Antibacterial resistance in Streptococcus pyogenes (GAS) from healthy carriers and tonsillitis patients and association with antibacterial sale in the Faroe Islands

The aim of this study was to investigate the antibacterial resistance of Streptococcus pyogenes (GAS), and correlate the findings with the sales of erythromycin and tetracycline. General practitioners in the Faroe Islands were recruited to send oropharyngeal swabs. From an ongoing pneumococcal study, nasopharyngeal swabs were sampled from healthy children 0–7 years of age. Erythromycin susceptibility data from Iceland were obtained from the reference laboratory at the Landspitali University Hospital. Susceptibility testing in the Faroe Islands and Iceland was performed according to CLSI methods and criteria. The resistance rate to erythromycin and tetracycline found in patients in the Faroe Islands in 2009/2010 was 6% and 30% respectively. Tetracycline resistance in patients declined significantly from 2009 to 2010 (37–10%, p‐value = 0.006 < 0.05) and differed significantly between age groups (p‐value = 0.03 < 0.05). In Iceland, there was a peak in erythromycin resistance in 2008 (44%) and a substantial decrease in 2009 (5%). Although the prevalence of erythromycin and tetracycline resistance in the Faroe Islands and Iceland may be associated with antimicrobial use, sudden changes can occur with the introduction of new resistant clones.     

Polyethyleneimine and quaternized ammonium polyethyleneimine: the versatile materials for combating bacteria and biofilms

Abstract

Bacterial infection has become a serious clinical concern due to the emergence of drug-resistance and biofilm formation. Therefore, it is in great demand to develop efficient antimicrobial agents to treat bacterial infection without using antibiotics. Herein, we successfully prepared four quaternized ammonium PEI (QPEI: PEI₁₂₀₀-C2, PEI₁₂₀₀-C4, PEI₁₂₀₀-C6 and PEI₁₂₀₀-C8) using the commercial available PEI₁₂₀₀. Both PEI and four QPEI presented broad-spectrum antimicrobial activity against Gram-negative bacteria (E. coli, and P. aeruginosa) and Gram-positive bacteria (B. amyloliquefaciens and S. aureus), especially PEI₁₂₀₀-C6 showed the strongest antimicrobial activity with good biocompatibility at the MIC concentrations. Besides, PEI₁₂₀₀-C6 showed 4-16-fold better antibacterial effect than PEI₁₂₀₀, and fluorescent microscope imaging demonstrated that both of them could efficiently eradicate biofilms formed by four bacterial strains in vitro. As the accessible broad-spectrum antibacterial agents, PEI₁₂₀₀ and PEI₁₂₀₀-C6 are significant candidates to treat bacterial infections or eradicate biofilms on indwelling medical devices.     

News and Notes

Abstract

The essential oil of nutmeg (600 or 900 mg/kg, IP) altered the young chicks' species-specific response to amphetamine (20 mg/kg, SQ). Nutmeg oil totally blocked the development of chirping and decreased the duration of wing droop and stereotyped behavior “b” (head and neck extended forward, parallel to but not touching floor), but increased the duration of stereotyped behavior “a” (head and neck drawn back with top of head almost touching back). Amphetamine caused a significant decrease in the duration of light and deep sleep in the group that received the higher dose level of nutmeg oil.     

稠环磺酰胺衍生物的合成与抗菌活性研究

为了寻找抗菌候选化合物,在前期研究基础上,18个稠环磺酰胺衍生物被设计合成,经1H NMR、13C NMR和MS确认结构。采用两倍稀释法对目标物进行体外抗菌活性测试,结果表明:该类衍生物对所测细菌有不同程度的抑制活性,尤以化合物Ⅱi、Ⅱr的抗菌活性最为突出,其中前者对金葡菌(S.aureus)、大肠埃希菌(E.coli)和耐甲氧西林金葡菌(MRSA)的最小抑菌浓度(MIC)分别为8、32和16μg·mL^-1,后者对S.aureus、E.coli及MRSA的MIC分别为8、64和32μg·mL^-1,两者的抗MRSA活性较显著,值得进一步结构优化和深入研究。     

Characterization of Hybrid Materials Prepared by Sol-Gel Method for Biomedical Implementations. A Critical Review

The interaction between tissues and biomaterials (BM) has the purpose of improving and replacing anatomical parts of the human body, avoiding the occurrence of adverse reactions in the host organism. Unfortunately, the early failure of implants cannot be currently avoided, since neither a good mixture of mechanical and chemical characteristics of materials nor their biocompatibility has been yet achieved. Bioactive glasses are recognized to be a fine class of bioactive substances for good repair and replacement. BM interact with living bones through the formation of a hydroxyapatite surface layer that is analogous to bones. Bioglasses’ composition noticeably affects their biological properties, as does the synthesis method, with the best one being the versatile sol-gel technique, which includes the change of scheme from a ‘sol’ fluid into a ‘gel’. This process is widely used to prepare many materials for biomedical implants (e.g., hip and knee prostheses, heart valves, and ceramic, glassy and hybrid materials to serve as carriers for drug release). Nanoparticles prepared by the sol-gel method are interesting systems for biomedical implementations, and particularly useful for cancer therapy. This review provides many examples concerning the synthesis and characterization of the above-mentioned materials either taken from literature and from recently prepared zirconia/polyethylene glycol (PEG) hybrids, and the corresponding results are extensively discussed.     

Synthesis and Biological Activities of Some Benzimidazolone Derivatives

The reaction of 5-nitrobenzimidazolone with phenoxyethyl bromide in presence of potassium carbonate in dimethyl formamide obtained 6-nitro-1,3-bis(2-phenoxyethyl)-1,3-dihydro-2H-benzimidazol-2-one. It was reduced using stannous chloride to get 6-amino -1,3-bis(2-phenoxyethyl)-1, 3-dihydro-2H-benzimidazol -2-one, which was further treated with aromatic sulphonyl chloride to obtain benzimidazolone derivatives, 6a-k. These compounds were tested for antibacterial, antituberculosis and antifungal activity. Most of them have shown very good activity against some gram positive and gram negative microorganisms and fungal strains. Some of them have shown moderate activity against Mycobacterium tuberculosis.     

血清降钙素原在肝硬化腹水中的早期抗菌治疗研究

目的通过对血清降钙素原(PCT)水平在肝硬化腹水多形核中性粒细胞(PMN)250个/μL患者中早期抗菌治疗的研究,为肝硬化腹水患者的早期抗菌治疗提供参考依据。方法选取我院2014年1月~2016年12月住院治疗腹水PMN250个/μL的肝硬化患者100例,随机选取23例为常规治疗组,77例为抗感染治疗组。根据治疗前测得的血清PCT值,将抗感染治疗组分为抗感染治疗A组(PCT0.43 ng/m L,32例)、抗感染治疗B组(0.43 ng/m L≤PCT≤2 ng/m L,24例)和抗感染治疗C组(PCT2 ng/m L,21例),治疗后对四组患者的临床疗效和肝功能指标进行检测。结果治疗后各PCT水平的抗感染治疗组与常规治疗组患者的临床综合疗效比较,差异无统计学意义(P0.05)。治疗后四组患者的ALT和TBIL值较治疗前均有显著降低(P0.05),ALB值显著升高(P0.05),但治疗后各组间各指标值比较无统计学意义(P0.05)。结论血清PCT水平对早期抗菌治疗的临床指导价值还有待进一步研究,不能作为肝硬化腹水早期抗感染的精确指标,需结合临床实际情况综合评估再确定是否行抗感染治疗。     

Gene characteristics,immune and stress responses of PmPrx1 in black tiger shrimp (Penaeus monodon): Insights from exposure to pathogenic bacteria and toxic environmental stressors

Peroxiredoxins (Prxs) are ubiquitous, multifunctional and evolutionarily conserved enzymes that can protect cells from oxidative damage caused by ROS and play a vital role in immune responses. Here, a full-length Prx1 cDNA sequence (PmPrx1) was isolated from Penaeus monodon. The PmPrx1 cDNA was 951 base pairs (bp), encoding 198 amino acid polypeptides. The results of qRT-PCR showed that the PmPrx1 mRNA was ubiquitously expressed in all tissues tested and had a comparatively high expression level in immune-associated tissues (gill, hepatopancreas). To explore the immune and anti-stress roles of PmPrx1, the gills and hepatopancreas were chosen as target tissues in Penaeus monodon and were challenged with bacteria (Vibrio harveyi and Streptococcus agalactiae) and toxic environmental stresses. To further clarify the immune function of PmPrx1 after bacterial challenge, the recombinant PmPrx1 protein was acquired using a prokaryotic expression method. The antioxidant activity of the recombinant PmPrx1 was assessed by the catalyzing hydrogen peroxide assay method, and the results showed obvious antioxidant activity in a dose-dependent and temperature-dependent manner. The antimicrobial activity of purified PmPrx1 protein was evaluated and further studied in vitro relying on a bacterial growth inhibition test which was conducted in both liquid and solid cultures. Furthermore, E. coli transferred with pRSET-PmPrx1 was dramatically protected in response to metal toxicity and H₂O₂ oxidative stress. In summary, this study provides useful information about the role of the Prx1 gene in defense against a variety of toxic factors in shrimps that help to further clarify the functional mechanism of Prx.     

Alternative mechanisms of action of cationic antimicrobial peptides on bacteria

Cationic antimicrobial peptides are a novel type of antibiotic offering much potential in the treatment of microbial-related diseases. They offer many advantages for commercial development, including a broad spectrum of action and modest size. However, despite the identification or synthetic production of thousands of such peptides, the mode of action remains elusive, except for a few examples. While the dogma for the mechanism of action of antimicrobial peptides against bacteria is believed to be through pore formation or membrane barrier disruption, some peptides clearly act differently and other intracellular target sites have been identified. This article presents an updated review of how cationic antimicrobial peptides are able to affect bacterial killing, with a focus on internal targets.     

Geographic map and evolution of primary Helicobacter pylori resistance to antibacterial agents

Antibiotic resistance in Helicobacter pylori is the major cause of eradication failure. Primary H. pylori susceptibility patterns, however, are becoming less predictable. Currently, high (≥20%) clarithromycin resistance rates have been observed in the USA and in developed countries in Europe and Asia, while the highest (≥80%) metronidazole-resistance rates have been reported in Africa, Asia and South America. Primary quinolone-resistance rates of 10% or more have already been reported in developed countries in Europe and Asia. Primary amoxicillin resistance has been low (0 to <2%) in Europe but higher (6–59%) in Africa, Asia and South America. Similarly, tetracycline resistance has been absent or low (<5%) in most countries and higher (9–27%) in Asia and South America. The increasing clarithromycin and quinolone resistance, and multidrug resistance detected in 0 to less than 5% in Europe and more often (14.2%) in Brazil are worrying. Growing resistance often parallels national antibiotic consumption and may vary within patient groups according to the geographic region, patient’s age and sex, type of disease, birthplace, other infections and other factors. The geographic map and evolution of primary H. pylori resistance are clinically important, should be considered when choosing eradication regimens, and should be monitored constantly at national and global levels in an attempt to reach the recently recommended goal of eradication of more than 95%.