Search Results (286)

Polymicrobial biofilms involving fungal and bacterial species are increasingly recognized as contributors to persistent infections, particularly in the oral cavity. Candida albicans and Aggregatibacter actinomycetemcomitans are two commensals that can turn into opportunistic pathogens and are able to form robust biofilms. Objectives: This study aimed to assess the interaction dynamics between these two microorganisms and to evaluate their susceptibility to fluconazole and azithromycin in single- and mixed-species forms. Methods: Biofilm biomass was quantified using crystal violet assays, while biofilm cell viability was assessed through CFU enumeration (biofilm viability assay). To assess the resistance properties of single versus mixed-species coincubations, we applied the antimicrobial susceptibility test (AST) to each drug, and analysed spatial organization with confocal laser scanning microscopy, using PNA-FISH. Results: The results indicated that both species can coexist without significant mutual inhibition. However, a non-reciprocal synergism was also observed, whereby mixed-species biofilm conditions promoted the growth of A. actinomycetemcomitans, while C. albicans growth remained stable. As expected, antimicrobial tolerance was elevated in mixed cultures, likely due to enhanced extracellular matrix production and potential quorum-sensing interactions, contributing to increased resistance against azithromycin and fluconazole. Conclusions: This study provides novel insights into previously rarely explored interactions between C. albicans and A. actinomycetemcomitans. These findings underscore the importance of investigating interspecies interactions within polymicrobial biofilms, as understanding their mechanisms, such as quorum-sensing molecules and metabolic cooperation, can contribute to improved diagnostics and more effective targeted therapeutic strategies against polymicrobial infections. Full article

This study explores the potential of biodegradable Bioglass 45S5 formulations as a dual-function approach for preventing and treating Staphylococcus aureus infections in orthopaedic surgery while addressing the growing concern of antimicrobial resistance (AMR). The research focuses on the development and characterisation of antibiotic-loaded BG45S5 formulations, assessing parameters such as drug loading efficiency, release kinetics, antimicrobial efficacy, and dissolution behaviour. Key findings indicate that the F2l-BG45S5-T-T-1.5 and F2l-BG45S5-T-V-1.5 formulations demonstrated controlled antibiotic release for up to seven days, with size distributions of D(10): 7.11 ± 0.806 µm, 4.96 ± 0.007 µm; D(50): 25.34 ± 1.730 µm, 25.20.7 ± 0.425 µm; and D(90): 53.7 ± 7.95 µm, 56.10 ± 0.579 µm, respectively. These formulations facilitated hydroxyapatite formation on their surfaces, indicative of osteogenic potential. The antimicrobial assessments revealed zones of inhibition against methicillin-susceptible Staphylococcus aureus (MSSA, ATCC-6538) measuring 20.3 ± 1.44 mm and 24.6 ± 1.32 mm, while for methicillin-resistant Staphylococcus aureus (MRSA, ATCC-43300), the inhibition zones were 21.6 ± 1.89 mm and 22 ± 0.28 mm, respectively. Time-kill assay results showed complete bacterial eradication within eight hours. Additionally, biocompatibility testing via MTT assay confirmed cell viability of >75%. In conclusion, these findings highlight the promise of antibiotic-loaded BG45S5 as a multifunctional biomaterial capable of both combating bone infections and supporting bone regeneration. These promising results suggest that in vivo studies should be undertaken to expedite these materials into clinical applications. Full article

Periodontitis is a multifactorial disease linked to host immune response and genetic predisposition. The TLR4 Asp299Gly single-nucleotide polymorphism (SNP, rs4986790) has been associated with altered responses to bacterial lipopolysaccharide (LPS) and may influence susceptibility to inflammatory diseases. Given the central role of TLR4 in innate immune recognition of periodontal pathogens, this study investigates the role of rs4986790 in modulating susceptibility to periodontal inflammatory destruction. A total of 1410 individuals from four populations were genotyped, with findings indicating a significant protective effect of the polymorphic allele. Functional assays demonstrated enhanced IL-8 secretion and increased sensitivity to CD14 inhibition in cells expressing the variant receptor. These results suggest that rs4986790 modifies the LPS response via TLR4, potentially offering protection against periodontal breakdown. Full article

Canine otitis externa caused by Pseudomonas aeruginosa is a relevant disease in veterinary medicine. Given P. aeruginosa’s high priority status for the development of new antimicrobials, innovative strategies like bacteriophage therapy are essential. Lytic bacteriophages are viruses with high specificity for their bacterial hosts, making them a promising therapeutic choice in both human and veterinary medicine. This study aimed to evaluate the antimicrobial potential of bacteriophages JG005 and JG024, first characterized in terms of their biofilm-forming ability and antimicrobial susceptibility profile, against P. aeruginosa isolates obtained from dogs with otitis externa,. Bacteriophages titer, host range, and activity were assessed against P. aeruginosa biofilms via microtiter assays using crystal violet and Alamar Blue. JG024 showed lytic activity against 61.2% (n = 30/49) of the isolates, while JG005 showed lytic activity against 38.8% (n = 19/49) of the isolates. Crystal violet quantification showed that JG005 can promote strong microbial suppression of 60% (n = 6/10) and 50% (n = 5/10) of the isolates at a multiplicity of infection (MOI) of 10 and 100, respectively. JG024 presented strong microbial suppression of 20% (n = 2/10) of the isolates regardless of the MOI level tested. These phages show promising potential as an innovative treatment for canine otitis externa caused by P. aeruginosa, but further studies are needed before future clinical use. Full article

Antibiotic overuse has contributed to the emergence of multidrug-resistant (MDR) bacteria, posing a serious public health threat. Pets may act as reservoirs of MDR bacteria, with the potential to transmit these pathogens to humans. This study aimed to identify probiotic alternatives to antibiotics by isolating and evaluating lactic acid bacteria (LAB) from feline milk. In addition to conventional in vitro assessments such as growth kinetics, adhesion ability, safety, and antipathogenic activity, this study also evaluated the antioxidant capacity and production of beneficial metabolites. Three LAB strains were isolated from feline milk, including two strains of Lactobacillus plantarum (M2 and M3) and one strain of Weissella confusa (M1). Resistance assays revealed that strains M2 and M3 exhibited high survival rates under stress conditions, including exposure to bile salts, acidic environments, artificial intestinal and gastric juice. Notably, strain M3 demonstrated strong auto-aggregation ability (73.39%) and high hydrophobicity toward trichloromethane (62.16%). It was also nonhemolytic and susceptible to various β-lactam antibiotics. Furthermore, strain M3 exhibited potent antimicrobial activity in both co-aggregation and Oxford cup assays. Overall, L. plantarum M3 displayed superior probiotic properties, suggesting its potential as an adjunct or alternative to antibiotics in managing MDR bacterial infections in cats. Full article

Antimicrobial resistance (AMR) is a rapidly growing global concern resulting from the overuse of antibiotics in both agricultural and clinical settings, the lack of surveillance for resistant bacteria, and the low quality of some available antimicrobial agents. Resistant pathogens are no longer susceptible to common clinical antimicrobials, which decreases the effectiveness of medicines used to treat infections caused by these organisms. Carbapenems are an important class of antibiotics due to their broad-spectrum effectiveness in treating infections caused by Gram-positive and Gram-negative organisms. Carbapenem-resistant bacteria have been found not only in healthcare but also in the environment and food supply chain, where they have the potential to spread to pathogens and infect humans and animals. Current methods of detecting AMR genes are expensive and time-consuming. While these methods, like polymerase chain reactions or whole-genome sequencing, are considered the “gold standard” for diagnostics, the development of inexpensive, rapid diagnostic assays is necessary for effective AMR detection and management. Biosensors have shown potential for success in diagnostic testing due to their ease of use, inexpensive materials, rapid results, and portable nature. Biosensors can be combined with nanomaterials to produce sensitive and easily interpretable results. This review presents an overview of carbapenem resistance, current and emerging detection methods of antimicrobial resistance, and the application of biosensors for rapid diagnostic testing for bacterial resistance. Full article

Chronic wounds represent a major clinical challenge due to their prolonged healing process and susceptibility to bacterial colonization, particularly by biofilm-forming bacteria. To address these issues, in this work, silver-treated silk fibroin scaffolds were developed and tested as multifunctional wound dressings, combining antimicrobial and regenerative properties. Silk fibroin, a natural protein derived from Bombyx mori cocoons, is widely recognized for its biocompatibility and suitability for tissue engineering. In this study, porous silk fibroin scaffolds were functionalized with silver nanoparticles through a photo-reduction process and were comprehensively tested for their cytocompatibility and wound healing potential. The excellent antibacterial activity of the silver-treated scaffolds was demonstrated against Escherichia coli and antibiotic-resistant Pseudomonas aeruginosa, as was extensively reported in a previous work. Biological assays were performed using 3T3 fibroblasts cultured on both untreated and silver-treated silk fibroin scaffolds. Biocompatibility assays, such as MTT, Live/Dead, and cytoskeleton analyses, demonstrated biocompatibility in both scaffold types, comparable to the control. Wound healing potential was assessed using in vitro scratch assays, revealing full wound closure (100%) after 24 h in cells cultured with untreated and silver-treated silk fibroin scaffolds, in contrast to 78.5% closure in the control. Notably, silver-treated scaffolds exhibited enhanced fibroblast repopulation within the wound gap, suggesting a synergistic effect of silver and fibroin in promoting tissue regeneration. These findings demonstrate that silver-treated silk fibroin scaffolds possess both anti-microbial and regenerative properties, making them promising candidates for chronic wound management applications. Full article

Background/Objectives: The rise of antibiotic-resistant bacteria presents a major global health challenge, highlighting the need for novel antimicrobial agents such as antimicrobial peptides (AMPs). AMPs are promising due to their broad-spectrum activity, membrane-disruptive mechanisms, and low development of resistance. This study aimed to design and evaluate novel AMPs derived from a synthetic parent peptide (PEP-38). Methods: Novel peptides were designed using bioinformatics tools, including CAMP_R3 and Peptide Ranker. Their antimicrobial potential was validated through in vitro assays, including bacterial susceptibility, antibiofilm activity, cytotoxicity, hemolysis, and time–kill kinetics. Results: Among the designed peptides, Hel-4K-12K showed potent activity against both Gram-positive and Gram-negative bacteria, with MICs ranging from 3.125 to 6.25 µM. It also effectively eradicated biofilms of resistant Staphylococcus aureus at an MBEC of 6.25 µM. Time–kill assays confirmed rapid bactericidal action, achieving complete bacterial elimination within one hour at its MIC. Moreover, Hel-4K-12K exhibited low toxicity toward mammalian MDCK cells (>82% viability at MIC) and minimal hemolytic activity on human erythrocytes. Conclusions: Hel-4K-12K demonstrates strong antibacterial and antibiofilm activities with a favorable safety profile, indicating its potential as a therapeutic candidate for treating infections caused by resistant bacteria. These findings support further development of this peptide as a basis for new antimicrobial drug strategies. In addition to its promising in vitro profile, future studies will investigate Hel-4K-12K in animal models and evaluate strategies for attaining stable formulations, such as peptide encapsulation or PEGylation. These steps are critical to ensure its therapeutic viability in systemic applications. Full article

Antimicrobial peptides (AMPs) have emerged as promising candidates in the fight against multidrug-resistant pathogens due to their broad-spectrum antimicrobial activity and low potential for resistance development. However, their clinical application is limited by poor stability and susceptibility to enzymatic degradation. This study aims to address these limitations by synthesizing a series of cyclic hexapeptides using the hydrazide method and evaluating their antimicrobial activity and stability. The hydrazide method facilitated the synthesis of 11 cyclic peptides through a reaction between C-terminal hydrazides and cysteine-containing peptides. Antimicrobial assays showed that Cy-f2 and Cy-f4 exhibited potent inhibitory effects against different kinds of bacteria, including E. coli, Staphylococcus aureus, and S. aureus. Hemolysis assays revealed minimal red blood cell lysis at effective antimicrobial concentrations, indicating good biocompatibility. Stability tests demonstrated improved stability of the cyclic peptides compared to linear counterparts in SGF and 80 °C. In conclusion, the cyclic hexapeptides synthesized in this study demonstrate excellent antimicrobial activity, enhanced stability, and low toxicity, suggesting their potential as new candidates for treating drug-resistant bacterial infections. Full article

This study addresses the challenge of rapidly and accurately distinguishing zones of microbial activity from antibiotic inhibition zones in Petri dishes. We propose a laser speckle imaging technique enhanced with subpixel correlation analysis to monitor dynamic changes in the inhibition zone surrounding an antibiotic disc. This method provides faster results compared to the standard disk diffusion assay recommended by EUCAST. To enable automated analysis, we used machine learning algorithms for classifying areas of bacterial or fungal activity versus inhibited growth. Classification is performed over short time windows (e.g., 1 h), supporting near-real-time assessment. To further improve accuracy, we introduce a correction method based on the known spatial dynamics of inhibition zone formation. The novelty of the study lies in combining a speckle imaging subpixel correlation algorithm with ML classification and with pre- and post-processing. This approach enables early automated assessment of antimicrobial effects with potential applications in rapid drug susceptibility testing and microbiological research. Full article

Bacterial leaf streak (BLS) is one of the internationally significant quarantine diseases in rice. Effectively utilizing BLS resistance genes from wild rice (Oryza rufipogon Griff.) to breed new varieties offers a fundamental solution for BLS control. This study focused on the fine mapping of the BLS resistance gene bls2 and the development of closely linked molecular markers for breeding BLS-resistant lines. Using a Guangxi common wild rice accession DY19 (carrying bls2) as the donor parent and the highly BLS-susceptible indica rice variety 9311 as the recipient parent, BLS-resistant rice lines were developed through multiple generations of backcrossing and selfing, incorporating molecular marker-assisted selection (MAS), single nucleotide polymorphism(SNP) chip genotyping, pathogen inoculation assays, and agronomic trait evaluation. The results showed that bls2 was delimited to a 113 kb interval between the molecular markers ID2 and ID5 on chromosome 2, with both markers exhibiting over 98% accuracy in detecting bls2. Four stable new lines carrying the bls2 segment were obtained in the BC₅F₄ generation. These four lines showed highly significant differences in BLS resistance compared with 9311, demonstrating moderate resistance or higher with average lesion lengths ranging from 0.69 to 1.26 cm. Importantly, no significant differences were observed between these resistant lines and 9311 in key agronomic traits, including plant height, number of effective panicles, panicle length, seed setting rate, grain length, grain width, length-to-width ratio, and 1000-grain weight. Collectively, two molecular markers closely linked to bls2 were developed, which can be effectively applied in MAS, and four new lines with significantly enhanced resistance to BLS and excellent agronomic traits were obtained. These findings provide technical support and core germplasm resources for BLS resistance breeding. Full article

Background: Chronic rhinosinusitis (CRS) affects 5.5–28% of the population and is primarily an inflammatory disease, with microbiota potentially playing a key role. Understanding microbial pathogens and resistance patterns is crucial for effective management. This study aimed to evaluate the incidence of Gram-negative rods in CRS in adults as a part of a prospective microbiological study. Methods: Over one year, paranasal sinus mucosa samples from CRS patients and nasal concha samples from controls were analyzed. Cultivable bacterial flora was assessed using culture-based methods. Biofilm formation was evaluated via a microtiter-plate assay, and antibiotic susceptibility was tested using the disk diffusion method. Results: Tissue samples from 74 CRS patients and 47 controls yielded 198 bacterial strains. Gram-positive cocci dominated, while Gram-negative rods accounted for 17.6%, with Escherichia coli, Klebsiella oxytoca, and Citrobacter spp. being most common. All Gram-negative rods formed biofilms in vitro. They were susceptible to cefotaxime, aztreonam, ciprofloxacin, and meropenem but showed varying sensitivity to ampicillin (20–67%), tigecycline (40–57%), and amoxicillin/clavulanic acid (73–83%). Conclusions: The result of this study underlines that treatment of CRS should be based on the result of drug susceptibility testing of the isolated microorganism. Full article

Fire blight, caused by Erwinia amylovora, is a devastating bacterial disease threatening apple, pear, and other Rosaceae species. In our prior study, transcriptome analysis identified a fire blight-resistant variety, Duli (Pyrus betulifolia Bunge), and highlighted the PR1 gene as a key resistance factor. Using Duli’s genomic data, we systematically identified and characterized the Pb-PR-1 gene family through bioinformatics analysis. A total of 31 Pb-PR-1 genes were found, encoding proteins of 123–341 amino acids. Phylogenetic analysis grouped these genes into four subfamilies, with 27 genes distributed across seven chromosomes, all contain a conserved CAP superfamily domain. Their promoter regions were enriched in hormone and stress-responsive elements. After inoculation with E. amylovora, susceptible Duli showed lesion development by day 2, with rapid disease progression, while resistant plants exhibited slower disease advancement and smaller lesions. Enzyme activity assays revealed that in resistant plants, PPO (polyphenol oxidase) and CAT (catalase) activities peaked on day 6, showing a 2.4-fold and 3.81-fold increase compared to susceptible Duli. At the same time, MDA (malondialdehyde) content decreased by 16.6%. The activities of SOD (superoxide dismutase) and PAL (phenylalanine ammonia-lyase) peaked on day 4, with increments of 34.32% and 47.1% over susceptible Duli. qRT-PCR showed significant differences in Pb-PR-1 gene family expression between resistant and susceptible plants post-inoculation. Notably, Pb-PR-1-11, Pb-PR-1-21, and Pb-PR-1-26 expression increased with infection duration, aligning with PPO and CAT activity trends. Other genes showed high early infection expression but declined by day 6. Pb-PR-1-3, Pb-PR-1-6, Pb-PR-1-8, Pb-PR-1-16, and Pb-PR-1-30 were upregulated 13.17-fold on average by day 2. In summary, the Pb-PR-1 family exhibited elevated expression during early infection and enhanced defense-related enzyme activities, improving plant resistance. This study provides a foundation for understanding the PR-1 family’s role in Duli and advancing fire blight resistance in Pyrus species. Full article

Background: Colistin resistance among Gram-negative nosocomial pathogens is an increasing concern. The bacteriophage-encoded lytic enzyme endolysin LysAB1245, which targets bacterial peptidoglycan, was evaluated as a potential antibacterial agent in combination with colistin as a therapeutic approach. Methods: Clinical isolates of Acinetobacter baumannii and Pseudomonas aeruginosa, along with two reference strains, were used to assess the antibacterial activity of LysAB1245 and colistin, individually and in combination. Antibacterial susceptibility was assessed by broth microdilution. Synergistic interactions were determined using checkerboard assays and confirmed by time-kill kinetics. Resistance development was assessed after several rounds of exposure to each agent, either alone or in combination. Results: In this study, the synergistic activity of the LysAB1245/colistin combination therapy was found in some clinical isolates of Acinetobacter baumannii and Pseudomonas aeruginosa, resulting in a reduction in the MICs of both LysAB1245 and colistin. The bactericidal effects, with a significant, more than 3-log reduction in CFU/mL (p < 0.01), were observed in representative synergistic isolates within 4 h of treatment with the combination of LysAB1245 at 1/4 × MIC and colistin at 1/4 × MIC. Scanning electron microscope micrographs confirmed bacterial cell damage upon treatment with the combination. Additionally, treatment with LysAB1245 in combination with colistin had no effect on the development of bacterial resistance after multiple passages. Conclusions: Combining LysAB1245 with a last-resort antibiotic like polymyxins (colistin) could be used as a promising new antibacterial strategy for preventing and controlling antibiotic-resistant Gram-negative bacteria. Full article

Background/Objectives: The overuse and misuse of antibiotics has contributed significatively to the growing problem of the emergence and spread of antibiotic resistance genes among bacteria, posing a serious global challenge to the treatment of bacterial infectious diseases. For these reasons, there is a current and growing interest in the development of effective alternative or complementary strategies to antibiotic therapy for the prevention of fish diseases, which are mainly based on the use of probiotics—in particular, those belonging to the Lactic Acid Bacteria (LAB) group. In this context, the aim of the present study was to characterise, evaluate the genetic diversity and assess the safety of candidate probiotic LAB strains for aquaculture isolated from faeces and intestines of European hakes (Merluccius merluccius, L.) caught in the Northeast Atlantic Ocean (Ireland). Methods: The direct antimicrobial activity of the LAB isolates was tested by the Stab-On-Agar method against key ichthyopathogens. Subsequently, their taxonomic classification and genetic diversity were determined by 16SrDNA sequencing and Enterobacterial Repetitive Intergenic Consensus-PCR (ERIC-PCR), respectively. To ensure the in vitro safety of the LAB isolates, their biofilm-forming ability was assessed by a microtiter plate assay; their sensitivity to major antibiotics used in aquaculture, human and veterinary medicine by a broth microdilution method and their haemolytic and gelatinase activity by microbiological assays. Results: All LAB isolates were biofilm producers and susceptible to chloramphenicol, oxytetracycline, flumequine and amoxicillin. A total of 30 isolates (85.7%) were resistant to at least one of the tested antibiotics. None of the 35 LAB isolates showed haemolytic or proteolytic activity. Conclusions: Among the isolated strains, five LAB strains exhibiting the highest antimicrobial activity against aquaculture-relevant ichthyopathogens, taxonomically identified as Streptococcus salivarius, Enterococcus avium and Latilactobacillus sakei, were selected for further characterisation as potential probiotic candidates to promote sustainable aquaculture. To our knowledge, this is the first study to report that hake intestines and faeces represent viable ecological niches for the isolation of LAB strains with antimicrobial activity. Full article