Search Results (606)

Background/Objectives: Mycobacterium abscessus is an opportunistic pathogen causing infections mainly in patients with immunosuppression and chronic pulmonary pathologies. Extended treatment periods are needed to tackle this pathogen, bacterial eradication is rare, and recurrence can take place with time. New alternative treatments are being investigated, such as bacteriophage therapy. This work describes the characterization of the mycobacteriophage P3MA, showing its ability to infect clinical and standard M. abscessus strains. Methods: Phylogenetic analysis, electron microscopy, growth curves, biofilm assays, checkerboard, and granuloma-like medium studies were performed. Results: P3MA inhibited the growth of clinical samples in both planktonic and biofilm states as well as in a granuloma-like model. The study of the interaction with antibiotics revealed that P3MA exhibited an antagonistic effect combined with clarithromycin, indifference with amikacin, and synergy with imipenem. Conclusions: All these results suggest that, after genetic engineering, P3MA could be a promising candidate for phage therapy in combination with imipenem, including lung infections. Full article

Cystic fibrosis produces viscous mucus in the lung that increases bacterial invasion, causing persistent infections and subsequent inflammation. Pseudomonas aeruginosa and Staphylococcus aureus are two of the most common infections in cystic fibrosis patients that are resistant to antibiotics. One antibiotic approved to treat these infections is levofloxacin (LVX), which functions to inhibit bacterial replication but can be further developed into tailorable particles. Nanoparticles are an emerging inhaled therapy due to enhanced targeting and delivery. The extracellular matrix (ECM) has been shown to possess pro-regenerative and non-toxic properties in vitro, making it a promising delivery agent. The combination of LVX and ECM formed into nanoparticles may overcome barriers to lung delivery to effectively treat cystic fibrosis bacterial infections. Our goal is to advance CF care by providing a combined treatment option that has the potential to address both bacterial infections and lung damage. Two hybrid formulations of a 10:1 and 1:1 ratio of LVX to ECM have shown neutral surface charges and an average size of ~525 nm and ~300 nm, respectively. The neutral charge and size of the particles may suggest their ability to attract toward and penetrate through the mucus barrier in order to target the bacteria. The NPs have also been shown to slow the drug dissolution, are non-toxic to human airway epithelial cells, and are effective in inhibiting Pseudomonas aeruginosa and Staphylococcus aureus. LVX-ECM NPs may be an effective treatment for pulmonary CF bacterial treatments. Full article

Background: Fowl typhoid (FT), a septicemic infection caused by Salmonella Gallinarum (SG), and H9N2 avian influenza are two economically important diseases that significantly affect the global poultry industry. Methods: We exploited the live attenuated Salmonella Gallinarum (SG) mutant JOL3062 (SG: ∆lon ∆pagL ∆asd) as a delivery system for H9N2 antigens to induce an immunoprotective response against both H9N2 and FT. To enhance immune protection against H9N2, a prokaryotic and eukaryotic dual expression plasmid, pJHL270, was employed. The hemagglutinin (HA) consensus sequence from South Korean avian influenza A virus (AIV) was cloned under the Ptrc promoter for prokaryotic expression, and the B cell epitope of neuraminidase (NA) linked with matrix protein 2 (M2e) was placed for eukaryotic expression. In vitro and in vivo expressions of the H9N2 antigens were validated by qRT-PCR and Western blot, respectively. Results: Oral immunization with JOL3121 induced a significant increase in SG and H9N2-specific serum IgY and cloacal swab IgA antibodies, confirming humoral and mucosal immune responses. Furthermore, FACS analysis showed increased CD4+ and CD8+ T cell populations. On day 28 post-immunization, there was a substantial rise in the hemagglutination inhibition titer in the immunized birds, demonstrating neutralization capabilities of immunization. Both IFN-γ and IL-4 demonstrated a significant increase, indicating a balance of Th1 and Th2 responses. Intranasal challenge with the H9N2 Y280 strain resulted in minimal to no clinical signs with significantly lower lung viral titer in the JOL3121 group. Upon SG wildtype challenge, the immunized birds in the JOL3121 group yielded 20% mortality, while 80% mortality was recorded in the PBS control group. Additionally, bacterial load in the spleen and liver was significantly lower in the immunized birds. Conclusions: The current vaccine model, designed with a host-specific pathogen, SG, delivers a robust immune boost that could enhance dual protection against FT and H9N2 infection, both being significant diseases in poultry, as well as ensure public health. Full article

Secondary methicillin-resistant Staphylococcus aureus (MRSA) infection causes high mortality in patients with influenza A virus (IAV). Our previous study observed that the relative abundance of Lactobacillus murinus (L. murinus) was significantly reduced in both the respiratory tract and gut of IAV-infected mice and negatively correlated with the severity of IAV–MRSA coinfection pneumonia, but the role of L. murinus remains unclear. Here, we supplemented the respiratory tract and gut of IAV-infected mice with live L. murinus and performed a secondary MRSA infection challenge to investigate the effects and potential mechanisms further. Data showed that L. murinus supplementation significantly reduced mortality and pathogen loads in IAV–MRSA coinfected mice and upregulated the lung T cell-independent (TI) IgA response in IAV-infected mice. The 16S rRNA gene sequencing results showed that L. murinus supplementation ameliorated microbiota composition disorder and regulated metabolic dysfunction in the gut of IAV-infected mice. The correlation analysis and antibiotic cocktail treatment experiment showed that the TI IgA response in lungs is dependent on gut microbiota. These findings demonstrated that L. murinus supplementation reduces susceptibility to secondary MRSA infection in IAV-infected mice by promoting the TI IgA response, and provide a new perspective on the use of probiotics to prevent secondary bacterial infection following IAV infection. Full article

Respiratory syncytial virus (RSV) represents one of the main respiratory infections found among immunocompromised patients. Objective: The study analyzes the incidence of RSV infection in different populations of immunocompromised patients as organ transplant recipients (lung, other solid organs, hematopoietic stem cells) and oncologic patients (solid organ malignancy and hematological malignancy) compared to a group of non-immunocompromised patients. We also assessed the prevalence of viral, bacterial, and mycotic coinfection. Moreover, we aimed at evaluating the efficacy of ribavirin treatment in terms of mortality reduction. Methods: We conducted a retrospective analysis on a total of 466 transplant patients undergoing bronchoscopy with bronchoalveolar lavage for suspected viral disease or surveillance between 2016 and 2023, compared to 460 controls. Results: The incidence of RSV was significantly higher in immunocompromised patients, particularly in those with lung and bone marrow transplants. Among RSV+ patients, a higher prevalence of viral (influenza virus), bacterial (S. pneumoniae, M. pneumoniae, Nocardia spp.), and fungal (Aspergillus spp.) coinfections were observed. The efficacy of ribavirin in reducing mortality did not show significant differences compared to supportive therapy alone. Conclusions: The results of our exploratory study suggest that immunocompromised patients are particularly vulnerable to RSV infection and coinfections. Our hypothesis-generating data warrant the need for future studies aimed at exploring preventive and therapeutic strategies for RSV infection in these high-risk patient groups. Full article

Background: Cystic fibrosis (CF) is an autosomal recessive disease caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Modulator therapies have the ability to improve CFTR function in CF patients, but despite the clear evidence of benefits regarding CFTR modulator therapy, including improved lung function, the reduced rate of exacerbations, and an overall improved quality of life, studies focusing on the reduction rates of P. aeruginosa infections during modulator therapy expressed the need for future research on this topic. Objective: This study aimed to evaluate the impact of CFTR modulator therapies on the prevalence, density, and persistence of P. aeruginosa infection in CF patients and to explore the mechanisms involved. Methods: A systematic literature review was performed by searching five major databases (PubMed, Cochrane Library, Scopus, Google Scholar, and Web of Science), and 21 relevant articles investigating the link between CFTR therapy and P. aeruginosa infections were selected following the PRISMA guidelines. Results: The data indicated that Ivacaftor and the combination Elexacaftor/Tezacaftor/Ivacaftor (ETI) can reduce total bacterial load and markers of systemic inflammation. However, clonal lines of P. aeruginosa persist in most cases, and complete eradication is rare, mainly due to biofilm formation and antimicrobial resistance. Conclusions: Although CFTR-modulating therapies help to improve clinical condition and reduce inflammation, they do not consistently lead to the elimination of P. aeruginosa. Full article

Calreticulin is a highly conserved and multifunctional molecular chaperone ubiquitously expressed in humans and animals. Beyond its well-established roles in calcium homeostasis, protein folding, and immune regulation, recent studies in aquatic species have suggested a previously unrecognized antimicrobial function of calreticulin. These findings raise the question of whether calreticulin also exerts antibacterial activity in terrestrial mammals, which has not been systematically investigated to date. To address this knowledge gap, we successfully constructed and expressed recombinant goat calreticulin using the Pichia pastoris expression system, yielding a protein of over 99% purity that predominantly exists in dimeric form. Functional assays demonstrated that both recombinant goat and human calreticulin exhibited preliminary inhibitory activity against Escherichia coli, Salmonella typhimurium, and Pasteurella multocida. Calreticulin was capable of binding to these three bacterial species as well as bacterial lipopolysaccharides (LPS). Notably, in the presence of Ca²⁺, calreticulin induced bacterial aggregation, indicating a potential mechanism for limiting bacterial dissemination and proliferation. Given the high anatomical, genetic, and physiological similarity between goats and humans—particularly in respiratory tract structure and mucosal immune function—neonatal goats were selected as a relevant model for evaluating the in vivo antimicrobial efficacy of calreticulin. Accordingly, we established an intranasal infection model using Pasteurella multocida to assess the protective role of calreticulin against respiratory bacterial challenge. Following infection, calreticulin expression was markedly upregulated in the nasal mucosa, trachea, and lung tissues. Moreover, intranasal administration of exogenous calreticulin significantly alleviated infection-induced pathological injury to the respiratory system and effectively decreased bacterial loads in infected tissues. Collectively, this study systematically elucidates the antimicrobial activity of calreticulin in a mammalian model and highlights its potential as a natural immune effector, providing novel insights for the development of host-targeted antimicrobial strategies. Full article

Pseudomonas aeruginosa is a major opportunistic pathogen with high levels of antibiotic resistance. Phage therapy represents a promising alternative for the treatment of difficult infections both alone and in combination with antibiotics. Here, we isolated and characterized three novel lytic myoviruses, Cisa, Nello, and Moonstruck. Genomic analysis revealed that Cisa and Nello belong to the Pbunavirus genus, while Moonstruck is a novel Pakpunavirus species. All lacked lysogeny, virulence, or resistance-associated genes, supporting their therapeutic suitability. Phage Nello and Moonstruck were active against P. aeruginosa Pa3GrPv, isolated from a patient with lung infection candidate for phage therapy. Moonstruck exhibited superior lytic activity with ciprofloxacin sub-MIC value (0.125 µg/mL), achieving bacterial suppression for 48 h. However, to improve the lytic efficacy of the phages on the clinical isolate, phage adaptation via serial passage was investigated. The killing efficacy of Nello was enhanced, whereas Moonstruck showed a less consistent improvement, suggesting phage-specific differences in evolutionary dynamics. Sequencing of the evolved phages revealed point mutations in tail-associated genes, potentially linked to a better phage–host interaction. These results support the use of phage–antibiotic combinations and directed evolution as strategies to enhance phage efficacy against drug-resistant infections. Overall, these findings support the therapeutic potential of the newly isolated phages in treating P. aeruginosa lung infections. Full article

Nocardia, an easily missed but potentially fatal opportunistic pathogen, can lead to serious infections like lung and brain abscesses. Intranasal inoculation (IN) is the traditional approach for constructing a Nocardia-induced pneumonia mice model, while it usually only results in limited local bacterial infection in the lungs. To comprehensively assess infection dynamics across distinct pulmonary inoculation routes in mice models, this study compared the pathogenicity of three different Nocardia farcinica pneumonia models established via IN, intratracheal aerosolization (ITA), and intratracheal instillation (ITI). C57BL/6J mice were infected with N. farcinica through IN, ITA and ITI with comparative analyses of bacterial distribution in lungs, survival rate, weight, bacterial load, inflammatory cytokines, histopathological characteristics and transcriptome differences. The findings suggest that ITA N. farcinica infections caused severer clinical symptoms, higher mortality, pulmonary bacterial load, levels of inflammatory cytokines in bronchoalveolar lavage fluid, and more significant histopathological damage to lungs than IN and ITI. Furthermore, ITA resulted in better lung bacterial distribution and delivery efficiency than ITI and IN. Transcriptome analysis of lungs from N. farcinica infected mice via IN, ITA and ITI revealed significant differential gene expression, whereas ITA route resulted in a larger fold change. ITA provides a more consistent and severe model of N. farcinica pneumonia in mice than IN and ITI, which can make the bacteria more evenly distributed in the lungs, leading to more severe pathological damage and higher mortality rates. In conclusion, ITA is an optimal route for developing animal models of N. farcinica pneumonia infections. Full article

Cystic fibrosis (CF) is a life-limiting autosomal recessive disorder affecting a large number of individuals in Europe. The disease arises from mutations in the CFTR gene encoding the cystic fibrosis transmembrane conductance regulator, a chloride ion channel crucial for maintaining epithelial ion and fluid homeostasis. Dysfunctional CFTR disrupts mucociliary clearance, particularly in the respiratory tract, resulting in persistent bacterial colonization, chronic inflammation, and progressive pulmonary damage—ultimately leading to respiratory failure, the principal cause of mortality in CF patients. Early diagnosis and advances in therapy have substantially improved both survival and quality of life. A hallmark of CF pathology is the establishment of polymicrobial infections within the thickened airway mucus. Pseudomonas aeruginosa is the dominant pathogen in chronic CF lung infections and demonstrates a remarkable capacity for adaptation via biofilm formation, metabolic reprogramming, and immune evasion. Biofilms confer increased tolerance to antimicrobial agents and facilitate long-term persistence in hypoxic, nutrient-limited microenvironments. P. aeruginosa exhibits a wide range of virulence factors, including exotoxins (e.g., ExoU, ExoS), pigments (pyoverdine, pyochelin), and motility structures (flagella and pili), which contribute to tissue invasion, immune modulation, and host damage. During chronic colonization, P. aeruginosa undergoes significant genotypic and phenotypic changes, such as mucoid conversion, downregulation of acute virulence pathways, and emergence of hypermutator phenotypes that facilitate rapid adaptation. Persistent cells, a specialized subpopulation characterized by metabolic dormancy and antibiotic tolerance, further complicate eradication efforts. The dynamic interplay between host environment and microbial evolution underlies the heterogeneity of CF lung infections and presents significant challenges for treatment. Elucidating the molecular mechanisms driving persistence, hypermutability, and biofilm resilience is critical for the development of effective therapeutic strategies targeting chronic P. aeruginosa infections in CF. Full article

Aerococcus urinaeequi is an opportunistic pathogen that has been isolated from humans, pigs, and chickens, but with no reports in geese until now. This research aimed to isolate and identify A. urinaeequi from four geese, and establish a specific PCR detection method for A. urinaeequi. Strain E1 was identified as A. urnaeequi through a combination of Gram staining (Gram-positive coccus), colony morphology (α-hemolysis), and whole genome sequencing analysis. Comparative genomics was used to analyze the genome sequences of five reference strains of A. urinaeequi to screen for a species-specific genomic region (401 bp). Based on this region, specific primers were designed to establish the PCR detection method for A. urnaeequi, and the specificity and sensitivity of this assay were tested. The results showed that the target sequence was specifically amplified only for the genome of A. urinaeequi, and that the minimum nucleic acid detection concentration was 7.08 × 10⁻³ ng/μL. The mouse infection model indicated that the target fragment could be amplified from the tissue samples of dead mice in the challenge groups, verifying the applicability of PCR for clinical sample detection. Specific sequences of A. urinaeequi were detected in the lungs of three pigs using the PCR method, confirmed to be consistent through whole genome sequencing, and previously identified as A. urinaeequi or A. viridans by 16S rRNA sequencing. For the detection of fecal samples from geese, canines, and felines using the PCR method, the highest positive rate was 36.9% (31/84) of geese, followed by 21.7% (20/90) of felines, and finally 6.9% (16/230) of canines. A strain of A. urinaeequi was isolated and identified in geese for the first time, and a species-specific PCR detection method for A. urinaeequi was established with high specificity and sensitivity, which could well distinguish the bacterial species A. urinaeequi from its phylogenetically related species, A. viridans. Full article

Klebsiella pneumoniae is a Gram-negative, encapsulated bacterium recognized by the World Health Organization (WHO) as a critical priority for new therapeutic strategies due to its increasing multidrug resistance (MDR). Antimicrobial photodynamic therapy (aPDT) has emerged as a promising alternative to antibiotics, exhibiting a broad spectrum of action and multiple molecular targets, and has been proposed for the treatment of clinically relevant infections such as pneumonia. However, despite excellent in vitro photodynamic inactivation outcomes, the success of in vivo therapy still faces challenges, particularly due to the presence of lung surfactant (LS) in the alveoli. LS entraps photosensitizers, preventing these molecules from reaching microbial targets. This study investigated the potential of indocyanine green (ICG) in combination with the biocompatible polymer Gantrez™ AN-139 for the photoinactivation of K. pneumoniae. Initial in vitro experiments demonstrated that aPDT with ICG alone is effective against K. pneumoniae in a concentration- and light dose-dependent manner, achieving total eradication at 75 µg/mL of ICG and 150 J/cm² of 808 nm light. When aPDT was performed with similar parameters in the presence of LS, no bacterial killing was observed. However, a significant synergistic effect was observed when ICG (25 µg/mL) was combined with a low concentration of Gantrez™ AN-139 (0.5% m/v) in the presence of dipalmitoylphosphatidylcholine (DPPC), the main component of LS. This formulation resulted in a substantial reduction (3.6 log₁₀) in K. pneumoniae viability. These findings highlight the potential of Gantrez™ AN-139 as an efficient carrier to enhance the efficacy of ICG-mediated aPDT against K. pneumoniae, even in the presence of lung surfactant, a necessary step before the in vivo experiments. Full article

The COVID-19 pandemic has highlighted the complex interplay between the gut microbiota and systemic immune responses, particularly through the gut–lung axis. Disruptions in gut microbial diversity and function—commonly referred to as dysbiosis—have been increasingly implicated in the pathogenesis of SARS-CoV-2 infection. In this study, we assessed the gut bacteriome and permeability in SARS-CoV-2-infected patients using 16S sequencing and ELISA assays, respectively. We also measured blood inflammatory cytokines and fecal secretory IgA to evaluate systemic and mucosal immune responses. Significant alterations in both alpha and beta diversity metrics were observed in patients with COVID-19 (n = 79) and those with post-COVID-19 condition (n = 141) compared to the controls (n = 97). Differential abundance and taxonomic analyses revealed distinct microbial profiles in the infected groups. Increased plasma levels of IL-2, IL-6, IL-17A, IFN-γ, and zonulin were detected in patient samples. Some genera were elevated during acute infection, which was positively correlated with C-reactive protein, while Enterobacteriaceae and Escherichia-Shigella were associated with increased zonulin levels, indicating compromised intestinal barrier function. These findings suggest that gut dysbiosis may contribute to bacterial translocation and systemic inflammation. Overall, our results highlight the importance of the gut–lung axis and suggest that modulating the gut microbiota could support immune regulation in SARS-CoV-2 infection. Full article

People with diabetes are at increased risk of developing lung infections and have more severe complications. However, the link between these risks and outcomes is unknown. These trends are also seen in people with chronic lung diseases, including cystic fibrosis (CF); however, less is known about the underlying mechanism of disease in these cases. Traditional CF bacterial pathogens are often associated with worse disease outcomes in non-CF individuals with diabetes or hyperglycemia who have other acute or chronic airway disease, yet how diabetes and hyperglycemia further compound chronic CF infections is less clear. In this review, we focus on what has been observed clinically regarding bacterial respiratory infections and diabetes, and we discuss model systems used to study these relationships. We also review what is known about the role of diabetes in chronic CF lung disease and how information gleaned from the general population can inform future research directions in the new era of highly effective modulator therapies for CF. Full article

Background/Objectives: Respiratory bacterial infections remain a significant global health challenge, with effective drug delivery to the lungs being crucial for successful treatment. This study aimed to develop a lactose-free dry powder inhaler (DPI) formulation containing azithromycin (AZM) microparticles for enhanced pulmonary delivery. Methods: Using a quality-by-design approach, an optimized formulation (4% AZM, 20% leucine, and 76% mannitol) was achieved. Results: The formulation demonstrated excellent aerodynamic properties with a mass median aerodynamic diameter (MMAD) of 2.72 μm ± 0.01 μm and fine particle fraction (FPF) (<5 μm) of 65.42% ± 5.12%. AZM-loaded microparticles exhibited enhanced efficacy against Pseudomonas aeruginosa with a two-fold reduction in the minimum bactericidal concentration (7.81 μg/mL vs. 15.62 μg/mL) compared to unprocessed AZM, while maintaining activity against Streptococcus pneumoniae. AZM microparticles demonstrated good biocompatibility with red blood cells and bronchial epithelial cells at therapeutic concentrations. Conclusions: These findings establish a promising lactose-free antibiotic formulation for targeted pulmonary delivery with enhanced antimicrobial efficacy. Full article