Gram-negative Research Articles

Paracoccus spongiarum sp. nov., isolated from the marine sponge, Phakellia elegans.

A facultative anaerobic Gram-negative bacterium, designated as strain 2205BS29-5T, was isolated from a marine sponge, Phakellia elegans, in Beomseom on Jeju Island, Republic of Korea, and taxonomically characterized. The cells were catalase and oxidase positive, non-motile, coccoid-rod shaped and capable of poly-β-hydroxybutyrate production. Growth was observed at 10-37 °C (optimum, 25 °C) and pH 5.0-8.0 (optimum, pH 7.0), and in the presence of 0-9% NaCl (w/v) (optimum, 3.0-4.0%). The major cellular fatty acids and respiratory quinone were identified as summed feature 8 (C18 : 1 ω7c/C18 : 1 ω6c) and Q-10, respectively. The major polar lipids comprised diphosphatidylglycerol, phosphatidylglycerol, four phosphoglycolipids, two unidentified amino lipids and eight unidentified lipids. The DNA G+C content was 67.8%. Strain 2205BS29-5T was most closely represented by Paracoccus amoyensis 11-3T and P. caeni MJ17T with 97.8 and 97.5% 16S rRNA gene sequence similarities, respectively. Phylogenetic analyses based on 16S rRNA genes and whole-genome sequences showed that strain 2205BS29-5T was affiliated with the genus Paracoccus. Genomic analysis showed that strain 2205BS29-5T could synthesize vitamin B family (folate and cobalamin) and ectoine. The average nucleotide identity and digital DNA-DNA hybridization values between strain 2205BS29-5T and P. amoyensis 11-3T were 77.1% and 18.8%, respectively, and with P. caeni MJ17T were 78.4 and 21.2%, respectively. Based on phylogenetic, chemotaxonomic and genome relatedness analyses, strain 2205BS29-5T represents a novel species of the genus Paracoccus, for which the name Paracoccus spongiarum sp. nov. is proposed. The type strain is 2205BS29-5T (=LMG 33062T =KACC 23240T).

Chemoselective modification of chitosan with arginine and hydroxyproline: Development of antibacterial composite films for wound healing applications

This study explored the enhancement of chitosan for wound dressing applications through selective functionalization with arginine and hydroxyproline amino acids, combined with polyvinyl pyrrolidone (PVP) and polyvinyl alcohol (PVA) in composite films. The research employed chemoselective amino acid grafting followed by solution casting to fabricate the composite materials. Fourier transform infrared (FTIR) analysis verified successful chitosan modification through the presence of a carbamate bond at 1719 cm−1 and an amide bond shift from 1660 to 1680 cm−1, with nuclear magnetic resonance (NMR) analysis providing additional confirmation. The composite films demonstrated exceptional properties, achieving maximum tensile strength of approximately 55 MPa and swelling ratio of about 400 %. Statistical analysis revealed significant variations in mechanical and swelling properties across formulations (p < 0.05), with analysis of variance (ANOVA) showing a between-group sum of squares of 122,980.519 for tensile strength and 352,306.333 for swelling. Duncan's multiple range test identified distinct groupings for tensile strength (5.67–119.67 MPa) and swelling ratios (320.33–565.33 %), demonstrating the impact of composition on material properties. Thermal stability analysis (25–600 °C) revealed a multi-step degradation process, confirming successful modification and composite formation. The amino acid-modified chitosan composites showed remarkable antibacterial enhancement, exhibiting 60 % greater activity against both Gram-positive and Gram-negative bacteria compared to unmodified chitosan. These findings demonstrate the potential of selectively functionalized chitosan composite films for advanced wound dressing applications, combining enhanced antibacterial efficacy with robust mechanical and thermal properties. Future research directions include formulation optimization and in vivo validation of clinical efficacy.

Dynamic interplay between a TonB-dependent heme transporter and a TonB protein in a membrane environment.

Gram-negative bacteria import scarce nutrients such as metals and vitamins by an energized mechanism involving a multicomponent protein system that spans the cell envelope. It consists of an outer membrane TonB-dependent transporter (TBDT) and a TonB complex in the inner membrane that provides the proton motive force energy for the nutrient entry. Despite the intense research efforts focused on this system (a) from structural and fundamental microbiology perspectives and (b) for the interest in the development of new antibacterial strategies, the molecular mechanism of the system is not at all well understood. The lack of understanding comes from incomplete structural data and the experimental difficulties of studying an inherently flexible multicomponent complex that resides within the heterogeneous environment of the double membrane bacterial cell envelope. To address these challenges and obtain a comprehensive view of the molecular interactions at atomic level, here, we have used the combined power of advanced molecular simulations and complementary microbiology and biochemical experiments. Our results represent a significant step forward in understanding the structural and molecular bases of this vital mechanism.

Synthesis and Antibacterial Activity of Alkylamine-Linked Pleuromutilin Derivatives

In an effort to expand the spectrum of the antibacterial activity of pleuromutilin, a series of amine- and polyamine-linked analogues were prepared and evaluated for activities against a panel of microorganisms. Simple C-22-substituted amino esters or diamines 16, 17, 18, and 22, as well as two unusual amine-linked bis-pleuromutilin examples 20 and 23, displayed variable levels of activity towards Staphylococcus aureus ATCC 25923 and methicillin-resistant S. aureus, but with no detectable activities towards Gram-negative bacteria. Fortunately, the incorporation of a longer-chain triamine or polyamine (spermine) at C-22 did afford analogues (30, 31) that exhibited activity towards both S. aureus ATCC 25923 and Escherichia coli ATCC 25922 with MIC 6.1–13.4 µM. Spermine–pleuromutilin analogue 31 was also able to enhance the action of doxycycline towards Pseudomonas aeruginosa ATCC 27853 by eight-fold, highlighting it as a useful scaffold for the development of new antibacterial pleuromutilin analogues that exhibit a broader spectrum of activity.

Effective combinations of silver nanoparticles and antimicrobial peptides against antibiotic-resistant bacteria

BACKGROUND: The problem of constantly growing resistance of microorganisms to the antibiotics used forces scientists to constantly search for new antimicrobial agents. AIM: To study the antimicrobial activity and toxicity of silver nanoparticles and antimicrobial peptides with a β-hairpin structure, and to characterize their combined antimicrobial action. MATERIALS AND METHODS: The antimicrobial activity of silver nanoparticles and antimicrobial peptides against antibiotic-resistant bacteria was assessed by serial dilutions in a liquid nutrient medium, and the combined antimicrobial activity – by serial dilutions according to the “checkerboard” method. The toxicity of the substances to human cells was determined using a hemolytic test. RESULTS: The studied silver nanoparticles have pronounced antimicrobial activity and low toxicity to human erythrocytes. Silver nanoparticles containing acetylcysteine are more active against gram-negative bacteria than against gram-positive ones. Synergism of the antibacterial action was detected with the combined use of silver nanoparticles stabilized with sodium oleate and protegrin-1. A synergistic antimicrobial effect was also noted for combinations of silver nanoparticles containing acetylcysteine with protegrin-1, ricaecilin and shuchin-4. CONCLUSIONS: Effective combinations of silver nanoparticles and antimicrobial peptides have been identified that act synergistically against antibiotic-resistant bacterial strains, i.e. they multiply the effect of each other. These combinations can be used as prototypes for the development of antibacterial drugs.

A predictive model of treatment effectiveness of refractory peritoneal dialysis-related peritonitis in patients with peritoneal dialysis: a single-center observational study in South China

Abstract Background To prevent loss of peritoneal function caused by persistent abdominal inflammation, the guidelines recommend early extubation in patients with refractory peritoneal dialysis-associated peritonitis (rPDAP). In attempt to pinpoint high-risk patient cohorts that did not respond to treatment for refractory peritonitis, we created a model to predict the effectiveness of peritonitis treatment. Methods This observational cohort study included peritoneal dialysis (PD) patients from January 1, 2011 to December 31, 2020. Multivariate logistic regression analysis was used to explore the factors affecting the occurrence and prognosis of rPDAP, and to construct a predictive model for the success of rPDAP treatment. Receiver operator characteristic (ROC) curve, calibration and decision curve were drawn to evaluate the predictive performance of the model. Results A total of 1, 397 cases of peritoneal dialysis-associated peritonitis (PDAP) occurred in our center during the study period, of which 558 cases were diagnosed as rPDAP. The incidence of refractory peritonitis was 0.047 cases/patient-year. In the study, 440 cases with rPDAP were included. Among them 304 cases (69.1%) had been successfully cured, while 136 cases (30.9%) were treatment failure, of which 19 cases (4.3%) died, 85 (19.3%) cases transferred to hemodialysis and 32 cases (7.2%) were relapse/recurrent peritonitis. Dialysate culture results showed 132 (30.0%) cases were infected with gram positive bacteria, 161 (36.6%) gram negative bacteria. Multivariate Logistic regression analysis showed that episodes of peritonitis previously ≤ 3 times were correlated with the better prognosis of rPDAP, but white blood cell (WBC) counts in peritoneal dialysate on the 3rd day of peritonitis or WBC counts on the 5th day ≥ 300 × 106/L, the pathogenic microorganism with gram-negative bacteria, as well as longer duration of PD were associated with poor outcomes. The C-statistical value of the training data set was 0.870 (95%CI: 0.821–0.918). The calibration curve and clinical decision-making curve also proved that this nomogram could accurately predict the success of treatment in patients with refractory peritonitis. Conclusion The nomogram model created through internal verification indicated a strong clinical application value and a high prognostic prediction accuracy for rPDAP.

Directed modification of characteristics of syntetyc analogue of proline-rich peptide ChBac3.4 through dendrimerisation

BACKGROUND: According to the World Health Organization, microbial resistance to antibiotics is one of the most serious threats to human health, food safety and economic development. Antimicrobial peptides of animal origin, to which resistance is difficult to develop, appear to be a promising option to overcome this problem. To solve one of the problems in the practical use of peptides — their rapid degradation in blood plasma — dendrimerization of linear analogues of already existing antimicrobial peptides can be used. This work shows that dendrimers of shortened analogue of the natural proline-rich peptide ChBac3.4 are superior in antimicrobial activity to the original peptide and are much more stable in blood serum. At the same time, as the original peptide, branched analogues do not have hemolytic activity. AIM: The aim of this study is to develop new structural analogues of a peptide that have improved stability in blood serum while maintaining high antimicrobial activity. To achieve this, we intend to create dendrimeric (branched) molecules by synthesizing peptides using solid-phase methods. MATERIALS AND METHODS: We will investigate the antimicrobial properties of the peptides using the method of serial dilutions in a liquid nutrient medium against both Gram-positive and Gram-negative bacteria. We will also assess the stability of the peptides by culturing them in the presence of human blood serum. RESULTS: After making modifications to the original peptide, we expect to see a significant increase in its antimicrobial activity against all strains tested. Additionally, we anticipate that the resistance of these peptides will increase many times over. CONCLUSIONS: Overall, our findings suggest that dendrimerization can effectively improve the properties of proline-rich peptides, making them more suitable for use in medical applications.

Novel plasmid-mediated CMY variant (CMY-192) conferring ceftazidime-avibactam resistance in multidrug-resistant Escherichia coli.

The rapid rise of multidrug resistance (MDR) among Gram-negative bacteria has accelerated the development of novel therapies. Ceftazidime-avibactam (CZA) is a novel β-lactam/β-lactamase inhibitor recently approved for the treatment of limited infectious diseases. Here, we describe a novel CMY variant, CMY-192, that confers high-level resistance to CZA. This gene was detected in a clinical MDR Escherichia coli strain (Ec73552) isolated from an outpatient with a community-acquired urinary tract infection who had not received prior CZA treatment. Ec73552 was typed as O101:H9-ST10, a high-risk clone associated with human and animal diseases. Ec73552 was able to colonize the bladder in a mouse model, suggesting that this strain was uropathogenic. CMY-192 shared the highest amino acid identity (98.95%) with CMY-172 and conferred at least a 32-fold increase in CZA MIC (from ≤0.125/4 to 8/4 mg/L) when cloned into a CZA-susceptible E. coli DH5α strain. Knockout of CMY-192 in Ec73552 resulted in a 256-fold reduction in CZA MIC (from 64/4 to 0.25/4 mg/L). CMY-192 was encoded on an IncB/O/K/Z-type plasmid (pCMY192). Conjugation assays confirmed that pCMY192 was self-transmissible, resulting in a 256-fold increase in the CZA MIC of the recipient. Notably, pCMY192 cured in Ec73552 did not confer a growth advantage, while the conjugant exhibited reduced biomass and growth rate, indicating that fitness costs imposed by pCMY192 may have been compensated in Ec73552. Our findings highlight the importance of continuous monitoring of CZA susceptibility to prevent the spread of resistance in clinical settings.

Assessment of Urinary Tract Infection and Estimation of Procalcitonin Serum Level Among Iraqi Children

Urinary tract infections (UTIs) considered as a serious public health issue, especially in children, which can be caused by a variety of organisms, especially gram-negative bacteria. Procalcitonin (PCT) is a precursor of the calcitonin hormone, which normally released in the thyroid gland, and this biomarker has become more effective in diagnosing bacterial infections in the last decade. Moreover, to establish the utility of procalcitonin for predicting urinary tract infections in children. The current study included two groups of patients of approximately sixty cases from patients with urinary tract infection (UTI), besides, sixty cases from healthy individuals. Samples were collected from Al Imamain Al-Kadhimain Medical City in Baghdad. The result showed a highly significant difference in procalcitonin levels in UTI patients compared to the control group. The results of this investigation support the use of PCT as an indicator for the diagnosis of UTI children.

Antimicrobial and antibiofilm activity of human recombinant H1 histones against bacterial infections.

Histones possess significant antimicrobial potential, yet their activity against biofilms remains underexplored. Moreover, concerns regarding adverse effects limit their clinical implementation. We investigated the antibacterial efficacy of human recombinant histone H1 subtypes against Pseudomonas aeruginosa PAO1, both planktonic and in biofilms. After the in vitro tests, toxicity and efficacy were assessed in a P. aeruginosa PAO1 infection model using Galleria mellonella larvae. Histones were also evaluated in combination with ciprofloxacin (Cpx) and gentamicin (Gm). Our results demonstrate antimicrobial activity of all three histones against P. aeruginosa PAO1, with H1.0 and H1.4 showing efficacy at lower concentrations. The bactericidal effect was associated with a mechanism of membrane disruption. In vitro studies using static and dynamic models showed that H1.4 had antibiofilm potential by reducing cell biomass. Neither H1.0 nor H1.4 showed toxicity in G. mellonella larvae, and both increased larvae survival when infected with P. aeruginosa PAO1. Although in vitro synergism was observed between ciprofloxacin and H1.0, no improvement over the antibiotic alone was noted in vivo. Differences in antibacterial and antibiofilm activity were attributed to sequence and structural variations among histone subtypes. Moreover, the efficacy of H1.0 and H1.4 was influenced by the presence and strength of the extracellular matrix. These findings suggest histones hold promise for combating acute and chronic infections caused by pathogens such as P. aeruginosa.IMPORTANCEThe constant increase of multidrug-resistant bacteria is a critical global concern. The inefficacy of current therapies to treat bacterial infections is attributed to multiple mechanisms of resistance, including the capacity to form biofilms. Therefore, the identification of novel and safe therapeutic strategies is imperative. This study confirms the antimicrobial potential of three histone H1 subtypes against both Gram-negative and Gram-positive bacteria. Furthermore, histones H1.0 and H1.4 demonstrated in vivo efficacy without associated toxicity in an acute infection model of Pseudomonas aeruginosa PAO1 in Galleria mellonella larvae. The bactericidal effect of these proteins also resulted in biomass reduction of P. aeruginosa PAO1 biofilms. Given the clinical significance of this opportunistic pathogen, our research provides a comprehensive initial evaluation of the efficacy, toxicity, and mechanism of action of a potential new therapeutic approach against acute and chronic bacterial infections.

Effects of combined action of proline-rich peptides of human saliva with antimicrobial proteins

BACKGROUND: The substances that make up mixed saliva exhibit activity against bacteria, viruses and fungi. Among them are various cationic antimicrobial peptides: alpha- and beta-defensins, cathelicidins, histatins, but their concentration is relatively low. On the other hand, saliva widely contains a fraction of proline-rich proteins and products of their proteolysis — peptides, the functions of which currently remain poorly studied and unclear. The study of the antimicrobial activity of proline-rich proteins, in particular, when they act together with antimicrobial peptides, and the deciphering of the molecular and cellular basis for the implementation of the protective functions of proline-rich peptides is an urgent task in medicine and biology. The data obtained will help to understand the mechanisms of anti-infective protection of the oral cavity with the participation of the innate immune system, and in the future will allow the creation of drugs based on proline-rich proteins in humans and animals. AIM: Study of the individual antibacterial action of proline-rich salivary proteins, their combined action with the antimicrobial proteins lactoferrin and lysozyme, as well as with one of the most significant endogenous protective peptides — cathelicidin LL-37 on the formation of bacterial biofilms. MATERIALS AND METHODS: Human lactoferrin and egg lysozyme were used in the work. The minimum inhibitory concentrations of peptides against gram-negative and gram-positive bacteria were estimated using serial dilutions in a liquid nutrient medium. Using serial dilutions using the “chessboard” method, it was shown that proline-rich proteins can increase the antibacterial activity of innate immunity peptides present in the oral cavity. The ability of combinations of cationic proline-rich peptides with cathelicidin LL-37 to prevent the formation of bacterial biofilms was studied. RESULTS: In the presence of proline-rich peptides, the antimicrobial activity of some antimicrobial peptides and proteins present in saliva against planktonic bacteria increases. The combined action of proline-rich proteins with LL-37 increases the inhibition of bacterial biofilm formation. CONCLUSIONS: As a result of the study, it was shown that the analyzed cationic proline-rich peptides of human saliva exhibit anti-inflammatory effects, which suggests their significant role in the regulation of inflammatory processes in the oral cavity, as well as their participation in recovery processes.

Effects of different carbapenemase and siderophore production on cefiderocol susceptibility in Klebsiella pneumoniae.

The resistance mechanism of Gram-negative bacteria to the siderophore antibiotic cefiderocol is primarily attributed to carbapenemase and siderophore uptake pathways; however, specific factors and their relationships remain to be fully elucidated. Here, we constructed cefiderocol-resistant Klebsiella pneumoniae (CRKP) strains carrying different carbapenemases and knocked out siderophore genes to investigate the roles of various carbapenemases and siderophores in the development of cefiderocol resistance. Antimicrobial susceptibility testing revealed that both blaNDM and blaKPC significantly increased the minimum inhibitory concentration (MIC) of Klebsiella pneumoniae (KP) to cefiderocol, while blaOXA-48 showed a modest increase. Notably, KP expressing NDM exhibited a higher cefiderocol MIC compared to KP expressing KPC, although expression of NDM alone did not induce cefiderocol resistance. Laboratory evolutionary experiments demonstrated that combining pNDM with mutations in the siderophore uptake receptor gene cirA and pKPC with a mutation in the two-component system gene envZ led to KP reaching a high level of cefiderocol resistance. Although combining pOXA with mutations in the two-component system gene baeS did not induce cefiderocol resistance, it significantly reduced susceptibility. Moreover, siderophores could influence the development of cefiderocol resistance. Strains deficient in enterobactin exhibited increased susceptibility to cefiderocol, while deficiencies in yersiniabactin and salmochelin showed no significant alterations. In conclusion, carbapenemase gene expression facilitates cefiderocol resistance, but its presence alone is insufficient. Cefiderocol resistance in CRKP typically involves abnormal expression of certain genes and other factors, such as mutations in siderophore uptake receptor genes and two-component system genes. The enterobactin siderophore synthesis gene entB may also contribute to resistance.

Evaluation of the Cytotoxicity Effects of Bacteriophage VbɸPA-1 on the Virulent Pseudomonas aeruginosa, A375 Human Skin Melanoma Epithelial, and HFSF PI3 Human Skin Fibroblast Cells

Background: Gram-negative bacteria are the most common infectious bacteria and are life-threatening in burn patients. Phage therapy studies can help the hospital community eliminate these bacterial pathogens. Objectives: This study aimed to evaluate the effects of the isolated bacteriophages from hospital wastewater against Gram-negative pathogenic bacteria and investigate their cytotoxicity on two human skin cell lines. Methods: The bacterial strains were isolated from burn wound infections. Bacteriophages were isolated from the hospital wastewater treatment plant in Isfahan, Iran. Transmission electron microscopy, spot tests, and restriction enzyme digestion were considered for phage identification. Finally, the lactate dehydrogenase (LDH) and tetrazolium-based MTT assays were used to realize the cytotoxicity impacts of the isolated phages. The statistical analysis of cell viability was performed using a two-way analysis of variance (ANOVA). Results: The results showed that among the isolated strains, P. aeruginosa strain NEG_RA1300 (GenBank accession number: MW845642) was sensitive to the isolated phage VbɸPA-1. The TEM results showed a possible viral taxonomy of VbɸPA-1 based on its morphology, which belonged to the Myoviridae (T4-like phages). The MTT and LDH experiments showed no cytotoxicity of VbɸPA-1 on two tested cell lines. Conclusions: Based on the results, the inhibitory effect of isolated phage on P. aeruginosa isolated from burn wounds with no toxic effect on cell lines was very significant. This phage can also be an acceptable selection against burn wound infections.

Synthesis and antimicrobial activity of yttrium-doped cerium oxide nano-composite against wound pathogen

Abstract Nanocomposite materials have attracted considerable interest in several disciplines owing to their distinctive characteristics and possible uses. The primary objective of this study was to synthesize and characterize a nanocomposite material consisting of cerium that has been doped with yttrium. The shape, structure, and properties of the synthesized nanocomposite was characterized using various characterization techniques including ultraviolet spectrophotometry, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-ray diffraction (XRD), zeta potential measurements, dynamic light scattering (DLS), and Fourier-transform infrared spectroscopy (FTIR).The antibacterial activity of the nanocomposite was assessed against a range of pathogenic bacteria including Gram-positive bacteria - Enterococcus faecalis, Staphylococcus aureus, and Gram-negative bacteria- Escherichia coli, Pseudomonas aeruginosa using standard microbiological techniques. The results indicate that the nanocomposite possesses strong antibacterial properties against a wide range of microorganisms, showcasing its potential as a highly effective antimicrobial agent for diverse applications in the biological, environmental, and industrial fields. Hemolysis is the process of red blood cell destruction, resulting in the release of hemoglobin into the surrounding fluid. In this study, 0.7:0.3M nanocomposite had showed effective biocompatibility with less than 5%. Furthermore, this particular composite remained identical in different time intervals, while other composites would normally fluctuate. Research has shown that meticulous material design and surface modification can reduce the harmful effects on red blood cells, hence improving the safety of nanocomposite for therapeutic purposes. In summary, this study offers valuable information on the creation, analysis, and assessment of nanocomposite materials with antimicrobial properties.

Valorization of Potato Peels (Solanum tuberosum) Using Infrared-Assisted Extraction: A Novel Sprouting Suppressant and Antibacterial Agent.

Recently, there has been a growing interest in reducing waste to promote environmental sustainability, with particular focus on agricultural by-products, especially fruits and vegetables. Potato, a widely used crop across various industries, generates a significant amount of peel waste. This study aims to valorize potato peels using water bath extraction (WBE) and infrared-assisted extraction (IRAE), both with distilled water as the solvent, followed by assessments of antioxidant, antibacterial, and anti-sprouting activities. Optimization using response surface methodology identified optimal extraction conditions for WBE (90 °C for 70 min) and IRAE (80 °C for 10 min), with both methods yielding 3.5 mg GAE/g DM in polyphenol content. IRAE demonstrated superior energy efficiency and enhanced antioxidant activity. The extracts exhibited antibacterial properties against both Gram-positive (Listeria monocytogenes) and Gram-negative bacteria (Proteus sp. and Salmonella sp.), with inhibition zones ranging from 10 to 14 mm. Furthermore, the potato peels extract showed significant anti-sprouting effects at room temperature, reducing both the number and size of sprouts compared with the control. HPLC analysis showed the presence of different phenolic compounds such as rutin, catechin, caffeic acid, protocatechuic acid, chlorogenic acid, p-coumaric acid, and gallic acid in one or both extracts. These findings suggest that potato peels extract holds potential for applications in the food industry as a natural preservative due to its antioxidant properties, as well as a sprout suppressant. The antibacterial activity of the extracts suggests their potential as a natural preservative as well, offering protection against both Gram-positive and Gram-negative bacteria that may be present in food.

Extended Spectrum β-Lactamase: Tackling Antibiotic Resistance and Overcoming Treatment Challenges

Antibiotics, also known as antibacterials, kill or inhibit bacterial growth but are ineffective against viruses, fungi, or parasites, often leading to misuse. They are categorized by molecular structure, mode of action, and spectrum of activity. Antimicrobial Resistance (AMR) occurs when pathogens no longer respond to antimicrobial drugs, arising naturally or through acquisition. Resistance mechanisms include enzymatic (most common), genetic and physical. Bacteria produce various β-lactamases, such as Extended Spectrum β-lactamases (ESBLs), AmpC enzymes, and carbapenemase to exert resistance to Beta-Lactam (βL) class of antibiotics. ESBL families include TEM, SHV, and CTX-M, with E. coli being the most prevalent host. Any Gram-Negative Bacteria (GNB) can be an ESBL producer, but most common ones are the Enterobacteriaceae including Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca and Proteus mirabilis. ESBL-producing Enterobacteriaceae (ESBL-E) resist penicillin, aztreonam, and cephalosporins except cephamycins and carbapenems, posing a significant public health risk. Genetic resistance mechanisms involve random mutations and horizontal gene transfer through either of the following processes namely conjugation, transformation, transduction. Physical mechanisms include efflux pump production and decreased porin channels. In some microbiological laboratories, ESBL production are often not determined, rather resistance based on MIC values to third generation Cephalosporins are considered as resistance due to ESBL production. Antibiotic use in agriculture and medicine has increased Multi-drug resistant (MDR) ESBL-producing E. coli and evidenced in retail meat and among meat shop employees. Community-acquired ESBL-E infections are a growing concern, with hospital transmission primarily occurring among patients sharing rooms with ESBL carriers. Empirical and definitive therapies for ESBL-E infections must be adjusted based on Antibiotic Susceptibility Testing (AST). The MERINO trial identified urinary tract infections as the most common source of ESBL-E bacteremia, with E. coli being predominant. For critically ill patients with non-urinary tract infections, Meropenem or Imipenem-cilastatin are recommended. For uncomplicated UTIs, Nitrofurantoin, Cotrimoxazole, and Piperacillin-Tazobactam (Pip-Taz) are effective, while Cotrimoxazole, Fluoroquinolones, and Ceftolozane-tazobactam are suitable for complicated UTIs. New β-lactamase inhibitors like avibactam, vaborbactam, and relebactam are promising for treatment. Misuse of antibiotics, such as inappropriate dosing and duration, contributes to AMR, a growing global challenge. Deaths from AMR, estimated at 1.27 million in 2019, could reach 10 million by 2050. ESBLs drive the use of broad-spectrum antibiotics, accelerating resistance development. Inadequate therapy exacerbates infections, leading to prolonged hospital stays, complications, and increased mortality. Balancing new drug development with resistance emergence is crucial to combat AMR.

Versatile iodinated styryl dyes: Promising probes for viscosity detection with dual anti-cancer and anti-bacterial properties

We have demonstrated how intramolecular charge transfer (ICT) dyes can be combined with the molecular rotor property to create fluorescent viscosity sensors. Cyanine styryl dyes with various substituents were synthesized to alter their photophysical properties in intracellular viscosity detection. The synthesized dyes had strong absorbance and emission properties that are suited for cellular imaging. Fluorescence intensity was observed to increase with the environment's viscosity, which was supported by theoretical calculations. I-Cy-Styryl-OMe outperformed the other Cy-Styryl dyes in terms of viscosity sensing and brightness. I-Cy-Styryl-OMe was also utilized to detect alterations in intracellular viscosity and fatty liver in a mouse model. Furthermore, experiments were performed on various cell lines to determine anti-cancer efficacy and selectivity. Finally, the antibacterial abilities of the dyes were then assessed against gram-positive and gram-negative bacteria. Therefore, our work shows that organic fluorescent viscosity sensors are feasible for a range of biological uses.

Evaluation of the antimicrobial and anticancer properties of Myrrh resin extract and its application in cacao beverages

Due to the potential health risks of synthetic food preservatives, there has been a noticeable increase in interest in finding natural food preservatives during the past few decades. The goal of this study was to investigate the use of a natural extract of Myrrh resin as an antimicrobial agent. The antioxidant properties of Myrrh resin extract (MRE) were analyzed using HPLC and GC–MS. The results showed that MRE contained potent antioxidant compounds, including 19 compounds, with the dominant compound being kaempferol, which had the highest value of 1896 µg/g. Quercetin was found to be the second most abundant compound, with a value of 520 µg/g.The efficacy of MRE as an antimicrobial agent against both Gram-positive and Gram-negative bacteria was tested, and its application in Cacao beverages was also studied. The results demonstrated that MRE was highly effective against all the tested bacteria both in vitro and in the total bacterial count of the produced cacao beverage. Additionally, the fungi in the cacao beverage were completely inhibited at all tested concentrations of MRE. The total soluble solids (TSS), pH value, and acidity of the produced untreated, treated cacao beverage with MRE and sodium benzoate were carried out, and all values mentioned were almost the same, with no differences noted. The sensory evaluation of Cacao beverage showed that the MRE had a minor impact on taste, odor, color, and texture of the produced cacao beverage in comparison with the control sample, which was very acceptable for judgments and recorded 95, 88, and 94 for the control and treated samples, respectively. Furthermore, the anti-cancer properties of MRE were evaluated, revealing significant cytotoxic effects against colon cancer (HCT) and liver cancer (HEPG2) cell lines. The IC50 values for HCT and HEPG2 cells were 55.69 µg/ml and 70.78 µg/ml, respectively, indicating the potential of MRE as an anti-cancer agent.

The oral cavity is a potential reservoir of gram-negative antimicrobial-resistant bacteria, which are correlated with ageing and the number of teeth

ObjectivesThe suppression of antimicrobial-resistant bacteria (ARB) is an important issue worldwide. In recent years, the presence of various ARB in the oral cavity has been reported, but the details remain unclear. Therefore, we aimed to isolate ARB from the oral cavity and investigate the factors affecting ARB colonization. MethodsThird-generation cephalosporin- or carbapenem-resistant gram-negative bacteria (GN-ARB) were isolated from the oral and nasal cavities of 514 participants who visited the dental clinic, and the whole-genome sequences of all the isolates were obtained. Additionally, the tongue microbiota was analysed by 16S rRNA sequencing. The correlations of GN-ARB isolation with clinical status and the tongue microbiota were subsequently investigated. ResultsAmong 514 participants, 131 and 13 GN-ARB strains were isolated from the oral cavities of 93 participants (18.1 %) and from the nasal cavities of 12 participants (2.3 %). The ARB were mainly affiliated with Acinetobacter spp. (39.7 %), Pseudomonas spp. (14.5 %) and Stenotrophomonas maltophilia (18.3 %). We found a correlation between the isolation of oral GN-ARB and ageing/the number of teeth. There were no significant correlations between the presence of GN-ARB and tongue microbiota composition. ConclusionsOur results suggest that the oral cavity is an important potential reservoir of GN-ARB and that ageing and tooth loss are risk factors for the presence of GN-ARB in the oral cavity.

Fluconazole worsened lung inflammation, partly through lung microbiome dysbiosis in mice with ovalbumin-induced asthma.

Innate immunity in asthma may be influenced by alterations in lung microbiota, potentially affecting disease severity. This study investigates the differences in lung inflammation and microbiome between asthma-ovalbumin (OVA) administered with and without fluconazole treatment in C57BL/6 mice. Additionally, the role of inflammation was examined in an in vitro study using a pulmonary cell line. At 30 days post-OVA administration, allergic asthma mice exhibited increased levels of IgE and IL-4 in serum and lung tissue, higher pathological scores, and elevated eosinophils in bronchoalveolar lavage fluid (BALF) compared to control mice. Asthma inflammation was characterized by elevated serum IL-6, increased lung cytokines (TNF-α, IL-6, IL-10), and higher fungal abundance confirmed by polymerase chain reaction (PCR). Fluconazole-treated asthma mice displayed higher levels of cytokines in serum and lung tissue (TNF-α and IL-6), increased pathological scores, and a higher number of mononuclear cells in BALF, with undetectable fungal levels compared to untreated mice. Lung microbiome analysis revealed similarities between control and asthma mice; however, fluconazole-treated asthma mice exhibited higher Bacteroidota levels, lower Firmicutes, and reduced bacterial abundance. Pro-inflammatory cytokine production was increased in supernatants of the pulmonary cell line (NCI-H292) after co-stimulation with LPS and beta-glucan (BG) compared to LPS alone. Fluconazole treatment in OVA-induced asthma mice exacerbated inflammation, partially due to fungi and Gram-negative bacteria, as demonstrated by LPS+BG-activated pulmonary cells. Therefore, fluconazole should be reserved for treating fungal asthma rather than asthma caused by other etiologies.