Drug-resistant Strains Research Articles

Using a Bacterial Protein to Selectively Target Bacterial Biofilms: Treatment of S. epidermidis Biofilms with Targeted Photothermal Gold Nanoparticles.

Biofilm-related infections are associated with high mortality and morbidity, combined with increased treatment costs. Traditional antibiotics are becoming less effective due to the emergence of drug-resistant bacterial strains. The need to treat biofilms on medical implants is particularly acute, and one persistent challenge is selectively directing nanoparticles to the biofilm site. Here, we present a protein-based functionalization strategy that targets the extracellular matrix of biofilms. The protein, derived from the extracellular Staphylococcus epidermidis autolysin, directs nanoparticles to S. epidermidis cell wall components, which are not expected to be present in mammalian tissues. This functionalization is applied to a gold nanoparticle (AuNP) core, along with elastin-like polypeptides (ELPs), which generate a robust photothermal response. In addition to biofilm targeting, the particles exhibit low protein binding, and the photothermal conversion can be modulated by changing the ELP transition temperature. These functionalized AuNPs strongly interact with biofilms under static and flow conditions but exhibit weak interactions with serum-coated surfaces. Near-infrared laser irradiation resulted in a 10,000-fold improvement in killing efficiency compared to untreated controls (p < 0.0001). The targeting strategy utilized here represents a versatile approach to targeting drug-resistant infections and could be readily expanded to other anti-biofilm nanoparticle platforms.

Distinctive features and prognostic utility of neutrophil in severe patients with Klebsiella pneumoniae infection.

Neutrophil plays a pivotal role in the management of Klebsiella pneumoniae infection. Delineate the clinical characteristics and prognostic utility of neutrophil in severe patients with K. pneumoniae infection are crucial for clinical management and prognostic assessment. K. pneumoniae patients with different infection sites were enrolled from Medical Information Mart for Intensive Care IV and eICU Collaborative Research Database. Temporal variations of neutrophil counts within 30 days of clinical onset were examined using locally weighted scatterplot smoothing curves. Logistic regression analysis was performed to assess the relationship between neutrophil counts and hospital mortality. A total of 1,705 patients caused by K. pneumonia were included in the study. The non-survivor group exhibited a comparatively older age and a higher proportion of K. pneumoniae infections originating from respiratory and bloodstream sources compared to the survivor group (38.4% vs 21.1%, p<0.0001, and 15.1% vs 10.3%, p=0.021). Patients combined with multiple drug resistance strains, respiratory infection, liver disease, and above 60 years exhibited a specific dynamic process of neutrophil levels. Neutrophils counts peaked at admission and 1-2 weeks later. There was a 'U'-shaped relationship between neutrophil counts and hospital mortality. Neutrophils in K. pneumoniae infected patients have distinctive features and dynamic clinical trajectories. Close monitoring of severe patients infected with K. pneumoniae upon admission and during the first 1-2 weeks after admission is of utmost importance, particularly for patients with a neutrophil count exceeding 8.0×109/L.

Tuberculosis Diagnosis: Current, Ongoing, and Future Approaches.

Tuberculosis (TB) remains an impactful infectious disease, leading to millions of deaths every year. Mycobacterium tuberculosis causes the formation of granulomas, which will determine, through the host-pathogen relationship, if the infection will remain latent or evolve into active disease. Early TB diagnosis is life-saving, especially among immunocompromised individuals, and leads to proper treatment, preventing transmission. This review addresses different approaches to diagnosing TB, from traditional methods such as sputum smear microscopy to more advanced molecular techniques. Integrating these techniques, such as polymerase chain reaction (PCR) and loop-mediated isothermal amplification (LAMP), has significantly improved the sensitivity and specificity of M. tuberculosis identification. Additionally, exploring novel biomarkers and applying artificial intelligence in radiological imaging contribute to more accurate and rapid diagnosis. Furthermore, we discuss the challenges of existing diagnostic methods, including limitations in resource-limited settings and the emergence of drug-resistant strains. While the primary focus of this review is on TB diagnosis, we also briefly explore the challenges and strategies for diagnosing non-tuberculous mycobacteria (NTM). In conclusion, this review provides an overview of the current landscape of TB diagnostics, emphasizing the need for ongoing research and innovation. As the field evolves, it is crucial to ensure that these advancements are accessible and applicable in diverse healthcare settings to effectively combat tuberculosis worldwide.

Pathogenic organism and risk factors of infection after acute ischemic stroke during the COVID-19 pandemic

This study aims to determine the pathogen organisms’ profile and risk factors for infection after acute ischemic stroke (AIS) during the COVID-19 pandemic because of few studies. We conducted a retrospective cross-sectional study using the medical records of AIS inpatients at the National Brain Center Hospital Prof. Dr. dr. Mahar Mardjono, Jakarta, Indonesia, from 2020-2021. We found the species of pathogen organisms based on the positive growth of microbiological cultures of various specimens. Among 479 AIS patients, the infection prevalence was 12.3%. This study found the common pathogenic organisms were Gram-negative bacteria, and there were drug-resistant strains in &lt;i&gt;S. aureus, S. epidermidis, K. pneumoniae,&lt;/i&gt; and &lt;i&gt;E. coli. &lt;/i&gt;The risk factors for infection in COVID-19-infected patients were pneumonia (OR 6.89, 95% CI 1.49-31.79, &lt;i&gt;p &lt;/i&gt;= 0.013) and intensive care stay (OR 0.13, 95% CI 0.05-0.36, &lt;i&gt;p &lt;/i&gt;&amp;lt; 0.001); meanwhile, in non-COVID-19 patients were HIV comorbidity (OR 1.55, 95% CI 1.18-2.06, &lt;i&gt;p &lt;/i&gt;= 0.002), leukocytosis (OR 0.07, 95% CI 0.01-0.43, &lt;i&gt;p &lt;/i&gt;= 0.004), use of CVC (OR 0.29, 95% CI 0.12-0.68, &lt;i&gt;p &lt;/i&gt;= 0.005), use of steroids (OR 0.21, 95% CI 0.06-0.70, &lt;i&gt;p &lt;/i&gt;= 0.011), and tracheostomy (OR 0.17, 95% CI 0.05-0.62, &lt;i&gt;p &lt;/i&gt;= 0.007). To sum up, the growth of pathogenic organisms indicated that the prevalence of infections after AIS during the COVID-19 pandemic did not increase. The risk factor for infections depends on the characteristics of patients, whether they have COVID-19 or have not been infected.

Drug resistance and genomic variations among Mycobacterium tuberculosis isolates from The Nile Delta, Egypt

Tuberculosis is a global public health concern. Earlier reports suggested the emergence of high rates of drug resistant tuberculosis in Egypt. This study included 102 isolates of Mycobacterium tuberculosis collected from two reference laboratories in Cairo and Alexandria. All clinical isolates were sub-cultured on Löwenstein–Jensen medium and analyzed using both BD BACTEC MGIT 960 SIRE Kit and standard diffusion disk assays to identify the antibiotic sensitivity profile. Extracted genomic DNA was subjected to whole genome sequencing (WGS) using Illumina platform. Isolates that belong to lineage 4 represented > 80%, while lineage 3 represented only 11% of the isolates. The percentage of drug resistance for the streptomycin, isoniazid, rifampicin and ethambutol were 31.0, 17.2, 19.5 and 20.7, respectively. Nearly 47.1% of the isolates were sensitive to the four anti-tuberculous drugs, while only one isolate was resistant to all four drugs. In addition, several new and known mutations were identified by WGS. High rates of drug resistance and new mutations were identified in our isolates. Tuberculosis control measures should focus on the spread of mono (S, I, R, E)- and double (S, E)-drug resistant strains present at higher rates throughout the whole Nile Delta, Egypt.

Transcriptomic Analyses to Unravel Cronobacter sakazakii Resistance Pathways.

The proliferation of antibiotic usage has precipitated the emergence of drug-resistant variants of bacteria, thereby augmenting their capacity to withstand pharmaceutical interventions. Among these variants, Cronobacter sakazakii (C. sakazakii), prevalent in powdered infant formula (PIF), poses a grave threat to the well-being of infants. Presently, global contamination by C. sakazakii is being observed. Consequently, research endeavors have been initiated to explore the strain's drug resistance capabilities, alterations in virulence levels, and resistance mechanisms. The primary objective of this study is to investigate the resistance mechanisms and virulence levels of C. sakazakii induced by five distinct antibiotics, while concurrently conducting transcriptomic analyses. Compared to the susceptible strains prior to induction, the drug-resistant strains exhibited differential gene expression, resulting in modifications in the activity of relevant enzymes and biofilm secretion. Transcriptomic studies have shown that the expression of glutathione S-transferase and other genes were significantly upregulated after induction, leading to a notable enhancement in biofilm formation ability, alongside the existence of antibiotic resistance mechanisms associated with efflux pumps, cationic antimicrobial peptides, and biofilm formation pathways. These alterations significantly influence the strain's resistance profile.

The Effect of Mesenchymal Stem Cells on the Wound Infection.

Wound infection often requires a long period of care and an onerous treatment process. Also, the rich environment makes the wound an ideal niche for microbial growth. Stable structures, like biofilm, and drug-resistant strains cause a delay in the healing process, which has become one of the important challenges in wound treatment. Many studies have focused on alternative methods to deal the wound infections. One of the novel and highly potential ways is mesenchymal stromal cells (MSCs). MSCs are mesoderm-derived pluripotent adult stem cells with the capacity for self-renewal, multidirectional differentiation, and immunological control. Also, MSCs have anti-inflammatory and antiapoptotic effects. MScs, as pluripotent stromal cells, differentiate into many mature cells. Also, MSCs produce antimicrobial compounds, such as antimicrobial peptides (AMP), as well as secrete immune modulators, which are two basic features considered in wound healing. Despite the advantages, preserving the structure and activity of MSCs is considered one of the most important points in the treatment. MSCs' antimicrobial effects on microorganisms involved in wound infection have been confirmed in various studies. In this review, we aimed to discuss the antimicrobial and therapeutic applications of MSCs in the infected wound healing processes.

Salmonella Typhi: A Review of Antibiogram Journey in Developing Countries.

Typhoid fever poses a significant health challenge in low- and middleincome countries (LMiCs), impacting millions of individuals across various age groups. Its prevalence is particularly pronounced in South Asia. Factors contributing to its transmission in South Asia include rapid unplanned urbanization, urban-rural disparities, provision of poor water and sanitation facilities, and open defecation. The mortality rate of typhoid fever is up to 1%, and those who survive have a protracted period of poor health and carry an enormous financial burden. The treatment is further complicated by the emerging antibiotic resistance leaving few treatment options in hands. This issue has become more urgent due to the further emergence of extended drug-resistant (XDR) and multidrug-resistant (MDR) typhoid strains, as well as their subsequent global spread. Fluoroquinolone-resistant Salmonella spp. is currently classified by the World Health Organization (WHO) as a high (Priority 2) pathogen. As a result, establishing minimum inhibitory concentrations (MIC) according to the latest guidelines may prove effective in treating typhoid fever and minimizing the rising threat of drug resistance.

Management of Refractory/Resistant Herpes Simplex Virus Infections in Haematopoietic Stem Cell Transplantation Recipients: A Literature Review.

Herpes simplex virus (HSV) infections in allogeneic haematopoietic stem cell transplantation (HSCT) recipients pose significant challenges, with higher incidence, severity, and risk of emergence of resistance to antivirals due to impaired T-cell mediated immunity. This literature review focuses on acyclovir-refractory/resistant HSV infections in HSCT recipients. The review addresses the efficacy of antiviral prophylaxis, the incidence of acyclovir-refractory/resistant HSV infections, and the identification of risk factors and potential prognostic impact associated with those infections. Additionally, alternative therapeutic options are discussed. While acyclovir prophylaxis demonstrates a significant benefit in reducing HSV infections in HSCT recipients and, in some cases, overall mortality, concerns arise about the emergence of drug-resistant HSV strains. Our systematic review reports a median incidence of acyclovir-resistant HSV infections of 16.1%, with an increasing trend in recent years. Despite limitations in available studies, potential risk factors of emergence of HSV resistance to acyclovir include human leucocyte antigen (HLA) mismatches, myeloid neoplasms and acute leukaemias, and graft-versus-host disease (GVHD). Limited evidences suggest a potentially poorer prognosis for allogeneic HSCT recipients with acyclovir-refractory/resistant HSV infection. Alternative therapeutic approaches, such as foscarnet, cidofovir, topical cidofovir, optimised acyclovir dosing, and helicase-primase inhibitors offer promising options but require further investigations. Overall, larger studies are needed to refine preventive and therapeutic strategies for acyclovir-refractory/resistant HSV infections in allogeneic HSCT recipients and to identify those at higher risk.

Mycobacterial Targets for Thiourea Derivatives: Opportunities for Virtual Screening in Tuberculosis Drug Discovery.

Tuberculosis (TB) remains a primary global health concern, necessitating the discovery and development of new anti-TB drugs, mainly to combat drug-resistant strains. In this context, thiourea derivatives have emerged as promising candidates in TB drug discovery due to their diverse chemical structures and pharmacological properties. This review aimed to explore this potential, identifying and exploring molecular targets for thiourea derivatives in Mycobacterium tuberculosis (Mtb) and the potential application of virtual screening techniques in drug discovery. We have compiled a comprehensive list of possible molecular targets of thiourea derivatives in Mtb. The enzymes are primarily involved in the biosynthesis of various cell wall components, including mycolic acids, peptidoglycans, and arabinans, or targets in the branched-chain amino acid biosynthesis (BCAA) pathway and detoxification mechanisms. We discuss the potential of these targets as critical constituents for the design of novel anti-TB drugs. Besides, we highlight the opportunities that virtual screening methodologies present in identifying potential thiourea derivatives that can interact with these molecular targets. The presented findings contribute to the ongoing efforts in TB drug discovery and lay the foundation for further research in designing and developing more effective treatments against this devastating disease.

In silico analysis of drug-resistant genes of Staphylococcus aureus

Drug-resistant strains of pathogenic bacteria are recently considered a devastating health problem. Staphylococcus aureus is a bacterium that commonly lives on the skin and in the nasal passages of approximately one-third of the population without causing any harm. One of the major concerns with Staphylococcus aureus is its ability to develop antibiotic resistance. Drug-resistant genes play an important role in determining the characteristics of bacteria mechanisms of drug resistance. The identification of promoters in a gene is an important part of the recognition of a gene's complete structure. An in silico study was done to analyze the promoter regions and transcription factors with the aid of the transcription start site, regulatory elements, and motifs of genes. Most of the predicted transcription start sites (75 %) were found above 500 bp value either upstream or downstream from the start codon of the gene being expressed. Motif I was identified as the most common motif for the predicted genes, which serves as binding sites to regulate the expression of the genes. A variety of regulatory elements including enhancers, insulators, transcription factors, and cellular proteins are involved in the regulation of gene expression. In general, in silico analysis of drug-resistant genes of Staphylococcus aureus could provide valuable insights about the transcription factor binding, and gene regulatory elements in the promoter regions that can lead to promising research targets in drug designing and development. Therefore, further studies should be made to study resistance-related proteins, the protein-protein interaction networks, the pathways involved in mechanisms underlying resistance, and facilitating the design of target-specific drugs.

Reaction-Induced Self-Assembly of Polymyxin Mitigates Cytotoxicity and Reverses Drug Resistance.

Polymyxins have been regarded as an efficient therapeutic against many life-threatening, multidrug resistant Gram-negative bacterial infections; however, the cytotoxicity and emergence of drug resistance associated with polymyxins have greatly hindered their clinical potential. Herein, the reaction-induced self-assembly (RISA) of polymyxins and natural aldehydes in aqueous solution is presented. The resulting assemblies effectively mask the positively charged nature of polymyxins, reducing their cytotoxicity. Moreover, the representative PMBA4 (composed of polymyxin B (PMB) and (E)-2-heptenal (A4)) assemblies demonstrate enhanced binding to Gram-negative bacterial outer membranes and exhibit multiple antimicrobial mechanisms, including increased membrane permeability, elevated bacterial metabolism, suppression of quorum sensing, reduced ATP synthesis, and potential reduction of bacterial drug resistance. Remarkably, PMBA4 assemblies reverse drug resistance in clinically isolated drug-resistant strains of Gram-negative bacteria, demonstrating exceptional efficacy in preventing and eradicating bacterial biofilms. PMBA4 assemblies efficiently eradicate Gram-negative bacterial biofilm infections in vivo and alleviate inflammatory response. This RISA strategy offers a practical and clinically applicable approach to minimize side effects, reverse drug resistance, and prevent the emergence of resistance associated with free polymyxins.

Harnessing PROTACs to combat H5N1 influenza: A new frontier in viral destruction.

H5N1, a highly pathogenic avian influenza virus, poses an ongoing and significant threat to global public health, primarily due to its potential to cause severe respiratory illness and high mortality rates in humans. Despite extensive efforts in vaccination and antiviral therapy, H5N1 continues to exhibit high mutation rates, resulting in recurrent outbreaks and the emergence of drug-resistant strains. Traditional antiviral therapies, such as neuraminidase inhibitors and M2 ion channel blockers, have demonstrated limited efficacy, necessitating the exploration of innovative therapeutic strategies. Proteolysis-targeting chimeras (PROTACs) emerge as a novel and promising approach, leveraging the ubiquitin-proteasome system to selectively degrade pathogenic proteins. Unlike conventional inhibitors that only block protein function, PROTACs eliminate the target protein, providing a sustained therapeutic effect and potentially reducing the development of resistance. This paper offers a comprehensive examination of the current landscape of H5N1 infections, detailing the pathogenesis and challenges associated with existing treatments. It further explores the mechanism of action, design, and therapeutic potential of PROTACs in inhibiting H5N1. By targeting essential viral proteins, such as hemagglutinin and the RNA-dependent RNA polymerase complex, PROTACs hold the potential to revolutionize the treatment of H5N1 infections, offering a new frontier in antiviral therapy.

Effect of a thiohydantoin salt derived from l-Arginine on Leishmania amazonensis and infected cells: Insights from biological effects to molecular docking interactions

Leishmaniasis is a neglected tropical disease caused by parasites of the genus Leishmania and is responsible for more than 1 million new cases and 70,000 deaths annually worldwide. Treatment has high costs, toxicity, complex and long administration time, several adverse effects, and drug-resistant strains, therefore new therapies are urgently needed. Synthetic compounds have been highlighted in the medicinal chemistry field as a strong option for drug development against different diseases. Organic salts (OS) have multiple biological activities, including activity against protozoa such as Leishmania spp. This study aimed to investigate the in vitro leishmanicidal activity and death mechanisms of a thiohydantoin salt derived from l-arginine (ThS) against Leishmania amazonensis. We observed that ThS treatment inhibited promastigote proliferation, increased ROS production, phosphatidylserine exposure and plasma membrane permeabilization, loss of mitochondrial membrane potential, lipid body accumulation, autophagic vacuole formation, cell cycle alteration, and morphological and ultrastructural changes, showing parasites death. Additionally, ThS presents low cytotoxicity in murine macrophages (J774A.1), human monocytes (THP-1), and sheep erythrocytes. ThS in vitro cell treatment reduced the percentage of infected macrophages and the number of amastigotes per macrophage by increasing ROS production and reducing TNF-α levels. These results highlight the potential of ThS among thiohydantoins, mainly related to the arginine portion, as a leishmanicidal drug for future drug strategies for leishmaniasis treatment. Notably, in silico investigation of key targets from L. amazonensis, revealed that a ThS compound from the l-arginine amino acid strongly interacts with arginase (ARG) and TNF-α converting enzyme (TACE), suggesting its potential as a Leishmania inhibitor.

Lactam Truncation Yields a Dihydroquinazolinone Scaffold with Potent Antimalarial Activity that Targets PfATP4.

The emergence of resistance against current antimalarial treatments has necessitated the need for the development of novel antimalarial chemotypes. Toward this goal, we recently optimised the antimalarial activity of the dihydroquinazolinone scaffold and showed it targeted PfATP4. Here, we deconstruct the lactam moiety of the tricyclic dihydroquinazolinone scaffold and investigate the structure-activity relationship of the truncated scaffold. It was shown that SAR between scaffolds was largely transferrable and generated analogues with potent asexual stage activity. Evaluation of the truncated analogues against PfATP4 mutant drug resistant parasite strains and in assays measuring PfATP4-associated ATPase activity demonstrated retention of PfATP4 as the molecular target. Analogues exhibited activity against both male and female gametes and multidrug resistant parasites. Limited efficacy of analogues in a P. berghei asexual stage mouse model was attributed to their moderate metabolic stability and low aqueous stability. Further development is required to address these attributes toward the potential use of the dihydroquinazolinone class in a curative and transmission blocking combination antimalarial therapy.

Design, synthesis and docking studies of new molecular hybrids bearing benzimidazole and thiazolidine-2,4-dione as potential antitubercular agents

Finding novel therapeutic medications to combat tuberculosis (TB) is crucial, as evidenced by the disease's growth as a worldwide health concern in recent decades and the rise of drug-resistant forms of Mycobacterium tuberculosis (Mtb). In this article, we describe the synthesis and design of a novel class of thiazolidine-2,4-dione derivatives (5a-i) based on 1H-benzo [d]imidazoles as antitubercular drugs. Spectroscopic techniques and elemental analysis were used to characterize each of the newly synthesized molecules. The antitubercular activity of all the newly synthesized title compounds was assessed against drug-sensitive Mtb H37Rv, multidrug-resistant (MDR-TB), and extensively drug-resistant (XDR-TB) tuberculosis. Compounds 5e and 5 h had the most antitubercular activity among all the newly synthesized hybrids against drug-sensitive, MDR-TB, and XDR-TB strains, with MIC values ranging from 0.21 to 47.84 μM. When it comes to drug-sensitive, drug-resistant, and XDR Mtb strains, compound 5 h with a trifluoromethyl group is 1.71, 10.86, and 3.50 times more potent, whereas compound 5e with a nitro group is 1.12, 8.50, and 2.61 times more active. Remarkably, the compounds' in vitro cytotoxicity test demonstrated good selectivity indices, highlighting their safety on the normal lung fibroblast (WI-38) cell line experiment. To further understand the interactions between potent hybrids and the target enzyme, molecular docking investigations were conducted against the decaprenyl-phosphoryl-ribose 2′-epimerase (DprE1) enzyme. The target protein exhibited preferentially positive interactions with the potent compounds 5e, 5f, 5 h, and 5i. Relationships between structure-activity as well as drug-likeness were used to connect the freshly synthesized compounds' physical and biological properties. When considered collectively, these results suggest that compounds 5e and 5 h might be promising candidates for the development of drug-sensitive and drug-resistant TB therapies in the future.

Antibacterial, Antibiofilm, and Wound Healing Activities of Rutin and Quercetin and Their Interaction with Gentamicin on Excision Wounds in Diabetic Mice.

Phytochemicals are effective and are gaining attention in fighting against drug-resistant bacterial strains. In the present study, rutin and quercetin were tested for antibacterial, antibiofilm, and wound healing activities on excision wounds infected with MDR-P. aeruginosa in diabetic mice. Antibacterial and antibiofilm activities were studied in vitro using broth dilution assay and crystal violet assay, respectively. These phytochemicals were tested alone for wound-healing activities at different concentrations (0.5% and 1% in ointment base) and in combination with gentamicin to evaluate any additive effects. Rutin and quercetin demonstrated effectiveness against MDR-P. aeruginosa at higher concentrations. Both phytochemicals inhibited biofilm formation in vitro and contributed to the healing of diabetic wounds by eradicating biofilm in the wounded tissue. Rutin at a low concentration (0.5%) had a lesser effect on reducing the epithelization period and regeneration of the epithelial layer compared to quercetin. When combined with gentamicin, quercetin (1%) displayed the maximum effect on epithelium regeneration, followed by rutin (1%) in combination with gentamicin. Both phytochemicals were found to be more effective in controlling biofilm and wound-healing activities when used as an additive with gentamicin. The study supports the traditional use of phytochemicals with antibacterial, antibiofilm, and wound-healing activities in managing diabetic infections.

Synthesis of Graphene@C3N4-Cu Beads Nanocomposites and their Antimicrobial Efficacy Against Drug-Resistant Bacteria and Fungi.

Increased intake of drugs worldwide and the subsequent advent of resistance to existing antibiotics have globally threatened health organizations. To combat the problem of these drug-resistant infections, as an alternative approach, graphene (GN)-related nanomaterials have attracted significant interest because of their effective anti-microbial potential. The present study shows the synthesis and characterization of nanocomposite of GN with carbon nitride viz. g- C3N4, g-C3N4-Cu, and GN@g-C3N4-Cu. Further, we investigated the anti-microbial potential of these nanocomposites against strains of Gram-negative and Gram-positive bacteria, viz., a multidrug- resistant strain of Pseudomonas aeruginosa (MDRPA), a methicillin-resistant strain of Staphylococcus aureus ATCC33593 (MRSA), and an azole-sensitive fungal strain (Candida albicans ATCC14053). The morphological characterization of GN@g-C3N4-Cu nanocomposite was executed by scanning electron microscopy, whereas the elemental analysis and their distribution were studied by energy-dispersive X-ray spectroscopy and elemental mapping methods. Furthermore, the anti-microbial and antibiofilm efficacies of g-C3N4, g-C3N4-Cu, and GN@g-C3N4-Cu nanocomposites were evaluated by disc diffusion, two-fold serial micro broth dilution, and 96 well microtiter plate methods. The ternary g-C3N4-Cu@GN, apart from the structures of g-C3N4-Cu, showed big sheets of GN. The observance of C, N, O, and Cu in the elemental analysis, as well as their uniform distribution in the mapping, indicated the successful fabrication of g-C3N4-Cu@GN. GN@g-C3N4-Cu followed by g-C3N4-Cu and (g-C3N4) exhibited significantly higher antimicrobial activity (zone of inhibition from 14.33 to 49.33 mm) against both the drug-resistant bacterial strains and azole-sensitive C. albicans. MICs of nanocomposites ranged from 32 -256 μg/ml against the tested strains. Whereas all three nanocomposites at sub-MICs (0.25 A- and 0.5 A- MICs) showed concentration- dependent inhibition of biofilm formation in MDRPA, MRSA, and C. albicans by allowing 11.35% to 32.59% biofilm formation. Our study highlights the enhanced efficiency of GN@g-C3N4-Cu nanocomposites as potential anti-microbial and antibiofilm agents to overcome the challenges of multi-drug-resistant bacteria and azole-sensitive fungi. Such kind of nanocomposites could be used to prevent nosocomial infections if coated on medical devices and food manufacturing instruments.

Unraveling the genetic basis of antibiotic resistance in Staphylococcus aureus: Focus on mecA and PVL Genes

Background Staphylococcus aureus infections, including Methicillin-Resistant S. aureus (MRSA) and Methicillin-Sensitive S. aureus (MSSA), present significant challenges in healthcare due to rising antimicrobial resistance. This study evaluates the genetic basis of antibiotic resistance in S. aureus, focusing on key resistance-associated genes mecA and PVL. Methods A total of 568 clinical specimens were analyzed for the presence of S. aureus. Demographic data were collected to assess age-dependent prevalence. Antimicrobial susceptibility testing was conducted to evaluate resistance patterns. The prevalence of the mecA and PVL genes was determined using molecular techniques. Results S. aureus was identified in 37.9% of cases, with the highest prevalence (60-79 age group). All S. aureus isolates showed 100% resistance to penicillin. Multidrug-resistant (MDR) strains accounted for 84.19% of isolates, with a significant presence of extensively drug-resistant (XDR) strains. The mecA gene was prevalent in 82.79% of MRSA isolates, indicating its strong association with methicillin resistance. Additionally, 41.86% of all S. aureus isolates were positive for the PVL gene, highlighting its widespread distribution. Conclusions The high prevalence of mecA and PVL genes in S. aureus strains underscores the challenges in managing these infections. These findings emphasize the necessity for judicious antibiotic use and enhanced collaborative efforts to combat antimicrobial resistance. Understanding the genetic basis of resistance can inform more effective diagnostic, therapeutic, and preventive strategies, ultimately improving patient outcomes in S. aureus infections.

Acinetobacter baumannii transformants expressing oxacillinases and metallo-β-lactamases that confer resistance to meropenem: new tools for anti-Acinetobacter drug development and AMR preparedness.

Antimicrobial resistance (AMR) in Acinetobacter baumannii is an unmet medical need. Multiple drug-resistant/extremely drug-resistant strains of A. baumannii do not display growth well in in vivo models, and consequently, their response to antibacterial therapy is inconsistent. We addressed this issue by engineering carbapenem resistance motifs into the highly virulent genetic background of A. baumannii AB5075. This strain has a chromosomally encoded oxa-23 that was deleted (Δoxa-23), then plasmids expressing oxa-23, oxa-24/40, oxa-58, imp-1, vim-2, and ndm-1 were introduced to create the mutant strains. Each transformant was used as a challenge strain in a neutropenic murine thigh infection model and assessed for the extent of growth and response to meropenem 200 mg/kg subcutaneously every 6 h (q6h). Pharmacodynamic analyses were performed by transforming drug exposure from dose (mg/kg) to the fraction of the dosing interval; free meropenem concentrations were >minimum inhibitory concentration (MIC) (fT > MIC). AB5075 and the AB5075Δoxa-23 mutant had a MICs of 32 and 4 mg/L, respectively. The transformants harboring oxacillinases oxa-24/40 and oxa-58 had an MIC of 64 mg/L. The metallo-β-lactamases imp-1, vim-2, and ndm-1 had MICs of 128, 64, and 64 mg/L, respectively. All vehicle-treated transformants displayed in vivo growth in the range of 0.75-1.4 log. The response to meropenem was consistent with the varying fT > MIC of the transformants and was readily described by an inhibitory sigmoid Emax relationship. Stasis was achieved with a fT > MIC of 0.36. These A. baumannii transformants are invaluable new tools for the assessment of anti-Acinetobacter compounds and provide a new pathway for AMR preparedness.