Central composite design for optimizing istamycin production by Streptomyces tenjimariensis.

Istamycins (ISMs) are 2-deoxyfortamine-containing aminoglycoside antibiotics (AGAs) produced by Streptomyces tenjimariensis ATCC 31603 with broad-spectrum bactericidal activities against most of the clinically relevant pathogens. Therefore, this study aimed to statistically optimize the environmental conditions affecting ISMs production using the central composite design (CCD). Both the effect of culture media composition and incubation time and agitation rate were studied as one factor at the time (OFAT). The results showed that both the aminoglycoside production medium and the protoplast regeneration medium gave the highest specific productivity. Results also showed that 6 days incubation time and 200 rpm agitation were optimum for their production. A CCD quadratic model of 17 runs was employed to test three key variables: initial pH, incubation temperature, and concentration of calcium carbonate. A significant statistical model was obtained including, an initial pH of 6.38, incubation temperature of 30 ˚C, and 5.3% CaCO3 concentration. This model was verified experimentally in the lab and resulted in a 31-fold increase as compared to the unoptimized conditions and a threefold increase to that generated by using the optimized culture media. To our knowledge, this is the first report about studying environmental conditions affecting ISM production as OFAT and through CCD design of the response surface methodology (RSM) employed for statistical optimization. In conclusion, the CCD design is an effective tool for optimizing ISMs at the shake flask level. However, the optimized conditions generated using the CCD model in this study should be scaled up in a fermenter for industrial production of ISMs by S. tenjimariensis ATCC 31603 considering the studied environmental conditions that significantly influence the production proces.

Tunable and Photoactivatable Mimics of Calicheamicin γ1 for DNA Cleavage.

Calicheamicin γ1 and related natural products are renowned for their potency in DNA cleavage, serving as the warheads in commercial ADCs used for treating leukemia. Their mechanism of action involves the formation of aryl radicals, which abstract hydrogen atoms from nucleic acids. However, the complex strained enediyne structure of calicheamicin γ1 presents significant challenges in synthesis, resulting in high production costs and limited structural and activity modularity for tuning the therapeutic window. This report describes the development of simple molecular mimics based on diazonium salts, synthesized in fewer than 3 steps, capable of generating aryl radicals upon green or red light irradiation. SAR studies conducted on over 30 analogues reveal a wide range of potencies in DNA cleavage, with EC50 values ranging from low nanomolar to micromolar. Forming benzenoid diradicals does not appear to be necessary for potent DNA cleavage; instead, DNA cleavage can be achieved with radicals distributed among different arenes when connected with proper linkages. The potency is influenced by electronic effects, stereochemistry, orbital orientations, the distance between multiradicals, and the number of diazonium motifs within the molecule. In addition to providing a more cost-effective, efficient, and modular alternative to calicheamicin γ1, this technology offers the potential for enhanced specificity through spatiotemporal control.

Lidamycin induces mitophagy in pancreatic cancer cells by regulating the expression of Mfn2.

Lidamycin (LDM) has been confirmed to have a strong anti-pancreatic cancer effect and can affect the mitochondrial function of pancreatic cancer cells. Mitofusin-2 (Mfn2) is located in the outer membrane of mitochondria, and Mfn2 is currently believed to play a role in cancer inhibition in pancreatic cancer. In order to explore whether the anti-pancreatic cancer effect of LDM is related to Mfn2-mediated mitophagy, Bioinformatics and in vitro cell experiments are used for experimental research. The experimental results demonstrated that Mfn2 is correlated with mitochondrial autophagy in pancreatic cancer. Lidamycin can increase the expression of Mfn2 in pancreatic cancer and affect the process of EMT, affect the level of reactive oxygen species and mitochondrial membrane potential, and increase the expression of mitochondrial autophagy marker proteins BNIP3L and Beclin1. These results demonstrate that Mfn2 affects mitophagy in pancreatic cancer cells by regulating the expression of Mfn2.

Heterologous Expression of Epoxomicin in Escherichia coli.

Epoxomicin is an epoxyketone proteasome inhibitor with synthetic derivatives approved or under investigation for treatment of multiple myeloma. To leverage the advantages of Escherichia coli as a rapidly growing and readily engineered host for the production of epoxomicin and analogues, we expressed codon-optimized versions of the epoxomicin biosynthetic genes, epxD, epxE, and epxF. Epoxomicin was detected, but the major product was a ketone resulting from α,ß-keto acid precursor decarboxylation. Epoxomicin yield was improved by altering the copy numbers of each gene and creating a fusion of epxE and epxF. Our optimized system offers promise for efficient engineering and biosynthesis of improved epoxomicin analogues.

Piplartine attenuates aminoglycoside-induced TRPV1 activity and protects from hearing loss in mice.

Hearing loss is a major health concern in our society, affecting more than 400 million people worldwide. Among the causes, aminoglycoside therapy can result in permanent hearing loss in 40% to 60% of patients receiving treatment, and despite these high numbers, no drug for preventing or treating this type of hearing loss has yet been approved by the US Food and Drug Administration. We have previously conducted high-throughput screenings of bioactive compounds, using zebrafish as our discovery platform, and identified piplartine as a potential therapeutic molecule. In the present study, we expanded this work and characterized piplartine's physicochemical and therapeutic properties. We showed that piplartine had a wide therapeutic window and neither induced nephrotoxicity in vivo in zebrafish nor interfered with aminoglycoside antibacterial activity. In addition, a fluorescence-based assay demonstrated that piplartine did not inhibit cytochrome C activity in microsomes. Coadministration of piplartine protected from kanamycin-induced hair cell loss in zebrafish and protected hearing function, outer hair cells, and presynaptic ribbons in a mouse model of kanamycin ototoxicity. Last, we investigated piplartine's mechanism of action by phospho-omics, immunoblotting, immunohistochemistry, and molecular dynamics experiments. We found an up-regulation of AKT1 signaling in the cochleas of mice cotreated with piplartine. Piplartine treatment normalized kanamycin-induced up-regulation of TRPV1 expression and modulated the gating properties of this receptor. Because aminoglycoside entrance to the inner ear is, in part, mediated by TRPV1, these results suggested that by regulating TRPV1 expression, piplartine blocked aminoglycoside's entrance, thereby preventing the long-term deleterious effects of aminoglycoside accumulation in the inner ear compartment.

Prevalence of resistance to macrolides and aminoglycosides in Mycobacterium avium, M. abscessus, and M. chelonae identified in the Laboratorio Nacional de Referencia of Colombia from 2018 to 2022 / Prevalencia de la resistencia a macrólidos y aminoglucósidos en los complejos Mycobacterium avium y M. abscessus y en Mycobacterium chelonae identificados en el Laboratorio Nacional de Referencia de Colombia entre el 2018 y el 2022.

Introduction: The Mycobacterium chelonae species and the M. avium and M. abscessus complexes are emerging pathogens that cause mycobacteriosis. Treatment depends on the species and subspecies identified. The drugs of choice are macrolides and aminoglycosides. However, due to the resistance identified to these drugs, determining the microbe's sensitivity profile will allow clinicians to improve the understanding of the prognosis and evolution of these pathologies. Objective: To describe the macrolide and aminoglycoside susceptibility profile of cultures identified by Colombia's Laboratorio Nacional de Referencia de Mycobacteria from 2018 to 2022, as Mycobacterium avium complex, M. abscessus complex, and M. chelonae. Materials and methods. This descriptive study exposes the susceptibility profile to macrolides and aminoglycosides of cultures identified as M. avium complex, M. abscessus complex, and M. chelonae using the GenoType® NTM-DR method. Materials and methods: This descriptive study exposes the susceptibility profile to macrolides and aminoglycosides of cultures identified as M. avium complex, M. abscessus complex, and M. chelonae using the GenoType® NTM-DR method. Results: We identified 159 (47.3 %) cultures as M. avium complex, of which 154 (96.9 %) were sensitive to macrolides, and 5 (3.1 %) were resistant; all were sensitive to aminoglycosides. From the 125 (37.2 %) cultures identified as M. abscessus complex, 68 (54.4 %) were sensitive to macrolides, 57 (45.6 %) were resistant to aminoglycosides, and just one (0.8 %) showed resistance to aminoglycosides. The 52 cultures (15.5 %) identified as M. chelonae were sensitive to macrolides and aminoglycosides. Conclusions: The three studied species of mycobacteria have the least resistance to Amikacin. Subspecies identification and their susceptibility profiles allow the establishment of appropriate treatment schemes, especially against M. abscessus.

Introducción. Mycobacterium chelonae y los complejos Mycobacterium avium y M. abscessus, son agentes patógenos emergentes causantes de micobacteriosis. El tratamiento de esta infección depende de la especie y la subespecie identificadas. Los fármacos de elección son los macrólidos y aminoglucósidos, contra los cuales se ha reportado resistencia; por esta razón, el determinar el perfil de sensibilidad le permite al médico tratante comprender mejor el pronóstico y la evolución de estas infecciones. Objetivo. Describir los perfiles de sensibilidad ante macrólidos y aminoglucósidos, de los cultivos identificados como complejo Mycobacterium avium, complejo M. abscessus o especie M. chelonae, en el Laboratorio Nacional de Referencia de Micobacterias durante los años 2018 a 2022. Materiales y métodos. Se llevó a cabo un estudio descriptivo del perfil de sensibilidad a macrólidos y aminoglucósidos, de los cultivos identificados como complejo M. avium, complejo M. abscessus o M. chelonae, mediante la metodología GenoType® NTM-DR. Resultados. Los cultivos del complejo M. avium fueron 159 (47,3 %), de los cuales, 154 (96,9 %) fueron sensibles y 5 (3,1 %) resistentes a los macrólidos; todos fueron sensibles a los aminoglucósidos. Del complejo M. abscessus se estudiaron 125 (37,2 %) cultivos, 68 (54,4 %) resultaron sensibles y 57 (45,6 %) resistentes a los macrólidos; solo un cultivo (0,8 %) fue resistente a los aminoglucósidos. De M. chelonae se analizaron 52 cultivos (15,5 %), todos sensibles a los macrólidos y aminoglucósidos. Conclusiones. En las tres especies de micobacterias estudiadas, la resistencia contra la amikacina fue la menos frecuente. La identificación de las subespecies y los perfiles de sensibilidad permiten instaurar esquemas de tratamiento adecuados, especialmente en las micobacteriosis causadas por M. abscessus.

[Assessment of the risk of hearing loss in children with cystic fibrosis]. / Otsenka riska patologii slukha pri mukovistsidoze u detei.

BACKGROUND: Cystic fibrosis (CF) is a severe hereditary disease with a multisystem lesion. Manifestations of CF include severe infectious purulent lesions of all parts of the respiratory tract, including purulent rhinosinusitis with nasal polyps. The involvement of the sinonasal region and the need for systemic use of ototoxic drugs (primarily aminoglycosides to treat resistant bacterial infection) potentially create a risk of both conductive and sensorineural hearing loss (SNHL). The available data on the epidemiology of hearing disorders in CF is contradictory. Currently, genetic determinants of the development of aminoglycoside SNHL have been identified. MATERIAL AND METHODS: For 136 CF patients (75 girls, 61 boys) aged 3 to 17 (9.4±3.9) years were performed audiological examination: tympanometry, transient-evoked otoacoustic emission and the pure tone threshold audiometry (standard frequency range) (n=126). History of systemic therapy with aminoglycosides was evaluated for each patient. Sequencing of c.35delG mutations in the GJB2 gene (nuclear DNA) and A1555G in the 12S rRNA gene (mitochondrial DNA) was performed in 215 patients with cystic fibrosis (the group partially overlaps with the audiological group), and as a control - 106 children with bronchial asthma and 103 healthy children, their age ranged from 3 to 17 (8.8±3.8) years. RESULTS: Audiological examination of CF children reveled a prevalence of conductive hearing loss comparable to the general population (2.4%). The frequency of SNHL was 1.6%, wich exceeds that of non-CF children. A genetic study revealed one case of heterozygous carriage of the c.35delG mutation in the GJB2 gene in a patient with bronchial asthma. In the group of patients with CF (n=215), mutations in the connexin 26 gene were not detected. No A1555G mutation was detected either in the group of patients with CF or in the control groups. CONCLUSIONS: Children with CF are at risk for the development of sensorineural, but not conductive hearing loss. Routine total screening for A1555G and c.35delG mutations probably seems not to be recommended.

APH(3')-Ie, an aminoglycoside-modifying enzyme discovered in a rabbit-derived Citrobacter gillenii isolate.

Background: Aminoglycoside-modifying enzymes (AMEs) play an essential role in bacterial resistance to aminoglycoside antimicrobials. With the development of sequencing techniques, more bacterial genomes have been sequenced, which has aided in the discovery of an increasing number of novel resistance mechanisms. Methods: The bacterial species was identified by 16S rRNA gene homology and average nucleotide identity (ANI) analyses. The minimum inhibitory concentration (MIC) of each antimicrobial was determined by the agar dilution method. The protein was expressed with the pCold I vector in E. coli BL21, and enzyme kinetic parameters were examined. The whole-genome sequence of the bacterium was obtained via the Illumina and PacBio sequencing platforms. Reconstruction of the phylogenetic tree, identification of conserved functional residues, and gene context analysis were performed using the corresponding bioinformatic techniques. Results: A novel aminoglycoside resistance gene, designated aph(3')-Ie, which confers resistance to ribostamycin, kanamycin, sisomicin and paromomycin, was identified in the chromosome of the animal bacterium Citrobacter gillenii DW61, which exhibited a multidrug resistance phenotype. APH(3')-Ie showed the highest amino acid identity of 74.90% with the functionally characterized enzyme APH(3')-Ia. Enzyme kinetics analysis demonstrated that it had phosphorylation activity toward four aminoglycoside substrates, exhibiting the highest affinity (K m, 4.22 ± 0.88 µM) and the highest catalytic efficiency [k cat/K m, (32.27 ± 8.14) × 104] for ribomycin. Similar to the other APH(3') proteins, APH(3')-Ie contained all the conserved functional sites of the APH family. The aph(3')-Ie homologous genes were present in C. gillenii isolates from different sources, including some of clinical significance. Conclusion: In this work, a novel chromosomal aminoglycoside resistance gene, designated aph(3')-Ie, conferring resistance to aminoglycoside antimicrobials, was identified in a rabbit isolate C. gillenii DW61. The elucidation of the novel resistance mechanism will aid in the effective treatment of infections caused by pathogens carrying such resistance genes.

Are Aminoglycoside Antibiotics TRPing Your Metabolic Switches?

Transient receptor potential (TRP) channels are broadly implicated in the developmental programs of most tissues. Amongst these tissues, skeletal muscle and adipose are noteworthy for being essential in establishing systemic metabolic balance. TRP channels respond to environmental stimuli by supplying intracellular calcium that instigates enzymatic cascades of developmental consequence and often impinge on mitochondrial function and biogenesis. Critically, aminoglycoside antibiotics (AGAs) have been shown to block the capacity of TRP channels to conduct calcium entry into the cell in response to a wide range of developmental stimuli of a biophysical nature, including mechanical, electromagnetic, thermal, and chemical. Paradoxically, in vitro paradigms commonly used to understand organismal muscle and adipose development may have been led astray by the conventional use of streptomycin, an AGA, to help prevent bacterial contamination. Accordingly, streptomycin has been shown to disrupt both in vitro and in vivo myogenesis, as well as the phenotypic switch of white adipose into beige thermogenic status. In vivo, streptomycin has been shown to disrupt TRP-mediated calcium-dependent exercise adaptations of importance to systemic metabolism. Alternatively, streptomycin has also been used to curb detrimental levels of calcium leakage into dystrophic skeletal muscle through aberrantly gated TRPC1 channels that have been shown to be involved in the etiology of X-linked muscular dystrophies. TRP channels susceptible to AGA antagonism are critically involved in modulating the development of muscle and adipose tissues that, if administered to behaving animals, may translate to systemwide metabolic disruption. Regenerative medicine and clinical communities need to be made aware of this caveat of AGA usage and seek viable alternatives, to prevent contamination or infection in in vitro and in vivo paradigms, respectively.

Metabolic disruption impairs ribosomal protein levels, resulting in enhanced aminoglycoside tolerance.

Aminoglycoside antibiotics target ribosomes and are effective against a wide range of bacteria. Here, we demonstrated that knockout strains related to energy metabolism in Escherichia coli showed increased tolerance to aminoglycosides during the mid-exponential growth phase. Contrary to expectations, these mutations did not reduce the proton motive force or aminoglycoside uptake, as there were no significant changes in metabolic indicators or intracellular gentamicin levels between wild-type and mutant strains. Our comprehensive proteomics analysis unveiled a noteworthy upregulation of proteins linked to the tricarboxylic acid (TCA) cycle in the mutant strains during the mid-exponential growth phase, suggesting that these strains compensate for the perturbation in their energy metabolism by increasing TCA cycle activity to maintain their membrane potential and ATP levels. Furthermore, our pathway enrichment analysis shed light on local network clusters displaying downregulation across all mutant strains, which were associated with both large and small ribosomal binding proteins, ribosome biogenesis, translation factor activity, and the biosynthesis of ribonucleoside monophosphates. These findings offer a plausible explanation for the observed tolerance of aminoglycosides in the mutant strains. Altogether, this research provides valuable insights into the mechanisms of aminoglycoside tolerance, paving the way for novel strategies to combat such cells.

Bacteria that are resistant to antibiotic drugs pose a significant challenge to human health around the globe. They have acquired genetic mutations that allow them to survive and grow in the presence of one or more antibiotics, making it harder for clinicians to eliminate such bacteria from human patients with life-threatening infections. Some bacteria may be able to temporarily develop tolerance to an antibiotic by altering how they grow and behave, without acquiring any new genetic mutations. Such drug-tolerant bacteria are more likely to survive long enough to gain mutations that may promote drug resistance. Recent studies suggest that genes involved in processes collectively known as energy metabolism, which convert food sources into the chemical energy cells need to survive and grow, may play a role in both tolerance and resistance. For example, Escherichia coli bacteria develop mutations in energy metabolism genes when exposed to members of a family of antibiotics known as the aminoglycosides. However, it remains unclear what exact role energy metabolism plays in antibiotic tolerance. To address this question, Shiraliyev and Orman studied how a range of E. coli strains with different genetic mutations affecting energy metabolism could survive in the presence of aminoglycosides. The experiments found that most of the mutant strains had a higher tolerance to the drugs than normal E. coli. Unexpectedly, this increased tolerance did not appear to be due to the drugs entering the mutant bacterium cells less than they enter normal cells (a common strategy of drug resistance and tolerance). Further experiments using a technique, known as proteomics, revealed that many genes involved in energy metabolism were upregulated in the mutant bacteria, suggesting these cells were compensating for the genetic abnormalities they have. Furthermore, the mutant bacteria had lower levels of the molecules the antibiotics target than normal bacteria. The findings of Shiraliyev and Orman offer critical insights into how bacteria become tolerant of aminoglycoside antibiotics. In the future, this may guide the development of new strategies to combat bacterial diseases.

PBI derivatives/surfactant-based fluorescent ensembles: Sensing of multiple aminoglycoside antibiotics and interaction mechanism studies.

Fluorescent aggregates and ensembles have been widely applied in fabrication of fluorescent sensors due to their capacity of encapsulating fluorophores and modulating their photophysical properties. In the present work, fluorescent ensembles based on anionic surfactant SDS assemblies and perylene derivatives (PBIs) were particularly constructed. Three newly synthesized neutral PBI derivatives with different structures, PO, PC1 and PC2, were used for the purpose to evaluate probe structure influence on constructing fluorescent ensembles. The one with hydrophilic side chains, PO, experienced distinct photophysical modulation effect by SDS assemblies. The ensemble based on PO@SDS assemblies displayed effective fluorescence variation to antibiotic aminoglycosides (AGs). To improve cross-reactivity and discrimination capability of ensembles, a second probe, coumarin, was introduced into PO@SDS assemblies. The resultant ternary sensor, CM-PO@SDS, exhibited good qualitative and quantitative detection capabilities, and achieved differentiation of eight AGs and mixed AG samples both in aqueous solution and actual biological fluid, like human serum. Sensing mechanism studies revealed that hydrogen bonding, electrostatic and hydrophobic interactions are involved in the sensing process. This surfactant-based fluorescent ensemble provides a simple and feasible method for assessing AGs levels. Meanwhile, this work may provide some insights to design reasonable probes for constructing effective single-system based discriminative fluorescent amphiphilic sensors.

An exonuclease III-driven dual-mode aptasensor based on Au-Pd@Fc nanozyme and magnetic separation pretreatment for aminoglycoside antibiotics detection.

A novel dual-mode aptasensor was constructed for aminoglycoside antibiotics (AAs) detection by using a broad-spectrum aptamer as a biorecognition element, and Au-Pd@Fc functionalized by signal DNA as nanoprobes. In electrochemical mode, the target-induced cyclic amplification reaction run under the action of exonuclease-III, which increased the number of nanoprobes on the electrode surface. AAs could be quantitatively detected with LOD of 0.0355 ± 0.00613 nM. In colorimetric mode, the Au-Pd@Fc nanozyme catalyzed the color reaction of 3,3',5,5'-tetramethylbenzidine. The blue-shifted absorbance will be observed with the change of AAs concentration, and the LOD was 0.0458 ± 0.00572 nM. Furthermore, a magnetic molecular-imprinted material capable of specific adsorption of AAs was prepared on milk sample pretreatment. The aptasensor was used to detect 10 kinds of AAs in milk and the recoveries were 97.19 ± 4.41% âˆ¼ 98.70 ± 4.45% and 96.38 ± 3.53%-97.54 ± 4.13% in electrochemical and colorimetric methods. This work provided a theoretical basis for the application of aptamers in simultaneous detection of antibiotics.

High-dose cytarabine plus gemtuzumab ozogamicin as consolidation therapy in patients with favorable- or intermediate-risk acute myeloid leukemia.

Previous prospective randomized trials have investigated the efficacy of gemtuzumab ozogamicin in the frontline treatment of acute myeloid leukemia (AML). We evaluated the efficacy of high-dose cytarabine with GO as consolidation therapy in 20 patients with favorable- or intermediate-risk AML in first complete remission. They included six patients with wild-type nucleophosmin (NPM1) core binding factor (CBF), ten with NPM1-mutated non-CBF, and four with wild-type NPM1 non-CBF. The median follow-up for the entire cohort was 62.0 months. The three-year overall survival (OS) and relapse-free survival (RFS) rates were 72.2% and 77.8%, respectively. OS and RFS were significantly higher for NPM1-mutated non-CBF AML than for wild-type NPM1 non-CBF AML (p = 0.001). We also examined the CD33 single-nucleotide polymorphism (SNP) rs12459419, which has been reported to influence the therapeutic efficacy of GO and CD33 expression. The CD33 expression ratio was higher in CD33 SNP C/C than in C/T (83.1% vs. 49.8%, p = 0.035), but 3-year OS and RFS did not differ significantly. These results suggest that consolidation therapy with high-dose cytarabine plus GO is highly effective in transplant-ineligible elderly patients and may be a reasonable treatment, especially for NPM1-mutated AML.

Chemical Synthesis and Antigenicity Evaluation of an Aminoglycoside Trisaccharide Repeating Unit of Pseudomonas aeruginosa Serotype O5 O-Antigen Containing a Rare Dimeric-ManpN3NA.

Pseudomonas aeruginosa bacteria are becoming increasingly resistant against multiple antibiotics. Therefore, the development of vaccines to prevent infections with these bacteria is an urgent medical need. While the immunological activity of lipopolysaccharide O-antigens in P. aeruginosa is well-known, the specific protective epitopes remain unidentified. Herein, we present the first chemical synthesis of highly functionalized aminoglycoside trisaccharide 1 and its acetamido derivative 2 found in the P. aeruginosa serotype O5 O-antigen. The synthesis of the trisaccharide targets is based on balancing the reactivity of disaccharide acceptors and monosaccharide donors. Glycosylations were analyzed by quantifying the reactivity of the hydroxyl group of the disaccharide acceptor using the orbital-weighted Fukui function and dual descriptor. The stereoselective formation of 1,2-cis-α-fucosylamine linkages was achieved through a combination of remote acyl participation and reagent modulation. The simultaneous SN2 substitution of azide groups at C2' and C2″ enabled the efficient synthesis of 1,2-cis-ß-linkages for both 2,3-diamino-D-mannuronic acids. Through a strategic orthogonal modification, the five amino groups on target trisaccharide 1 were equipped with a rare acetamidino (Am) and four acetyl (Ac) groups. Glycan microarray analyses of sera from patients infected with P. aeruginosa indicated that trisaccharides 1 and 2 are key antigenic epitopes of the serotype O5 O-antigen. The acetamidino group is not an essential determinant of antibody binding. The ß-D-ManpNAc3NAcA residue is a key motif for the antigenicity of serotype O5 O-antigen. These findings serve as a foundation for the development of glycoconjugate vaccines targeting P. aeruginosa serotype O5.

An open-label, randomized, non-inferiority trial of the efficacy and safety of ciprofloxacin versus an aminoglycoside + ciprofloxacin in the treatment of bubonic plague (IMASOY): study protocol for a randomized control trial-an update to the published protocol.

This article reports an update to the protocol of the IMASOY trial, which was prospectively registered on clinicaltrials.gov (NCT04110340) in October 2019.

Prevalence and mechanisms of aminoglycoside resistance among drug-resistant Pseudomonas aeruginosa clinical isolates in Iran.

BACKGROUND: Aminoglycosides have been a cornerstone of the treatment of nosocomial infections caused by Pseudomonas aeruginosa for over 80 years. However, escalating emergence of resistance poses a significant challenge. Therefore, this study aimed to investigate the prevailing patterns of aminoglycoside resistance among clinical isolates of P. aeruginosa in Iran; as well as the underlying resistance mechanisms observed in patients referred to Ardabil hospitals. METHODS: A total of 200 isolates from five hospitals were evaluated. The resistance profiles of P. aeruginosa isolates to tobramycin, amikacin, and netilmicin were determined using the disk diffusion method. The capacity of aminoglycoside-resistant isolates to form biofilms was assessed through a phenotypic assay, and the results were confirmed using the gene amplification technique. The presence of genes associated with aminoglycoside resistance was detected using polymerase chain reaction (PCR). Quantitative reverse transcription PCR (qRT-PCR) was performed to measure the expression levels of genes encoding the MexXY-OprM efflux pump and PhoPQ two-component system (TCS). RESULTS: The prevalence of aminoglycoside-resistant P. aeruginosa isolates was 48%, with 94.7% demonstrating multidrug resistance (MDR). All aminoglycoside-resistant P. aeruginosa strains exhibited biofilm-forming capabilities and harbored all the genes associated with biofilm production. Among the nine genes encoding 16S rRNA methylase and aminoglycoside-modifying enzymes, three genes were detected in these isolates: aac(6')-Ib (85.4%), ant(2'')-Ia (18.7%), and aph(3')-VI (3.1%). Additionally, all aminoglycoside-resistant P. aeruginosa isolates carried mexY and phoP genes, although the expression levels of mexY and phoP were 75% and 87.5%, respectively. CONCLUSION: Given the considerably high prevalence of aminoglycoside-resistant P. aeruginosa strains, urgent measures are warranted to transition towards the use of novel aminoglycosides and to uphold vigilant surveillance of resistance patterns.

Sophisticated natural products as antibiotics.

In this Review, we explore natural product antibiotics that do more than simply inhibit an active site of an essential enzyme. We review these compounds to provide inspiration for the design of much-needed new antibacterial agents, and examine the complex mechanisms that have evolved to effectively target bacteria, including covalent binders, inhibitors of resistance, compounds that utilize self-promoted entry, those that evade resistance, prodrugs, target corrupters, inhibitors of 'undruggable' targets, compounds that form supramolecular complexes, and selective membrane-acting agents. These are exemplified by ß-lactams that bind covalently to inhibit transpeptidases and ß-lactamases, siderophore chimeras that hijack import mechanisms to smuggle antibiotics into the cell, compounds that are activated by bacterial enzymes to produce reactive molecules, and antibiotics such as aminoglycosides that corrupt, rather than merely inhibit, their targets. Some of these mechanisms are highly sophisticated, such as the preformed ß-strands of darobactins that target the undruggable ß-barrel chaperone BamA, or teixobactin, which binds to a precursor of peptidoglycan and then forms a supramolecular structure that damages the membrane, impeding the emergence of resistance. Many of the compounds exhibit more than one notable feature, such as resistance evasion and target corruption. Understanding the surprising complexity of the best antimicrobial compounds provides a roadmap for developing novel compounds to address the antimicrobial resistance crisis by mining for new natural products and inspiring us to design similarly sophisticated antibiotics.