B against carbapenem-resistant Acinetobacter baumannii

ObjectivesIncreased rates of carbapenem-resistant strains of Acinetobacter baumannii have forced clinicians to rely upon last-line agents, such as the polymyxins, or empirical, unoptimized combination therapy. Therefore, the objectives of this study were: (a) to evaluate the in vitro pharmacodynamics of meropenem and polymyxin B (PMB) combinations against A. baumannii; (b) to utilize a mechanism-based mathematical model to quantify bacterial killing; and (c) to develop a genetic algorithm (GA) to define optimal dosing strategies for meropenem and PMB.MethodsA. baumannii (N16870; MIC_meropenem = 16 mg/L, MIC_PMB = 0.5 mg/L) was studied in the hollow-fibre infection model (initial inoculum 10⁸ cfu/mL) over 14 days against meropenem and PMB combinations. A mechanism-based model of the data and population pharmacokinetics of each drug were used to develop a GA to define the optimal regimen parameters.ResultsMonotherapies resulted in regrowth to ~10¹⁰ cfu/mL by 24 h, while combination regimens employing high-intensity PMB exposure achieved complete bacterial eradication (0 cfu/mL) by 336 h. The mechanism-based model demonstrated an SC₅₀ (PMB concentration for 50% of maximum synergy on meropenem killing) of 0.0927 mg/L for PMB-susceptible subpopulations versus 3.40 mg/L for PMB-resistant subpopulations. The GA had a preference for meropenem regimens that improved the %T > MIC via longer infusion times and shorter dosing intervals. The GA predicted that treating 90% of simulated subjects harbouring a 10⁸ cfu/mL starting inoculum to a point of 10⁰ cfu/mL would require a regimen of meropenem 19.6 g/day 2 h prolonged infusion (2 hPI) q5h + PMB 5.17 mg/kg/day 2 hPI q6h (where the 0 h meropenem and PMB doses should be ‘loaded’ with 80.5% and 42.2% of the daily dose, respectively).ConclusionThis study provides a methodology leveraging in vitro experimental data, a mathematical pharmacodynamic model, and population pharmacokinetics provide a possible avenue to optimize treatment regimens beyond the use of the ‘traditional’ indices of antibiotic action.     

Comparison of efficacy and safety of ciprofloxacin otic solution 0.2% versus polymyxin B-neomycin-hydrocortisone in the treatment of acute diffuse otitis externa

ABSTRACT

Objective: To compare the efficacy and safety of ciprofloxacin otic solution 0.2% to polymyxin B-neomycin-hydrocortisone (PNH) otic solution in the treatment of acute diffuse otitis externa in children, adolescents, and adults.

Methods: This was a randomized, parallel-group, evaluator-blind, active-controlled, multicenter, noninferiority study. The primary efficacy endpoint was clinical cure of otitis symptoms at the test-of-cure (TOC) visit. Clinical cure at the end-of-treatment (EOT) visit and percentages of patients with clinical improvement and resolution and/or improvement of otalgia at EOT and TOC visits were secondary efficacy endpoints.

Results: A total of 630 patients were randomized to ciprofloxacin twice daily (n = 318) or PNH 3 times daily (n = 312) for 7 days. Ciprofloxacin was shown to be noninferior to PNH. The percentage of patients with clinical cure at the TOC visit was 86.6% with ciprofloxacin and 81.1% with PNH; the treatment difference was 5.6% in favor of ciprofloxacin (95% CI: ?0.9 to 12.1). At the EOT visit, clinical cure was achieved in 70.0% and 60.5% of patients, respectively, with a treatment difference in favor of ciprofloxacin (9.5%, 95 CI: 1.2 to 17.9). In all secondary efficacy variables, ciprofloxacin and PNH showed similar results, including pain duration and resolution. The clinical cure rate for patients with baseline cultures showing P. aeruginosa was 87.5% in the ciprofloxacin group and 78.6% in the PNH group, a treatment difference of 8.9% in favor of ciprofloxacin (95% CI: 0.6 to 17.3); for patients with baseline cultures showing S. aureus, the clinical cure rate was 72.7% for the ciprofloxacin group and 75.9% for the PNH group (treatment difference of 3.1% in favor of PNH, 95% CI: ?21.1% to 27.4%). Most adverse events were mild and unrelated to study medication in both treatment groups. A limitation of this study is the assessment of signs and symptoms at baseline and after treatment, which does not provide data to evaluate the interim response.

Conclusions: Ciprofloxacin otic solution 0.2% was found to be noninferior to PNH. This efficacy, good tolerability, and ease of administration make ciprofloxacin otic solution 0.2% without a topical steroid an attractive option for the treatment of acute otitis externa.     

Rapid Polymyxin NP test for the detection of polymyxin resistance mediated by the mcr-1/mcr-2 genes

The Rapid Polymyxin NP test has been recently developed to rapidly detect polymyxin resistance in Enterobacteriaceae. Here we evaluated this test for detecting MCR-1/MCR-2-producing Enterobacteriaceae using a collection of 70 non-redundant strains either recovered from the environment, animals, or humans. Sensitivity and specificity were found to be 100%.     

临床药师参与治疗鲍曼不动杆菌颅内感染患儿的药学实践

目的为临床救治重症难治性鲍曼不动杆菌颅内感染患儿提供用药参考。方法通过分析临床药师参与救治我院1例鲍曼不动杆菌颅内感染患儿提供的药学服务,根据患者的病情变化,临床药师结合药物的药理药化知识,查阅相关文献资料,与临床医师共同协商,制定出最优的药物治疗方案。结果通过临床医师及临床药师的共同努力,最终成功救治该患儿。结论临床药师的参与可以协助医师制订安全、有效的治疗方案。     

Poly(Ethyleneimine)‐Immobilized‐Cloth Enzyme Immunoassay for the Detection of Salmonella Lipopolysaccharide

Poly(ethyleneimine) (PEI) was immobilized on non‐woven polyester cloth and examined for application on a simple, rapid and economical “cloth enzyme immunoassay (CEIA)” which was developed originally as polymyxin‐CEIA for the detection of Salmonella lipopolysaccharide (LPS). PEI‐cloth regardless of the PEI molecular weight, but with the amine group contents of 0.1 ～ 0.35 meq/g immobilized either in a physisorption‐like or chemisorption‐like manner, adsorbed LPS rapidly, preferentially and effectively. The captured LPS was then able to be detected qualitatively and quantitatively as an antigen by enzyme immunoassay. PEI‐CEIA had a detection limit for Salmonella LPS of 10 ng/ml, which was equivalent to 1.6 × 10⁵ cell/ml and was ten times more sensitive than polymyxin‐CEIA. It was possible to detect Salmonella LPS in the presence of a 100‐fold excess of E. coli LPS. PEI‐CEIA was found to be more sensitive and much easier to carry out than polymyxin‐CEIA but had the same advantages as polymyxin‐CEIA.     

静脉联合鞘内或脑室内注射多黏菌素对多重耐药鲍曼不动杆菌#br# 颅内感染疗效及安全性Meta分析

目的 系统评价多黏菌素静脉联合鞘内或脑室内注射对多重耐药鲍曼不动杆菌的疗效及安全性。方法 计算机检索PubMed、Embase、CNKI、VIP、万方数据库等数据库,检索时间为建库至2019年6月,筛选有关多黏菌素静脉联合鞘内或脑室内给药治疗多重耐药鲍曼不动杆菌感染的文献,采用RevMan 5.3软件对提取的数据进行Meta分析。结果 纳入7篇文献、178例患者。Meta分析结果显示,静脉联合鞘内或脑室内组的临床死亡率(OR=0.18, 95%CI：0.09~0.37, P＜0.00001)低于静脉组、细菌清除率(OR=20.40, 95%CI：5.94~70.12, P＜0.00001)高于静脉组;两组不良反应发生率无统计学差异(OR=0.60, 95%CI: 0.16~2.23, P=0.44)。结论 多黏菌素静脉联合鞘内或脑室内给药治疗多重耐药鲍曼不动杆菌颅内感染疗效优于静脉滴注,安全性无显著差异。     

Development and validation of a multiplex polymerase chain reaction assay for detection of the five families of plasmid-encoded colistin resistance

Plasmid-mediated colistin resistance is increasingly described worldwide in Enterobacteriaceae from animal and human isolates. Diffusion of these resistance traits among carbapenem-resistant enterobacterial isolates is of particular concern as colistin has become the last resort antibiotic for treating human infections with these organisms. Therefore, being able to monitor the presence of these transferable colistin resistance genes (mcr-1 to mcr-5-variants) is crucial. This paper describes the development of a multiplex polymerase chain reaction (PCR) protocol for detection of all currently known transferable colistin resistance genes in Enterobacteriaceae. Five primer pairs were designed to amplify mcr-1, mcr-2, mcr-3, mcr-4 and mcr-5 gene products in a multiplex PCR. This assay was validated retrospectively on colonies of 50 Escherichia coli, 44 Klebsiella pneumoniae and 12 Salmonella enterica isolates of animal and human origin, all well characterized, and validated prospectively on 450 carbapenem-resistant enterobacterial isolates received by the French National Reference Centre. In addition, 82 Aeromonas spp. and 10 Shewanella spp. known to be the progenitors of mcr-3 and mcr-4 alleles, respectively, were screened. Mcr-multiplex PCR assay displayed 100% specificity, sensitivity, negative predictive value and positive predictive value. The assay was able to detect all variants of the different mcr alleles, and was able to detect chromosomally encoded mcr-4-like variants present in two Shewanella bicestrii JAB-1 and Shewanella woodyi S539. In conclusion, a rapid and robust multiplex PCR assay able to detect all known mcr gene families described in Enterobacteriaceae was developed and validated. This type of test is critical for the epidemiological surveillance of plasmid-encoded resistance, especially in carbapenem-resistant bacteria.