Search Results (33)

A diverse bacterial community colonizes the respiratory system, including commensals such as Staphylococcus epidermidis (S. epidermidis) and Streptococcus salivarius (S. salivarius), as well as facultative pathogens like Staphylococcus aureus (S. aureus). This study aimed to establish a colonized cell culture model to investigate the impact of these bacteria on influenza A virus (IAV) infection. Respiratory epithelial cells were exposed to S. epidermidis, S. salivarius, or S. aureus, using either live or heat-inactivated bacteria, followed by IAV infection. Cell integrity was assessed microscopically, cytotoxicity was measured via LDH assay, and inflammatory responses were analyzed through cytokine expression. Additionally, macrophage function was examined in response to bacterial colonization and IAV infection. While commensals maintained epithelial integrity for 48 h, S. aureus induced severe cell damage and death. The most pronounced epithelial destruction was caused by coinfection with S. aureus and IAV. Notably, commensals did not confer protection against IAV but instead enhanced epithelial inflammation. These effects were dependent on live bacteria, as inactivated bacteria had no impact. However, prior exposure to S. epidermidis and S. salivarius improved macrophage-mediated immune responses against IAV. These findings suggest that while individual commensals do not directly protect epithelial cells, they may contribute to immune training and enhance lung defense mechanisms. Full article

Post-COVID-19 is a chronic infection-related syndrome, including exacerbations of pre-existing or newly diagnosed conditions that have been established after the acute phase of COVID-19 and have demonstrated a wide range of systemic effects beyond the lungs. SARS-CoV-2 attaches to its receptor, angiotensin-converting enzyme 2 (ACE-2). Transmembrane serine protease 2 (TMPRSS2) facilitates viral entry and spread. ACE-2 receptors are detectable in several tissues, including the respiratory mucosa, digestive tract, heart, kidney, and brain. Several investigations have demonstrated an increase in digestive manifestations post-acute COVID-19, likely related to an alteration in the intestinal microbiota following infection. These changes can lead to a loss of species diversity, resulting in an overgrowth of opportunistic pathogens and deprivation of commensal bacteria. In this context, post-infection irritable bowel syndrome shows an increased incidence compared to controls. Growing evidence also suggests the enduring presence of SARS-CoV-2 in the gut tissue. Studies are ongoing to investigate antiviral agents that counteract prolonged COVID-19 symptoms. Therefore, the objectives of this review were to summarize the digestive manifestations, focusing on irritable bowel syndrome and therapeutic strategies. This review gives an overview of studies published in English in the last two years on the PubMed database. Full article

It is important to understand which bacterial taxa are most abundant during SARS-CoV-2 infection and to promote mitigation strategies for conditions subsequent to infection. Nasopharyngeal swab samples were collected from patients infected with SARS-CoV-2 and their family contacts (uninfected and asymptomatic) during the outbreak of the P.1 variant of SARS-CoV-2 in Parintins, Amazonas–Brazil, in March 2021. The samples were investigated by a shotgun sequencing metagenomic approach using the NextSeq 500 Illumina® system. The samples were stratified according to the presence or absence of SARS-CoV-2, household group, sex, and age. Of the total of 63 individuals, 37 (58.73%) were positive for SARS-CoV-2 and 26 (41.27%) were negative for SARS-CoV-2 and other respiratory viruses (FLU, AdV, HBoV, HCoV, HMPV, RSV, PIV, HRV). The alpha diversity indexes Chao1, species observed, Simpson, and Inv Simpson demonstrated a significant difference (p < 0.05) in both the diversity of observed species and the abundance of some taxa between positive and negative individuals. We also observed an abundance of opportunists such as Klebsiella pneumoniae, Staphylococcus spp, and Shigella sonnei, previously associated with the severity of COVID-19. Our results suggest that SARS-CoV-2 infection causes changes in the microenvironment of the nasopharyngeal region, allowing greater proliferation of opportunistic bacteria and decreased abundance of commensal bacteria. Full article

Heated tobacco products (THPs) are increasingly promoted as potential harm reduction tools, offering an alternative to traditional cigarettes. Despite these claims, understanding of their toxicological impact on respiratory health and associated microbial communities is limited. Comprehensive investigations are needed to elucidate the biological mechanisms and potential health implications associated with their use. Methods: This study evaluated the toxicological effects of aerosols produced by THPs (IQOS 3 Duo with Heets “Sienna Selection”) in comparison to conventional cigarette smoke (1R6F). Antibacterial activity was evaluated using Streptococcus pneumoniae and Klebsiella pneumoniae as representative species of the respiratory microbiota through agar diffusion assays and MIC/MBC determinations. Cytotoxicity was assessed in human lung fibroblast cells (MRC5) through the neutral red uptake (NRU) assay, whereas mutagenicity was investigated using the Ames test. Results: THP aerosols demonstrated the ability to inhibit the growth of both S. pneumoniae and K. pneumoniae, exerting bacteriostatic effects at lower concentrations and bactericidal effects at higher concentrations. While these antibacterial effects might initially seem beneficial against pathogens such as K. pneumoniae, they raise concerns about the potential disruption of the respiratory microbial balance, particularly in relation to S. pneumoniae. Despite these microbiological effects, THP aerosols demonstrated minimal cytotoxicity on human lung fibroblasts and lacked detectable mutagenic activity, contrasting with the significant cytotoxicity and mutagenicity caused by cigarette smoke. Conclusions: THPs present a reduced short-term toxicological profile compared with conventional cigarettes; however, their effects on respiratory microorganisms deserve attention. The observed inhibition of commensal bacteria highlights the need to explore potential changes in the microbial ecosystem that could affect respiratory health. These findings highlight the need for additional studies to evaluate the long-term effect of THP use on respiratory microbiota and the stability of the overall microbial ecosystem. Full article

This study evaluated the minimum inhibitory concentration (MIC) of pradofloxacin against various swine respiratory pathogens, including Bordetella bronchiseptica, Glaesserella parasuis, Mycoplasma hyopneumoniae, Pasteurella multocida, and Streptococcus suis (S. suis), associated with disease in swine. This research was conducted in two phases: the initial phase examined isolates from the lungs that could be either commensal or pathogenic, while the second phase focused on systemic S. suis strains that spread from the respiratory tract to the brain. The pradofloxacin MIC values of the second phase were within the MIC range of the initial phase, with MIC₅₀ and MIC₉₀ values highlighting its potential as an effective antimicrobial agent. Quality control data validated the reliability of our MIC findings, with all pradofloxacin MIC values for control organisms within approved ranges. These findings suggest that pradofloxacin has broad-spectrum activity against Gram-positive and Gram-negative bacteria and may serve as a reliable therapeutic option for managing S. suis and other swine respiratory infections. This study highlights pradofloxacin as an alternative antimicrobial therapy for swine respiratory diseases, offering a potential solution amidst rising concerns over antibiotic resistance. Full article

The currently dominant SARS-CoV-2 omicron variant, while causing mild respiratory symptoms, exhibits high transmissibility, drug resistance, and immune evasion. We investigated whether the presence of the SARS-CoV-2 affected the dynamics of fecal microbial composition isolated in culture in moderate COVID-19 patients. Blood, stool, and medical records were collected from 50 patients with confirmed SARS-CoV-2 infection. Two samples were taken per patient, at disease onset (within 5 days) and after symptom resolution (30–35 days). The part of the gut microbiota identifiable using MALDI-TOF MS was analyzed, and inflammatory cytokines and blood markers were measured in serum. The analysis identified 566 isolates at the species level, including 83 bacterial and 9 fungal species. Our findings indicate a change in the gut microbiota composition isolated in culture during the initial phase of infection, characterized by the proliferation of opportunistic bacteria such as Enterococcus spp. and Citrobacter spp., at the expense of beneficial commensal bacteria from the genus Bacillus and Lactobacillus. Additionally, the enrichment of fungal pathogens in fecal samples collected 30 days after the cessation of disease symptoms might suggest a prolonged disruption of the gut microbiota even after the resolution of COVID-19 symptoms. This study contributes to a growing body of evidence on the systemic effects of SARS-CoV-2 and highlights the importance of considering gastrointestinal involvement in the management and treatment of COVID-19. Full article

Streptococcus gordonii is a gram-positive, mutualistic bacterium found in the human body. It is found in the oral cavity, upper respiratory tract, and intestines, and presents a serious clinical problem because it can lead to opportunistic infections in individuals with weakened immune systems. Streptococci are the most prevalent inhabitants of oral microbial communities, and are typical oral commensals found in the human oral cavity. These streptococci, along with many other oral microbes, produce multispecies biofilms that can attach to salivary pellicle components and other oral bacteria via adhesin proteins expressed on the cell surface. Antibiotics are effective against this bacterium, but resistance against antibodies is increasing. Therefore, a more effective treatment is needed. Vaccines offer a promising method for preventing this issue. This study generated a multi-epitope vaccine against Streptococcus gordonii by targeting the completely sequenced proteomes of five strains. The vaccine targets are identified using a pangenome and subtractive proteomic approach. In the present study, 13 complete strains out of 91 strains of S. gordonii are selected. The pangenomics results revealed that out of 2835 pan genes, 1225 are core genes. Out of these 1225 core genes, 643 identified as non-homologous proteins by subtractive proteomics. A total of 20 essential proteins are predicted from non-homologous proteins. Among these 20 essential proteins, only five are identified as surface proteins. The vaccine construct is designed based on selected B- and T-cell epitopes of the antigenic proteins with the help of linkers and adjuvants. The designed vaccine is docked against TLR2. The expression of the protein is determined using in silico gene cloning. Findings concluded that Vaccine I with adjuvant shows higher interactions with TLR2, suggesting that the vaccine has the ability to induce a humoral and cell-mediated response to treat and prevent infection; this makes it promising as a vaccine against infectious diseases caused by S. gordonii. Furthermore, validation of the vaccine construct is required by in vitro and in vivo trials to check its actual potency and safety for use to prevent infectious diseases caused by S. gordonii. Full article

Sequence variation in the 16S gene is widely used to characterize diverse microbial communities. This was the first pilot study carried out in our region where the pulmonary microbiota of critically ill patients was investigated and analyzed, with the aim of finding a specific profile for these patients that can be used as a diagnostic marker. An study of critical patients mechanically ventilated for non-respiratory indications, in a polyvalent intensive care unit, was carried out; samplee were extracted by endotracheal aspiration and subsequently the microbiota was characterized through Next-Generation Sequencing Technology (NGS). The predominant phyla among the critically ill patients were Proteobacteria, Firmicutes and Bacteroidata. In the surviving patients group, the predominant phyla were Proteobacteria, Bacteroidata and Firmicutes, in the group of deceased patients thy were Firmicutes, Proteobacteria, and Bacteroidata. We found a decrease in commensal bacteria in deceased patients and a progressive increase in in-hospital germs. Full article

Lipopolysaccharide (LPS) is a bacterial component that activates intracellular signaling pathways upon binding to the Toll-like receptor (TLR)-4/MD-2 complex. It is well known that LPS injected into animals and high-dose (100 ng/mL to 1 μg/mL) LPS treatment to innate immune cells induce an inflammatory response. In contrast, LPS is naturally present in the gastrointestinal tract, respiratory tract, and skin of humans and animals, and it has been shown that TLR-4-deficient animals cannot maintain their immune balance and gut homeostasis. LPS from commensal bacteria can help maintain homeostasis against mucosal stimulation in healthy individuals. Oral LPS administration has been shown to be effective in preventing allergic and lifestyle-related diseases. However, this effect was not observed after treatment with LPS at high doses. In mice, oral LPS administration resulted in the detection of LPS at a low concentration in the peritoneal fluid. Therefore, LPS administered at low and high doses have different effects. Moreover, the results of in vitro experiments using low-dose LPS may reflect the effects of oral LPS administration. This review summarizes the utility of in vitro models using cells stimulated with LPS at low concentrations (50 pg/mL to 50 ng/mL) in elucidating the mechanisms of oral LPS administration. Low-dose LPS administration has been demonstrated to suppress the upregulation of proinflammatory cytokines and promote wound healing, suggesting that LPS is a potential agent that can be used for the treatment and prevention of lifestyle-related diseases. Full article

Background: The upper respiratory tract harbors diverse communities of commensal, symbiotic, and pathogenic organisms, originating from both the oral and nasopharyngeal microbiota. Among the primary sites of microbial colonization in the upper airways are the adenoids. Alterations in the adenoid microbiota have been implicated in the development of various conditions, including secretory otitis media. Aim: This study aims to employ 16S rRNA genetic sequencing to identify the most common bacteria present on the surface of adenoids in children with otitis media with effusion and compare them with children without pathologies in the tympanic cavity. Additionally, we seek to determine and compare the bacterial diversity in these two study groups. Materials and Methods: A total of nineteen samples from the adenoid surfaces were collected, comprising two groups: thirteen samples from children without middle ear effusion and six samples from children with secretory otitis media. The libraries of the V3–V4 hypervariable region of the bacterial 16S rRNA gene was made and sequenced using MiSeq platform. Results: The most prevalent phyla observed in both groups were Proteobacteria, Firmicutes, and Bacteroidetes. The most common bacterial genera identified in both groups were Haemophilus, Streptococcus, Moraxella, Fusobacterium, and Bordetella, with Fusobacterium and Moraxella being more prevalent in the groups that had no middle ear effusion, while Haemophulus and Streptococcus were more prevalent in the otitis media with effusion group, although not in a statistically significant way. Statistical analysis shows a trend towards bacterial composition and beta diversity being similar between the study groups; however, due to the limited sample size and unevenness between groups, we should approach this data with caution. Conclusion: The lack of prolific difference in bacterial composition between the study groups suggests that the role of the adenoid microbiome in the development of otitis media with effusion may be less significant. Full article

Data on bacterial or fungal pathogens and their impact on the mortality rates of Western Romanian COVID-19 patients are scarce. As a result, the purpose of this research was to determine the prevalence of bacterial and fungal co- and superinfections in Western Romanian adults with COVID-19, hospitalized in in-ward settings during the second half of the pandemic, and its distribution according to sociodemographic and clinical conditions. The unicentric retrospective observational study was conducted on 407 eligible patients. Expectorate sputum was selected as the sampling technique followed by routine microbiological investigations. A total of 31.5% of samples tested positive for Pseudomonas aeruginosa, followed by 26.2% having co-infections with Klebsiella pneumoniae among patients admitted with COVID-19. The third most common Pathogenic bacteria identified in the sputum samples was Escherichia coli, followed by Acinetobacter baumannii in 9.3% of samples. Commensal human pathogens caused respiratory infections in 67 patients, the most prevalent being Streptococcus penumoniae, followed by methicillin-sensitive and methicillin-resistant Staphylococcus aureus. A total of 53.4% of sputum samples tested positive for Candida spp., followed by 41.1% of samples with Aspergillus spp. growth. The three groups with positive microbial growth on sputum cultures had an equally proportional distribution of patients admitted to the ICU, with an average of 30%, compared with only 17.3% among hospitalized COVID-19 patients with negative sputum cultures (p = 0.003). More than 80% of all positive samples showed multidrug resistance. The high prevalence of bacterial and fungal co-infections and superinfections in COVID-19 patients mandates for strict and effective antimicrobial stewardship and infection control policies. Full article

Inborn errors of immunity (IEI) can present with infections, autoimmunity, lymphoproliferation, granulomas, and malignancy. IEIs are due to genetic abnormalities that disrupt normal host-immune response or immune regulation. The microbiome appears essential for maintaining host immunity, especially in patients with a defective immune system. Altered gut microbiota in patients with IEI can lead to clinical symptoms. Microbial dysbiosis is the consequence of an increase in pro-inflammatory bacteria or a reduction in anti-inflammatory bacteria. However, functional and compositional differences in microbiota are also involved. Dysbiosis and a reduced alpha-diversity are well documented, particularly in conditions like common variable immunodeficiency. Deranged microbiota is also seen in Wiskott–Aldrich syndrome, severe combined immunodeficiency, chronic granulomatous disease, selective immunoglobulin-A deficiency, Hyper IgE syndrome (HIGES), X-linked lymphoproliferative disease-2, immunodysregulation, polyendocrinopathy, enteropathy, x-linked syndrome, and defects of IL10 signalling. Distinct gastrointestinal, respiratory, and cutaneous symptoms linked to dysbiosis are seen in several IEIs, emphasizing the importance of microbiome identification. In this study, we discuss the processes that maintain immunological homeostasis between commensals and the host and the disruptions thereof in patients with IEIs. As the connection between microbiota, host immunity, and infectious illnesses is better understood, microbiota manipulation as a treatment strategy or infection prevention method would be more readily employed. Therefore, optimal prebiotics, probiotics, postbiotics, and fecal microbial transplantation can be promising strategies to restore the microbiota and decrease disease pathology in patients with IEIs. Full article

The importance of the microbiome, and of the gut-lung axis in the origin and persistence of asthma, is an ongoing field of investigation. The process of microbial colonisation in the first three years of life is fundamental for health, with the first hundred days of life being critical. Different factors are associated with early microbial dysbiosis, such as caesarean delivery, artificial lactation and antibiotic therapy, among others. Longitudinal cohort studies on gut and airway microbiome in children have found an association between microbial dysbiosis and asthma at later ages of life. A low α-diversity and relative abundance of certain commensal gut bacterial genera in the first year of life are associated with the development of asthma. Gut microbial dysbiosis, with a lower abundance of Phylum Firmicutes, could be related with increased risk of asthma. Upper airway microbial dysbiosis, especially early colonisation by Moraxella spp., is associated with recurrent viral infections and the development of asthma. Moreover, the bacteria in the respiratory system produce metabolites that may modify the inception of asthma and is progression. The role of the lung microbiome in asthma development has yet to be fully elucidated. Nevertheless, the most consistent finding in studies on lung microbiome is the increased bacterial load and the predominance of proteobacteria, especially Haemophilus spp. and Moraxella catarrhalis. In this review we shall update the knowledge on the association between microbial dysbiosis and the origins of asthma, as well as its persistence, phenotypes, and severity. Full article

Bovine Respiratory Disease (BRD) is a multifactorial condition affecting cattle worldwide resulting in high rates of morbidity and mortality. The disease can be triggered by Bovine Herpesvirus-1 (BoHV-1) infection, stress, and the subsequent proliferation and lung colonization by commensal bacteria such as Mannheimia haemolytica, ultimately inducing severe pneumonic inflammation. Due to its polymicrobial nature, the study of BRD microbes requires co-infection models. While several past studies have mostly focused on the effects of co-infection on host gene expression, we focused on the relationship between BRD pathogens during co-infection, specifically on M. haemolytica’s effect on BoHV-1 replication. This study shows that M. haemolytica negatively impacts BoHV-1 replication in a dose-dependent manner in different in vitro models. The negative effect was observed at very low bacterial doses while increasing the viral dose counteracted this effect. Viral suppression was also dependent on the time at which each microbe was introduced to the cell culture. While acidification of the culture medium did not grossly affect cell viability, it significantly inhibited viral replication. We conclude that M. haemolytica and BoHV-1 interaction is dose and time-sensitive, wherein M. haemolytica proliferation induces significant viral suppression when the viral replication program is not fully established. Full article

In a previous work, we demonstrated that nasally administered Corynebacterium pseudodiphtheriticum 090104 beneficially modulated the respiratory innate immune response and improved the protection against Respiratory Syncytial Virus and Streptococcus pneumoniae in mice. In this work, we aimed to evaluate whether the immunomodulatory 090104 strain was able to enhance the resistance against the respiratory infection induced by hypermucoviscous carbapenemase-producing (KPC-2) Klebsiella pneumoniae strains belonging to the sequence type (ST) 25. The nasal treatment of mice with C. pseudodiphtheriticum 090104 before the challenge with multiresistant K. pneumoniae ST25 strains significantly reduced lung bacterial cell counts and lung tissue damage. The protective effect of the 090104 strain was related to its ability to regulate the respiratory innate immune response triggered by K. pneumoniae challenge. C. pseudifteriticum 090104 differentially modulated the recruitment of leukocytes into the lung and the production of TNF-α, IFN-γ and IL-10 levels in the respiratory tract and serum. Our results make an advance in the positioning of C. pseudodiphtheriticum 090104 as a next-generation probiotic for the respiratory tract and encourage further research of this bacterium as a promising alternative to develop non-antibiotic therapeutical approaches to enhance the prevention of infections produced by microorganisms with multiple resistance to antimicrobials such as KPC-2-producing hypermucoviscous K. pneumoniae strains belonging to ST25. Full article