Microbial Infections Research Articles

Preliminary human health risk assessment of antibiotic exposures in human waste handling occupations

Exposure to biosolids in human waste handling occupations is associated with a risk for illness due to microbial infections. Although several years of exposure to biosolids might be hypothesized to be a prophylaxis against infection, the risks associated with infections from antibiotic-resistant organisms can also be a potential concern. Therefore, this study aimed to conduct a screening level risk assessment by deriving occupational exposure limits (OELs) characterizing the risks of adverse health effects among workers in human waste handling occupations with a focus on exposure to two pharmaceuticals commonly found in biosolids: ciprofloxacin (CIP) and azithromycin (AZ). Epidemiological and exposure studies of workers exposed to biosolids were identified through searches of major scientific databases. Screening OELs (sOELs) for these antibiotics were derived using a standardized methodology. The airborne concentrations of CIP and AZ antibiotics were determined using an exposure factors approach. The health-based exposure limits (i.e., sOELs) and the acceptable daily exposure (ADE) values for both of these antibiotics were derived as 80 μg/m3 and 12 μg/kg-day, respectively. An exposure factor approach suggested that inhalation route exposures to CIP and AZ are well below the sOELs and ADE daily doses, and likely too low to cause direct adverse health effects through antibiotic inhalation. A critical review of epidemiological studies on different occupations handling biosolids showed that the workers in industries with potential biosolids exposure have experienced an increased incidence of microbial-exposure-related illness. The health effects seen in the workers have been attributed to bacterial, viral, and protozoan infections. To the extent that bacteria are the pathogen of concern, it is not clear whether these bacteria are resistant to antibiotics commonly found in biosolids. It is also unclear whether the presence of antibiotics or antibiotic-resistant bacteria increases the susceptibility of these workers. Additional studies will provide more definitive estimates of inhalation and dermal exposures to CIP and AZ and could verify the exposure estimates in this study based on the literature and common exposure factors.

Electrochemical biosensors on microfluidic chips as promising tools to study microbial biofilms: a review.

Microbial biofilms play a pivotal role in microbial infections and antibiotic resistance due to their unique properties, driving the urgent need for advanced methodologies to study their behavior comprehensively across varied environmental contexts. While electrochemical biosensors have demonstrated success in understanding the dynamics of biofilms, scientists are now synergistically merging these biosensors with microfluidic technology. This combined approach offers heightened precision, sensitivity, and real-time monitoring capabilities, promising a more comprehensive understanding of biofilm behavior and its implications. Our review delves into recent advancements in electrochemical biosensors on microfluidic chips, specifically tailored for investigating biofilm dynamics, virulence, and properties. Through a critical examination of these advantages, properties and applications of these devices, the review highlights the transformative potential of this technology in advancing our understanding of microbial biofilms in different settings.

Antimicrobial Effect of Waterborne Polyurethane-Based Cellulose Nanofibril/Silver Nanoparticles Composites and Acacia concinna (Willd.) DC Extract (Shikakai).

Antimicrobial coatings are becoming increasingly popular in functional material modification and are essential in addressing microbial infection challenges. In this study, the phytochemical and antimicrobial potential of aqueous, 80% methanol and 80% ethanol pod extracts of Acacia concinna (Willd.) DC (AC) and its application in the green in situ (one pot) synthesis of silver nanoparticles on Cellulose nano fibrils (CNF) and Waterborne polyurethane (WPU) were prepared. The phytochemical evaluation of Acacia concinna crude extracts showed the presence of alkaloids, flavonoids, phenols, tannins, terpenoids, saponins, steroids. The surface plasmon Resonance peak of CNF/AC-AgNPs was 450 nm and the FTIR result confirmed functional groups such as carbonyl, phenols and carboxyl were present which was important for the bio-reduction of silver nanoparticles. The crude AC aqueous pods extract against Gram-positive and Gram-negative bacteria compared with AC ethanol and AC methanol extracts. The WPU/CNF/AC-AgNPs composite dispersion was also good in terms of its antibacterial activities. The WPU/CNF/AC-AgNPs nanocomposites could be applied as bifunctional nanofillers as an antimicrobial agent in food packaging systems and other biological applications.

Silicone allergy manifestation in pediatric ventriculoperitoneal shunting: navigating diagnostic challenges and customizing therapeutic approaches. Illustrative case.

A silicone allergy can significantly impact the efficacy of ventriculoperitoneal shunt devices used in hydrocephalus treatment. Its clinical presentation often resembles infectious ventriculitis, characterized by altered cerebrospinal fluid (CSF) parameters, including low glucose levels, elevated protein concentrations, and increased white blood cell counts predominantly comprising eosinophils. The authors report the case of an 18-month-old male who experienced recurrent shunt malfunction linked to CSF changes indicative of infectious ventriculitis. The patient underwent surgeries for suspected infection management. Notably, he exhibited increased eosinophil counts in both blood and CSF, as well as the development of neoformation tissue. This, along with the absence of microbial infection, indicated silicone hypersensitivity. While navigating medical device scarcity, innovative methods were employed to secure a silicone-free valve, markedly improving the patient's clinical outcome. Clinicians must be vigilant for silicone allergy in patients with ventriculoperitoneal shunts, particularly when elevated serum eosinophil counts and negative microbiological tests are present. This rare condition demands a multidisciplinary approach for timely diagnosis and management to reduce morbidity, unnecessary surgeries, and healthcare costs. The limited availability of non-silicone-based shunts further complicates management. This case emphasizes the need for considering silicone allergy in differential diagnoses, especially in pediatric patients. https://thejns.org/doi/10.3171/CASE2474.

Quantitative proteomic analysis reveals Ga(III) polypyridyl catecholate complexes disrupt Aspergillus fumigatus mitochondrial function.

Infections caused by the airborne fungal pathogen, Aspergillus fumigatus, are increasing in severity due to growing numbers of immunocompromised individuals and the increasing incidence of antifungal drug resistance, exacerbating treatment challenges. Gallium has proven to be a strong candidate in the fight against microbial pathogens due to its iron-mimicking capability and substitution of Ga(III) in place of Fe(III), disrupting iron-dependent pathways. Since the antimicrobial properties of 2,2'-bipyridine and derivatives have been previously reported, we assessed the in vitro activity and proteomic effects of a recently reported heteroleptic Ga(III) polypyridyl catecholate compound against A. fumigatus. This compound has demonstrated promising growth-inhibition and impact on the A. fumigatus proteome compared to untreated controls. Proteins associated with DNA replication and repair mechanisms along with lipid metabolism and the oxidative stress responses were elevated in abundance compared to control. Crucially, a large number of mitochondrial proteins were reduced in abundance. Respiration is an important source of energy to fuel metabolic processes required for growth, survival and virulence, the disruption of which may be a viable strategy for the treatment of microbial infections.

Experimental study on the use of green antimicrobial and plasticized agents during the lining of oil paintings with gelatinous materials

Purpose This paper aims to assess the efficiency of emulsified essential oils in glycerol as eco-friendly antimicrobial and plasticized agents added to the biopolymer of gelatin for lining historical oil paintings on canvases. Design/methodology/approach Cedar oil, cinnamon oil and their mixtures were emulsified in glycerol and incorporated into gelatin adhesive as green biocides and plasticizers. Physical, biological, chemical and mechanical tests were conducted on experimental mock-ups to assess the gelatin-based adhesive formulations for the reinforcement of canvas supports. Scanning electron microscope, colorimetric measurements, antimicrobial activity test, attenuated total reflection-Fourier transform infrared spectroscopy, tensile strength and elongation tests were carried out on the mock-ups before and after the artificial aging. Findings The formulations of gelatin-based adhesive with cinnamon and cinnamon-cedar mixture emulsified in glycerol proved their efficiency on the antimicrobial activity test, chemically delaying the decomposition of gelatin and accordingly providing compatible mechanical properties. Gelatin-based adhesive with emulsified cinnamon oil showed a slight yellowing that was quite improved with the mixture of the cinnamon-cedar-based adhesive formulation. Originality/value This study promotes a green approach to lining historical oil paintings by developing green formulations from bio-based origins that minimize the shrinkage and microbial infection of gelatin for lining paintings.

Capsaicin Promotes Apoptosis and Inhibits Cell Migration via the Tumor Necrosis Factor-Alpha (TNFα) and Nuclear Factor Kappa B (NFκB) Signaling Pathway in Oral Cancer Cells.

Background Oral squamous cell carcinoma (OSCC) is a highly prevalent cancer worldwide. Microbial infections, poor oral hygiene, and chronic viral infections such as human papillomavirus (HPV) contribute to its incidence. Capsaicin, known for its presence in chili peppers, has demonstrated potential antiproliferative effects in cancer cells. It operates by inducing programmed cell death, regulating the expression of transcription factors, halting cell cycle progression, and influencing growth signal transduction pathways. These findings suggest capsaicin's promising role as a candidate for further exploration in combating oral cancer. Aim This study intends to identify and evaluate the anticancer properties of capsaicin on oral cancer cells through in vitro investigations. Methodology Using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) technique, the cell viability of oral cancer cells treated with capsaicin was evaluated. Capsaicin was applied to the KB1 cells in a range of concentrations (25-150 µg/mL) over 24 hours. The morphological alterations of the cells were assessed using a phase contrast microscope. Nuclear factor kappa B (NFκB) and tumor necrosis factor-alpha (TNFα) were subjected to quantitative real-time polymerase chain reaction (PCR) gene expression analysis. To investigate nuclear morphological changes, oral cancer cells were stained with acridine orange/ethidium bromide (AO/EtBr). The apoptotic nuclei were visualized using a fluorescent microscope. A scratch wound healing test was performed to check for capsaicin's anti-migratory potential. Result In our investigation of oral cancer cells treated with capsaicin, there was a significant drop in cell viability between the control and treatment groups (p < 0.05). The inhibitory concentration (IC50) was found to be 74.4 μM/mL in oral cancer cells. Following treatment, fewer cells were present, and those that were present shriveled and exhibited cytoplasmic membrane blebbing. Under AO/EtBr staining, treated cells exhibited chromatin condensation and nuclear disintegration. Furthermore, the migration of capsaicin-treated cells was significantly lower than that of control cells. The results of gene expression analysis demonstrated a considerable downregulation of TNFα and NFκB following capsaicin administration. Conclusion The study's findings suggest that capsaicin may have anti-tumor properties in oral cancer cells. More research is desperately needed to fully understand the mechanism underlying capsaicin's anticancer potential and therapeutic applicability.

MAIT Cells in the Bone Marrow of Patients with Aplastic Anemia.

Mucosal-associated invariant T cells (MAIT cells) are a subset of T cells with innate, effector-like properties that play an essential role in the immune response to microbial infections. In humans, MAIT cells are detectable in the blood, liver, and lungs, but little is known about the frequency of these cells in the bone marrow. Also, the pathogenic role, if any, of MAIT cells in the development of aplastic anemia, a disease with an exquisite origin in the bone marrow, is currently unknown. We investigated the frequency and clinical relevance of bone marrow MAIT cells in a cohort of 14 patients (60.6 ± 23 and 57% women) with aplastic anemia. MAIT cells in the bone marrow samples obtained at diagnosis were evaluated by flow cytometry, and their association with various blood cell parameters and the patients' clinical features was analyzed. MAIT cells were detectable in the bone marrow of all patients, with considerable variations among them. Bone marrow MAIT cells expressing the activator receptor natural killer group 2D - NKG2D (NKG2D+ MAIT cells) were significantly more abundant in the specimens of the aplastic anemia patients than in patients with bone marrow failure distinct from aplastic anemia. In addition, the NKG2D+ MAIT cells positively correlated with whole blood cell counts (WBC), platelet counts, and neutrophil counts, as well as with various inflammatory markers, including neutrophil-to-lymphocyte rate (NLR), platelet-to-lymphocyte rate (PLR), and systemic inflammatory index (SII). In functional studies, bone marrow CD34+ hematopoietic cells exposed to phytohemagglutinin or bacterial-derived lipopolysaccharide and acetyl-6-formylpterin upregulated MR1 (major histocompatibility complex, class I-related, known to interact with MAIT cells) and MICA/B (MHC class I chain-related gene A, a ligand of NKG2D) proteins on their cell surface, suggesting that under stress conditions, CD34+ hematopoietic cells are more likely to interact with NKG2D+ MAIT cells. In addition, NKG2D+ MAIT cells upregulated perforin and granzyme B in response to their interaction with recombinant MICA protein in vitro. This study reports for the first time the frequency of MAIT cells in the bone marrow of patients with aplastic anemia and assesses the potential implications of these cells in the pathogenesis or progression of aplastic anemia.

Patterns of Microbial Infections in Post-Infective Hydrocephalus and Treatment Methods at Bugando Medical Center

Background: Post Infective Hydrocephalus is among the complicated types of hydrocephalus and poses a challenge in management of these patients, globally. Antibiotics susceptibility patterns of common bacteria implicating in pyogenic ventriculitis complicated with hydrocephalus were not clearly known at our setting. Therefore, we determined antibiotics susceptibility patterns of common bacteria implicating in pyogenic ventriculitis complicated with hydrocephalus to recommend empirical therapy while waiting for culture and sensitivity results at Bugando Medical Centre (BMC) in Mwanza, Tanzania. Methods: Thirty-five patients with hydrocephalus who had undergone cerebrospinal fluid (CSF) tapping and analysis were selected randomly retrospectively and their bacteriological culture and sensitivity results were analyzed to determine the common microbial patterns. Patients were rationally prescribed antibiotics depending on laboratory results for 7 days and were later done control CSF cultures until negative cultures were achieved. Results: A total of 35 patients with median (interquartile range [IQR]) age was 5.5 [2-8] months were reviewed. The majority of participants were males, 62.9% (22/35). 20% (7/35) and 37.1% (13/35) had turbid CSF-shunt sample and first culture positive results, respectively, whereas one patient had culture positive with two pathogens resulting to 14 isolates. Gram positive bacteria were predominantly isolated (66.7%, 8/14), whereby S. aureus was frequently encountered (35.7%, 5/14). Overall, gram positive and negative bacteria exhibited least resistance against tetracycline (16.7% and 25%) and ciprofloxacin (16.7% and 25%) respectively. Three (8.6%) patients died from respiratory complications. Conclusion: Post infective hydrocephalus is a clinically challenging but treatable form of hydrocephalus and Staphylococcus aurous is the most common cause. This study found that the use of a seven-day regimen as cost effective and associated with a shorter hospital stay with the focus on CSF analysis with subsequent microbial targeted antibiotic therapy to achieve sterile CSF culture. Treatment strategy should be multidisciplinary approach with collaboration from microbiologists, radiologists, pediatricians and neurosurgeons.

Characterization of Tfgal-9: A galectin in innate immune system of Trachidermus fasciatus - Insights into its sequence analysis, expression patterns, and in vitro bioactivities

An in-depth understanding of the immune system of endangered species is crucial for successful conservation efforts. Galectins, as members of the lectin family, play a crucial role in the fish innate immune system. Galectin-9 (Tfgal-9) was cloned from endangered species Trachidermus fasciatus, revealing a cDNA sequence of 1453 bp with an open reading frame of 900 bp encoding a protein of 299 amino acids. Tfgal-9 protein features two repeated carbohydrate-binding domains, each characterized by two conserved galactose-binding sites (H-NPR and WG-EER), and it possesses neither a signal peptide nor a transmembrane domain. The qRT-PCR analysis revealed that Tfgal-9 was widely expressed across all examined tissues, with the highest expression in the intestine, followed by the blood, heart and brain. Expression was notably up-regulated in the blood, skin, liver, stomach, and heart when challenged with LPS. Following induction by the heavy metal solution containing Cu, Pb, Cd, and Hg, the expression Tfgal-9 was dramatically induced to 32 times higher than that of the control group in the brain. The recombinant Tfgal-9 protein exhibits calcium-independent binding and agglutination of selected bacteria and yeast. Antimicrobial activity of recombinant Tfgal-9 protein against Gram positive bacteria Staphylococcus aureus was confirmed using the cylinder-plate method. In vitro antioxidant experiments showed that radical scavenging activity of DPPH was 50.38 % when Tfgal-9 concentration reached 200 μg/mL. These results indicate that Tfgal-9 may play important roles in the immune response against microbial infections and the maintaining of redox homeostasis.

Glucose-responsive carboxymethyl chitosan/ sodium alginate film protects against mechanical wound on postharvest blueberry

Fresh fruits and vegetables, particularly berries, are highly susceptible to mechanical damage, which results in nutrient loss, reduced quality, and increased decay from microbial infections, ultimately leading to significant losses. Here, a biodegradable polysaccharide film was employed to encapsulate glucose oxidase (Gox), thereby creating a glucose/wounding-responsive active package that reduced fruit respiration, promoted healing and protected blueberry wounds from mold infection. The combination of carboxymethyl chitosan and sodium alginate resulted in the formation of the polysaccharides film CSF that effectively restricted the permeation of oxygen, water, and carbon dioxide around the surface of the fruit. The encapsulation of Gox in the CSF film (CSFG) reduced glucose levels through enzymatic reaction in surface wounds of the fruit, thereby competing for glucose to establish a starvation-like microenvironment for the pathogenic fungus Botrytis cinerea. The enzymatic reaction also facilitated the production of hydrogen peroxide, which functioned as a fungicide that inhibits the growth of B. cinerea and served as a secondary messenger in fruit immunity. The CSFG film increased beta-glucanase activity, and decreased lipid peroxidation in wounds of blueberries. Therefore, this glucose-responsive CSFG barrier significantly reduced the decay rates of gray mold, caused by B. cinerea in wounded blueberries, by 66.7% compared to the control at 6 d of storage. Taken together, the glucose-responsive active packaging film provides an alternative package for safeguarding blueberries against mechanical damage.

A multifunctional composite scaffold responds to microenvironment and guides osteogenesis for the repair of infected bone defects

Treating bone defect concomitant with microbial infection poses a formidable clinical challenge. Addressing this dilemma necessitates the implementation of biomaterials exhibiting dual capabilities in anti-bacteria and bone regeneration. Of particular significance is the altered microenvironment observed in infected bones, characterized by acidity, inflammation, and an abundance of reactive oxygen species (ROS). These conditions, while challenging, present an opportunity for therapeutic intervention in the context of contaminated bone defects. In this study, we developed an oriented composite scaffold containing copper-coated manganese dioxide (MnO2) nanoparticles loaded with parathyroid hormone (PMPC/Gelatin). The characteristics of these scaffolds were meticulously evaluated and confirmed the high sensitivity to H+, responsive drug release and ROS elimination. In vitro antibacterial analysis underscored the remarkable ability of PMPC/Gelatin scaffolds to substantially suppressed bacterial proliferation and colony formation. Furthermore, this nontoxic material demonstrated efficacy in mitigating ROS levels, thereby fostering osteogenic differentiation of bone marrow mesenchymal stem cells and enhancing angiogenic ability. Subsequently, the infected models of bone defects in rat skulls were established to investigate the effects of composite scaffolds on anti-bacteria and bone formation in vivo. The PMPC/Gelatin treatment exhibited excellent antibacterial activity, coupled with enhanced vascularization and osteogenesis at the defect sites. These compelling findings affirm that the PMPC/Gelatin composite scaffold represents a promising avenue for anti-bacteria and bone regeneration.

The role of infection in signalling root resorption: Anarrative review.

Root resorption consists of complex, multistep processes that involve cell signalling caused by inflammation and stromal cells, which promotes the secretion of receptor activator of nuclear factor κB ligand/ macrophage-colony stimulating factor (RANKL/M-CSF) resulting in a resorptive process. The aim of this narrative review was to analyse the literature related to root resorption resulting from microbial infection and to comparing it with non-microbial infection. An electronic literature search was performed using the PubMed database and applying keywords of articles published in English. Eligible papers were reviewed to reveal the descriptions of bone and root resorption processes. The abstracts were searched manually to identify articles about infection-stimulating bone and root resorption. Three main types of root resorption were identified, two associated with primary bacterial infection and one secondary to bacterial infection. These include external inflammatory resorption, internal inflammatory resorption and external cervical (invasive) resorption. The magnitude of cytokine involvement that promotes resorption and M-CSF/RANKL production depends on multiple factors, including pathogen virulence, site of infection and host genetic factors that activate the inflammation at the infection site. Two mechanisms activate the resorption mechanisms-the canonical and non-canonical pathways that can activate clastic cells independently of the RANKL/RANK canonical pathways. Two pathways of root resorption co-exist in the body. When resorption is caused by infection, chronic inflammation due to bacterial infection prolongs the secretions of pro-inflammatory cytokines that intensify root and bone resorption. The second pathway is bacterial independent of the non-infection root resorption that is part of the wound healing process, which is limited in time due to its innate ability.

Engineered food-derived hesperetin as heterojunction photosensitizer for inhibiting Staphylococcus aureus and degrading patulin, and its application in perishable strawberries

The potential contamination, including microbial and mycotoxin infection, may escape from the naked eye, posing great threats to food products. Recently, photodynamic inactivation (PDI)-based technology particular has received particular attention because of their high safety. Herein, food-derived hesperetin (Hst) was innovatively introduced as an esculent photosensitizer, engineering with food-grade TiO2 nanoparticles (NPs) to form an organic-inorganic heterojunction structure. Triggered by visible light, the obtained TiO2/Hst NPs were endowed with efficient photoactivity, achieving higher inhibition of Staphylococcus aureus (antibacterial ratio of 98.3 %). The removal capacities of the TiO2/Hst NPs towards patulin (PAT) reached approximately 17.76 μg mg−1, approximately 2 times higher than TiO2 and Hst. The engineered TiO2/Hst NPs were used as the food surface detergent to achieve the ideal inhibition of Staphylococcus aureus and patulin performance on the surface of perishable strawberries, extending the storage life of strawberries.

Evaluation of the Antimicrobial Activity of Triple Enzyme-Embedded Organic-Inorganic Hybrid Nanoflowers (hNFs) in Comparison with Powerful Antimicrobial Agent Chitosan.

Organic-inorganic hybrid nanoflowers (hNFs) have high stability, reusability, low production cost, and overcome substrate/product inhibition. Antimicrobial activity of various hNFs has been reported to overcome environmental microbial contaminations and infections, which are considered major public health problems. α-amylase, protease, and lipase are the most common industrial enzymes exerting antimicrobial activity; therefore, we synthesized triple enzyme (α-amylase, protease, and lipase)-embedded hNFs by using pancreatin to evaluate their antimicrobial activity in comparison with one of the most potent antimicrobial polymer chitosan. The broad spectrum of the antimicrobial properties of chitosan is used in industrial products, including cosmetics, food, agriculture, pharmaceuticals, and textiles. SEM analysis, thermogravimetric analysis (TGA), and the degree of deacetylation (%DD) were performed for chitosan characterization, where SEM, FTIR, EDX, and XRD analyses were performed for the characterization of hNFs. The catalytic activity of pancreatin and hNFs was evaluated by measuring lipase, α-amylase, and protease enzyme activities at 37°C. Antibacterial activities of hNFs, pancreatin, and chitosan were tested on gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) bacteria, compared to the pancreatin and chitosan via agar and broth dilution methods. hNFs showed enhanced catalytic activity for protease, lipase, and α-amylase compared to pancreatin at different pH values (pH 8, 9). hNFs showed catalytic activity after being washed and reused up to six times, indicating their reusability and recoverability. hNFs showed significant antimicrobial activity, such as chitosan, Staphylococcus aureus, and Escherichia coli, compared to pancreatin. Our novel hNFs can be used to develop antimicrobial technologies to fight against environmental microbial contaminations and antibiotic resistance-driven environmental pathogens.

Genetic requirements for uropathogenic E. coli proliferation in the bladder cell infection cycle.

Urinary tract infections (UTIs) are one of the most frequent infections worldwide. Uropathogenic Escherichia coli (UPEC), which accounts for ~80% of UTIs, must rapidly adapt to highly variable host environments, such as the gut, bladder sub-surface, and urine. In this study, we searched for UPEC genes required for bacterial growth and survival throughout the cellular infection cycle. Genes required for de novo synthesis of biomolecules and cell envelope integrity appeared to be important, and other genes were also implicated in bacterial dispersal and recovery from infection of cultured bladder cells. With further studies of individual gene function, their potential as therapeutic targets may be realized. This study expands knowledge of the UTI cycle and establishes an approach to genome-wide functional analyses of stage-resolved microbial infections.

Progress in the Study of Natural Antimicrobial Active Substances in Pseudomonas aeruginosa.

The prevalence of antimicrobial resistance reduces the effectiveness of antimicrobial drugs in the prevention and treatment of infectious diseases caused by pathogens such as bacteria, fungi, and viruses. Microbial secondary metabolites have been recognized as important sources for new drug discovery and development, yielding a wide range of structurally novel and functionally diverse antimicrobial drugs for the treatment of a variety of diseases that are considered good producers of novel antimicrobial drugs. Bacteria produce a wide variety of antimicrobial compounds, and thus, antibiotics derived from natural products still dominate over purely synthetic antibiotics among the antimicrobial drugs developed and introduced over the last four decades. Among them, Pseudomonas aeruginosa secondary metabolites constitute a richly diverse source of antimicrobial substances with good antimicrobial activity. Therefore, they are regarded as an outstanding resource for finding novel bioactive compounds. The exploration of antimicrobial compounds among Pseudomonas aeruginosa metabolites plays an important role in drug development and biomedical research. Reports on the secondary metabolites of Pseudomonas aeruginosa, many of which are of pharmacological importance, hold great promise for the development of effective antimicrobial drugs against microbial infections by drug-resistant pathogens. In this review, we attempt to summarize published articles from the last twenty-five years (2000-2024) on antimicrobial secondary metabolites from Pseudomonas aeruginosa.

The composition of the stent microbiome is associated with morbidity and adverse events during endoscopic drainage therapy of pancreatic necroses and pseudocysts.

Development of pancreatic necroses or pseudocysts are typical complications of pancreatitis and may require endoscopic drainage therapy using metal or plastic stents. Microbial infection of these lesions poses a major challenge. So far, the composition and significance of the microbial colonization on drainage stents are largely unknown although it may impact outcomes during endoscopic drainage therapy. A total of 26 stents used for drainage of pancreatic lesions were retrieved and the stent microbiome was determined by 16S rRNA gene sequencing. Additional analysis included comparison of the stent microbiome to the intracavitary necrosis microbiome as well as scanning electron microscopy (SEM) and micro-computed tomography (μCT) imaging of selected metal or plastic stents. The stent microbiome comprises a large proportion of opportunistic enteric pathogens such as Enterococcus (14.4%) or Escherichia (6.1%) as well as oral bacteria like Streptococcus (13.1%). Increased levels of opportunistic enteric pathogens were associated with a prolonged hospital stay (r = 0.77, p = 3e-06) and the occurrence of adverse events during drainage therapy (p = 0.011). Higher levels of oral bacteria were associated (r = -0.62, p = 8e-04) with shorter durations of inpatient treatment. SEM and μCT investigations revealed complex biofilm networks on the stent surface. The composition of the stent microbiome is associated with prolonged hospital stays and adverse events during endoscopic drainage therapy, highlighting the need for effective infection control to improve patient outcomes. In addition to systemic antibiotic therapy, antimicrobial stent coatings could be a conceivable option to influence the stent microbiome and possibly enhance control of the necrotic microflora.

Isolation, characterization and antimicrobial activity study of Thymus vulgaris

Herbal medicines are important for ensuring sustainable development goals (SDGs) in healthcare, particularly in developing countries with high rates of antimicrobial resistance (AMR) and little access to medical facilities. Thymus vulgaris is a widely used herbal medicinal plant known for its secondary metabolites and antimicrobial properties. The present study involved a comprehensive examination of the isolation, characterization, and antibacterial activity of Thymus vulgaris obtained from Ethiopia. The aerial part of the plant Thymus vulgaris was successively extracted with hexane, chloroform, and methanol based on differences in polarity. Phytochemical screening tests conducted against hexane, chloroform and MeOH crude extracts indicated the presence of some secondary metabolites. Based on the thin-layer chromatography tests, the chloroform extract was subjected to column chromatography, yielding Tv-2 compounds, namely 5-isopropyl-2-methylphenol. The structures of the compounds were elucidated via spectroscopic methods (UV–Vis, FT-IR and NMR). We investigated the antibacterial properties of hexane crude extract, chloroform crude extract, MeOH crude extract, and isolated fractions derived from T. vulgaris against various bacterial strains. This study contributes to a better understanding of the bioactive components present in Thymus vulgaris crude extracts and their potential role in tackling microbial infections.

Harnessing piperine for enhanced antimicrobial activity of carbon dot-modified cellulose fibers

Microbial infections are a global health challenge often treated with antibiotics, but their overuse can lead to antibiotic resistance. To address this, there is a need for more efficient personal protective equipment (PPE) with novel antimicrobial techniques. One such technique involves using carbon dots (CDs) to create self-disinfecting fabrics. This study focused on synthesizing phenylboronic-acid-functionalized piperine-based carbon dots (PBA-PPCDs) and boronic acid carbon dots (BACDs) as potential antimicrobial agents. The materials were successfully synthesized using a hydrothermal method and characterized using various techniques to confirm the size, charge, fluorescence properties, and inner morphology of the CDs. The CDs showed bactericidal activity against gram-positive and gram-negative bacteria, with potent inhibition in growth especially in the presence of simulated sunlight. The antibacterial properties of the CDs were tested on cellulose discs, demonstrating strong adherence and significant inhibition of bacterial cells. The cytotoxicity studies showed that these CDs, at concentrations up to 0.1 mg/mL, and the CD-modified fibers are benign to mammalian cells, emphasizing their safety for human use. Overall, the study concluded that PBA-PPCDs and BACDs are promising candidates for modifying fibers and inducing antimicrobial activity in fabrics made of cellulose fibers.Graphical