A Mitocentric View of the Main Bacterial and Parasitic Infectious Diseases in the Pediatric Population

Infectious diseases occur worldwide with great frequency in both adults and children. Both infections and their treatments trigger mitochondrial interactions at multiple levels: (i) incorporation of damaged or mutated proteins to the complexes of the electron transport chain, (ii) mitochondrial genome (depletion, deletions, and point mutations) and mitochondrial dynamics (fusion and fission), (iii) membrane potential, (iv) apoptotic regulation, (v) generation of reactive oxygen species, among others. Such alterations may result in serious adverse clinical events with great impact on children’s quality of life, even resulting in death. As such, bacterial agents are frequently associated with loss of mitochondrial membrane potential and cytochrome c release, ultimately leading to mitochondrial apoptosis by activation of caspases-3 and -9. Using Rayyan QCRI software for systematic reviews, we explore the association between mitochondrial alterations and pediatric infections including (i) bacterial: M. tuberculosis, E. cloacae, P. mirabilis, E. coli, S. enterica, S. aureus, S. pneumoniae, N. meningitidis and (ii) parasitic: P. falciparum. We analyze how these pediatric infections and their treatments may lead to mitochondrial deterioration in this especially vulnerable population, with the intention of improving both the understanding of these diseases and their management in clinical practice.     

Development of an Experimental Ex Vivo Wound Model to Evaluate Antimicrobial Efficacy of Topical Formulations

Wound infections are considered a major cause for wound-associated morbidity. There is a high demand for alternative, robust, and affordable methods that can provide relatable and reproducible results when testing topical treatments, both in research and in the pharmaceutical industry. Here we present an ex vivo wound infection model using porcine skin and a burn wounding method, allowing for the efficacy evaluation of topical antimicrobial formulations. Utilizing this model, we demonstrate the potential of topical treatments after infecting the wounds with clinically significant bacteria, P. aeruginosa and S. aureus. We show that the method is compatible with several analytical tools used to analyze infection and antimicrobial effects. Both bacterial strains successfully infected the wound surface, as well as deeper regions of the tissue. Quantification of viable bacteria on the wound surface and in the tissue, longitudinal measurements of bioluminescence, fluorescence microscopy, and scanning electron microscopy were used to confirm the effects of antibacterial treatments. Furthermore, we show that biofilms are formed on the wound surface, indicating that the demonstrated method mirrors typical in vivo infections.     

Characterization of an Endolysin Targeting Clostridioides difficile That Affects Spore Outgrowth

Clostridioides difficile is a spore-forming enteric pathogen causing life-threatening diarrhoea and colitis. Microbial disruption caused by antibiotics has been linked with susceptibility to, and transmission and relapse of, C. difficile infection. Therefore, there is an urgent need for novel therapeutics that are effective in preventing C. difficile growth, spore germination, and outgrowth. In recent years bacteriophage-derived endolysins and their derivatives show promise as a novel class of antibacterial agents. In this study, we recombinantly expressed and characterized a cell wall hydrolase (CWH) lysin from C. difficile phage, phiMMP01. The full-length CWH displayed lytic activity against selected C. difficile strains. However, removing the N-terminal cell wall binding domain, creating CWH_351—656, resulted in increased and/or an expanded lytic spectrum of activity. C. difficile specificity was retained versus commensal clostridia and other bacterial species. As expected, the putative cell wall binding domain, CWH_1—350, was completely inactive. We also observe the effect of CWH_351—656 on preventing C. difficile spore outgrowth. Our results suggest that CWH_351—656 has therapeutic potential as an antimicrobial agent against C. difficile infection.     

Fe-BTC表面氨基化及对染料和重金属离子的吸附性能研究

目的:为抗菌药物监管提供相关分析数据,分析评价某肿瘤专科医院2017年I类切口手术围手术期预防用抗菌药物情况。方法:对本院2017年期间抽取的共计300例清洁手术病历进行回顾性研究,针对其围手术期抗菌药物预防使用信息以及相关药物成本-效果比等数据进行统计、对比分析。结果:2017年I类切口手术围手术期间抗菌药物使用率约为16.33%;49例使用抗菌药物病历中,以头孢唑林（55.11%）、头孢呋辛（28.57%）预防使用为主;预防用抗菌药物DUI值均≤1,单日用药剂量合理;不合理预防用药主要表现在“预防给药品种不适宜”,占总不合理率的63.64%。结论:从药物经济性角度考虑,头孢唑林是较好的清洁手术围手术期预防性抗菌用药方案。     

Selectively guanidinylated aminoglycosides as antibiotics

The emergence of virulent, drug-resistant bacterial strains coupled with a minimal output of new pharmaceutical agents to combat them makes this a critical time for antibacterial research. Aminoglycosides are a well-studied, highly potent class of naturally occurring antibiotics with scaffolds amenable to modification, and therefore, they provide an excellent starting point for the development of semisynthetic, next-generation compounds. To explore the potential of this approach, we synthesized a small library of aminoglycoside derivatives selectively and minimally modified at one or two positions with a guanidine group replacing the corresponding amine or hydroxy functionality. Most guanidino-aminoglycosides showed increased affinity for the ribosomal decoding rRNA site, the cognate biological target of the natural products, when compared with their parent antibiotics, as measured by an in vitro fluorescence resonance energy transfer (FRET) A-site binding assay. Additionally, certain analogues showed improved minimum inhibitory concentration (MIC) values against resistant bacterial strains, including methicillin-resistant Staphylococcus aureus (MRSA). An amikacin derivative holds particular promise with activity greater than or equal to the parent antibiotic in the majority of bacterial strains tested.     

The AT2 Domain of KirCI Loads Malonyl Extender Units to the ACPs of the Kirromycin PKS

The antibiotic kirromycin is assembled by a hybrid modular polyketide synthases (PKSs)/nonribosomal peptide synthetases (NRPSs). Five of six PKSs of this complex assembly line do not have acyltransferase (AT) and have to recruit this activity from discrete AT enzymes. Here, we show that KirCI is a discrete AT which is involved in kirromycin production and displays a rarely found three‐domain architecture (AT₁‐AT₂‐ER). We demonstrate that the second AT domain, KirCI‐AT₂, but not KirCI‐AT₁, is the malonyl‐CoA‐specific AT which utilizes this precursor for loading the acyl carrier proteins (ACPs) of the trans‐AT PKS in vitro. In the kirromycin biosynthetic pathway, ACP5 is exclusively loaded with ethylmalonate by the enzyme KirCII and is not recognized as a substrate by KirCI. Interestingly, the excised KirCI‐AT₂ can also transfer malonate to ACP5 and thus has a relaxed ACP‐specificity compared to the entire KirCI protein. The ability of KirCI‐AT₂ to load different ACPs provides opportunities for AT engineering as a potential strategy for polyketide diversification.     

现代生物技术在抗生素生产中的应用

为了提高我国抗生素产品在国际市场的核心竞争力,综述了国内外抗生素生产技术的相关研究成果,分析了各种生物技术的优劣.结果表明,发酵过程控制的优化成为抗生素发酵生产中迫切需要解决的课题;利用酶工程技术生产抗生素虽具有高效能、低消耗、无公害、长寿命、安全、自动化等优点,但将新的生物工程技术全部应用到酶工程上来使之能源源不断地生产出适合人类需要的酶来还需时日;原生质体融合技术和基因工程技术在实验条件下产生了新的抗生素,但在生产中还需解决工程菌的质量和抗生素的基因表达等问题;代谢工程的实质就是基因工程,只是涉及的基因改变的量远比基因工程巨大;以生物整体为研究对象的系统生物学技术、组学技术和重塑生命体的合成生物学技术将为抗生素的生产带来革故鼎新的变化,但也面临很多诸如系统复杂性难以处理、很多元件不相容和线路系统难以预料等技术挑战和合成生命等伦理挑战.     

Antibiotic‐Releasing Silk Biomaterials for Infection Prevention and Treatment

Effective treatment of infections in avascular and necrotic tissues can be challenging due to limited penetration into the target tissue and systemic toxicities. Controlled‐release polymer implants have the potential to achieve the high local concentrations needed while also minimizing systemic exposure. Silk biomaterials possess unique characteristics for antibiotic delivery, including biocompatibility, tunable biodegradation, stabilizing effects, water‐based processing, and diverse material formats. The functional release of antibiotics spanning a range of chemical properties from different material formats of silk (films, microspheres, hydrogels, coatings) is reported. The release of penicillin and ampicillin from bulk‐loaded silk films, drug‐loaded silk microspheres suspended in silk hydrogels and bulk‐loaded silk hydrogels is investigated and the in vivo efficacy of the ampicillin‐releasing silk hydrogels is demonstrated in a murine infected‐wound model. Silk sponges with nanofilm coatings are loaded with gentamicin and cefazolin, and release is sustained for 5 and 3 days, respectively. The capability of silk antibiotic carriers to sequester, stabilize, and then release bioactive antibiotics represents a major advantage over implants and pumps based on liquid drug reservoirs, where instability at room or body temperature is limiting. The present studies demonstrate that silk biomaterials represent a novel, customizable antibiotic platform for focal delivery of antibiotics using a range of material formats (injectable to implantable).