Generation Of Antibiotics Research Articles

Streptomyces from traditional medicine: sources of new innovations in antibiotic discovery.

Given the increased reporting of multi-resistant bacteria and the shortage of newly approved medicines, researchers have been looking towards extreme and unusual environments as a new source of antibiotics. Streptomyces currently provides many of the world’s clinical antibiotics, so it comes as no surprise that these bacteria have recently been isolated from traditional medicine. Given the wide array of traditional medicines, it is hoped that these discoveries can provide the much sought after core structure diversity that will be required of a new generation of antibiotics. This review discusses the contribution of Streptomyces to antibiotics and the potential of newly discovered species in traditional medicine. We also explore how knowledge of traditional medicines can aid current initiatives in sourcing new and chemically diverse antibiotics.

Effect of Flexible and Rigid Linkers on Biological Activity of Recombinant Tetramer Variants of S3 Antimicrobial Peptide

Antimicrobial peptides (AMPs) mainly introduced as a new generation of antibiotics, could be used for broad medical and biotechnological applications including treatment of multi drug resistant bacterial infections, anti-biofilm agents, wound healing, drug delivery and biosensors. High cost of peptide synthesis is one of the major obstacles of industrial scale production of AMPs. Recombinant expression of tandem repeats (multimeric forms) of AMPs with proper linkers is a useful approach for overcoming the high cost of peptides synthesis. In the present study, the effect of using glycine- serine [(GGGGS) 3] and aspartic acid-proline (DP) Linkers between four tandem repeats of sushi S3 antimicrobial peptide on its biological activity was investigated. S3 peptide, derived from factor C of horseshoe crab hemolymph has been known as a promising candidate as anti-Gram negative bacterial agent. Each variant of S3 tetramers with (GGGGS) 3 and DP linkers (named S3-4mer-GS and S3-4mer-DP, respectively) were expressed in E. coli. BL21 (DE3) as inclusion bodies and were purified by using immobilized metal affinity chromatography (IMAC). Antimicrobial activities and cytotoxic properties of variants were evaluated by determination of minimum inhibitory concentration assay (MIC) and MTT assay. Statistical analysis revealed that glycine serine linker improved antimicrobial activity of S3-tetramer approximately 25% and 86% in comparison to tetramer with aspartic acid - proline linker and S3 monomer respectively. According to the enhanced antibacterial activity of glycine- serine linker without any significant effects on its cytotoxicity, this linker will be a good choice for recombinant tandem expression of small antimicrobial peptides.

Analysis of the Microorganism’s Sensitivity in Patients with Chronic Adenoiditis to Pharmacotherapy with Antibacterial Drugs

Introduction: The prevalence of chronic pathology of the pharyngeal lymphatic system in preschool children reaches 45% and is mainly manifested by hypertrophy of adenoid vegetations, which in half of cases are combined with chronic inflammation, which, with repeated periods of exacerbation, leads to the development of severe chronic pathology of the upper respiratory tract. The role of microorganisms toleranceto pharmacological agents is widely proven in formation of chronic inflammatory disorders and demand correction of therapeutic schemes. Research tasks: The aim of this research was to study the microbial landscape of oropharynx in children who received surgical for adenoiditis and determine the sensitivity of the identified microorganisms to the pharmacotherapy with antibiotics. Material and Methods: We conducted a study of 1577 children aged from 1 year to 17 years and 11 months who received inpatient treatment at the otorhinolaryngological Department of the OO “Scientific and clinical multidisciplinary center named after Z. I. Kruglaya” in the city of Oryol in the period from 2015 to 2017 for hypertrophy of adenoid vegetations. The patients were divided into three groups based on the years of the study. The study of the oropharyngeal microbial association was performed by preparing a smear followed by Gram staining and bacterioscopy. Determination of the sensitivity of microorganisms to antibacterial drugs was performed by discdiffusion method. Results: We found in patients oropharynx microbial landscape with hypertrophy of chronic vegetation in dynamics over the period from 2015 to 2017, an increase in the number of opportunistic saprophytic flora was detected, which was observed against the background of a clear increase in the number of patients with this pathology an increase in the number of cases associated with saprophytic MRCA flora, represented mainly by Staphylococcus aureus, leads to a decrease in the effectiveness of conservative treatment of chronic adenoiditis, which is expressed in an increase in the number of adenotomies. Conclusion: The study revealed negative consequences of uncontrolled use of antibiotic therapy at the pre-hospital stage and irrational schemes of chemotherapy in hospital units, which is manifested in the growing resistance of microorganisms to both “old” antibacterial drugs and a decrease in sensitivity to pharmacotherapy with the latest generation of antibiotics and requires active revision of the schemes of antibiotic therapy and prevention.

Recombinant Oncorhyncin II Effect on the Treatment of Methicillin-Resistant Staphylococcus aureus Skin Infection

Background: Methicillin-resistant Staphylococcus aureus (MRSA) is known to be one of the most potentially pathogenic organisms in the world. Skin infections are one of the significant infections of S. aureus. Therefore, therapeutic constraints have challenged researchers to seek new strategies to produce new medicines. Antimicrobial peptides (AMPs) are a new generation of natural drugs with antimicrobial properties and high fatality potency. Oncorhyncin II AMP is a group of peptides with bacteriostatic activity and antimicrobial effect against Gram-positive and Gram-negative bacteria. Therefore, the development and promotion of antimicrobial peptides can be a new step in the treatment of skin infections due to bacterial resistant S. aureus in hospitals. Objectives: The objective of this study was to produce recombinant Oncorhyncin II protein and evaluate its antimicrobial effects on MRSA to determine the outcomes of the treatment. Methods: In this experimental study, the Oncorhyncin II Antimicrobial peptide was synthesized by the recombinant method. The effectiveness of this peptide was assessed by the minimum inhibitory concentration (MIC) test. The activity of recombinant protein against S. aureus was investigated using in vitro and in vivo experiments. Results: The effectiveness of this peptide obtained by the MIC test was 225 μg/mL. The activity test confirmed the MIC test and showed that this antimicrobial peptide has been able to reduce MRSA cell growth. All mice infected with MRSA responded positively to the protein treatment. Conclusions: According to Oncorhyncin II antimicrobial peptide activity studies, this peptide, as a new generation of antibiotics, was expected to have positive outcomes in the improvement of S. aureus skin infections. Therefore, the results of the efficacy require further studies to be confirmed.

Multifunctional Acidocin 4356 Combats Pseudomonas aeruginosa through Membrane Perturbation and Virulence Attenuation: Experimental Results Confirm Molecular Dynamics Simulation.

A longstanding awareness in generating resistance to common antimicrobial therapies by Gram-negative bacteria has made them a major threat to global health. The application of antimicrobial peptides as a therapeutic agent would be a great opportunity to combat bacterial diseases. Here, we introduce a new antimicrobial peptide (∼8.3 kDa) from probiotic strain Lactobacillus acidophilus ATCC 4356, designated acidocin 4356 (ACD). This multifunctional peptide exerts its anti-infective ability against Pseudomonas aeruginosa through an inhibitory action on virulence factors, bacterial killing, and biofilm degradation. Reliable performance over tough physiological conditions and low hemolytic activity confirmed a new hope for the therapeutic setting. Antibacterial kinetic studies using flow cytometry technique showed that the ACD activity is related to the change in permeability of the membrane. The results obtained from molecular dynamic (MD) simulation were perfectly suited to the experimental data of ACD behavior. The structure-function relationship of this natural compound, along with the results of transmission electron microscopy analysis and MD simulation, confirmed the ability of the ACD aimed at enhancing bacterial membrane perturbation. The peptide was effective in the treatment of P. aeruginosa infection in mouse model. The results support the therapeutic potential of ACD for the treatment of Pseudomonas infections.IMPORTANCE Multidrug-resistant bacteria are a major threat to global health, and the Pseudomonas bacterium with the ability to form biofilms is considered one of the main causative agents of nosocomial infections. Traditional antibiotics have failed because of increased resistance. Thus, finding new biocompatible antibacterial drugs is essential. Antimicrobial peptides are produced by various organisms as a natural defense mechanism against pathogens, inspiring the possible design of the next generation of antibiotics. In this study, a new antimicrobial peptide was isolated from Lactobacillus acidophilus ATCC 4356, counteracting both biofilm and planktonic cells of Pseudomonas aeruginosa A detailed investigation was then conducted concerning the functional mechanism of this peptide by using fluorescence techniques, electron microscopy, and in silico methods. The antibacterial and antibiofilm properties of this peptide may be important in the treatment of Pseudomonas infections.

Recent Progress in the Development of Small-Molecule FtsZ Inhibitors as Chemical Tools for the Development of Novel Antibiotics.

Antibiotics are potent pharmacological weapons against bacterial pathogens, nevertheless their efficacy is becoming compromised due to the worldwide emergence and spread of multidrug-resistant bacteria or “superbugs”. Antibiotic resistance is rising to such dangerous levels that the treatment of bacterial infections is becoming a clinical challenge. Therefore, urgent action is needed to develop new generations of antibiotics that will help tackle this increasing and serious public health problem. Due to its essential role in bacterial cell division, the tubulin-like protein FtsZ has emerged as a promising target for the development of novel antibiotics with new mechanisms of action. This review highlights the medicinal chemistry efforts towards the identification of small-molecule FtsZ inhibitors with antibacterial activity in the last three years.

Human skin bacterial flora differ with altitudes in different ethnic groups of Nepal

Background: Largest organ of human body, the skin, is colonized by millions of microorganisms, most of which are not only harmless but also beneficial to the host. Human skin microbes depend upon geographical variations, ethnicity and various host factors. Despite several studies on human skin microbiota in various parts of the globe, it has not been studied in Nepalese population.
 Aims and Objective: To identify skin bacterial normal flora in different ethnic groups residing in different altitude of Nepal.
 Materials and Methods: We cultured skin swabs of 166 randomly selected volunteers belonging to 10 major ethnic groups from 3 distinct geographical altitudes of Nepal, viz. Bharatpur (415 m from sea level), Kathmandu (1,400 m from sea level) and Lukla (2,860 m from sea level). The isolated organisms were characterized and tested for their susceptibility against different antibiotics.
 Results: Altogether 231 bacterial isolates were characterized from 166 skin samples. Among them, 140 isolates (60.60 %) were Gram positive and 91 isolates (39.40 %) were Gram negative bacteria. Staphylococcus aureus (35.49%) was the most dominant skin bacterial flora followed by Escherichia coli (22.51%) and Streptococcus spp. (17.75%). Medium altitude Kathmandu exhibited the highest growth (120 isolates) followed by low land Bharatpur (66 isolates) and high land Lukla (51 isolates) which is statistically significant (p value =0.0124). Theantibiotic susceptibility testing against 14 antibiotics exhibited the Gram positive isolates were the most sensitive to Imipenem (94.93 %) whereas the least sensitive to Cephalexin (31.36 %) and the Gram negative isolates were the most sensitive to Amikacin (100%) whereas the least sensitive to Amoxycillin (28.57 %).
 Conclusion: Our data indicates that the skin bacterial normal flora; which is directly exposed to external environment; has significant relationship with altitudes where individuals live. The result desires further study for the adaptability of normal flora found in different altitudes. Some bacterial commensals were found resistant even against new generations of antibiotics as well, and hence can cause life-threatening infections if they happen to cross the skin physical barrier.

Defect‐Rich Adhesive Nanozymes as Efficient Antibiotics for Enhanced Bacterial Inhibition

AbstractNanozymes have emerged as a new generation of antibiotics with exciting broad‐spectrum antimicrobial properties and negligible biotoxicities. However, their antibacterial efficacies are unsatisfactory due to their inability to trap bacteria and their low catalytic activity. Herein, we report nanozymes with rough surfaces and defect‐rich active edges. The rough surface increases bacterial adhesion and the defect‐rich edges exhibit higher intrinsic peroxidase‐like activity compared to pristine nanozymes due to their lower adsorption energies of H2O2 and desorption energy of OH*, as well as the larger exothermic process for the whole reaction. This was demonstrated using drug‐resistant Gram‐negative Escherichia coli and Gram‐positive Staphylococcus aureus in vitro and in vivo. This strategy can be used to engineer nanozymes with enhanced antibacterial function and will pave a new way for the development of alternative antibiotics.

Defect-Rich Adhesive Nanozymes as Efficient Antibiotics for Enhanced Bacterial Inhibition.

Nanozymes have emerged as a new generation of antibiotics with exciting broad-spectrum antimicrobial properties and negligible biotoxicities. However, their antibacterial efficacies are unsatisfactory due to their inability to trap bacteria and their low catalytic activity. Herein, we report nanozymes with rough surfaces and defect-rich active edges. The rough surface increases bacterial adhesion and the defect-rich edges exhibit higher intrinsic peroxidase-like activity compared to pristine nanozymes due to their lower adsorption energies of H2 O2 and desorption energy of OH*, as well as the larger exothermic process for the whole reaction. This was demonstrated using drug-resistant Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus in vitro and in vivo. This strategy can be used to engineer nanozymes with enhanced antibacterial function and will pave a new way for the development of alternative antibiotics.

Exploring the role of the various methionine residues in the Escherichia coli CusB adapter protein.

The dissemination of resistant pathogenic microbes has become one of the most challenging problems that modern medicine has faced. Developing novel drugs based on new molecular targets that previously were not targeted, is therefore the highest priority in antibiotics research. One approach that has been recently suggested is to inhibit copper transporters in prokaryotic systems. Copper is required for many biological pathways, but sometimes it can harm the cell. Pathogenic systems have a highly sophisticated copper-regulation network; therefore, a better understanding of how this network operates at the molecular level should assist in developing the next generation of antibiotics. The CusB protein is part of the CusCBA periplasmic Cu(I) efflux system in Gram-negative bacteria, and was recently reported to play a key role in the functioning of the whole CusCBA system, in which conformational changes as well as the assembly/disassembly process control the opening of the transporter. More knowledge of the underlying mechanism is needed to attain a full understanding of CusB functioning, which is associated with targeting specific and crucial residues in CusB. Here, we combine in-vitro structural measurements, which use EPR spectroscopy and UV-Vis measurements, with cell experiments to explore the role of the various methionine residues in CusB. We targeted two methionine residues (M227 and M241) that are essential for the proper functioning of CusB.

Determination of ceftriaxone in human plasma using liquid chromatography–tandem mass spectrometry

Ceftriaxone is a cephalosporin antibiotic drug used as first-line treatment for several bacterial diseases. Ceftriaxone belongs to the third generation of antibiotics and is available as an intramuscular or intravenous injection. Previously published pharmacokinetic studies have mainly used high-performance liquid chromatography coupled with ultraviolet detection (HPLC-UV) for the quantification of ceftriaxone. This study aimed to develop and validate a bioanalytical method for the quantification of ceftriaxone in human plasma using liquid chromatography followed by tandem mass spectrometry (LC-MS/MS). Sample preparation was performed by protein precipitation in combination with phospholipid-removal techniques for cleaning up matrix interferences. The chromatographic separation was performed on an Agilent Zorbax Eclipse Plus C18 column with 10 mM ammonium formate containing 2% formic acid: acetonitrile as mobile phase at a flow rate of 0.4 ml/min. Both the analyte and cefotaxime (internal standard) were quantified using the positive electrospray ionization (ESI) mode and selected reaction monitoring (SRM) for the precursor-product ion transitions m/z 555.0→396.1 for ceftriaxone and 456.0→324.0 for cefotaxime. The method was validated over the concentration range of 1.01-200 μg/ml. Calibration response showed good linearity (correlation coefficient > 0.99) and no significant matrix effects were observed. The intra-assay and inter-assay precision were less than 5% and 10%, respectively, and therefore well within standard regulatory acceptance criterion of ±15%.

Very Short and Stable Lactoferricin-Derived Antimicrobial Peptides: Design Principles and Potential Uses.

The alarming rate at which micro-organisms are developing resistance to conventional antibiotics represents one of the global challenges of our time. There is currently ample space in the antibacterial drug pipeline, and scientists are trying to find innovative and novel strategies to target the microbial enemies. Nature has remained a source of inspiration for most of the antibiotics developed and used, and the immune molecules produced by the innate defense systems, as a first line of defense, have been heralded as the next source of antibiotics. Most living organisms produce an arsenal of antimicrobial peptides (AMPs) to rapidly fend off intruding pathogens, and several different attempts have been made to transform this versatile group of compounds into the next generation of antibiotics. However, faced with the many hurdles of using peptides as drugs, the success of these defense molecules as therapeutics remains to be realized. AMPs derived from the proteolytic degradation of the innate defense protein lactoferrin have been shown to display several favorable antimicrobial properties. In an attempt to investigate the biological and pharmacological properties of these much shorter AMPs, the sequence dependence was investigated, and it was shown, through a series of truncation experiments, that these AMPs in fact can be prepared as tripeptides, with improved antimicrobial activity, via the incorporation of unnatural hydrophobic residues and terminal cappings. In this Account, we describe how this class of promising cationic tripeptides has been developed to specifically address the main challenges limiting the general use of AMPs. This has been made possible through the identification of the antibacterial pharmacophore and via the incorporation of a range of unnatural hydrophobic and cationic amino acids. Incorporation of these residues at selected positions has allowed us to extensively establish how these compounds interact with the major proteolytic enzymes trypsin and chymotrypsin and also the two major drug-binding plasma proteins serum albumin and α-1 glycoprotein. Several of the challenges associated with using AMPs relate to their size, susceptibility to rapid proteolytic degradation, and poor oral bioavailability. Our studies have addressed these issues in detail, and the results have allowed us to effectively design and prepare active and metabolically stable AMPs that have been evaluated in a range of functional settings. The optimized short AMPs display inhibitory activities against a plethora of micro-organisms at low micromolar concentrations, and they have been shown to target resistant strains of both bacteria and fungi alike with a very rapid mode of action. Our Account further describes how these compounds behave in in vivo experiments and highlights both the challenges and possibilities of the intriguing compounds. In several areas, they have been shown to exhibit comparable or superior activity to established antibacterial, antifungal, and antifouling commercial products. This illustrates their ability to effectively target and eradicate various microbes in a variety of settings ranging from the ocean to the clinic.

Anti-leishmanial activity of Brevinin 2R and its Lauric acid conjugate type against L. major: In vitro mechanism of actions and in vivo treatment potentials.

Leishmaniasis, as a major health problem in tropical and sub-tropical areas in the world, needs novel, safe, nontoxic and plausible therapeutic solutions for its control. As a part of innate immune system, natural antimicrobial peptides have a potential to be used as new generation of antibiotics especially after persistent resistance of conventional antimicrobial agents. Brevinin 2R, a member of Defensin families of host defense peptides, showed promising effects against bacterial and fungal infections as well as cancerous cell lines. In the current research, the anti-leishmanial effect of Brevinin 2R and its lauric acid conjugate was investigated against Leishmania major (L. major) parasite. The data revealed that, conjugation of fatty acid to Brevinin 2R, strengthen its effect on L. major promastigotes as well as toxicity and hemolytic effect. These peptides showed anitleishmanial activity through cell membrane disruption and changes in the electrical and mitochondrial membrane potential. No signs of apoptosis induction or caspase activation were detected. Despite its hemolytic and cytotoxic effect in in vitro conditions, lauric acid- Brevinin 2R (L- Brevinin 2R) did not show site specific adverse reactions in animal model. Treatment course with L- Brevinin 2R in the L. major infected mice exhibited decreased parasite load in the lymph nodes adjacent to the infected site despite cytokine production profile and footpad swelling data.

Molecular Simulations Give Insights into the NDM-1/Membrane Interaction that Causes Rise of a Super-Bacterium

Antibiotic resistance is widely seen as one of the biggest threats to global health for the next decades. WHO estimates that in 2050, up to 10 millions deaths per year will be caused by multi-resistant bacteria, unless action is taken. Therefore, it is of vital importance to analyse and elucidate the mechanisms that bring resistance to microorganisms, in order to plan strategies that will lead, eventually, to the development of new generations of antibiotics. Metallo-β-lactamases (MBLs) are bacterial enzymes that generate resistance towards a wide variety of antibiotics. The response of the immune system consists in supplying metal chelators, which retrieve zinc ions, causing the degradation of MBLs. New Delhi MBL 1 (NDM-1) is a B1 subclass MBL that came to the fore in the last years because of its resistance to metal chelators. It was demonstrated that a lipidated version of NDM-1 is able to anchor to the outer bacterial membrane, hence providing resistance towards zinc starvation. However, the molecular mechanisms that lie beyond this phenomenon remain elusive. Molecular simulations show that, although lipidation is essential for stabilizing membrane anchoring, the first interaction is driven by simple electrostatics. The natural affinity of NDM-1 for the membrane could explain why, among MBLs, this peculiar mechanism evolved within NDM-1 only, eventually helping to predict which other MBLs are likely to develop similar features. Indeed, the affinity for the membrane presents ample variability across different MBLs, as we highlighted by comparing NDM-1 to other enzymes of the same class, such as VIM-2. The simulations also show that a specific lipid patch is necessary to drive the protein/membrane recognition, and that removing charged lipids can strongly affect the binding. Experimental tests were conducted to support and confirm these findings.

Dilemma of community-acquired pneumonia

The lungs are particularly susceptible to infection, owing to continuous direct interaction with the external atmosphere in the process of gas exchange, and many anatomical facts, such as the presence of the pharynx, which constitutes a common pathway for both of the lung and stomach. With the process of development of many new generations of antibiotics, pneumonia still continues to be an important unsolved problem worldwide. Community-acquired pneumonia is still considered a problem and is associated with significant morbidity and mortality with cost load, especially with the emergent pathogens that presented with aggressive pictures of community-acquired pneumonia.

Analysis of Typhoid Fever Clinical Pathway Implementation in the Era of National Health Insurance in Indonesia

Starting in November 2016, pricing policy for private hospital in Indonesia was specifically set in a fixed tariff called INA-CBGs (Indonesian Case Base Groups). PMI Hospital which was affected by INA-CBGs regulation built Clinical Pathway for Typhoid fever in order to cope with the challenge. It admitted 705 cases in less than a year in 2016 yet it was claimed that the reimbursement for each case was still lower than the hospital cost. Study aimed to explore variation of medical practices based on Clinical Pathway considering INA-CBGs 2016 pricing policy. Cases included in the study were 156 cases with homogenous severity level chosen from October 2016 to March 2017. Historical data was taken from hospital information system including medical record and billing details. Data was processed using ClinPath V.2.0 tools developed by Faculty of Public Health Universitas Indonesia resulting in distribution of variation. Variation resulted in Length of Stay was (4.27 days) and it was expected to be 4–5 days in clinical pathway while not all patients utilized the same procedure within one period of care. There were also non-value added diagnosis such as Complete Urine (0.01) and Electrolyte test (0.01) included. Consumption of antibiotic (0.28) which consisted of 25 different trade names from different structures resulted in various tariff of services. Variation drives medical cost resulted in tariff increment. Typhidot test can be taken into consideration and the use of later generation of antibiotics are recommended considering affordability and availability.

Semisynthesis of Platensimycin Derivatives with Antibiotic Activities in Mice via Suzuki-Miyaura Cross-Coupling Reactions.

Platensimycin (PTM), originally isolated from soil bacteria Streptomyces platensis, is a potent FabF inhibitor against many Gram-positive pathogens, such as methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci. However, the further clinical development of PTM is hampered by its poor pharmacokinetic properties. In this study, 20 PTM derivatives were prepared by Suzuki-Miyaura cross-coupling reactions catalyzed by Pd (0)/C. Compared to PTM, 6-pyrenyl PTM (6t) showed improved antibacterial activity against MRSA in a mouse peritonitis model. Our results support the strategy to target the essential fatty acid synthases in major pathogens, in order to discover and develop new generations of antibiotics.

Awareness of Bacterial Resistance to Antibiotics among Healthcare Providers in Sana’a City, Yemen

Objectives: To assess the awareness of healthcare providers in Sana’a city of the most frequently antibiotic-resistant bacterial isolates encountered in clinical settings, the factors associated with the emergence of such resistance and the strategies to counteract antibiotic resistance. Methods: This cross-sectional study included 416 healthcare providers; namely, 167 physicians, 61 pharmacists and 188 nurses, from four public and two private hospitals in Sana’a. Data about demographics, awareness of the most frequently isolated antibiotic-resistant bacteria in clinical settings, the factors possibly associated with such resistance and the best strategies to counteract antibiotic resistance were collected using a pre-designed questionnaire. Data were then analyzed using suitable statistical tests. Results: The majority of healthcare providers were aware of methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa as the two most frequently encountered bacterial species in clinical practice, with non-statistically significant differences in the awareness level among physicians, pharmacists and nurses. However, a statistically significant difference was found among healthcare providers regarding their awareness of the most possible factors contributing to antibiotic resistance. In this regard, pharmacists were significantly more aware of the contribution of the extensive use of newer generations of antibiotics (P = 0.030), inappropriate prescribing of antibiotics (P = 0.010) and use of antibiotics without prescription (P = 0.045) to the emergence and spread of antibiotic resistance than physicians and nurses. On the other hand, physicians and nurses were significantly more aware of the role of reducing the length of hospital stay (P = 0.005), limiting the use of medical instrumentation (P = 0.036), use of narrow-spectrum antibiotics (P = 0.005), surveillance for antibiotic resistance (P = 0.004), development of infection control policies and procedures (P <0.001) and consultation with infectious disease specialists (P = 0.010) as key strategies to minimize the emergence of antibiotic-resistant bacteria compared to pharmacists. Moreover, nurses showed significantly higher awareness of the use of narrow-spectrum antibiotics (P = 0.005) and surveillance of antibiotic resistance (P = 0.003) as key strategies to reduce the emergence and spread of antibiotic resistance. Conclusions: There is a discrepancy in the awareness of Yemeni healthcare providers’ of the most frequently encountered antibiotic-resistant bacteria in clinical practice, the factors possibly contributing to such resistance and the key strategies to counteract it. Therefore, continuing medical education of physicians, pharmacists and nurses is recommended to keep them updated on antibiotic resistance and the best strategies and approaches to its containment. In addition, there is a need for the development of infectious disease protocols for hospitals to optimize the selection and treatment with antibiotics, to reduce side effects and costs and to minimize the development of antibiotic resistance.

An Artificial Yeast Genetic Circuit Enables Deep Mutational Scanning of an Antimicrobial Resistance Protein

Understanding the molecular mechanisms underlying antibiotic resistance requires concerted efforts in enzymology and medicinal chemistry. Here we describe a new synthetic biology approach to antibiotic development, where the presence of tetracycline antibiotics is linked to a life-death selection in Saccharomyces cerevisiae. This artificial genetic circuit allowed the deep mutational scanning of the tetracycline inactivating enzyme TetX, revealing key functional residues. We used both positive and negative selections to confirm the importance of different residues for TetX activity, and profiled activity hotspots for different tetracyclines to reveal substrate-specific activity determinants. We found that precise positioning of FAD and hydrophobic shielding of the tetracycline are critical for enzymatic inactivation of doxycycline. However, positioning of FAD is suboptimal in the case of anhydrotetracycline, potentially explaining its comparatively poor degradation and potential as an inhibitor for this family of enzymes. By combining artificial genetic circuits whose function can be modulated by antimicrobial resistance determinants, we establish a framework to select for the next generation of antibiotics.

Ficellomycin: an aziridine alkaloid antibiotic with potential therapeutic capacity.

Ficellomycin is an aziridine antibiotic produced by Streptomyces ficellus, which displays high in vitro activity against Gram-positive bacteria including multidrug resistant strains of Staphylococcus aureus. Compared to currently available antibiotics, ficellomycin exhibits a unique mechanism of action-it impairs the semiconservative DNA replication by inducing the formation of deficient 34S DNA fragments, which lack the ability to integrate into larger DNA pieces and eventually the complete bacterial chromosome. Until recently, some important progress has been made in research on ficellomycin synthesis and biosynthesis, opening the perspective to develop a new generation of antibiotics with better clinical performance than the currently used ones. In this review, we will cover the discovery and biological activity of ficellomycin, its biosynthesis, mode of action, and related synthetic analogs. The role of ficellomycin and its analogs as an important source of drug prototypes will be discussed together with future research prospects.