Search Results (1,264)

Aminoglycosides are commonly partnered with β-lactam antibiotics for empirical treatment of severe Gram-negative bacterial infections, including those caused by Pseudomonas aeruginosa. However, the optimal duration of aminoglycoside therapy when co-administered with β-lactam antibiotics remains poorly defined. This study compared the antibacterial efficacy of short (one-day, three-day) versus long course (seven-day) of tobramycin therapy, co-administered with piperacillin/tazobactam, against piperacillin/tazobactam-resistant clinical isolates of P. aeruginosa in a hollow fibre infection model (HFIM). A broth microdilution method was used to determine the minimum inhibitory concentration (MIC) of the antibiotics. The HFIM experiments were performed using two piperacillin/tazobactam-resistant clinical isolates, CTAP-32 and CTAP-72 (both with piperacillin/tazobactam MICs > 128 mg/L). The clinical dose of tobramycin (10 mg/kg/day IV) was simulated for one, three, and seven days, each in combination with piperacillin/tazobactam (4.5 g every six hours infused over 30 min). In the HFIM, the one-day, three-day, and seven-day courses of tobramycin administered with piperacillin/tazobactam resulted in comparable bacterial kill with ~3log₁₀ CFU/mL bacterial density reduction within the first 8 h of treatment against the CTAP-32 bacterial isolate. Similarly, these three combination regimens resulted in equivalent bacterial killing effects against the CTAP-72 isolate with a ~5log₁₀ CFU/mL bacterial reduction during the initial treatment period. However, despite this early decline, comparable bacterial regrowth was observed thereafter with the short versus the long course of tobramycin co-administered with piperacillin/tazobactam. In conclusion, short-course and long-course tobramycin therapy, when combined with piperacillin/tazobactam, achieved comparable antibacterial efficacy against P. aeruginosa isolates in the HFIM. However, these findings warrant further validation in clinical studies. Full article

Infectious wounds are plagued by persistent infection, uncontrolled inflammation, and delayed repair, while traditional therapies suffer from the poor solubility of natural drugs, low bioavailability, and bacterial drug resistance. To address these issues, this study developed a photo-responsive chitosan composite hydrogel (BBR-AS@Ce6@Matrix) cross-linked by chitosan (CS) and oxidized sodium alginate (OSA), co-loaded with Berberine–Asiaticoside cocrystal (BBR-AS) and chlorin e6-loaded chitosan nanoparticles (Ce6@CS NPs). The BBR-AS co-crystal was prepared by solvent method and verified to significantly improve the solubility and dissolution of asiaticoside. The Ce6@CS NPs were fabricated via non-solvent-assisted counterion complexation, showing high encapsulation efficiency, uniform particle size, and efficient singlet oxygen generation under irradiation. The hydrogel exhibited a three-dimensional porous network, favorable rheology, high water content, pH-dependent swelling and erosion behaviors, and significantly promoted BBR/AS release in vitro. In vitro experiments demonstrated strong antibacterial activity against Escherichia coli and Staphylococcus aureus, good cytocompatibility, and enhanced migration of L929 and Hacat cells. In a rat infectious wound model, the hydrogel combined with light irradiation markedly accelerated wound closure, promoted collagen deposition and angiogenesis, upregulated VEGF/CD31, and downregulated TNF-α/IL-6. In conclusion, BBR-AS@Ce6@Matrix integrates co-crystal solubilization, nanoparticle-facilitated release, and photodynamic synergy to achieve antibacterial, anti-inflammatory, pro-angiogenic and tissue remodeling effects, providing a promising multifunctional platform for infectious wound repair. Full article

Salmonella is a globally significant foodborne intracellular pathogen, and invasive salmonellosis poses a major global public health threat. The NLR family CARD-containing protein 4 (NLRC4) inflammasome, a pivotal cytosolic innate immune sensor, specifically recognizes Salmonella flagellin and type III secretion system (T3SS) components via the NAIP (NLR family apoptosis inhibitory protein) family. Upon activation, it triggers pyroptosis, pro-inflammatory cytokine release, and infected intestinal epithelial cell extrusion, serving as a central pathway for host defense against Salmonella colonization and systemic spread. This work systematically summarizes the structural composition, activation mechanisms, post-translational modifications, and regulatory protein network of the NLRC4 inflammasome, and highlights the molecular mechanisms by which Salmonella evades NLRC4 surveillance through multiple strategies: transcriptional downregulation of immunogenic ligands, structural modification of T3SS components, secretion of effector proteins, and chemotaxis-virulence synergy. A comprehensive delineation of the co-evolutionary arms race between Salmonella and the NLRC4 inflammasome provides an integrated mechanistic framework for understanding host–pathogen immune interplay. Deciphering the mechanisms of bacterial immune evasion on this basis holds critical importance for identifying novel anti-infective targets and advancing translational preventive and therapeutic strategies against salmonellosis. Full article

Background: Peri-implant infections remain a major cause of dental implant failure, largely due to bacterial adhesion and biofilm formation on implant surfaces. This study aimed to investigate how surface topography influences bacterial colonisation and osteoblastic response. Methods: Titanium discs with machined (Ma), sandblasted, large-grit, and acid-etched (SLA), and nanostructured (Nano) surfaces were prepared, sterilised, and seeded with pre-differentiated dental follicle mesenchymal stem cells. Co-cultures with Enterococcus faecalis (E. faecalis) and Streptococcus oralis (S. oralis) were established under CO₂-free conditions, and cell–bacteria interactions were evaluated using fluorescence microscopy and quantitative image analysis. Results: Nano surfaces showed the highest osteoblastic adhesion and viability, while significantly reducing bacterial proliferation and biofilm formation compared with Ma and SLA surfaces. The sequence of colonisation influenced cell–bacteria dynamics, with early cell attachment limiting subsequent bacterial adhesion. Conclusions: Nano titanium surfaces may offer a dual benefit by promoting osseointegration while limiting bacterial adhesion. These findings support their potential use as surface modifications to reduce peri-implant infection risk and improve long-term implant success. Full article

Sexually transmitted infections remain a major public health concern among men who have sex with men (MSM), particularly due to the high frequency of coinfections and the limitations of syndromic management. This study aimed to describe the frequency of bacterial sexually transmitted and urogenital pathogens among symptomatic MSM attending two specialized sexual health clinics in Mexico City. A prospective cross-sectional study was conducted with 150 adult MSM presenting symptoms suggestive of urethritis. Urethral swab samples were analyzed using a multiplex real-time polymerase chain reaction (PCR) assay for the detection of Neisseria gonorrhoeae, Chlamydia trachomatis, Mycoplasma genitalium, Mycoplasma hominis, Ureaplasma urealyticum, Ureaplasma parvum, and Trichomonas vaginalis. At least one pathogen was detected in 91/150 participants (60.7%). N. gonorrhoeae was the most frequent pathogen (33.3%), followed by U. urealyticum (15.3%), M. genitalium (9.3%), and C. trachomatis (9.3%). Coinfections were identified in 15 participants, representing 10.0% of the total population and 16.5% of those with a positive PCR result. Most coinfections involved N. gonorrhoeae, particularly with C. trachomatis. These findings provide descriptive microbiological evidence on the frequency and coinfection patterns of bacterial sexually transmitted infections (STIs) associated pathogens among symptomatic MSM attending specialized sexual health clinics in Mexico City. The high detection rate and occurrence of concurrent infections highlight the limitations of syndromic management and support the value of timely multiplex molecular diagnostics to improve etiological characterization, antimicrobial stewardship, and clinical decision-making in this population. Full article

Objectives: To assess the prevalence of high-risk human papillomavirus (hrHPV) infection and selected genitourinary pathogens and to examine their co-detection patterns in sexually active adolescent females. Methods: In this single-center cross-sectional study, 167 consecutive outpatients aged 13–17 years with self-reported sexual initiation underwent multi-pathogen polymerase chain reaction (PCR) testing for hrHPV, Chlamydia trachomatis (CT), Ureaplasma urealyticum (UU), Ureaplasma parvum (UP), and Mycoplasma genitalium (MG). Prevalence estimates are reported with 95% confidence intervals (CIs). Associations with hrHPV positivity were explored using univariable and parsimonious multivariable logistic regression; sensitivity analyses examined alternative age parameterization and exclusion of sparse variables. Results: The prevalence of hrHPV was 28.1% (47/167; 95% CI: 21.5–35.6). The prevalence of CT, UU, UP, and MG was 3.0%, 28.1%, 25.1%, and 0.6%, respectively. Any bacterial pathogen was detected in 61/167 participants (36.5%), while hrHPV–bacterial co-detection was observed in 24/167 (14.4%). In univariable analysis, UU was associated with hrHPV positivity (OR 2.55, 95% CI: 1.24–5.24; p = 0.013); this signal remained in the primary multivariable model (adjusted OR 2.46, 95% CI: 1.07–5.93; p = 0.035). A graded increase in hrHPV positivity was observed with increasing bacterial burden (p for trend = 0.018). Conclusions: Sexually active adolescent girls attending gynecologic outpatient care showed a substantial burden of hrHPV and bacterial genitourinary pathogen detection. This Central and Eastern European adolescent outpatient cohort contributes integrated multi-pathogen PCR-based epidemiologic data from a clinically relevant and underreported population. An exploratory association between UU and hrHPV positivity was observed; this signal is best interpreted as reflecting shared sexual exposure or the cervicovaginal microbial milieu rather than as evidence of an independent causal role for UU. The absence of vaccination status, behavioral, and longitudinal data represents a principal limitation. Prospective studies incorporating these variables are needed to clarify the epidemiology of hrHPV and co-detected pathogens in adolescents. Full article

Background: Adults hospitalized with COVID-19, influenza A/B, or respiratory syncytial virus (RSV) frequently receive empirical antibiotics, but antibiotic prescribing, confirmed bacterial co-infection, antimicrobial resistance (AMR), and outcomes have not been jointly synthesized across these infections. Methods: We conducted a PRISMA 2020 systematic review and meta-analysis of 39 studies including 839,531 hospitalized adults. Random-effects models with Freeman–Tukey double-arcsine transformation pooled prevalence estimates; sensitivity and publication-bias analyses were performed where appropriate. Results: Pooled antibiotic use was 62.56% (95% CI, 53.75–70.97%) for COVID-19, 57.48% (25.76–86.09%) for influenza A/B, and 76.03% (67.62–83.53%) for RSV, with very high heterogeneity. Confirmed bacterial co-infection was lower: 5.31% (3.43–7.56%), 18.66% (9.98–29.30%), and 24.36% (18.53–30.70%), respectively. Prescribing-to-confirmed infection ratios ranged from 3.0 to 46.2. AMR evidence was restricted to COVID-19 studies and was dominated by carbapenem-resistant Gram-negative organisms, mainly in secondary, ICU-associated, or healthcare-associated infections. Confirmed bacterial complications were associated with ICU admission, longer hospitalization, and higher mortality. Conclusions: Antibiotic prescribing exceeded confirmed bacterial infection across all viral groups, but estimates require cautious interpretation due to heterogeneity, diagnostic uncertainty, observational evidence, and the absence of low-risk-of-bias studies. The evidence base was dominated by COVID-19 cohorts, while influenza A/B and RSV data, especially virus-specific AMR evidence, remain limited. COVID-19-specific AMR findings should not be generalized to influenza A/B or RSV. Virus-specific stewardship should prioritize rapid diagnostics, systematic sampling, reassessment, and de-escalation when bacterial infection is not confirmed. Full article

Ovine Respiratory Complex is a multifactorial disease involving interactions between pathogens, host factors, and environmental conditions. This study investigated associations between selected bacterial agents, including Mycoplasma ovipneumoniae infection and members of the Pasteurellaceae family, and clinical, auscultatory, ultrasonographic, and post-mortem findings in Lacaune fattening lambs. A total of 80 animals were evaluated using clinical examination, thoracic auscultation, ultrasonography, post-mortem assessment, bacteriological culture, and quantitative PCR (qPCR) for Mycoplasma ovipneumoniae. Associations between microbial detection and disease severity scores were analyzed. Mycoplasma ovipneumoniae was the most frequently detected organism (50%), followed by Pasteurella multocida (32.9%) and Trueperella pyogenes (27.8%). Detection of specific microorganisms was more frequently observed in animals with increased disease severity across multiple diagnostic modalities. Coinfection was identified in 60.8% of animals and was significantly associated with increased severity according to clinical, auscultatory, ultrasonographic, and post-mortem scores. These findings underscore the polymicrobial nature of ORC and emphasise the necessity of employing complementary diagnostic approaches for disease evaluation. Full article

Staphylococcus epidermidis is a major cause of periprosthetic and other implant-associated orthopedic infections because of its ability to adhere to biomaterial surfaces and form biofilm. Tranexamic acid (TXA) is routinely used in arthroplasty to reduce perioperative blood loss; however, emerging evidence suggests that it may also modulate bacterial behavior and antibiotic activity. This study investigated the in vitro effects of TXA in combination with teicoplanin on planktonic growth and biofilm biomass formation in clinical Staphylococcal isolates. Clinical Staphylococcal isolates were evaluated using disk diffusion assays, microtiter plate-based planktonic growth assays, and crystal violet biofilm biomass assays. Microplate-based growth and biofilm assays were performed using five clinical isolates, whereas disk diffusion assays were performed using a separate set of seven clinical staphylococcal isolates. Teicoplanin was tested at literature-based low concentrations of 0.1 and 0.4 µg/mL, either alone or in combination with TXA at 10 and 50 mg/mL. In disk diffusion assays, inhibition zone diameters were quantified using ImageJ. Planktonic growth was assessed by optical density at 600 nm, and biofilm biomass accumulation was quantified by crystal violet staining at 570 nm. Disk diffusion data were analyzed using paired t-tests, while microplate-based growth and biofilm data were analyzed using two-way analysis of variance (ANOVA) followed by Tukey’s multiple-comparisons test. In disk diffusion assays, TXA co-application was associated with larger teicoplanin inhibition zones on both blood agar and Mueller–Hinton agar, suggesting an increased apparent inhibitory zone under agar-based conditions. In microplate-based planktonic growth assays, responses were isolate-dependent. However, co-exposure to TXA, particularly at 50 mg/mL, was associated with reduced OD600-based bacterial growth in several isolates compared with teicoplanin alone. A similar isolate-dependent pattern was observed for crystal violet-based biofilm biomass accumulation. In most tested isolates, teicoplanin combined with 50 mg/mL TXA was associated with lower biofilm biomass than teicoplanin alone, whereas one isolate showed minimal responsiveness. Under the tested in vitro conditions, TXA–teicoplanin co-exposure was associated with reduced planktonic growth and crystal violet-based biofilm biomass accumulation in several clinical staphylococcal isolates. However, because TXA-only controls were not available across the full experimental framework and formal synergy assays were not included, these findings do not establish synergistic activity or distinguish combination-specific effects from TXA-associated effects alone. Further studies are needed to clarify the biological and translational relevance of these observations. Full article

Bacterial infections pose a serious threat to human health, and antibiotics remain the first-line therapeutic agents in clinical practice. However, the vast majority of antibiotics lack the ability to penetrate cell membranes, which severely limits the number of clinically available options for treating intracellular bacterial infections. Developing efficient intracellular antibiotic delivery strategies is therefore of considerable clinical significance, both for reducing antibiotic dosage and for expanding the repertoire of drugs applicable to intracellular infections. To address this challenge, we constructed a protein-based delivery platform mediated by a cell-penetrating miniprotein for efficient intracellular antibiotic delivery. In this system, bovine serum albumin (BSA), which possesses broad antibiotic-binding capability, was employed as the drug carrier, while the cell-penetrating miniprotein ZF5.3, which is capable of endosomal escape, served as the transmembrane delivery mediator. ZF5.3 was conjugated to BSA via a bioorthogonal reaction, and ceftriaxone (CRO) was selected as the model antibiotic to construct a nanoscale delivery system. The binding interaction between CRO and BSA was characterized using UV-Vis, HPLC, and molecular docking techniques. The assembly of the ZF5.3–BSA delivery platform was confirmed by UV-Vis absorption spectroscopy and gel electrophoresis. Intracellular delivery efficiency was evaluated by confocal fluorescence imaging and flow cytometry, and the results demonstrated that ZF5.3 conjugation enhanced intracellular protein delivery efficiency by over 5-fold. Fluorescence co-localization analysis revealed that ZF5.3-mediated cargo is mainly distributed in the cytoplasm and does not completely co-localize with lysosomal markers, suggesting its ability to effectively escape from lysosomes. An intracellular infection model using Staphylococcus aureus was established. Colony-forming unit (CFU) counting experiments confirmed that the delivery system significantly enhanced the intracellular antibacterial activity of ceftriaxone. CCK8 cytotoxicity assays confirmed that the system is non-toxic to cells. Full article

Background: Non-pharmaceutical interventions during the COVID-19 pandemic altered respiratory pathogen circulation, and a bacterial rebound followed once restrictions were lifted. We describe pediatric pneumococcal respiratory infections and their bacterial co-detections in the immediate post-pandemic period. Methods: We retrospectively analyzed respiratory specimens from children aged 0–18 years tested with a multiplex real-time PCR panel (Allplex Respiratory Panel, Seegene, Seoul, South Korea; seven bacterial pathogens) restricted to this predefined bacterial spectrum at a tertiary pediatric hospital in Galați, Romania, during 2022 and 2023. A total of 2546 panels were performed in 2022 and 3250 in 2023, allowing pneumococcal positivity rates to be calculated. Proportions are reported with Wilson 95% confidence intervals; associations were tested with Pearson chi-square and Fisher exact tests in SPSS v.23. Results: Children with detected Streptococcus pneumoniae rose from 100 to 415, corresponding to a rise in pneumococcal positivity from 3.9% (100/2546) to 12.8% (415/3250). Among the positive children, pneumococcus–Haemophilus influenzae co-detection increased from 33.0% to 45.1% (odds ratio 1.63, 95% CI 1.02–2.61; p = 0.029), while pneumococcus alone fell from 60.0% to 50.1%. Boys, urban residence, and early childhood predominated, and community-acquired pneumonia diagnoses rose from 61 to 214. No profile–demographic association reached significance (panel–residence 2023, p = 0.063). Conclusions: A post-pandemic rise in pediatric pneumococcal detections and increasing H. influenzae co-detection were observed, supporting syndromic multiplex PCR in rapid pediatric diagnostics and antimicrobial stewardship. Full article

This study characterizes AP-20-A, a lytic podovirus infecting Sinorhizobium meliloti, isolated from agricultural chernozem. Its 49.4 kbp genome shows negligible intergenomic similarity with known rhizobiophages (<2%). Core structural proteins—the major capsid protein (MCP) and terminase large subunit (TerL)—show closest homology to podoviruses infecting Paenibacillus, rather than to alphaproteobacterial viruses, suggesting cross-phylum horizontal gene transfer. This exchange is ecologically plausible, as Paenibacillus and Sinorhizobium co-exist in the rhizosphere. Over 63% of predicted proteins are functionally uncharacterized, with structural homologs detected in bacteria, archaea, and eukaryotes. We report the first identification in a rhizobiophage of a Tad2-like domain, predicted to block the bacterial Thoeris type II anti-phage defense. AP-20-A infected 56% of native S. meliloti strains; agrocenose isolates showed higher resistance than phytocenose isolates, evidence of local co-evolution. Among susceptible strains, 60% entered putative pseudolysogeny (with one strain exhibiting growth stimulation), whereas a symbiotically elite inoculant strain was completely lysed within hours. Some host strains carry additional AbiE systems; whether these independent defense–counterdefense layers interact during infection remains unknown. We conclude that resident phages represent a selective force that can disrupt inoculant establishment, underscoring the need to integrate soil virome assessment into agricultural microbiome management. Full article

Photodynamic therapy (PDT) represents a promising non-antibiotic strategy for addressing bacterial and fungal infections, particularly in the context of increasing antimicrobial resistance and biofilm-associated disease. PDT is based on the light-induced activation of photosensitizers, leading to the generation of reactive oxygen species (ROS), including singlet oxygen (¹O₂), which induce oxidative damage to multiple microbial targets. Unlike conventional antimicrobial drugs that often act through specific molecular pathways, antimicrobial PDT produces simultaneous damage to membranes, proteins, nucleic acids, and extracellular biofilm components, thereby reducing the probability of resistance development. This review critically analyzes the cellular, biochemical, and biophysical determinants that govern PDT selectivity toward bacterial and fungal cells in comparison with mammalian host tissues. Particular attention is given to photosensitizer localization, membrane interactions, photobleaching, oxygen dependence, light penetration, and the balance between Type I and Type II photochemical mechanisms. The review provides a comparative overview of major molecular photosensitizer classes, including phenothiazines, porphyrins, chlorins, phthalocyanines, xanthene dyes, natural polyphenols, endogenous compounds, and advanced targeted photosensitizers. In addition, this review distinguishes molecular photosensitizers from nanotechnology-based platforms and delivery systems. Nanoparticles, polymeric carriers, hydrogels, and light-activated coatings are discussed not only as photosensitizer delivery tools, but also as systems that modulate aggregation, improve localization, enhance biofilm penetration, and enable surface-confined ROS generation. ROS are capable of causing phototoxic effects wherever they are located. Unless selectively accumulated by target organisms, there can be systemic phototoxicity. Overall, PDT should be regarded as a modular antimicrobial platform in which photosensitizer chemistry, formulation, light delivery, oxygen availability, and infection biology must be co-optimized. Although further studies are required to address clinical translation, regulatory complexity, material safety, and standardized treatment protocols, PDT offers a scientifically robust and clinically relevant approach that may complement conventional antibacterial and antifungal therapies, especially in localized, biofilm-associated, and device-related infections. Full article

The innate immune response is a critical defense mechanism by which vertebrates recognize and eliminate invading pathogens. Pattern recognition receptors (PRRs) detect pathogen-associated molecular patterns and activate downstream signaling pathways. NOD1, a classic PRR of the NLR family, recruits the adaptor protein RIPK2 to initiate antibacterial signaling. In this study, we cloned and characterized the NOD1 gene from snakehead (Channa argus). Briefly, the full-length NOD1 cDNA is 2829 bp encoding 943 amino acids, showing high homology with Perciformes. The qPCR analysis revealed widespread NOD1 gene expression in various tissues, with significant upregulation in the gill (p < 0.05) and spleen (p < 0.05) following bacterial infection. Overexpression of the NOD1 gene activated the NF-κB signaling pathway in a dose- and time-dependent manner, and specifically responded to the bacterial ligand iE-DAP but not to other tested ligands. Furthermore, NOD1 synergized with the downstream adaptor RIPK2 to enhance NF-κB activity, and direct protein interaction between NOD1 and RIPK2 was confirmed by co-immunoprecipitation. Taken together, these findings demonstrate that snakehead NOD1 plays a critical role in the host antimicrobial immune response. Full article

Pseudomonas aeruginosa (P. aeruginosa) is a multidrug-resistant opportunistic pathogen that causes both acute and chronic infections and is known for its ability to form biofilms. In the current study, we applied a hypothesis-generating framework primarily based on integrating four different datasets and applying batch correction. Weighted Gene Co-Expression Network Analysis (WGCNA) was performed in parallel with differential expression analysis using limma. Therefore, we aimed to identify potential biofilm-associated gene candidates. Significant candidate genes were subjected to functional analysis and gene ontology, followed by the construction of a protein–protein interaction network using STRING. The Pseudomonas Genome Database was used to highlight the candidate genes. A total of 271, 687, 533, and 277 significantly up-regulated differentially expressed genes (DEGs), as well as 306, 985, 472, and 312 significantly down-regulated DEGs, resulted from the exploratory analysis. Through WGCNA/limma integration, 223 common significantly up-regulated/positively correlated gene candidates were identified. Functional analysis results showed significant enrichment in virulence-related pathways, such as biofilm formation (PA0083, PA0084, hcp1, hcpC, pilH, pilI, pilJ, vfr, pqsA, pqsB, pqsC, pqsE, PA1657, and PA1658). In addition, other virulence-related pathways, such as quorum sensing, phenazine biosynthesis, the bacterial secretion system, and secondary metabolite biosynthesis, were enriched. In conclusion, our hypothesis-generating integrative analysis identifies candidate genes and potential pathways associated with biofilm formation, virulence, and other processes in P. aeruginosa. In light of this, we point out that all candidate genes presented in this study remain hypothesis-generating. Further validation is recommended, including large-scale in silico analyses and in vitro experimental studies. Full article