Review on Multiple Facets of Drug Resistance: A Rising Challenge in the 21st Century

Morpholinium-based Ionic Liquids as Potent Antibiofilm and Sensitizing Agents for the Control of Pseudomonas aeruginosa

Rising antimicrobial resistance is a critical threat to worldwide public health. To address the increasing antibiotic tolerance, diverse antimicrobial agents are examined for their ability to decrease bacterial resistance. One of the most relevant and persistent human pathogens is Pseudomonas aeruginosa. Our study investigates the anti-biofilm and sensitizing activity of 12 morpholinium-based ionic liquids with herbicidal anions on four clinically relevant P. aeruginosa strains. Among all tested compounds, four ionic liquids prevented biofilm formation at sub-minimum inhibitory concentrations for all investigated strains. For the first time, we established a hormetic effect on biofilm formation for P. aeruginosa strains subjected to an ionic liquid treatment. Interestingly, while ionic liquids with 4,4-didecylmorpholinium [Dec2Mor]+ are more efficient against planktonic bacteria, 4-decyl-4-ethylmorpholinium [DecEtMor]+ showed more potent inhibition of biofilm formation. Ionic liquids with 4,4-didecylmorpholinium ([Dec2Mor]+) cations even induced biofilm formation by strain 39016 at high concentrations due to flocculation. Morpholinium-based ionic liquids were also shown to enhance the efficacy of commonly used antibiotics from different chemical groups. We demonstrate that this synergy is associated with the mode of action of the antibiotics.

Mechanism of antibacterial phytoconstituents: an updated review

The increase of multiple drug resistance bacteria significantly diminishes the effectiveness of antibiotic armory and subsequently exaggerates the level of therapeutic failure. Phytoconstituents are exceptional substitutes for resistance-modifying vehicles. The plants appear to be a deep well for the discovery of novel antibacterial compounds. This is owing to the numerous enticing characteristics of plants, they are easily accessible and inexpensive, extracts or chemicals derived from plants typically have significant levels of action against infections, and they rarely cause serious adverse effects. The enormous selection of phytochemicals offers very distinct chemical structures that may provide both novel mechanisms of antimicrobial activity and deliver us with different targets in the interior of the bacterial cell. They can directly affect bacteria or act together with the crucial events of pathogenicity, in this manner decreasing the aptitude of bacteria to create resistance. Abundant phytoconstituents demonstrate various mechanisms of action toward multi drug resistance bacteria. Overall, this comprehensive review will provide insights into the potential of phytoconstituents as alternative treatments for bacterial infections, particularly those caused by multi drug resistance strains. By examining the current state of research in this area, the review will shed light on potential future directions for the development of new antimicrobial therapies.

Understanding the burden of antibiotic resistance: a decade of carbapenem-resistant Gram-negative bacterial infections in Italian intensive care units

Introduction

In patients admitted to intensive care units (ICUs), Gram-negative bacteria (GNB) infections pose significant challenges due to their contribution to morbidity, mortality, and healthcare costs. During the SARS-CoV-2 pandemic, Italy witnessed a rise in healthcare-associated infections (HAIs), with GNBs involved in a substantial proportion of cases. Concerningly, carbapenem-resistant GNBs (CR-GNBs) have increased worldwide, posing therapeutic challenges.

Methods

Retrospective multicentre study analysing data from over 299,000 patients admitted to Italian ICUs from 2013 to 2022.

Results

The study revealed an average of 1.5 infections per patient, with HAIs peaking during the pandemic years. Ventilator associated pneumonia (VAP) emerged as the most common HAI, with Klebsiella spp. and Pseudomonas aeruginosa predominating. Alarmingly, CR-GNBs accounted for a significant proportion of infections, particularly in VAP, bloodstream infections, and intra-abdominal infections.

Discussion

Our findings underscore the pressing need for enhanced infection control measures, particularly in the ICU setting, to mitigate the rising prevalence of CR-GNBs and their impact on patient outcomes. The study provides valuable insights into the epidemiology of HAIs in Italian ICUs and highlights the challenges posed by CR-GNBs, especially in the context of the SARS-CoV-2 pandemic, which exacerbated the issue and may serve as a crucial example for the management of future viral pandemics.

Potential Surviving Effect of Cleome droserifolia Extract against Systemic Staphylococcus aureus Infection: Investigation of the Chemical Content of the Plant

The increasing rates of morbidity and mortality owing to bacterial infections, particularly Staphylococcus aureus have necessitated finding solutions to face this issue. Thus, we elucidated the phytochemical constituents and antibacterial potential of Cleome droserifolia extract (CDE). Using LC-ESI-MS/MS, the main phytoconstituents of CDE were explored, which were kaempferol-3,7-O-bis-alpha-L-rhamnoside, isorhamnetin, cyanidin-3-glucoside, kaempferide, kaempferol-3-O-alpha-L-rhamnoside, caffeic acid, isoquercitrin, quinic acid, isocitrate, mannitol, apigenin, acacetin, and naringenin. The CDE exerted an antibacterial action on S. aureus isolates with minimum inhibitory concentrations ranging from 128 to 512 µg/mL. Also, CDE exhibited antibiofilm action using a crystal violet assay. A scanning electron microscope was employed to illuminate the effect of CDE on biofilm formation, and it considerably diminished S. aureus cell number in the biofilm. Moreover, qRT-PCR was performed to study the effect of CDE on biofilm gene expression (cna, fnbA, and icaA). The CDE revealed a downregulating effect on the studied biofilm genes in 43.48% of S. aureus isolates. Regarding the in vivo model, CDE significantly decreased the S. aureus burden in the liver and spleen of CDE-treated mice. Also, it significantly improved the mice's survival and substantially decreased the inflammatory markers (interleukin one beta and interleukin six) in the studied tissues. Furthermore, CDE has improved the histology and tumor necrosis factor alpha immunohistochemistry in the liver and spleen of the CDE-treated group. Thus, CDE could be considered a promising candidate for future antimicrobial drug discovery studies.

Exposure to imipenem at sub-minimum inhibitory concentration leads to altered expression of major outer membrane proteins in Acinetobacter baumannii

AIMS

Acinetobacter baumannii is a nosocomial pathogen known to be multidrug-resistant (MDR), especially to drugs of the carbapenem class. Several factors contribute to resistance, including efflux pumps, β-lactamases, alteration of target sites, and permeability defects. In addition, outer membrane proteins (OMPs), like porins are involved in the passage of antibiotics, and their alteration could lead to resistance development. This study aimed to explore the possible involvement of porins and OMPs in developing carbapenem resistance due to differential expression.

METHODS AND RESULTS

The antibiotic-susceptible and MDR isolates of A. baumannii were first studied for differences in their transcriptional levels of OMP expression and OMP profiles. The antibiotic-susceptible isolates were further treated with imipenem, and it was found that the omp genes were differentially expressed. Six of the nine genes studied were upregulated at 1 h of exposure to imipenem. Their expression gradually decreased with time, further confirmed by their OMP profile and two-dimensional gel electrophoresis.

CONCLUSIONS

This study could identify OMPs that were differentially expressed on exposure to imipenem. Hence, this study provides insights into the role of specific OMPs in antibiotic resistance in A. baumannii.

An Antimicrobial Copper-Plastic Composite Coating: Characterization and In Situ Study in a Hospital Environment

A method has been proposed for creating an operationally durable copper coating with antimicrobial properties for the buttons of electrical switches based on the gas dynamic spray deposition of copper on acrylonitrile butadiene styrene (ABS) plastic. It is shown that during the coating process, a polymer film is formed on top of the copper layer. Comparative in situ studies of microbial contamination have shown that the copper-coated buttons have a significant antimicrobial effect compared to standard buttons. Analysis of swabs over a 22-week study in a hospital environment showed that the frequency of contamination for a copper-coated button with various microorganisms was 2.7 times lower than that of a control button. The presented results allow us to consider the developed copper coating for plastic switches an effective alternative method in the fight against healthcare-associated infections.

Detection of multidrug-resistant organisms of concern including Stenotrophomonas maltophilia and Burkholderia cepacia at a referral hospital in Kenya

Regular monitoring of bacterial susceptibility to antibiotics in clinical settings is key for ascertaining the current trends as well as re-establish empirical therapy. This study aimed to determine bacterial contaminants and their antimicrobial susceptibility patterns from medical equipment, inanimate surfaces and clinical samples obtained from Thika Level V Hospital (TLVH), Thika, in Central Kenya. Three hundred and five samples were collected between the period of March 2021 to November 2021 and comprised urine, pus swabs, catheter swabs, stool, and environmental samples. Bacterial identification and antimicrobial susceptibility were performed using VITEK 2 and disc diffusion respectively. We observed that Coagulase-negative Staphylococci (28 /160, 17.5%) were the most commonly isolated species from clinical samples followed by E. coli (22 /160 13.8%) and S. aureus (22/160, 13.8%). The bed rails were the mostly contaminated surface with S. aureus accounting for 14.2% (6/42). Among the clinical samples, pus swabs yielded the highest number of pathogens was pus (92/160). Trauma patients had the highest proportion of isolates (67/160, 41.8%). High level of antimicrobial resistance to key antimicrobials, particularly among Enterobacterales was observed. Extended Spectrum Beta Lactamase (ESBL) phenotype was noted in 65.9% (29/44) of enteric isolates. While further ESBL genetic confirmatory studies are needed, this study highlights the urgent need for actions that mitigate the spread of antibiotic-resistant bacteria.

Characterization of genes related to the efflux pump and porin in multidrug-resistant Escherichia coli strains isolated from patients with COVID-19 after secondary infection

BACKGROUND

Escherichia coli (E. coli) is a multidrug resistant opportunistic pathogen that can cause secondary bacterial infections in patients with COVID-19. This study aimed to determine the antimicrobial resistance profile of E. coli as a secondary bacterial infection in patients with COVID-19 and to assess the prevalence and characterization of genes related to efflux pumps and porin.

METHODS

A total of 50 nonduplicate E. coli isolates were collected as secondary bacterial infections in COVID-19 patients. The isolates were cultured from sputum samples. Confirmation and antibiotic susceptibility testing were conducted by Vitek 2. PCR was used to assess the prevalence of the efflux pump and porin-related genes in the isolates. The phenotypic and genotypic evolution of antibiotic resistance genes related to the efflux pump was evaluated.

RESULTS

The E. coli isolates demonstrated high resistance to ampicillin (100%), cefixime (62%), cefepime (62%), amoxicillin-clavulanic acid (60%), cefuroxime (60%), and ceftriaxone (58%). The susceptibility of E. coli to ertapenem was greatest (92%), followed by imipenem (88%), meropenem (86%), tigecycline (80%), and levofloxacin (76%). Regarding efflux pump gene combinations, there was a significant association between the acrA gene and increased resistance to levofloxacin, between the acrB gene and decreased resistance to meropenem and increased resistance to levofloxacin, and between the ompF and ompC genes and increased resistance to gentamicin.

CONCLUSIONS

The antibiotics ertapenem, imipenem, meropenem, tigecycline, and levofloxacin were effective against E. coli in patients with COVID-19. Genes encoding efflux pumps and porins, such as acrA, acrB, and outer membrane porins, were highly distributed among all the isolates. Efflux pump inhibitors could be alternative antibiotics for restoring tetracycline activity in E. coli isolates.

Genomic Insight of Leishmania Parasite: In-Depth Review of Drug Resistance Mechanisms and Genetic Mutations

Leishmaniasis, which is caused by a parasitic protozoan of the genus Leishmania, is still a major threat to global health, impacting millions of individuals worldwide in endemic areas. Chemotherapy has been the principal method for managing leishmaniasis; nevertheless, the evolution of drug resistance offers a significant obstacle to therapeutic success. Drug-resistant behavior in these parasites is a complex phenomenon including both innate and acquired mechanisms. Resistance is frequently related to changes in drug transportation, drug target alterations, and enhanced efflux of the drug from the pathogen. This review has revealed specific genetic mutations in Leishmania parasites that are associated with resistance to commonly used antileishmanial drugs such as pentavalent antimonials, miltefosine, amphotericin B, and paromomycin, resulting in changes in gene expression along with the functioning of various proteins involved in drug uptake, metabolism, and efflux. Understanding the genetic changes linked to drug resistance in Leishmania parasites is essential for creating approaches for tackling and avoiding the spread of drug-resistant variants. Based on which specific treatments focus on mutations and pathways could potentially improve treatment efficacy and help long-term leishmaniasis control. More study is needed to uncover the complete range of genetic changes generating medication resistance and to develop new therapies based on available information.

Antimicrobial Action Mechanisms of Natural Compounds Isolated from Endophytic Microorganisms

Infectious diseases are a significant challenge to global healthcare, especially in the face of increasing antibiotic resistance. This urgent issue requires the continuous exploration and development of new antimicrobial drugs. In this regard, the secondary metabolites derived from endophytic microorganisms stand out as promising sources for finding antimicrobials. Endophytic microorganisms, residing within the internal tissues of plants, have demonstrated the capacity to produce diverse bioactive compounds with substantial pharmacological potential. Therefore, numerous new antimicrobial compounds have been isolated from endophytes, particularly from endophytic fungi and actinomycetes. However, only a limited number of these compounds have been subjected to comprehensive studies regarding their mechanisms of action against bacterial cells. Furthermore, the investigation of their effects on antibiotic-resistant bacteria and the identification of biosynthetic gene clusters responsible for synthesizing these secondary metabolites have been conducted for only a subset of these promising compounds. Through a comprehensive analysis of current research findings, this review describes the mechanisms of action of antimicrobial drugs and secondary metabolites isolated from endophytes, antibacterial activities of the natural compounds derived from endophytes against antibiotic-resistant bacteria, and biosynthetic gene clusters of endophytic fungi responsible for the synthesis of bioactive secondary metabolites.

Medicinal herbs, especially Hibiscus sabdariffa, inhibit oral pathogenic bacteria

OBJECTIVES

Medicinal herbs are plants with potential medicinal and health benefits. In recent years, they are being increasingly used as a treatment alternative owing to their effectiveness against various diseases. In this study, we investigated the inhibitory effects of 15 medicinal herbs on causative bacteria for dental caries and periodontal disease.

METHODS

This study evaluated the effects of the extracts of 15 medicinal herbs on growth and biofilm formation in five oral pathogenic bacterial strains. The herbs were processed into extracts, and bacterial strains were cultured. Then, bacterial growth and biofilm formation were assessed using various methods. Finally, the extract of the herb Hibiscus sabdariffa (hibiscus) was analyzed using high-performance liquid chromatography.

RESULTS

Incubation of bacteria with the herbal extracts showed that hibiscus exerted a significant inhibitory effect on all the oral pathogenic bacterial strains evaluated in this study. In addition, the pigment delphinidin-3-sambubioside, which is found in hibiscus extract, was identified as a particularly important inhibitory component.

CONCLUSIONS

These results lay the ground work for the potential development of novel therapeutic or preventive agents against dental caries and periodontal disease, two major oral diseases.

Synthesis and biological evaluation of novel benzenesulfonamide incorporated thiazole-triazole hybrids as antimicrobial and antioxidant agents

A library of 20 novel benzenesulfonamide incorporating thiazole tethered 1,2,3-triazoles 1-4a-e was synthesized and screened for their antimicrobial, antioxidant, and cytotoxicity studies. Amoxicillin and fluconazole were used as reference antibacterial and antifungal drugs, respectively. Further, energies of frontier molecular orbitals were calculated for all the synthesized target compounds 1-4a-e to correlate electronic parameters with the observed biological results. Global reactivity descriptors, including highest occupied molecular orbitals-lowest unoccupied molecular orbitals energy gap, electronegativity, chemical hardness, chemical softness, and electrophilicity index, were also calculated for the synthesized molecules. All the tested compounds possessed moderate to excellent antibacterial potency; however, 3d and 4d exhibited the overall highest antibacterial effect (minimum inhibitory concentration [MIC] values 5-11 µM) while 2c showed the highest antifungal effect (MIC value 6 µM). Compound 3c exhibited the highest antioxidant activity with a % radical scavenging activity value of 95.12. The cytotoxicity of the compounds 1-4a-e was also checked against an animal cell line and a plant seed germination cell line, and the compounds were found to be safe against both the tested cell lines.

Engineered phage enzymes against drug-resistant pathogens: a review on advances and applications

In recent decades, the expansion of multi and extensively drug-resistant (MDR and XDR) bacteria has reached an alarming rate, causing serious health concerns. Infections caused by drug-resistant bacteria have been associated with morbidity and mortality, making tackling bacterial resistance an urgent and unmet challenge that needs to be addressed properly. Endolysins are phage-encoded enzymes that can specifically degrade the bacterial cell wall and lead to bacterial death. There is remarkable evidence that corroborates the unique ability of endolysins to rapidly digest the peptidoglycan particular bonds externally without the assistance of phage. Thus, their modulation in therapeutic approaches has opened new options for therapeutic applications in the fight against bacterial infections in the human and veterinary sectors, as well as within the agricultural and biotechnology areas. The use of genetically engineered phage enzymes (EPE) promises to generate endolysin variants with unique properties for prophylactic and therapeutic applications. These approaches have gained momentum to accelerate basic as well as translational phage research and the potential development of therapeutics in the near future. This review will focus on the novel knowledge into EPE and demonstrate that EPE has far better performance than natural endolysins and phages in dealing with antibiotic-resistant infections. Therefore, it provides essential information for clinical trials involving EPE.

Diversity, molecular phylogenetics, and antibiotic biosynthetic potential of endophytic Actinobacteria isolated from medicinal plants in Nigeria

Actinobacteria that are found in nature have enormous promise for the growth of the pharmaceutical sector. There is a scarce report on the antimicrobial activities of endophytic Actinobacteria from Nigeria. As a result, this study evaluated the Actinobacteria isolated from Nigerian medicinal plants in terms of their biodiversity, phylogenetics, and ability to produce antimicrobial compounds. Following accepted practices, Actinobacteria were isolated from the surface-sterilized plant parts. They were identified using 16S rRNA sequencing, microscopic, and morphological methods. The cell-free broth of Actinobacteria isolates was subjected to antimicrobial assay by agar well diffusion. Molecular evolutionary and genetic analysis (MEGA) version X was used for phylogenetic analysis, and the interactive tree of life (iTOL) version 6.0 was used to view the neighbour-joining method-drawn tree. A total of 13 Actinobacteria were recovered, belonging to three genera including 10 strains of Streptomyces, 2 strains of Saccharomonospora, and only 1 strain of Saccharopolyspora. They showed inhibitory activity against several bacterial pathogens. The phylogenetic tree generated from the sequences showed that our isolates are divergent and distinct from other closely related strains on the database. Further, optimization of the antibiotic production by selected Saccharomonospora sp. PNSac2 was conducted. It showed that the optimal conditions were the ISP2 medium (1-2% w/v salt) adjusted to pH of 8 at 30-32℃ for 12-14 days. In conclusion, endophytic Actinobacteria dwelling in Nigerian soils could be a promising source of new antibiotics. Future research is warranted because more genomic analysis and characterization of their metabolites could lead to the development of new antibacterial medicines.

Unveiling therapeutic efficacy of extract and multi-targeting phytocompounds from Christella dentata (Forssk.) Brownsey & Jermy against multidrug-resistant Pseudomonas aeruginosa

Christella dentata (Forssk.) Brownsey & Jermy has been commonly used in traditional medicinal practices but its effects on multi-drug-resistant (MDR) bacteria have remained unexplored. We aimed to assess the in vitro antibacterial potential of the ethanol extract of Christella dentata (EECD) against MDR Pseudomonas aeruginosa and to identify potential multi-targeting antibacterial phytocompounds through computer-aided drug design focusing on the LasR and LpxC proteins. PPS, FT-IR and GC-MS were used for profiling of the phytocompounds in EECD. The antimicrobial activity of EECD was assessed using in vitro agar well diffusion, disc diffusion, MIC and MBC. Computer-aided drug design was used to identify multi-targeting leads from GC-MS-annotated phytocompounds. EECD exhibited dose-dependent antibacterial activity and revealed the presence of 51 phytocompounds in GC-MS analysis. Among these, three phytocompounds; (2E,4E)-N-isobutylhexadeca-2,4-dienamide (CID 6442402), bicyclo[4.3.0]nonane, 2,2,6,7-tetramethyl-7-hydroxy- (CID 536446) and 1,4-diethylbenzene (CID 7734) were identified as promising antibacterial phytocompounds as they strongly bonded with LasR and LpxC. Of them, CID 536446 and CID 7734 exhibited multiple targeting abilities with LasR and LpxC. On further screening, both CID 536446 and CID 7734 exhibited favorable drug-able, pharmacokinetics and toxicity properties. Finally, molecular dynamics (MD) simulation proved the binding stability of bicyclo[4.3.0]nonane, 2,2,6,7-tetramethyl-7-hydroxy- and 1,4-diethylbenzene to active pockets of LasR and LpxC. The results of this study offer scientific validation for the traditional use of Christella dentata in bacterial infection-related diseases. It also suggests that bicyclo[4.3.0]nonane, 2,2,6,7-tetramethyl-7-hydroxy- and 1,4-diethylbenzene from Christella dentata might be responsible for the antibacterial activity and could act as phytopharmacological leads for the development of LasR and LpxC inhibitors against MDR P. aeruginosa.

Combating antimicrobial resistance: the silent war

Once hailed as miraculous solutions, antibiotics no longer hold that status. The excessive use of antibiotics across human healthcare, agriculture, and animal husbandry has given rise to a broad array of multidrug-resistant (MDR) pathogens, posing formidable treatment challenges. Antimicrobial resistance (AMR) has evolved into a pressing global health crisis, linked to elevated mortality rates in the modern medical era. Additionally, the absence of effective antibiotics introduces substantial risks to medical and surgical procedures. The dwindling interest of pharmaceutical industries in developing new antibiotics against MDR pathogens has aggravated the scarcity issue, resulting in an exceedingly limited pipeline of new antibiotics. Given these circumstances, the imperative to devise novel strategies to combat perilous MDR pathogens has become paramount. Contemporary research has unveiled several promising avenues for addressing this challenge. The article provides a comprehensive overview of these innovative therapeutic approaches, highlighting their mechanisms of action, benefits, and drawbacks.

Cell membrane-coated biomimetic nanomedicines: productive cancer theranostic tools

As the second-leading cause of human death, cancer has drawn attention in the area of biomedical research and therapy from all around the world. Certainly, the development of nanotechnology has made it possible for nanoparticles (NPs) to be used as a carrier for delivery systems in the treatment of tumors. This is a biomimetic approach established to craft remedial strategies comprising NPs cloaked with membrane obtained from various natural cells like blood cells, bacterial cells, cancer cells, etc. Here we conduct an in-depth exploration of cell membrane-coated NPs (CMNPs) and their extensive array of applications including drug delivery, vaccination, phototherapy, immunotherapy, MRI imaging, PET imaging, multimodal imaging, gene therapy and a combination of photothermal and chemotherapy. This review article provides a thorough summary of the most recent developments in the use of CMNPs for the diagnosis and treatment of cancer. It critically assesses the state of research while recognizing significant accomplishments and innovations. Additionally, it indicates ongoing problems in clinical translation and associated queries that warrant deeper research. By doing so, this study encourages creative thinking for future projects in the field of tumor therapy using CMNPs while also educating academics on the present status of CMNP research.

Unveiling the mechanisms and challenges of cancer drug resistance

Cancer treatment faces many hurdles and resistance is one among them. Anti-cancer treatment strategies are evolving due to innate and acquired resistance capacity, governed by genetic, epigenetic, proteomic, metabolic, or microenvironmental cues that ultimately enable selected cancer cells to survive and progress under unfavorable conditions. Although the mechanism of drug resistance is being widely studied to generate new target-based drugs with better potency than existing ones. However, due to the broader flexibility in acquired drug resistance, advanced therapeutic options with better efficacy need to be explored. Combination therapy is an alternative with a better success rate though the risk of amplified side effects is commonplace. Moreover, recent groundbreaking precision immune therapy is one of the ways to overcome drug resistance and has revolutionized anticancer therapy to a greater extent with the only limitation of being individual-specific and needs further attention. This review will focus on the challenges and strategies opted by cancer cells to withstand the current therapies at the molecular level and also highlights the emerging therapeutic options -like immunological, and stem cell-based options that may prove to have better potential to challenge the existing problem of therapy resistance. Video Abstract.

Recent Advances in the Development of Antibiotics-Coated Gold Nanoparticles to Combat Antimicrobial Resistance

Antimicrobial resistance (AMR) has become an alarming threat to the successful treatment of rapidly growing bacterial infections due to the abuse and misuse of antibiotics. Traditional antibiotics bear many limitations, including restricted bioavailability, inadequate penetration and the emergence of antimicrobial-resistant microorganisms. Recent advances in nanotechnology for the introduction of nanoparticles with fascinating physicochemical characteristics have been predicted as an innovative means of defence against antimicrobial-resistant diseases. The use of nanoparticles provides several benefits, including improved tissue targeting, better solubility, improved stability, enhanced epithelial permeability and causes minimal side effects. However, except for gold nanoparticles (AuNPs), the biological safety of the majority of metal nanoparticles remains a serious problem. AuNPs appear to be promising for drug delivery and medicinal applications because of their minimal toxicity, biocompatibility, functional flexibility, chemical stability and versatile biological activities, such as their antiviral, antifungal, anti-inflammatory and antimicrobial properties. Hence, we are focusing on the gold nanoparticles possessing antimicrobial activity in this article. This review will cover recent strategies in the preparation of gold nanoparticles, with special emphasis placed on antibiotics-coated AuNPs with enhanced antimicrobial properties and how they fight against disease-causing bacteria and eradicate biofilms, along with their activities and physicochemical properties.

Chemical Modification of Dental Dimethacrylate Copolymer with Tetramethylxylylene Diisocyanate-Based Quaternary Ammonium Urethane-Dimethacrylates-Physicochemical, Mechanical, and Antibacterial Properties

In this study, two novel quaternary ammonium urethane-dimethacrylates (QAUDMAs) were designed for potential use as comonomers in antibacterial dental composite restorative materials. QAUDMAs were synthesized via the reaction of 1,3-bis(1-isocyanato-1-methylethyl)benzene with 2-(methacryloyloxy)ethyl-2-decylhydroxyethylmethylammonium bromide (QA10+TMXDI) and 2-(methacryloyloxy)ethyl-2-dodecylhydroxyethylmethylammonium bromide (QA12+TMXDI). Their compositions with common dental dimethacrylates comprising QAUDMA 20 wt.%, urethane-dimethacrylate monomer (UDMA) 20 wt.%, bisphenol A glycerolate dimethacrylate (Bis-GMA) 40 wt.%, and triethylene glycol dimethacrylate (TEGDMA) 20 wt.%, were photocured. The achieved copolymers were characterized for their physicochemical and mechanical properties, including their degree of conversion (DC), glass transition temperature (Tg), polymerization shrinkage (S), water contact angle (WCA), flexural modulus (E), flexural strength (FS), hardness (HB), water sorption (WS), and water leachability (WL). The antibacterial activity of the copolymers was characterized by the minimum bactericidal concentration (MBC) and minimum inhibitory concentration (MIC) against Staphylococcus aureus and Escherichia coli. The achieved results were compared to the properties of a typical dental copolymer comprising UDMA 40 wt.%, Bis-GMA 40 wt.%, and TEGDMA 20 wt.%. The introduction of QAUDMAs did not deteriorate physicochemical and mechanical properties. The WS and WL increased; however, they were still satisfactory. The copolymer comprising QA10+TMXDI showed a higher antibacterial effect than that comprising QA12+TMXDI and that of the reference copolymer.

Ningalins, Pyrrole-Bearing Metabolites Isolated from Didemnum spp. Synthesis and MDR-Reversion Activity in Cancer Therapy

Multi-Drug Resistance (MDR) is one of the most frequent problems observed in the course of cancer chemotherapy. Cells under treatment, tend to develop survival mechanisms to drug-action thus generating drug-resistance. One of the most important mechanism to get it is the over expression of P-gp glycoprotein, which acts as an efflux-pump releasing the drug outside of the cancer cell. A strategy for a succesfull treatment consists in the co-administration of one compound that acts against P-gp and another which acts against the cell during chemotherapy. Ningalins are pyrrole-containing naturally occurring compounds isolated mainly from the marine tunicate Didemnum spp and also they are some of the top reversing agents in MDR treatment acting on P-gp. Considering the relevance displayed for some of these isolated alkaloids or their core as a drug for co-administration in cancer therapy, all the total synthesis described to date for the members of ningalins family are reviewed herein.

The therapeutic effect of engineered phage, derived protein and enzymes against superbug bacteria

Defending against antibiotic-resistant infections is similar to fighting a war with limited ammunition. As the new century unfolded, antibiotic resistance became a significant concern. In spite of the fact that phage treatment has been used as an effective means of fighting infections for more than a century, researchers have had to overcome many challenges of superbug bacteria by manipulating phages and producing engineered enzymes. New enzymes and phages with enhanced properties have a significant impact on the ability to fight antibiotic-resistant infections, which is considered a window of hope for the future. This review, therefore, illustrates not only the challenges caused by antibiotic resistance and superbug bacteria but also the engineered enzymes and phages that are being developed to solve these issues. Our study found that engineered phages, phage proteins, and enzymes can be effective in treating superbug bacteria and destroying the biofilm caused by them. Combining these engineered compounds with other antimicrobial substances can increase their effectiveness against antibiotic-resistant bacteria. Therefore, engineered phages, proteins, and enzymes can be used as a substitute for antibiotics or in combination with antibiotics to treat patients with superbug infections in the future.

Methicillin Resistant Staphylococcus aureus: Molecular Mechanisms Underlying Drug Resistance Development and Novel Strategies to Combat

Antimicrobial resistance (AMR) represents a major threat to global health. Infection caused by Methicillin-resistant Staphylococcus aureus (MRSA) is one of the well-recognized global public health problem globally. In some regions, as many as 90% of S. aureus infections are reported to be MRSA, which cannot be treated with standard antibiotics. WHO reports indicated that MRSA is circulating in every province worldwide, significantly increasing the risk of death by 64% compared to drug-sensitive forms of the infection which is attributed to its antibiotic resistance. The emergence and spread of antibiotic-resistant MRSA strains have contributed to its increased prevalence in both healthcare and community settings. The resistance of S. aureus to methicillin is due to expression of penicillin-binding protein 2a (PBP2a), which renders it impervious to the action of β-lactam antibiotics including methicillin. The other is through the production of beta-lactamases. Although the treatment options for MRSA are limited, there are promising alternatives to antibiotics to combat the infections. Innovative therapeutic strategies with wide range of activity and modes of action are yet to be explored. The review highlights the global challenges posed by MRSA, elucidates the mechanisms underlying its resistance development, and explores mitigation strategies. Furthermore, it focuses on alternative therapies such as bacteriophages, immunotherapy, nanobiotics, and antimicrobial peptides, emphasizing their synergistic effects and efficacy against MRSA. By examining these alternative approaches, this review provides insights into the potential strategies for tackling MRSA infections and combatting the escalating threat of AMR. Ultimately, a multifaceted approach encompassing both conventional and novel interventions is imperative to mitigate the impact of MRSA and ensure a sustainable future for global healthcare.

Virtual Screening and ADMET Prediction to Uncover the Potency of Flavonoids from Genus Erythrina as Antibacterial Agent through Inhibition of Bacterial ATPase DNA Gyrase B

The emergence of antimicrobial resistance due to the widespread and inappropriate use of antibiotics has now become the global health challenge. Flavonoids have long been reported to be a potent antimicrobial agent against a wide range of pathogenic microorganisms in vitro. Therefore, new antibiotics development based on flavonoid structures could be a potential strategy to fight against antibiotic-resistant infections. This research aims to screen the potency of flavonoids of the genus Erythrina as an inhibitor of bacterial ATPase DNA gyrase B. From the 378 flavonoids being screened, 49 flavonoids show potential as an inhibitor of ATPase DNA gyrase B due to their lower binding affinity compared to the inhibitor and ATP. Further screening for their toxicity, we identified 6 flavonoids from these 49 flavonoids, which are predicted to have low toxicity. Among these flavonoids, erystagallin B (334) is predicted to have the best pharmacokinetic properties, and therefore, could be further developed as new antibacterial agent.

Bioprospecting of unexplored halophilic actinobacteria against human infectious pathogens

Human pathogenic diseases received much attention recently due to their uncontrolled spread of antimicrobial resistance (AMR) which causes several threads every year. Effective alternate antimicrobials are urgently required to combat those disease causing infectious microbes. Halophilic actinobacteria revealed huge potentials and unexplored cultivable/non-cultivable actinobacterial species producing enormous antimicrobials have been proved in several genomics approaches. Potential gene clusters, PKS and NRPKS from Nocardia, Salinospora, Rhodococcus, and Streptomyces have wide range coding genes of secondary metabolites. Biosynthetic pathways identification via various approaches like genome mining, In silico, OSMAC (one strain many compound) analysis provides better identification of knowing the active metabolites using several databases like AMP, APD and CRAMPR, etc. Genome constellations of actinobacteria particularly the prediction of BGCs (Biosynthetic Gene Clusters) to mine the bioactive molecules such as pigments, biosurfactants and few enzymes have been reported for antimicrobial activity. Saltpan, saltlake, lagoon and haloalkali environment exploring potential actinobacterial strains Micromonospora, Kocuria, Pseudonocardia, and Nocardiopsis revealed several acids and ester derivatives with antimicrobial potential. Marine sediments and marine macro organisms have been found as significant population holders of potential actinobacterial strains. Deadly infectious diseases (IDs) including tuberculosis, ventilator-associated pneumonia and Candidiasis, have been targeted by halo-actinobacterial metabolites with promising results. Methicillin resistant Staphylococus aureus and virus like Encephalitic alphaviruses were potentially targeted by halophilic actinobacterial metabolites by the compound Homoseongomycin from sponge associated antinobacterium. In this review, we discuss the potential antimicrobial properties of various biomolecules extracted from the unexplored halophilic actinobacterial strains specifically against human infectious pathogens along with prospective genomic constellations.

Redox modulating small molecules having antimalarial efficacy

The search for effective antimalarial agents remains a critical priority because malaria is widely spread and drug-resistant strains are becoming more prevalent. In this review, a variety of small molecules capable of modulating redox processes were showcased for their potential as antimalarial agents. The compounds were designed to target the redox balance of Plasmodium parasites, which has a pivotal function in their ability to survive and multiply within the host organism. A thorough screening method was utilized to assess the effectiveness of these compounds against both drug-sensitive and drug-resistant strains of Plasmodium falciparum, the malaria-causing parasite. The results revealed that several of the tested compounds exhibited significant effectiveness against malaria, displaying IC50 values at a low micromolar range. Furthermore, these compounds displayed promising selectivity for the parasite, as they exhibited low cytotoxicity towards mammalian cells. Thorough mechanistic studies were undertaken to clarify how the active compounds exert their mode of action. The findings revealed that these compounds disrupted the parasites' redox balance, causing oxidative stress and interfering with essential cellular functions. Additionally, the compounds showed synergistic effects when combined with existing antimalarial drugs, suggesting their potential for combination therapies to combat drug resistance. Overall, this study highlights the potential of redox-modulating small molecules as effective antimalarial agents. The identified compounds demonstrate promising antimalarial activity, and their mechanism of action offers insights into targeting the redox balance of Plasmodium parasites. Further optimization and preclinical studies are warranted to determine their efficacy, safety, and potential for clinical development as novel antimalarial therapeutics.

Antibacterial and phytochemical analysis of traditional medicinal plants: An alternative therapeutic Approach to conventional antibiotics

The purpose of this study was to carry out antibacterial and phytochemical analyses on six selected medicinal plants that have been traditionally used by the local people to treat and control different diseases. The antibacterial activities of methanolic extracts of these plants were assessed using the Agar well diffusion and Microtiter broth dilution methods. The root extract of Andrachne aspera showed significantly (p < 0.05) highest mean zone of inhibition at concentrations of 100 mg/ml (33 ± 0.17) and 200 mg/ml (33.5 ± 0.84) against S. epidermidis. The second highest mean zone of inhibition (24.8 ± 0.41) was recorded by Dichrostachys cinerea leaf extract against S. epidermidis at 200 mg/ml concentration. The minimum inhibitory concentrations 1.0 ± 0.0 was recorded by Andrachne aspera against E. faecalis and 2.0 ± 0.0 against S. aureus by Dichrostachys cinerea. The preliminary phytochemical analysis showed that Andrachne aspera and Dichrostachys cinerea contained strong concentration of Polyphenols and Flavonoids. Therefore, these two medicinal plant species have promising potential for further detailed investigations, including safety tests, characterization and isolation of bioactive secondary metabolites for the development of alternative drugs.

Efficacy of Different Encapsulation Techniques on the Viability and Stability of Diverse Phage under Simulated Gastric Conditions

Salmonella causes a range of diseases in humans and livestock of considerable public health and economic importance. Widespread antimicrobial use, particularly in intensively produced livestock (e.g., poultry and pigs) may contribute to the rise of multidrug-resistant Salmonella strains. Alternative treatments such as bacteriophages have shown promise when used to reduce the intestinal carriage of Salmonella in livestock. However, the digestive enzymes and low pH encountered in the monogastric GI tract can significantly reduce phage viability and impact therapeutic outcomes. This study deployed alginate-carrageenan microcapsules with and without CaCO3 to protect a genomically diverse set of five Salmonella bacteriophages from simulated gastrointestinal conditions. None of the unprotected phage could be recovered following exposure to pH < 3 for 10 min. Alginate-carrageenan encapsulation improved phage viability at pH 2-2.5 after exposure for 10 min, but not at pH 2 after 1 h. Including 1% (w/v) CaCO3 in the formulation further reduced phage loss to <0.5 log10 PFU/mL, even after 1 h at pH 2. In all cases, phage were efficiently released from the microcapsules following a shift to a neutral pH (7.5), simulating passage to the duodenum. In summary, alginate-carrageenan-CaCO3 encapsulation is a promising approach for targeted intestinal delivery of genomically diverse Salmonella bacteriophages.

Multidrug-resistant Gram-negative bacterial infections and associated factors in a Kenyan intensive care unit: a cross-sectional study

BACKGROUND

Patients admitted to intensive care units (ICU) are at risk of Gram-negative bacteria (GNB) infections, especially those caused by multidrug-resistant (MDR) isolates, increasing morbidity, mortality, and healthcare costs. However, epidemiological surveillance data on MDR bacteria to inform infection prevention and control (IPCs) interventions is limited in our study setting. Here we assessed the prevalence and factors associated with GNB infections in ICU- patients admitted in our study setting.

METHODS

This was a hospital-based cross-sectional study among patients admitted to ICU at the Nairobi West Hospital, Kenya, between January and October 2022. Altogether, we recruited 162 patients, excluding those hospitalized for less than 48 h and declining consent, and collected demographics and clinical data by case report form. Blood, wound and throat swab, ascetic tap, stool, urine, tracheal aspirate, and sputum samples were collected cultured. Isolates identity and antimicrobial susceptibility were elucidated using the BD Phoenix system.

RESULTS

The prevalence of GNB infections was 55.6%, predominated by urinary tract infections (UTIs). We recovered 13 GNB types, with Escherichia coli (33.3%) and Klebsiella pneumoniae (31.1%) as the most common isolates. Factors associated with GNB infections were a history of antibiotic use (aOR = 4.23, p = 0.001), nasogastric tube use (NGT, aOR = 3.04, p = 0.013), respiratory tract (RT, aOR = 5.3, p = 0.005) and cardiovascular (CV, aOR = 5.7, p = 0.024) conditions. 92% of the isolates were MDR,predominantly Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa.

CONCLUSION

We report a high prevalence of MDR-GNB infections, predominated by UTI, in ICU, whereby patients with a history of antibiotic use, using the NGT, and having RT and CV conditions were at increased risk. To improve the management of ICU-admitted patients, continuous education, training, monitoring, evaluation and feedback on infection prevention and control are warranted in our study setting.

Total Bio-Based Material for Drug Delivery and Iron Chelation to Fight Cancer through Antimicrobial Activity

Bacterial involvement in cancer's development, along with their impact on therapeutic interventions, has been increasingly recognized. This has prompted the development of novel strategies to disrupt essential biological processes in microbial cells. Among these approaches, metal-chelating agents have gained attention for their ability to hinder microbial metal metabolism and impede critical reactions. Nanotechnology has also contributed to the antibacterial field by offering various nanomaterials, including antimicrobial nanoparticles with potential therapeutic and drug-delivery applications. Halloysite nanotubes (HNTs) are naturally occurring tubular clay nanomaterials composed of aluminosilicate kaolin sheets rolled multiple times. The aluminum and siloxane groups on the surface of HNTs enable hydrogen bonding with biomaterials, making them versatile in various domains, such as environmental sciences, wastewater treatment, nanoelectronics, catalytic studies, and cosmetics. This study aimed to create an antibacterial material by combining the unique properties of halloysite nanotubes with the iron-chelating capability of kojic acid. A nucleophilic substitution reaction involving the hydroxyl groups on the nanotubes' surface was employed to functionalize the material using kojic acid. The resulting material was characterized using infrared spectroscopy (IR), thermogravimetric analysis (TGA), energy-dispersive X-ray spectroscopy (EDX), and scanning electron microscopy (SEM), and its iron-chelating ability was assessed. Furthermore, the potential for drug loading-specifically, with resveratrol and curcumin-was evaluated through ultraviolet (UV) analysis. The antibacterial assay was evaluated following CLSI guidelines. The results suggested that the HNTs-kojic acid formulation had great antibacterial activity against all tested pathogens. The outcome of this work yielded a novel bio-based material with dual functionality as a drug carrier and an antimicrobial agent. This innovative approach holds promise for addressing challenges related to bacterial infections, antibiotic resistance, and the development of advanced therapeutic interventions.

Antimicrobial Resistance: A Growing Serious Threat for Global Public Health

Antibiotics are among the most important discoveries of the 20th century, having saved millions of lives from infectious diseases. Microbes have developed acquired antimicrobial resistance (AMR) to many drugs due to high selection pressure from increasing use and misuse of antibiotics over the years. The transmission and acquisition of AMR occur primarily via a human-human interface both within and outside of healthcare facilities. A huge number of interdependent factors related to healthcare and agriculture govern the development of AMR through various drug-resistance mechanisms. The emergence and spread of AMR from the unrestricted use of antimicrobials in livestock feed has been a major contributing factor. The prevalence of antimicrobial-resistant bacteria has attained an incongruous level worldwide and threatens global public health as a silent pandemic, necessitating urgent intervention. Therapeutic options of infections caused by antimicrobial-resistant bacteria are limited, resulting in significant morbidity and mortality with high financial impact. The paucity in discovery and supply of new novel antimicrobials to treat life-threatening infections by resistant pathogens stands in sharp contrast to demand. Immediate interventions to contain AMR include surveillance and monitoring, minimizing over-the-counter antibiotics and antibiotics in food animals, access to quality and affordable medicines, vaccines and diagnostics, and enforcement of legislation. An orchestrated collaborative action within and between multiple national and international organizations is required urgently, otherwise, a postantibiotic era can be a more real possibility than an apocalyptic fantasy for the 21st century. This narrative review highlights on this basis, mechanisms and factors in microbial resistance, and key strategies to combat antimicrobial resistance.

Crystal structure of the engineered endolysin mtEC340M

Endolysins produced by bacteriophages play essential roles in the release of phage progeny by degrading the peptidoglycan layers of the bacterial cell wall. Bacteriophage-encoded endolysins have emerged as a new class of antibacterial agents to combat surging antibiotic resistance. The crystal structure of mtEC340M, an engineered endolysin EC340 from the PBEC131 phage that infects Escherichia coli, was determined. The crystal structure of mtEC340M at 2.4 Å resolution consists of eight α-helices and two loops. The three active residues of mtEC340M were predicted by structural comparison with peptidoglycan-degrading lysozyme.

Clinical Diagnostics of Bacterial Infections and Their Resistance to Antibiotics-Current State and Whole Genome Sequencing Implementation Perspectives

Antimicrobial resistance (AMR), defined as the ability of microorganisms to withstand antimicrobial treatment, is responsible for millions of deaths annually. The rapid spread of AMR across continents warrants systematic changes in healthcare routines and protocols. One of the fundamental issues with AMR spread is the lack of rapid diagnostic tools for pathogen identification and AMR detection. Resistance profile identification often depends on pathogen culturing and thus may last up to several days. This contributes to the misuse of antibiotics for viral infection, the use of inappropriate antibiotics, the overuse of broad-spectrum antibiotics, or delayed infection treatment. Current DNA sequencing technologies offer the potential to develop rapid infection and AMR diagnostic tools that can provide information in a few hours rather than days. However, these techniques commonly require advanced bioinformatics knowledge and, at present, are not suited for routine lab use. In this review, we give an overview of the AMR burden on healthcare, describe current pathogen identification and AMR screening methods, and provide perspectives on how DNA sequencing may be used for rapid diagnostics. Additionally, we discuss the common steps used for DNA data analysis, currently available pipelines, and tools for analysis. Direct, culture-independent sequencing has the potential to complement current culture-based methods in routine clinical settings. However, there is a need for a minimum set of standards in terms of evaluating the results generated. Additionally, we discuss the use of machine learning algorithms regarding pathogen phenotype detection (resistance/susceptibility to an antibiotic).

A Comparative Study of the Inhibitory Action of Berberine Derivatives on the Recombinant Protein FtsZ of E. coli

Medicinal plants belonging to the genus Berberis may be considered an interesting source of drugs to counteract the problem of antimicrobial multiresistance. The important properties associated with this genus are mainly due to the presence of berberine, an alkaloid with a benzyltetrahydroisoquinoline structure. Berberine is active against both Gram-negative and Gram-positive bacteria, influencing DNA duplication, RNA transcription, protein synthesis, and the integrity of the cell surface structure. Countless studies have shown the enhancement of these beneficial effects following the synthesis of different berberine analogues. Recently, a possible interaction between berberine derivatives and the FtsZ protein was predicted through molecular docking simulations. FtsZ is a highly conserved protein essential for the first step of cell division in bacteria. The importance of FtsZ for the growth of numerous bacterial species and its high conservation make it a perfect candidate for the development of broad-spectrum inhibitors. In this work, we investigate the inhibition mechanisms of the recombinant FtsZ of Escherichia coli by different N-arylmethyl benzodioxolethylamines as berberine simplified analogues appropriately designed to evaluate the effect of structural changes on the interaction with the enzyme. All the compounds determine the inhibition of FtsZ GTPase activity by different mechanisms. The tertiary amine 1c proved to be the best competitive inhibitor, as it causes a remarkable increase in FtsZ Km (at 40 μM) and a drastic reduction in its assembly capabilities. Moreover, a fluorescence spectroscopic analysis carried out on 1c demonstrated its strong interaction with FtsZ (Kd = 26.6 nM). The in vitro results were in agreement with docking simulation studies.

Role of Nanocarrier Systems in Drug Delivery for Overcoming Multi-Drug Resistance in Bacteria

Multidrug-resistant (MDR) bacteria have risen alarmingly in the last few decades, posing a serious threat to human health. The need for effective bacterial resistance treatment is urgent and unmet due to the rise in morbidity and mortality that has coincided with the prevalence of infections caused by MDR bacteria. Using its creative and unconventional methods, effective antibiotics for MDR bacteria could be developed using nanomedicine techniques. To combat microbial resistance, a number of strategies have been developed, including the use of natural bactericides, the introduction of fresh antibiotics, the application of combination therapy and the creation of NP-based antibiotic nanocarriers. The absence of novel antibacterial agents has worsened the situation for MDR bacteria. Ineffective antibiotics used to treat MDR bacteria also contribute to the bacteria's tolerance growing. Nanoparticles (NPs) are the most efficient method for eliminating MDR bacteria because they serve as both carriers of natural antibiotics and antimicrobials and active agents against bacteria. Additionally, surface engineering of nanocarriers has important benefits for focusing on and modifying a variety of resistance mechanisms. The use of nanocarrier systems in drug delivery for overcoming bacterial resistance is covered in this review along with various mechanisms of antibiotic resistance.

Biochemical and molecular mechanisms of antibiotic resistance in Salmonella spp

Salmonella is a diverse Gram-negative bacterium that represents the major disease burden worldwide. According to WHO, Salmonella is one of the fourth global causes of diarrhoeal disease. Antibiotic resistance is a worldwide health concern, and Salmonella spp. is one of the microorganisms that can evade the toxicity of antimicrobials via antibiotic resistance. This review aims to deliver in-depth knowledge of the molecular mechanisms and the underlying biochemical alterations perceived in antibiotic resistance in Salmonella. This information will help understand and mitigate the impact of antibiotic-resistant bacteria on humans and contribute to the state-of-the-art research developing newer and more potent antibiotics.

Recent advances of cell membrane-coated nanoparticles for therapy of bacterial infection

The rapid evolution of antibiotic resistance and the complicated bacterial infection microenvironments are serious obstacles to traditional antibiotic therapy. Developing novel antibacterial agents or strategy to prevent the occurrence of antibiotic resistance and enhance antibacterial efficiency is of the utmost importance. Cell membrane-coated nanoparticles (CM-NPs) combine the characteristics of the naturally occurring membranes with those of the synthetic core materials. CM-NPs have shown considerable promise in neutralizing toxins, evading clearance by the immune system, targeting specific bacteria, delivering antibiotics, achieving responsive antibiotic released to the microenvironments, and eradicating biofilms. Additionally, CM-NPs can be utilized in conjunction with photodynamic, sonodynamic, and photothermal therapies. In this review, the process for preparing CM-NPs is briefly described. We focus on the functions and the recent advances in applications of several types of CM-NPs in bacterial infection, including CM-NPs derived from red blood cells, white blood cells, platelet, bacteria. CM-NPs derived from other cells, such as dendritic cells, genetically engineered cells, gastric epithelial cells and plant-derived extracellular vesicles are introduced as well. Finally, we place a novel perspective on CM-NPs' applications in bacterial infection, and list the challenges encountered in this field from the preparation and application standpoint. We believe that advances in this technology will reduce threats posed by bacteria resistance and save lives from infectious diseases in the future.

Review on the Developments of Benzothiazole-containing Antimicrobial Agents

The infectious diseases caused by bacterial resistance to antibiotics constitute an increasing threat to human health on a global scale. An increasing number of infections, including tuberculosis, pneumonia, salmonellosis and gonorrhea, are becoming progressively challenging to cure owing to the ineffectiveness of current clinically used antibiotics and presents a serious health threat worldwide in medical community. The major concern of this global health threat is the ability of microorganisms to develop one or several mechanisms of resistance to antibiotics, making them inefficient to therapeutic treatment. The quest for discovering novel scaffold with antimicrobial property is particularly in great need to face future challenges in hospital and healthcare settings. Hence, the development of benzothiazoles is of considerable interest to medicinal chemists. Benzothiazole, being part of an important class of heterocyclic scaffold retains a wide spectrum of various attractive pharmacological activities. Antibiotic resistance represents an increasing burden comprising medical cost, hospital stay and mortality. Several derivatives containing a benzothiazole scaffold, reported in the literature, were found to display remarkable potencies towards diverse Grampositive and Gram-negative bacterial pathogens. The principal focus concerns the antibacterial potential of benzothiazole-based derivatives as antimicrobial agents interacting with targets in bacterial pathogens. In this review, we also disclose the significance of the benzothiazole moiety in the discovery of new antibacterial compounds, the potential of benzothiazole-based derivatives in the case of resistant bacterial strains, optimization of their antibacterial activity, and their future perspectives. The structure-activity relationship study and the mode of action of the title derivatives are highlighted too.

Antibiotics in development for multiresistant gram-negative bacilli

The rapid increase in antibiotic(ATB) resistance among Gram-negative bacilli(BGN), especially in strains of Enterobacteriaceae, Pseudomonas aeruginosa, and Acinetobacter baumannii, with high resistance patterns (XDR), poses a huge threat to health systems worldwide. In the last decade, different ATBs have been developed against XDR, some of which combine a lactam β along with a β-lactamase inhibitor, while others use non-β-lactam inhibitors. Most of them have adequate "in vitro" activity on several β-lactamases of class A, C and D of Ambler. However, combinations such as Ceftazidime/avibactam, Ceftolozane/Tazobactam and Meropenem/vaborbactam have no activity against metallo-β-lactamases(MβL). New combinations such as Aztreonan/AVI, Cefepime/Zidebactam, or new cephalosporins such as Cefiderocol, have efficacy against MβL enzymes. Although some of these combinations are already approved and in the commercialization phase, many of them have yet to define their place within the treatment of microorganisms with high resistance through clinical studies.

Molecular characterization and antibiogram of the carbapenemase gene variants in clinical strains of Pseudomonas aeruginosa

BACKGROUND

Carbapenemase-producing Pseudomonas aeruginosa (CPPA) is a substantial clinical concern because it jeopardizes therapeutic choices. This study characterizes the gene variants of CPPA and report its antibiogram.

METHODS

CPPA was isolated prospectively from diverse clinical sources in a tertiary care setting using a routine microbiological approach. Carbapenem-resistant P. aeruginosa strains were phenotypically identified using the modified carbapenem inactivation (mCIM) method. Minimum inhibitory concentration (MIC) breakpoints of several antibacterial drug groups were determined using broth microdilution methods and the MicroScan WalkAway plus system. Carbapenemase gene variants bla_NDM, bla_VIM, bla_OXA,bla_GES, and bla_IMP were amplified using polymerase chain reaction (PCR), and the purified gene products were sequenced.

RESULTS

Seventy-one P. aeruginosa-infected cases were found, with 47 (66.2%) carrying CPPA; 46.8% of the latter were significantly associated with intensive care units (p = 0.03). CPPA was frequently detected in wound swabs (13; 27.7%), sputum (11; 23.4%), and blood (9; 19.1%). All strains were multidrug-resistant (MDR), and several were extensively drug-resistant. MIC₅₀ and MIC₉₀ breakpoints of all antibiotics, except colistin, were within the resistance range. MIC₉₀ breakpoints of aztreonam, amikacin, cefepime, and piperacillin-tazobactam were > 512 µg/mL. The multiple antibiotic resistance index (MARI) was remarkably high, with a range of 0.38-0.92. The most commonly detected carbapenemase genes were bla_VIM (74%), bla_NDM-1 (19%), bla_OXA-23 (14.9%), and bla_GES (10.6%), while 12 of 47 strains co-harbored different combinations of carbapenemase gene variants.

CONCLUSION

A large proportion of CPPA strains carried the bla_VIM gene variant, indicating intimidating health problems and emphasizing the need for extensive surveillance and antibiotic stewardship.

The Association of Organ Preservation Fluid Pathogens with Early Infection-Related Events after Kidney Transplantation

(1) Background: The need to elucidate the microbial patterns in preservation fluid and explore their relationship with early infection-related events post kidney transplant and investigate antimicrobial resistance and the effects of preemptive antibiotic therapy. (2) Methods: This retrospective study analyzed the clinical data of 514 kidney transplant donors and 808 recipients from April 2015 to October 2020. Clinical data of donor and recipient characteristics, preservation fluid microbes, early infections (≤30 days), probable donor-derived infections (P-DDIs), antimicrobial resistance and preemptive antibiotic therapy was collected. (3) Results: The incidence of bloodstream (10.3% versus 5.2%, p = 0.006) and graft-site infections (9.7% versus 4.6%, p = 0.004) was significantly higher in recipients with culture-positive preservation fluid. In addition, recipients with ESKAPE pathogens or Candida species had a notably higher rate of bloodstream infections (14.1% versus 6.9%, p = 0.033) and graft-site infections (16.7% versus 3.5%, p < 0.01) than those with other positive pathogens. Preemptive antibiotic therapy decreased the bloodstream infection rate (11.8% versus 35.7%, p = 0.047) when preservation fluid was positive for ESKAPE pathogens. (4) Conclusions: Culture-positive preservation fluid has potential implications for kidney transplant recipients. ESKAPE pathogens or Candida species in preservation fluid as well as their antimicrobial resistance properties and non-preemptive antibiotic therapy could pose a risk of early infection-related events.

Analysis of the Distribution and Antibiotic Resistance of Pathogens Causing Infections in Hospitals from 2017 to 2019

Background. Antibiotic resistance is a global public health problem, leading to high mortality and treatment costs. To achieve more efficient treatment protocols and better patient recovery, the distribution and drug resistance of pathogens in our hospital were investigated, allowing significant clinical guidance for the use of antimicrobials. Methods. In this retrospective study (2017–2019), 3482 positive samples were isolated from 43,981 specimens in 2017; 3750 positive specimens were isolated from 42,923 specimens in 2018; and 3839 positive pathogens were isolated from 46,341 specimens in 2019. These samples were from various parts of the patients, including the respiratory tract, urine, blood, wound secretions, bile, and puncture fluids. The distribution and antibiotic resistance of these isolated pathogens from the whole hospital were analyzed. Results. The results from pathogen isolation showed that Escherichia coli (12.8%), Staphylococcus aureus (11%), Klebsiella pneumoniae (10.8%), Pseudomonas aeruginosa (10.7%), and Acinetobacter baumannii (6.4%) represented the five main pathogenic bacteria in our hospital. Pseudomonas aeruginosa (16.2% and 17.5%) occupied the largest proportion in the central intensive care unit (central ICU) and respiratory intensive care unit (RICU), while Acinetobacter baumannii (15.4%) was the most common pathogen in the emergency intensive care unit (EICU). The resistance rate of Escherichia coli to trimethoprim and minocycline was 100%, and the sensitivity rate to ertapenem, furantoin, and amikacin was above 90%. The resistance rate of Pseudomonas aeruginosa to all antibiotics, such as piperacillin and ciprofloxacin, was under 40%. The sensitivity rate of Acinetobacter baumannii to tigecycline and minocycline was less than 30%, and the resistance rate to many drugs such as piperacillin, ceftazidime, and imipenem was above 60%. Extended-spectrum β-lactamases (ESBLs)-producing Klebsiella pneumoniae (ESBLs-KPN) and carbapenem-resistant Klebsiella pneumoniae (CRE-KPN), ESBLs-producing Escherichia coli (ESBLs-ECO) and carbapenem-resistant Escherichia coli (CRE-ECO), multidrug-resistant Acinetobacter baumannii (MDR-AB), multidrug-resistant Pseudomonas aeruginosa (MDR-PAE), and methicillin-resistant Staphylococcus aureus (MRSA) are all important multidrug-resistant bacteria found in our hospital. The resistance rate of ESBLs-producing Enterobacteriaceae to ceftriaxone and amcarcillin-sulbactam was above 95%. CRE Enterobacteriaceae bacteria showed the highest resistance to amcarcillin-sulbactam (97.1%), and the resistance rates of MDR-AB to cefotaxime, cefepime, and aztreonam were 100%. The resistance rates of MDR-PAE to ceftazidime, imipenem, and levofloxacin were 100%, and the sensitivity rate to polymyxin B was above 98%. The resistance rate of MRSA to oxacillin was 100%, and the sensitivity rate to linezolid and vancomycin was 100%. Conclusion. The distribution of pathogenic bacteria in different hospital departments and sample sources was markedly different. Therefore, targeted prevention and control of key pathogenic bacteria in different hospital departments is necessary, and understanding both drug resistance and multiple drug resistance of the main pathogenic bacteria may provide guidance for the rational use of antibiotics in the clinic.

Emergence and spread of antibiotic-resistant foodborne pathogens from farm to table

Antibiotics have been overused and misused for preventive and therapeutic purposes. Specifically, antibiotics are frequently used as growth promoters for improving productivity and performance of food-producing animals such as pigs, cattle, and poultry. The increasing use of antibiotics has been of great concern worldwide due to the emergence of antibiotic resistant bacteria. Food-producing animals are considered reservoirs for antibiotic resistance genes (ARGs) and residual antibiotics that transfer from the farm through the table. The accumulation of residual antibiotics can lead to additional antibiotic resistance in bacteria. Therefore, this review evaluates the risk of carriage and spread of antibiotic resistance through food chain and the potential impact of antibiotic use in food-producing animals on food safety. This review also includes in-depth discussion of promising antibiotic alternatives such as vaccines, immune modulators, phytochemicals, antimicrobial peptides, probiotics, and bacteriophages.

Clostridioides difficile Modifies its Aromatic Compound Metabolism in Response to Amidochelocardin-Induced Membrane Stress

Amidochelocardin is a broad-spectrum antibiotic with activity against many Gram-positive and Gram-negative bacteria. According to recent data, the antibiotic effect of this atypical tetracycline is directed against the cytoplasmic membrane, which is associated with the dissipation of the membrane potential. Here, we investigated the effect of amidochelocardin on the proteome of Clostridioides difficile to gain insight into the membrane stress physiology of this important anaerobic pathogen. For the first time, the membrane-directed action of amidochelocardin was confirmed in an anaerobic pathogen. More importantly, our results revealed that aromatic compounds potentially play an important role in C. difficile upon dissipation of its membrane potential. More precisely, a simultaneously increased production of enzymes required for the synthesis of chorismate and two putative phenazine biosynthesis proteins point to the production of a hitherto unknown compound in response to membrane depolarization. Finally, increased levels of the ClnAB efflux system and its transcriptional regulator ClnR were found, which were previously found in response to cationic antimicrobial peptides like LL-37. Therefore, our data provide a starting point for a more detailed understanding of C. difficile's way to counteract membrane-active compounds. IMPORTANCE C. difficile is an important anaerobe pathogen causing mild to severe infections of the gastrointestinal tract. To avoid relapse of the infection following antibiotic therapy, antibiotics are needed that efficiently eradicate C. difficile from the intestinal tract. Since C. difficile was shown to be substantially sensitive to membrane-active antibiotics, it has been proposed that membrane-active antibiotics might be promising for the therapy of C. difficile infections. Therefore, we studied the response of C. difficile to amidochelocardin, a membrane-active antibiotic dissipating the membrane potential. Interestingly, C. difficile's response to amidochelocardin indicates a role of aromatic metabolites in mediating stress caused by dissipation of the membrane potential.

A comprehensive review on genomics, systems biology and structural biology approaches for combating antimicrobial resistance in ESKAPE pathogens: computational tools and recent advancements

In recent decades, antimicrobial resistance has been augmented as a global concern to public health owing to the global spread of multidrug-resistant strains from different ESKAPE pathogens. This alarming trend and the lack of new antibiotics with novel modes of action in the pipeline necessitate the development of non-antibiotic ways to treat illnesses caused by these isolates. In molecular biology, computational approaches have become crucial tools, particularly in one of the most challenging areas of multidrug resistance. The rapid advancements in bioinformatics have led to a plethora of computational approaches involving genomics, systems biology, and structural biology currently gaining momentum among molecular biologists since they can be useful and provide valuable information on the complex mechanisms of AMR research in ESKAPE pathogens. These computational approaches would be helpful in elucidating the AMR mechanisms, identifying important hub genes/proteins, and their promising targets together with their interactions with important drug targets, which is a crucial step in drug discovery. Therefore, the present review aims to provide holistic information on currently employed bioinformatic tools and their application in the discovery of multifunctional novel therapeutic drugs to combat the current problem of AMR in ESKAPE pathogens. The review also summarizes the recent advancement in the AMR research in ESKAPE pathogens utilizing the in silico approaches.

Pathogenesis-Related Gene Expression in Response to Trachyspermum ammi Supplementation Along With Probiotics in Chicken Salmonellosis and Insights in Drug Therapeutics

Salmonella enterica serovar typhimurium (S. typhimurium) is the leading cause of foodborne illness. Since Salmonella continues to have a detrimental effect on public health, there is an ongoing need to develop more advanced methods for combating Salmonellosis in foods before they reach consumers. In addition, the quest for alternative natural products has recently intensified due to increasingly stringent regulations regarding the use of antibiotics as growth promoters and consumer demand for antibiotic-free poultry products. This study evaluated the effect of Ajwain extract (AJE) on immune response and antioxidant status in broiler chicks challenged with Salmonella typhimurium. The chicks were infected with S. typhimurium and were divided into the different groups, except for the control group (CON). The challenged chicks received different treatments with 3 × 109 colony-forming unit (CFU) AciproTM-WS probiotic (PRO), 200 mg/kg Ajwain extract (AJE), 200 mg/100 kg of enrofloxacin (ENR), and a combination of 3 × 109 CFU AciproTM-WS probiotic and 200 mg/kg Ajwain extract (COM). Five days posttreatment, the tissue samples (liver and spleen) were analyzed. The results showed that basal diet supplemented with Ajwain extract (AJE) and a combination of probiotic and Ajwain extract (COM) significantly (P &lt; 0.0.5) reduced the cytokine expression in broiler chicks challenged with S. typhimurium. Our findings suggest that AJE can clear the bacterial infection, improve antioxidant status, and suppress the inflammation response. Additionally, AJE supplementation significantly mitigated the S. typhimurium-induced increase in the interleukin-6 (IL-6) (liver and spleen), interleukin-8 (IL-8) (liver and spleen), interleukin-17A (IL-17A) (liver and spleen), and inducible nitric oxide (iNOS) (spleen and liver) levels (P &lt; 0.05). We conclude that Ajwain is an efficient feed additive with antioxidant and anti-inflammatory properties. The interaction networks developed in this study provide a novel lead that could be targeted for anti-inflammatory and antioxidant properties.

Vaccinomics to Design a Multi-Epitopes Vaccine for Acinetobacter baumannii

Antibiotic resistance (AR) is the result of microbes’ natural evolution to withstand the action of antibiotics used against them. AR is rising to a high level across the globe, and novel resistant strains are emerging and spreading very fast. Acinetobacter baumannii is a multidrug resistant Gram-negative bacteria, responsible for causing severe nosocomial infections that are treated with several broad spectrum antibiotics: carbapenems, β-lactam, aminoglycosides, tetracycline, gentamicin, impanel, piperacillin, and amikacin. The A. baumannii genome is superplastic to acquire new resistant mechanisms and, as there is no vaccine in the development process for this pathogen, the situation is more worrisome. This study was conducted to identify protective antigens from the core genome of the pathogen. Genomic data of fully sequenced strains of A. baumannii were retrieved from the national center for biotechnological information (NCBI) database and subjected to various genomics, immunoinformatics, proteomics, and biophysical analyses to identify potential vaccine antigens against A. baumannii. By doing so, four outer membrane proteins were prioritized: TonB-dependent siderphore receptor, OmpA family protein, type IV pilus biogenesis stability protein, and OprD family outer membrane porin. Immuoinformatics predicted B-cell and T-cell epitopes from all four proteins. The antigenic epitopes were linked to design a multi-epitopes vaccine construct using GPGPG linkers and adjuvant cholera toxin B subunit to boost the immune responses. A 3D model of the vaccine construct was built, loop refined, and considered for extensive error examination. Disulfide engineering was performed for the stability of the vaccine construct. Blind docking of the vaccine was conducted with host MHC-I, MHC-II, and toll-like receptors 4 (TLR-4) molecules. Molecular dynamic simulation was carried out to understand the vaccine-receptors dynamics and binding stability, as well as to evaluate the presentation of epitopes to the host immune system. Binding energies estimation was achieved to understand intermolecular interaction energies and validate docking and simulation studies. The results suggested that the designed vaccine construct has high potential to induce protective host immune responses and can be a good vaccine candidate for experimental in vivo and in vitro studies.

Silver and Gold Nanoparticles for Antimicrobial Purposes against Multi-Drug Resistance Bacteria

Several pieces of research have been done on transition metal nanoparticles and their nanocomplexes as research on their physical and chemical properties and their relationship to biological features are of great importance. Among all their biological properties, the antibacterial and antimicrobial are especially important due to their high use for human needs. In this article, we will discuss the different synthesis and modification methods of silver (Ag) and gold (Au) nanoparticles and their physicochemical properties. We will also review some state-of-art studies and find the best relationship between the nanoparticles' physicochemical properties and potential antimicrobial activity. The possible antimicrobial mechanism of these types of nanoparticles will be discussed in-depth as well.