Synergistic effects between silibinin and antibiotics on methicillin-resistant Staphylococcus aureus isolated from clinical specimens

Deinococcus wulumuqiensis R12 synthesized silver nanoparticles with peroxidase-like activity for synergistic antibacterial application

The use of a combination of several antibacterial agents for therapy holds great promise in reducing the dosage and side effects of these agents, improving their efficiency, and inducing potential synergistic therapeutic effects. Herein, this study provides an innovative antibacterial treatment strategy by synergistically combining R12-AgNPs with H2O2 therapy. R12-AgNPs were simply produced with the supernatant of an ionizing radiation-tolerant bacterium Deinococcus wulumuqiensis R12 by one-step under room temperature. In comparison with chemically synthesized AgNPs, the biosynthesized AgNPs presented fascinating antibacterial activity and peroxidase-like properties, which endowed it with the capability to catalyze the decomposition of H2O2 to generate hydroxyl radical. After the combination of R12-AgNPs and H2O2, an excellent synergistic bacteriostatic activity was observed for both Escherichia coli and Staphylococcus aureus, especially at low concentrations. In addition, in vitro cytotoxicity tests showed R12-AgNPs had good biocompatibility. Thus, this work presents a novel antibacterial agent that exhibits favorable synergistic antibacterial activity and low toxicity, without the use of antibiotics or a complicated synthesis process.

Interactions of naturally occurring compounds with antimicrobials

Antibiotics are among the most often used medications in human healthcare and agriculture. Overusing these substances can lead to complications such as increasing antibiotic resistance in bacteria or a toxic effect when administering large amounts. To solve these problems, new solutions in antibacterial therapy are needed. The use of natural products in medicine has been known for centuries. Some of them have antibacterial activity, hence the idea to combine their activity with commercial antibiotics to reduce the latter's use. This review presents collected information on natural compounds (terpenes, alkaloids, flavonoids, tannins, sulfoxides, and mycotoxins), of which various drug interactions have been observed. Many of the indicated compounds show synergistic or additive interactions with antibiotics, which suggests their potential for use in antibacterial therapy, reducing the toxicity of the antibiotics used and the risk of further development of bacterial resistance. Unfortunately, there are also compounds which interact antagonistically, potentially hindering the therapy of bacterial infection. Depending on its mechanism of action, each compound can behave differently in combination with different antibiotics and when acting against various bacterial strains.

Antimicrobial activity in Asterceae: The selected genera characterization and against multidrug resistance bacteria

Plants from the Asteraceae family are widely used as ethno medicines to treatment parasitic, malaria, hematemesis, pruritus, pyretic, anthelmintic, wound healing. The aim of this review is to provide an overview of Asteraceae plants antimicrobial activity. The most relevant results from the published studies are summarized and discussed. The species in genus of Artemisia, Echinacea, Centaurea, Baccharis, and Calendula showed antimicrobial activity. Most of these species are usually used as ethno medicines to treat infection, inflammation, and parasitics. The effective part or component for antimicrobial was essential oil and crude extract, and essential oil attracted more attention. It was also reported that nanoparticles coated with crude extract were effective against multidrug resistant bacteria. For multidrug resistant bacteria study, the species in Armtemisia were the most investigated, and Staphylococcus aureus and Escherichia coli were the most studied multidrug resistant strains. The antimicrobial activity was evaluated mainly based on the results of minimum inhibitory concentration (MIC). Few reports have been reported on minimum bactericide concentration (MBC) and its antibacterial mechanisms. According to the reported study results, some plants in Asteraceae have the potential to be developed as bacteriostatic agents and against multidrug resistant bacteria. However, most studies are still in vitro, further clinical and applied studies are needed.

Effects of Traditional Chinese Medicine and its Active Ingredients on Drug-Resistant Bacteria

The increasing and widespread application of antibacterial drugs makes antibiotic resistance a prominent and growing concern in clinical practice. The emergence of multidrug-resistant bacteria presents a global threat. However, the development and use of novel antibacterial agents involves time-consuming and costly challenges that may lead to yet further drug resistance. More recently, researchers have turned to traditional Chinese medicine to stem the rise of antibiotic resistance in pathogens. Many studies have shown traditional Chinese medicines to have significant bacteriostatic and bactericidal effects, with the advantage of low drug resistance. Some of which when combined with antibiotics, have also demonstrated antibacterial activity by synergistic effect. Traditional Chinese medicine has a variety of active components, including flavonoids, alkaloids, phenols, and quinones, which can inhibit the growth of drug-resistant bacteria and be used in combination with a variety of antibiotics to treat various drug-resistant bacterial infections. We reviewed the interaction between the active ingredients of traditional Chinese medicines and antibiotic-resistant bacteria. At present, flavonoids and alkaloids are the active ingredients that have been most widely studied, with significant synergistic activity demonstrated when used in combination with antibiotics against drug-resistant bacteria. The reviewed studies show that traditional Chinese medicine and its active ingredients have antimicrobial activity on antibiotic-resistant bacteria, which may enhance the susceptibility of antibiotic-resistant bacteria, potentially reduce the required dosage of antibacterial agents and the rate of drug resistance. Our results provide direction for finding and developing alternative methods to counteract drug-resistant bacteria, offering a new therapeutic strategy for tackling antibiotic resistance.

Flavonolignans from silymarin modulate antibiotic resistance and virulence in Staphylococcus aureus

Antibiotic resistance is currently a serious health problem. Since the discovery of new antibiotics no longer seems to be a sufficient tool in the fight against multidrug-resistant infections, adjuvant (combination) therapy is gaining in importance as well as reducing bacterial virulence. Silymarin is a complex of flavonoids and flavonolignans known for its broad spectrum of biological activities, including its ability to modulate drug resistance in cancer. This work aimed to test eleven, optically pure silymarin flavonolignans for their ability to reverse the multidrug resistance phenotype of Staphylococcus aureus and reduce its virulence. Silybin A, 2,3-dehydrosilybin B, and 2,3-dehydrosilybin AB completely reversed antibiotic resistance at concentrations of 20 µM or less. Both 2,3-dehydrosilybin B and AB decreased the antibiotic-induced gene expression of representative efflux pumps belonging to the major facilitator (MFS), multidrug and toxic compound extrusion (MATE), and ATP-binding cassette (ABC) families. 2,3-Dehydrosilybin B also inhibited ethidium bromide accumulation and efflux in a clinical isolate whose NorA and MdeA overproduction was induced by antibiotics. Most of the tested flavonolignans reduced cell-to-cell communication on a tetrahydrofuran-borate (autoinducer-2) basis, with isosilychristin leading the way followed by 2,3-dehydrosilybin A and AB, which halved communication at 10 µM. Anhydrosilychristin was the only compound that reduced communication based on acyl-homoserine lactone (autoinducer 1), with an IC₅₀ of 4.8 µM. Except for isosilychristin and anhydrosilychristin, all of the flavonolignans inhibited S. aureus surface colonization, with 2,3-dehydrosilybin A being the most active (IC₅₀ 10.6 µM). In conclusion, the selected flavonolignans, particularly derivatives of 2,3-dehydrosilybin B, 2,3-dehydrosilybin AB, and silybin A are non-toxic modulators of S. aureus multidrug resistance and can decrease the virulence of the bacterium, which deserves further detailed research.

Kinetics of bactericidal potency with synergistic combination of allicin and selected antibiotics

Synergistic therapy against the resurgence of bacterial pathogenesis is a modern trend for antibacterial chemotherapy. The phytochemical allicin, found in garlic extract is a commendable antimicrobial agent that can be used in synergistic combination with modern antibiotics. Determination of optimal antibacterial combination for the target species is vital for maximizing efficacy, lowering toxicity, total eradication of the bacterial cells and minimization of the risk of resistance generation. In this present investigation, Hill function-based pharmacodynamics models were employed to elaborate various time-kill kinetics parameters. The bactericidal potency of the synergistic combinations of allicin and individual antibiotic was assessed in comparison to their monotherapy application viz. using sole allicin and sole antibiotics (levofloxacin, ciprofloxacin, oxytetracycline, rifaximin, ornidazole and azithromycin) on actively growing Bacillus subtilis and Escherichia coli bacteria. Here, all the synergistic combinations showed significantly better (t-test p-value < 0.05) killing effect and biofilm reduction potential compared to their respective monotherapy application, where the highest killing effect was observed with rifaximin-allicin combination (kill rate was more than 5.5 h^-1). Moreover, the average inhibition potential to protein denaturation by the synergistic combination group was significantly higher (3.4 fold) than the sole antibiotic's group manifests reduction in the dose-related toxicity. The potential of synergism between antibiotics and allicin combination demonstrated greater killing efficiency at significantly lower concentration compared to monotherapy with increased kill rates in all cases.

Progress in Alternative Strategies to Combat Antimicrobial Resistance: Focus on Antibiotics

Antibiotic resistance, and, in a broader perspective, antimicrobial resistance (AMR), continues to evolve and spread beyond all boundaries. As a result, infectious diseases have become more challenging or even impossible to treat, leading to an increase in morbidity and mortality. Despite the failure of conventional, traditional antimicrobial therapy, in the past two decades, no novel class of antibiotics has been introduced. Consequently, several novel alternative strategies to combat these (multi-) drug-resistant infectious microorganisms have been identified. The purpose of this review is to gather and consider the strategies that are being applied or proposed as potential alternatives to traditional antibiotics. These strategies include combination therapy, techniques that target the enzymes or proteins responsible for antimicrobial resistance, resistant bacteria, drug delivery systems, physicochemical methods, and unconventional techniques, including the CRISPR-Cas system. These alternative strategies may have the potential to change the treatment of multi-drug-resistant pathogens in human clinical settings.

Antimicrobial Potential of Naturally Occurring Bioactive Secondary Metabolites

The use of traditional medicines of natural origin has been prevalent since ancient times globally as the plants produce a great diversity in their secondary metabolites. The naturally occurring bioactive constituents in food and other plant materials have shown widespread attention for their use as alternative medicine to prevent and cure microbial growth with the least toxic manifestations. The inclusion of these contents revealed their crucial role to improve the therapeutic efficacy of the classical drugs against various pathogenic microorganisms. Furthermore, several metabolites have also been explored in combination with antimicrobial agents to overcome the problems associated with drug resistance. This current review discusses the antimicrobial activities of secondary metabolites as well as their role in drug sensitivity against multiple-drug resistant pathogenic microbes.

Induction of the Stringent Response Underlies the Antimicrobial Action of Aliphatic Isothiocyanates

Bacterial resistance to known antibiotics comprises a serious threat to public health. Propagation of multidrug-resistant pathogenic strains is a reason for undertaking a search for new therapeutic strategies, based on newly developed chemical compounds and the agents present in nature. Moreover, antibiotic treatment of infections caused by enterotoxin toxin-bearing strain—enterohemorrhagic Escherichia coli (EHEC) is considered hazardous and controversial due to the possibility of induction of bacteriophage-encoded toxin production by the antibiotic-mediated stress. The important source of potentially beneficial compounds are secondary plant metabolites, isothiocyanates (ITC), and phytoncides from the Brassicaceae family. We reported previously that sulforaphane and phenethyl isothiocyanate, already known for their chemopreventive and anticancer features, exhibit significant antibacterial effects against various pathogenic bacteria. The mechanism of their action is based on the induction of the stringent response and accumulation of its alarmones, the guanosine penta- and tetraphosphate. In this process, the amino acid starvation path is employed via the RelA protein, however, the precise mechanism of amino acid limitation in the presence of ITCs is yet unknown. In this work, we asked whether ITCs could act synergistically with each other to increase the antibacterial effect. A set of aliphatic ITCs, such as iberin, iberverin, alyssin, erucin, sulforaphen, erysolin, and cheirolin was tested in combination with sulforaphane against E. coli. Our experiments show that all tested ITCs exhibit strong antimicrobial effect individually, and this effect involves the stringent response caused by induction of the amino acid starvation. Interestingly, excess of specific amino acids reversed the antimicrobial effects of ITCs, where the common amino acid for all tested compounds was glycine. The synergistic action observed for iberin, iberverin, and alyssin also led to accumulation of (p)ppGpp, and the minimal inhibitory concentration necessary for the antibacterial effect was four- to eightfold lower than for individual ITCs. Moreover, the unique mode of ITC action is responsible for inhibition of prophage induction and toxin production, in addition to growth inhibition of EHEC strains. Thus, the antimicrobial effect of plant secondary metabolites by the stringent response induction could be employed in potential therapeutic strategies.

A significant therapeutic effect of silymarin administered alone, or in combination with chemotherapy, in experimental pulmonary tuberculosis caused by drug-sensitive or drug-resistant strains: In vitro and in vivo studies

For many years, tuberculosis (TB) has been a major public health problem worldwide. Advances for treatment and eradication have been very limited. Silymarin (Sm) is a natural product with antioxidant and hepatoprotective activities that has been proposed as a complementary medicine to reduce the liver injury produced by the conventional anti-TB chemotherapy. Sm also has immunoregulatory and microbicide properties. In this study, we determined the effect of Sm on the growth control of mycobacteria. In vitro studies showed that Sm and Silibinin (the principal active compound of Sm) have microbicidal activity against drug-sensitive and multidrug-resistant (MDR) mycobacteria, induce the production of protective cytokines from infected macrophages, and improve the growth control of mycobacteria (p ≤ 0.0001). Studies in vivo using a model of progressive pulmonary TB in BALB/c mice infected with drug-sensitive or MDR mycobacteria have shown that Sm induces significant expression of Th-1 cytokines such as IFN-γ and IL-12 as well as TNFα, which produce significant therapeutic activity when administered alone and apparently have a synergistic effect with chemotherapy. These results suggest that Sm has a bactericidal effect and can contribute to the control and establishment of a TH1 protective immune response against mycobacterial infection. Thus, it seems that this flavonoid has a promising potential as adjuvant therapy in the treatment of TB.

Antimicrobial and Synergistic Effects of Commercial Piperine and Piperlongumine in Combination with Conventional Antimicrobials

Microbial resistance to currently available antibiotics is a public health problem in the fight against infectious diseases. Most antibiotics are characterized by numerous side effects that may be harmful to normal body cells. To improve the efficacy of these antibiotics and to find an alternative way to minimize the adverse effects associated with most conventional antibiotics, piperine and piperlongumine were screened in combination with conventional rifampicin, tetracycline, and itraconazole to evaluate their synergistic, additive, or antagonistic interactions against Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans. The fractional inhibitory concentration index was used to estimate the synergistic effects of various combination ratios of the piperamides and antibiotics against the bacterial and fungal strains. Both piperine and piperlongumine showed synergistic effects against S. aureus when combined at various ratios with rifampicin. Synergistic interaction was also observed with piperine in combination with tetracycline against S. aureus, while antagonistic interaction was recorded for piperlongumine and tetracycline against S. aureus. All the piperamide/antibacterial combinations tested against P. aeruginosa showed antagonistic effects, with the exception of piperine and rifampicin, which recorded synergistic interaction at a ratio of 9:1 rifampicin/piperine. No synergistic interaction was observed when the commercial compounds were combined with itraconazole and tested against C. albicans. The results showed that piperine and piperlongumine are capable of improving the effectiveness of rifampicin and tetracycline. Dosage combinations of these bioactive compounds with the antibiotics used may be a better option for the treatment of bacterial infections that aims to minimize the adverse effects associated with the use of these conventional antibacterial drugs.

Discovery of natural products with metal-binding properties as promising antibacterial agents

INTRODUCTION

More than 50% of the clinically established antibiotics are either genuine natural products or derivatives thereof, featuring a mode of action decisively depending on their metal affinity and suitability as metal complex ligands. As their structural diversity and harvest from renewable sources is well-nigh inexhaustible, any future quest for affordable new antibiotics will have to concentrate on natural drugs with obvious metal ligating properties. Areas covered: The authors provide an overview of the promising developments in the field of antibiotic natural products with metal-binding properties with a specific focus on metal binders such as polyphenols, quinones, 3-acyltetramic and -tetronic acids. Works published by the authors are discussed in this manuscript as well as articles derived from PubMed and Scifinder. Expert opinion: Natural products with metal-binding properties possess a great potential for the development of drugs against various bacteria. There are many derivatives with great potential against multidrug-resistant bacteria as well. Synthetic approaches to structurally complex and/or rare natural products have added significantly to the cracking of synthetic problems. Thus, this field of scientific research appears attractive both to chemists and to clinicians.

High and long-term antibacterial activity against Escherichia coli via synergy between the antibiotic penicillin G and its carrier ZnAl layered double hydroxide

Antibiotic-resistant bacterial infections are a global health problem. A commonly-used antibiotic Penicillin G was incorporated into ZnAl-layered double hydroxides (PNG/LDH) with a varied amount of PNG. PNG/LDH nanocomposites were well characterized in structure and composition using elemental analysis, X-ray diffraction pattern, Fourier transform infrared spectroscopy and TEM images, revealing that PNG were mostly adsorbed on the LDH surfaces at a lower PNG loading but some were intercalated into LDH interlayers at a higher PNG loading. The typical release profile of PNG and Zn²⁺ from PNG/LDH was a quick release, followed by a sustainable slow release. The antibacterial tests against Escherichia coli demonstrated that PNG/LDH with a suitable composition synergistically improved bacterial inhibition compared with free PNG and pristine LDHs. In specific, PNG/LDH with much higher cost-effectiveness showed a potent antimicrobial activity and maintained the activity for up to 10 days, significantly elongating the antibacterial effect compared with just 1 day for free PNG in the same conditions. Our results suggest suitable composition of nanoparticle carriers and antibiotics could significantly enhance antibacterial activity of antibiotics for a long period via the synergistic effect between carrier and antibiotics, a potential approach to overcome the bacterial resistance to antibiotics.

Ameliorative effect of silymarin against linezolid-induced hepatotoxicity in methicillin-resistant Staphylococcus aureus (MRSA) infected Wistar rats

Linezolid has a better choice for eradication of methicillin-resistant Staphylococcus aureus (MRSA) infections, but its use is limited because of linezolid-induced hepatotoxicity, myelosuppression, and lactic acidosis. This research elucidated the role of silymarin against hepatoxicity of linezolid therapy in MRSA infected Wistar rats. The rats were rendered neutropenic by an intraperitoneal injection of cyclophosphamide injection. The neutropenic rats were injected subcutaneously with 10⁶ CFU/ml of MRSA. The rats were divided into 6 groups. Normal control, Infected, Infected animals treated with linezolid 50 mg/kg/twice/day and Infected animals treated with linezolid and different dose of silymarin 25, 50, and 100 mg/kg/twice/day for 14 days. On the 15th day, the blood, liver, kidney, and bone marrow were collected for biochemical and histopathological examination. The MRSA was confirmed by PCR assay. The minimum inhibitory concentration of linezolid was 0.5-2 μg/ml. The linezolid induced liver damage was confirmed by elevation of marker enzymes alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), Lactate dehydrogenase (LDH) levels, serum bilirubin, lactate, and histopathological studies of the liver. The linezolid treated rats also showed myelosuppression, lactic acidosis, oxidative stress and decreased intestinal alkaline phosphatase (IAP). The silymarin administration exhibited marked hepatoprotective effect by significantly lowering the liver marker enzymes, serum parameters, and cytological findings reflect the hepatoprotection. Additionally, Silymarin showed protection against myelosuppression and lactic acidosis evidenced by bone marrow smear and serum lactate estimation. Antioxidant effect of silymarin was confirmed by decreased levels of lipid peroxidation, restored the enzymatic and non-enzymatic antioxidants of the liver nearer to normal. The present study indicates that the silymarin could be a better herbal therapeutic agent which protects against the linezolid induced hepatotoxicity in MRSA infected rats.

Looking to nature for a new concept in antimicrobial treatments: isoflavonoids from Cytisus striatus as antibiotic adjuvants against MRSA

The spread of multidrug-resistant Staphylococcus aureus strains, including methicillin-resistant S. aureus (MRSA), has shortened the useful life of anti-staphylococcal drugs enormously. Two approaches can be followed to address this problem: screening various sources for new leads for antibiotics or finding ways to disable the resistance mechanisms to existing antibiotics. Plants are resistant to most microorganisms, but despite extensive efforts to identify metabolites that are responsible for this resistance, no substantial progress has been made. Plants possibly use multiple strategies to deal with microorganisms that evolved over time. For this reason, we searched for plants that could potentiate the effects of known antibiotics. From 29 plant species tested, Cytisus striatus clearly showed such an activity and an NMR-based metabolomics study allowed the identification of compounds from the plant extracts that could act as antibiotic adjuvants. Isoflavonoids were found to potentiate the effect of ciprofloxacin and erythromycin against MRSA strains. For the structure-activity relationship (SAR), 22 isoflavonoids were assessed as antibiotic adjuvants. This study reveals a clear synergy between isoflavonoids and the tested antibiotics, showing their great potential for applications in the clinical therapy of infections with antibiotic-resistant microorganisms such as MRSA.

Silibinin protects Staphylococcus aureus from UVC-induced bactericide via enhanced generation of reactive oxygen species

ROS produced by silibinin suppresses UVC-inducedStaphylococcus aureuscell death.

Antibacterial Action of Curcumin against Staphylococcus aureus: A Brief Review

Curcumin, the major constituent of Curcuma longa L. (Zingiberaceae family) or turmeric, commonly used for cooking in Asian cuisine, is known to possess a broad range of pharmacological properties at relatively nontoxic doses. Curcumin is found to be effective against Staphylococcus aureus (S. aureus). As demonstrated by in vitro experiment, curcumin exerts even more potent effects when used in combination with various other antibacterial agents. Hence, curcumin which is a natural product derived from plant is believed to have profound medicinal benefits and could be potentially developed into a naturally derived antibiotic in the future. However, there are several noteworthy challenges in the development of curcumin as a medicine. S. aureus infections, particularly those caused by the multidrug-resistant strains, have emerged as a global health issue and urgent action is needed. This review focuses on the antibacterial activities of curcumin against both methicillin-sensitive S. aureus (MSSA) and methicillin-resistant S. aureus (MRSA). We also attempt to highlight the potential challenges in the effort of developing curcumin into a therapeutic antibacterial agent.

In vitro effects on biofilm viability and antibacterial and antiadherent activities of silymarin

Limited treatment options in infectious diseases caused by resistant microorganisms created the need to search new approaches. Several herbal extracts are studied for their enormous therapeutic potential. Silymarin extract, from Silybum marianum (milk thistle), is an old and a new remedy for this goal. The purpose of this study is to evaluate the antibacterial and antiadherent effects of silymarin besides biofilm viability activity on standard bacterial strains. Minimal inhibitory concentration (MIC), minimal bactericidal concentration (MBC), antiadherent/antibiofilm activity, and effects on biofilm viability of silymarin were evaluated against standard bacterial strains. MIC values were observed between 60 and >241 μg/mL (0.25->1 mmol/L). Gram-positive bacteria were inhibited at concentrations between 60 and 120 μg/mL. Gram-negative bacteria were not inhibited by the silymarin concentrations included in this study. MBC values for Gram-positive bacteria were greater than 241 μg/mL. Adherence/biofilm formations were decreased to 15 μg/mL silymarin concentration when compared with silymarin-untreated group. Silymarin reduced the biofilm viabilities to 13 and 46 % at 1 and 0.5 mmol/L concentrations, respectively. We demonstrated that silymarin shows antibacterial and antiadherent/antibiofilm activity against certain standard bacterial strains which may be beneficial when used as a dietary supplement or a drug.

The use of platensimycin and platencin to fight antibiotic resistance

Infectious diseases are known as one of the most life-threatening disabilities worldwide. Approximately 13 million deaths related to infectious diseases are reported each year. The only way to combat infectious diseases is by chemotherapy using antimicrobial agents and antibiotics. However, due to uncontrolled and unnecessary use of antibiotics in particular, surviving bacteria have evolved resistance against several antibiotics. Emergence of multidrug resistance in bacteria over the past several decades has resulted in one of the most important clinical health problems in modern medicine. For instance, approximately 440,000 new cases of multidrug-resistant tuberculosis are reported every year leading to the deaths of 150,000 people worldwide. Management of multidrug resistance requires understanding its molecular basis and the evolution and dissemination of resistance; development of new antibiotic compounds in place of traditional antibiotics; and innovative strategies for extending the life of antibiotic molecules. Researchers have begun to develop new antimicrobials for overcoming this important problem. Recently, platensimycin - isolated from extracts of Streptomyces platensis - and its analog platencin have been defined as promising agents for fighting multidrug resistance. In vitro and in vivo studies have shown that these new antimicrobials have great potential to inhibit methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, and penicillin-resistant Streptococcus pneumoniae by targeting type II fatty acid synthesis in bacteria. Showing strong efficacy without any observed in vivo toxicity increases the significance of these antimicrobial agents for their use in humans. However, at the present time, clinical trials are insufficient and require more research. The strong antibacterial efficacies of platensimycin and platencin may be established in clinical trials and their use in humans for coping with multidrug resistance may be allowed in the foreseeable future.