Infectious Diseases, Bacteriology & Virology

Tittle:

Antibacterial Potential and mechanism of Crude Extracts from Cylindrospermum alatosporum NR125682 and Loriellopsis cavernicola NR117881 isolated from fresh water

Abstract

The challenges of antimicrobial resistance (AMR) to human health have pushed for the discovery of a new antibiotics’ agent from natural products. Cyanobacteria are oxygen-producing photosynthetic prokaryotes found in a variety of water habitats. Secondary metabolites are produced by cyanobacteria to survive extreme environmental stress factors, including microbial competition. This study presents the antibacterial activity and mechanism of the crude extracts from Cylindrospermum alatosporum NR125682 (A) and Loriellopsis cavernicola NR117881 (B) isolated from freshwater. The cyanobacteria were identified through 16S rRNA sequencing. Crude extracts were sequentially prepared using hexane, dichloromethane, and ethanol consistently. The minimum inhibition concentration (MIC), minimum bactericidal concentration (MBC) using the CSLI microdilution test protocol, and crude extract potential to inhibit the growth of the tested clinical bacteria strains were evaluated. The mechanism of action of the extracts including membrane damage, efflux pump, β-lactamase activity, DNA degradation, and extract–drug interaction was investigated using standard procedures. The hexane extract of B performed the best with a MIC (0.7–1.41 mg/mL) and MBC (1.41–2.81 mg/mL) range. All the crude extracts inhibited efflux pump activity against the bacteria tested. However, the extracts poorly inhibited β-lactamase. The ethanol extract of B exhibited the most appreciable antibacterial activity. The dichloromethane extract of B showed the highest significant DNA degradation potential, when compared with other samples. The extracts exhibited synergism when combined with erythromycin against some test bacteria, indicating primary microbial activity through membrane interactions. Hence, this study demonstrates the significance of cyanobacteria for antibiotic development.

Title:

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Abstract:

Healthcare-associated infections are among the most significant complications in hospitalized patients, posing a major challenge due to the antimicrobial resistance of pathogenic agents such as Staphylococcus spp. The study aims to identify and evaluate the phenotypic and molecular resistance profile of Staphylococcus spp. in co-infection with respiratory viruses, including COVID-19, as a respiratory virus, in samples from children admitted to ICUs. Nasopharyngeal samples from the biorepository were stored at -80 °C in medium containing gentamicin and amphotericin B. Bacterial strains were isolated, and antibiograms were performed using the Kirby-Bauer method with antimicrobials specific to Staphylococcus spp. and the method of evaluating molecular resistance, carrying out the amplification of resistance genes, using specific oligonucleotides. A multidrug-resistant profile was observed in Staphylococcus spp., highlighting the need for monitoring to ensure appropriate treatment. Antimicrobial resistance emphasized the importance of strict control over antibiotic use in hospital environments. This study contributes to the understanding of antimicrobial resistance in bacterial co-infections, providing insights for more effective treatments and HAI control strategies

Title: Nanotechnology-Based Therapeutic Strategies for Biofilm-Associated Antimicrobial Resistance

Abstract:

The escalating prevalence of antimicrobial resistance (AMR) and multidrug-resistant (MDR) pathogens represents a critical global health challenge, demanding the development of innovative and mechanistically driven therapeutic strategies beyond conventional antibiotics. This work presents a novel integrative approach combining nanotechnology, natural bioactive compounds, and targeted delivery systems to engineer multifunctional nanoplatforms for combating resistant microbial infections. Building upon our research on bovine serum albumin–chitosan nanocarriers encapsulating fungal bioactives, cerium-doped magnesium oxide nanoparticles, bioengineered Cordyceps militaris–MgO nanocomposites, Centella asiatica-fabricated MgO nanoparticles, and curcumin-loaded mesoporous superparamagnetic iron oxide nanoparticles (SPIONs), the study investigates their synthesis, physicochemical characterization, antimicrobial mechanisms, and therapeutic efficacy against MDR pathogens. The novelty of this work lies in the rational design of biofunctionalized, compositionally engineered, and magnetically targetable nanostructures that enhance antimicrobial potency, bioavailability, and site-specific delivery. Green synthesis and bioengineering strategies enabled precise control over nanoparticle size, morphology, and surface properties, facilitating efficient microbial interaction and cellular internalization. The developed nanoplatforms demonstrated potent antimicrobial and antibiofilm activity against MDR pathogens through multimodal mechanisms, thereby reducing the likelihood of resistance development. In particular, curcumin-loaded mesoporous SPIONs exhibited targeted disruption of biofilm-associated MDR bacteria, highlighting the importance of nanocarrier- mediated delivery for overcoming biofilm-mediated resistance. Mechanistic investigations revealed that reactive oxygen species (ROS)-mediated oxidative stress serves as a primary bactericidal pathway, inducing lipid peroxidation, protein denaturation, and nucleic acid damage. Additionally, nanoparticle-induced membranolytic effects, including bacterial membrane disruption and flippase-mediated lipid leakage, contribute to enhanced antimicrobial activity. Protein–polysaccharide nanocarrier systems improved controlled drug release and biocompatibility, while cerium doping significantly enhanced redox activity and antimicrobial performance, underscoring the role of compositional modification in optimizing therapeutic outcomes. Beyond antimicrobial efficacy, selected nanoplatforms demonstrated promising anticancer potential and favorable safety profiles supported by physiologically based pharmacokinetic modeling. Collectively, this study establishes a mechanistically guided and sustainable framework for next-generation nanotherapeutics, offering significant translational potential in targeted antimicrobial therapy, antibiofilm interventions, biomedical coatings, and precision nanomedicine strategies for the clinical management of MDR infections.

Title: Helminth-Driven Immune Modulation Shapes Viral Disease Pathology and TCell Responses with Implications for Vaccine Performance

Abstract:

Helminth infections are highly prevalent in regions disproportionately affected by emerging infectious diseases. However, their influence on antiviral immunity and vaccine-induced protection remains insufficiently characterised. Elucidating how helminth-driven immune modulation alters viral disease outcomes is critical for addressing persistent challenges in
vaccine performance in endemic settings. Clinical and immunological analyses were conducted. A retrospective cohort study evaluated the association between helminth seropositivity, COVID-19 disease severity, systemic cytokine profiles, and SARS-CoV-2– specific antibody responses. In parallel, functional in vitro assays using peripheral blood mononuclear cells from individuals infected with Onchocerca volvulus assessed the impact of helminth antigens on SARS-CoV-2–induced T-cell activation. Helminth seropositivity was associated with asymptomatic COVID-19 infection (p = 0.018). Helminth–SARS-CoV-2 coexposure was associated with attenuated Th1 and Th17 cytokine responses, reduced SARSCoV-2–specific IgA and IgG levels, and diminished neutralising capacity, accompanied by increased Th2 cytokines and IL-10 expression. Helminth antigens significantly modulated SARS-CoV-2-induced T-cell activation, characterised by reduced CD4⁺CD154⁺ T-cell responses and altered CD8⁺ T-cell activation in O. volvulus–infected individuals. Consistently, helminth-specific IgG levels inversely correlated with SARS-CoV-2–induced CD4⁺ T-cell activation. These findings provide mechanistic evidence that helminth infections profoundly shape antiviral immune responses, simultaneously limiting cytokine-mediated immunopathology while impairing immune functions critical for robust vaccine-induced protection. This dual effect poses a significant challenge to vaccine efficacy and the identification of immune correlates of protection in helminth-endemic regions. Integrating helminth-associated immune modulation into vaccine design, evaluation, and deployment strategies will be essential for improving global infectious disease control.