Intranasal Inoculation of Cryptococcus neoformans in Mice Produces Nasal Infection with Rapid Brain Dissemination

ABSTRACT Cryptococcus neoformans is an important fungal pathogen, causing life-threatening pneumonia and meningoencephalitis. Brain dissemination of C. neoformans is thought to be a consequence of an active infection in the lung which then extravasates to other sites. Brain invasion results from dissemination via either transport by free yeast cells in the bloodstream or Trojan horse transport within mononuclear phagocytes. We assessed brain dissemination in three mouse models of infection: intravenous, intratracheal, and intranasal models. All three modes of infection resulted in dissemination of C. neoformans to the brain in less than 3 h. Further, C. neoformans was detected in the entirety of the upper respiratory tract and the ear canals of mice. In recent years, intranasal infection has become a popular mechanism to induce pulmonary infection because it avoids surgery, but our findings show that instillation of C. neoformans produces cryptococcal nasal infection. These findings imply that immunological studies using intranasal infection should assume that the initial sites of infection of infection are brain, lung, and upper respiratory tract, including the nasal airways. IMPORTANCE Cryptococcus neoformans causes an estimated 181, 000 deaths each year, mostly associated with untreated HIV/AIDS. C. neoformans has a ubiquitous worldwide distribution. Humans become infected from exposure to environmental sources, after which the fungus lays dormant within the human body. Upon AIDS-induced immunosuppression or therapy-induced immunosuppression (required for organ transplant recipients or those suffering from autoimmune disorders), cryptococcal disease reactivates and causes life-threatening meningitis and pneumonia. This study showed that upon contact with the host, C. neoformans can quickly (a few hours) reach the host brain and also colonizes the nose of infected animals. Therefore, this work paves the way to better knowledge of how C. neoformans travels through the host body. Understanding how C. neoformans infects, disseminates, and survives within the host is critically required so that we can prevent infections and the disease caused by this deadly fungus.

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Intranasal inoculation of Cryptococcus neoformans in mice produces nasal infection with rapid brain dissemination

10.1101/709204 ◽

2019 ◽

Author(s):

Carolina Coelho ◽

Emma Camacho ◽

Antonio Salas ◽

Alexandre Alanio ◽

Arturo Casadevall

Keyword(s):

Respiratory Tract ◽

Cryptococcus Neoformans ◽

Organ Transplant ◽

Mononuclear Phagocytes ◽

Yeast Cells ◽

Upper Respiratory Tract ◽

Intranasal Infection ◽

Brain Invasion ◽

Life Threatening ◽

Upper Respiratory

AbstractCryptococcus neoformans is an important fungal pathogen, causing life-threatening pneumonia and meningoencephalitis. Brain dissemination of C. neoformans is thought to be a consequence of an active infection in the lung which then extravasates to other sites. Brain invasion results from dissemination via the bloodstream, either by free yeast cells in bloodstream or Trojan horse transport within mononuclear phagocytes. We assessed brain dissemination in three mouse models of infection: intravenous, intratracheal, and intranasal. All three modes of infection resulted in dissemination of C. neoformans to the brain in under 3 hours. Further, C. neoformans was detected in the entirety of the upper respiratory tract and the ear canals of mice. In recent years, intranasal infection has become a popular mechanism to induce pulmonary infection because it avoids surgery but our findings show that instillation of C. neoformans produces cryptococcal nasal infection. These findings imply that immunological studies using intranasal infection should assume the initial sites of infection of infection are brain, lung and upper respiratory tract, including the nasal airways.ImportanceCryptococcus neoformans causes an estimated 181, 000 deaths each year, mostly associated with untreated HIV/AIDS. C. neoformans has a ubiquitous worldwide distribution. Humans become infected from exposure to environmental sources and the fungus lays dormant within the human body. Upon immunosuppression, such as AIDS or therapy-induced as required by organ transplant recipients or autoimmune disease patients, cryptococcal disease reactivates and causes life-threatening meningitis and pneumonia. This study has detected that upon contact with the host, C. neoformans can quickly (a few hours) reach the host brain and will also colonize the nose of infected animals. Therefore, this work paves the way to better knowledge of how C. neoformans travels through the host body. Understanding how C. neoformans infects, disseminates and survives within the host is critically required so that we can prevent infections and the disease caused by this deadly fungus.

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Challenges in the delivery of critical care in India during the COVID-19 pandemic

Journal of the Intensive Care Society ◽

10.1177/1751143720952590 ◽

2020 ◽

pp. 175114372095259

Author(s):

Bharath Kumar Tirupakuzhi Vijayaraghavan ◽

Sheila Nainan Myatra ◽

Meghena Mathew ◽

Nirmalyo Lodh ◽

Jigeeshu Vasishtha Divatia ◽

...

Keyword(s):

Critical Care ◽

Acute Respiratory Distress Syndrome ◽

Intensive Care ◽

Respiratory Tract ◽

Respiratory Distress Syndrome ◽

Distress Syndrome ◽

Upper Respiratory Tract ◽

Care Services ◽

Life Threatening ◽

Upper Respiratory

Coronavirus disease 2019 cases in India continue to increase and are expected to peak over the next few weeks. Based on some projection models, India is expected to have more than 10 million cases by September 2020. The spectrum of disease can vary from mild upper respiratory tract symptoms to life-threatening acute respiratory distress syndrome and multi-organ failure requiring intensive care. Even if less than 5% of patients require critical care services, this will still rapidly overwhelm the healthcare system in a country, where intensive care services and resources are scarce and unevenly distributed. In this perspective article, we highlight the critical care preparedness of India for the pandemic and the associated challenges.

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Identification of Pneumococcal Factors Affecting Pneumococcal Shedding Shows that thedltLocus Promotes Inflammation and Transmission

mBio ◽

10.1128/mbio.01032-19 ◽

2019 ◽

Vol 10 (3) ◽

Cited By ~ 7

Author(s):

M. Ammar Zafar ◽

Alexandria J. Hammond ◽

Shigeto Hamaguchi ◽

Weisheng Wu ◽

Masamitsu Kono ◽

...

Keyword(s):

Streptococcus Pneumoniae ◽

Respiratory Tract ◽

Capsular Polysaccharide ◽

Inflammatory Responses ◽

Transposon Mutagenesis ◽

Respiratory Pathogen ◽

Invasive Infection ◽

Upper Respiratory Tract ◽

Content Type ◽

Upper Respiratory

ABSTRACTHost-to-host transmission is a necessary but poorly understood aspect of microbial pathogenesis. Herein, we screened a genomic library of mutants of the leading respiratory pathogenStreptococcus pneumoniaegenerated by mariner transposon mutagenesis (Tn-Seq) to identify genes contributing to its exit or shedding from the upper respiratory tract (URT), the limiting step in the organism’s transmission in an infant mouse model. Our analysis focused on genes affecting the bacterial surface that directly impact interactions with the host. Among the multiple factors identified was thedltlocus, which addsd-alanine onto lipoteichoic acids (LTA) and thereby increases Toll-like receptor 2-mediated inflammation and resistance to antimicrobial peptides. The more robust proinflammatory response in the presence ofd-alanylation promotes secretions that facilitate pneumococcal shedding and allows for transmission. Expression of thedltlocus is controlled by the CiaRH system, which senses cell wall stress in response to antimicrobial activity, including in response to lysozyme, the most abundant antimicrobial along the URT mucosa. Accordingly, in alysM−/−host, there was no longer an effect of thedltlocus on pneumococcal shedding. Thus, our findings demonstrate how a pathogen senses the URT milieu and then modifies its surface characteristics to take advantage of the host response for transit to another host.IMPORTANCEStreptococcus pneumoniae(the pneumococcus) is a common cause of respiratory tract and invasive infection. The overall effectiveness of immunization with the organism’s capsular polysaccharide depends on its ability to block colonization of the upper respiratory tract and thereby prevent host-to-host transmission. Because of the limited coverage of current pneumococcal vaccines, we carried out an unbiasedin vivotransposon mutagenesis screen to identify pneumococcal factors other than its capsular polysaccharide that affect transmission. One such candidate was expressed by thedltlocus, previously shown to addd-alanine onto the pneumococcal lipoteichoic acid present on the bacterial cell surface. This modification protects against host antimicrobials and augments host inflammatory responses. The latter increases secretions and bacterial shedding from the upper respiratory tract to allow for transmission. Thus, this study provides insight into a mechanism employed by the pneumococcus to successfully transit from one host to another.

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Two Different Life-Threatening Cases: Presenting with Torticollis

Case Reports in Pediatrics ◽

10.1155/2016/7808734 ◽

2016 ◽

Vol 2016 ◽

pp. 1-3 ◽

Cited By ~ 1

Author(s):

Gülsüm Alkan ◽

Melike Emiroğlu ◽

Ayşe Kartal

Keyword(s):

Respiratory Tract ◽

Arachnoid Cyst ◽

Upper Respiratory Tract ◽

Cervical Muscles ◽

Common Causes ◽

Inflammatory Processes ◽

Life Threatening ◽

Spinal Arachnoid Cyst ◽

Upper Respiratory

Acquired torticollis can be the result of several different pathological mechanisms. It is generally related to trauma, tumors, and inflammatory processes of the cervical muscles, nerves, and vertebral synovia. Although upper respiratory tract and neck inflammation are common causes of acute febrile torticollis in children, diseases with as yet undefined relationships may also result in torticollis. This is the case of spinal arachnoid cyst and pneumonia.

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Type I Interferon Signaling Is a Common Factor Driving Streptococcus pneumoniae and Influenza A Virus Shedding and Transmission

mBio ◽

10.1128/mbio.03589-20 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Tonia Zangari ◽

Mila B. Ortigoza ◽

Kristen L. Lokken-Toyli ◽

Jeffrey N. Weiser

Keyword(s):

Streptococcus Pneumoniae ◽

Respiratory Tract ◽

Influenza A Virus ◽

Influenza A ◽

Common Factor ◽

Type I ◽

Upper Respiratory Tract ◽

Content Type ◽

Infant Mouse ◽

Upper Respiratory

ABSTRACT The dynamics underlying respiratory contagion (the transmission of infectious agents from the airways) are poorly understood. We investigated host factors involved in the transmission of the leading respiratory pathogen Streptococcus pneumoniae. Using an infant mouse model, we examined whether S. pneumoniae triggers inflammatory pathways shared by influenza A virus (IAV) to promote nasal secretions and shedding from the upper respiratory tract to facilitate transit to new hosts. Here, we show that amplification of the type I interferon (IFN-I) response is a critical host factor in this process, as shedding and transmission by both IAV and S. pneumoniae were decreased in pups lacking the common IFN-I receptor (Ifnar1−/− mice). Additionally, providing exogenous recombinant IFN-I to S. pneumoniae-infected pups was sufficient to increase bacterial shedding. The expression of IFN-stimulated genes (ISGs) was upregulated in S. pneumoniae-infected wild-type (WT) but not Ifnar1−/− mice, including genes involved in mucin type O-glycan biosynthesis; this correlated with an increase in secretions in S. pneumoniae- and IAV-infected WT compared to Ifnar1−/− pups. S. pneumoniae stimulation of ISGs was largely dependent on its pore-forming toxin, pneumolysin, and coinfection with IAV and S. pneumoniae resulted in synergistic increases in ISG expression. We conclude that the induction of IFN-I signaling appears to be a common factor driving viral and bacterial respiratory contagion. IMPORTANCE Respiratory tract infections are a leading cause of childhood mortality and, globally, Streptococcus pneumoniae is the leading cause of mortality due to pneumonia. Transmission of S. pneumoniae primarily occurs through direct contact with respiratory secretions, although the host and bacterial factors underlying transmission are poorly understood. We examined transmission dynamics of S. pneumoniae in an infant mouse model and here show that S. pneumoniae colonization of the upper respiratory tract stimulates host inflammatory pathways commonly associated with viral infections. Amplification of this response was shown to be a critical host factor driving shedding and transmission of both S. pneumoniae and influenza A virus, with infection stimulating expression of a wide variety of genes, including those involved in the biosynthesis of mucin, a major component of respiratory secretions. Our findings suggest a mechanism facilitating S. pneumoniae contagion that is shared by viral infection.

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Anterior Nares Diversity and Pathobionts Represent Sinus Microbiome in Chronic Rhinosinusitis

mSphere ◽

10.1128/msphere.00532-19 ◽

2019 ◽

Vol 4 (6) ◽

Cited By ~ 5

Author(s):

Ilke De Boeck ◽

Stijn Wittouck ◽

Katleen Martens ◽

Jos Claes ◽

Mark Jorissen ◽

...

Keyword(s):

Respiratory Tract ◽

Haemophilus Influenzae ◽

Chronic Rhinosinusitis ◽

Nasal Polyps ◽

Sinus Surgery ◽

Disease Development ◽

Healthy Controls ◽

Upper Respiratory Tract ◽

Content Type ◽

Upper Respiratory

ABSTRACT It is generally believed that the microbiome plays a role in the pathophysiology of chronic rhinosinusitis (CRS), though its exact contribution to disease development and severity remains unclear. Here, samples were collected from the anterior nares, nasopharynx, and maxillary and ethmoid sinuses of 190 CRS patients and from the anterior nares and nasopharynx of 100 controls. Microbial communities were analyzed by Illumina sequencing of the V4 region of 16S rRNA. The phenotype and patient characteristics were documented, and several serum inflammatory markers were measured. Our data indicate a rather strong continuity for the microbiome in the different upper respiratory tract (URT) niches in CRS patients, with the microbiome in the anterior nares being most similar to the sinus microbiome. Bacterial diversity was reduced in CRS patients without nasal polyps compared to that in the controls but not in CRS patients with nasal polyps. Statistically significant differences in the presence/absence or relative abundance of several taxa were found between the CRS patients and the healthy controls. Of these, Dolosigranulum pigrum was clearly more associated with URT samples from healthy subjects, while the Corynebacterium tuberculostearicum, Haemophilus influenzae/H. aegyptius, and Staphylococcus taxa were found to be potential pathobionts in CRS patients. However, CRS versus health as a predictor explained only 1 to 2% of the variance in the microbiome profiles in an adonis model. A history of functional endoscopic sinus surgery, age, and sex also showed a minor association. This study thus indicates that functional studies on the potential beneficial versus pathogenic activity of the different indicator taxa found here are needed to further understand the pathology of CRS and its different phenotypes. (This study has been registered at ClinicalTrials.gov under identifier NCT02933983.) IMPORTANCE There is a clear need to better understand the pathology and specific microbiome features in chronic rhinosinusitis patients, but little is known about the bacterial topography and continuity between the different niches of the upper respiratory tract. Our work showed that the anterior nares could be an important reservoir for potential sinus pathobionts. This has implications for the diagnosis, prevention, and treatment of CRS. In addition, we found a potential pathogenic role for the Corynebacterium tuberculostearicum, Haemophilus influenzae/H. aegyptius, and Staphylococcus taxa and a potential beneficial role for Dolosigranulum. Finally, a decreased microbiome diversity was observed in patients with chronic rhinosinusitis without nasal polyps compared to that in healthy controls but not in chronic rhinosinusitis patients with nasal polyps. This suggests a potential role for the microbiome in disease development or progression of mainly this phenotype.

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Primary Tuberculosis of pharynx-diagnostic difficulties, complications and treatment

Bhutan Health Journal ◽

10.47811/bhj.12 ◽

2015 ◽

Vol 1 (1) ◽

pp. 62-65

Author(s):

Tika R. Adhikari ◽

Rahmat Omar

Keyword(s):

Respiratory Tract ◽

Airway Compromise ◽

Upper Respiratory Tract ◽

Diagnostic Challenge ◽

Primary Tuberculosis ◽

Delay In Diagnosis ◽

Emergency Tracheostomy ◽

Diagnostic Difficulties ◽

Life Threatening ◽

Upper Respiratory

Primary tuberculosis of the upper respiratory tract is extremely rare and poses a diagnostic challenge. Due to delay in diagnosis the disease may progress to life threatening airway compromise. Here we report a case of chronic granulomatous infection of the upper respiratory tract involving the oropharynx. Initial biopsy revealed acute on chronic inflammation with no epitheloid granuloma and no acid fast bacilli was found on Ziehl-Nielsen staining of the biopsy. As a result of delay in diagnosis the disease progressed to involve the soft palate, valopharyngeal isthmus, and supraglottis compromising the airway and needed emergency tracheostomy. Where there is strong clinical suspicion repeat biopsy should be performed. The life threatening complication of pharyngeal tuberculosis such as stenosis and adhesion leading to airway compromise can occur during the course of treatment and should be closely monitored . It can be managed effectively with radiofrequency uvulopalatoplasty as demonstrated in the case report.

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Upper Respiratory Tract Microbial Communities, Acute Otitis Media Pathogens, and Antibiotic Use in Healthy and Sick Children

Applied and Environmental Microbiology ◽

10.1128/aem.01051-12 ◽

2012 ◽

Vol 78 (17) ◽

pp. 6262-6270 ◽

Cited By ~ 103

Author(s):

Melinda M. Pettigrew ◽

Alison S. Laufer ◽

Janneane F. Gent ◽

Yong Kong ◽

Kristopher P. Fennie ◽

...

Keyword(s):

Respiratory Tract ◽

Microbial Communities ◽

Otitis Media ◽

Acute Otitis Media ◽

Antibiotic Use ◽

Healthy Children ◽

Upper Respiratory Tract ◽

Content Type ◽

The Past ◽

Upper Respiratory

ABSTRACTThe composition of the upper respiratory tract microbial community may influence the risk for colonization by the acute otitis media (AOM) pathogensStreptococcus pneumoniae,Haemophilus influenzae, andMoraxella catarrhalis. We used culture-independent methods to describe upper respiratory tract microbial communities in healthy children and children with upper respiratory tract infection with and without concurrent AOM. Nasal swabs and data were collected in a cross-sectional study of 240 children between 6 months and 3 years of age. Swabs were cultured forS. pneumoniae, and real-time PCR was used to identifyS. pneumoniae,H. influenzae, andM. catarrhalis. The V1-V2 16S rRNA gene regions were sequenced using 454 pyrosequencing. Microbial communities were described using a taxon-based approach. Colonization byS. pneumoniae,H. influenzae, andM. catarrhaliswas associated with lower levels of diversity in upper respiratory tract flora. We identified commensal taxa that were negatively associated with colonization by each AOM bacterial pathogen and with AOM. The balance of these relationships differed according to the colonizing AOM pathogen and history of antibiotic use. Children with antibiotic use in the past 6 months and a greater abundance of taxa, includingLactococcusandPropionibacterium, were less likely to have AOM than healthy children (odds ratio [OR], 0.46; 95% confidence interval [CI], 0.25 to 0.85). Children with no antibiotic use in the past 6 months, a low abundance ofStreptococcusandHaemophilus, and a high abundance ofCorynebacteriumandDolosigranulumwere less likely to have AOM (OR, 0.51; 95% CI, 0.31 to 0.83). An increased understanding of polymicrobial interactions will facilitate the development of effective AOM prevention strategies.

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Nasal Tissue Extraction Is Essential for Characterization of the Murine Upper Respiratory Tract Microbiota

mSphere ◽

10.1128/msphere.00562-20 ◽

2020 ◽

Vol 5 (6) ◽

Author(s):

L. Patrick Schenck ◽

Joshua J. C. McGrath ◽

Daphnée Lamarche ◽

Martin R. Stämpfli ◽

Dawn M. E. Bowdish ◽

...

Keyword(s):

Streptococcus Pneumoniae ◽

Respiratory Tract ◽

Research Design ◽

Respiratory Infections ◽

Upper Respiratory Tract ◽

Content Type ◽

Nasal Tissue ◽

Colonization Success ◽

Upper Respiratory ◽

Nasal Microbiota

ABSTRACT Respiratory infections are a leading cause of morbidity and mortality worldwide. Bacterial pathogens often colonize the upper respiratory tract (nose or mouth) prior to causing lower respiratory infections or invasive disease. Interactions within the upper respiratory tract between colonizing bacteria and the resident microbiota could contribute to colonization success and subsequent transmission. Human carriage studies have identified associations between pathogens such as Streptococcus pneumoniae and members of the resident microbiota, although few mechanisms of competition and cooperation have been identified and would be aided by the use of animal models. Little is known about the composition of the murine nasal microbiota; thus, we set out to improve assessment, including tissue sampling, composition, and comparison between mouse sources. Nasal washes were efficient in sampling the nasopharyngeal space but barely disrupted the nasal turbinates. Nasal tissue extraction increased the yield of cultivable bacterial compared to nasal washes, revealing distinct community compositions. Experimental pneumococcal colonization led to dominance by the colonizing pathogen in the nasopharynx and nasal turbinates, but the composition of the microbiota, and interactions with resident microbes, differed depending on the sampling method. Importantly, vendor source has a large impact on microbial composition. Bacterial interactions, including cooperation and colonization resistance, depend on the biogeography of the nose and should be considered during research design of experimental colonization with pathogens. IMPORTANCE The nasal microbiota is composed of species that play a role in the colonization success of pathogens, including Streptococcus pneumoniae and Staphylococcus aureus. Murine models provide the ability to explore disease pathogenesis, but little is known about the natural murine nasal microbiota. This study established techniques to allow the exploration of the bacterial members of the nasal microbiota. The mouse nasal microbiota included traditional respiratory bacteria, including Streptococcus, Staphylococcus, and Moraxella species. Analyses were affected by different sampling methods as well as the commercial source of the mice, which should be included in future research design of infectious disease research.

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Demonstration of N , N -Dimethyldithiocarbamate as a Copper-Dependent Antibiotic against Multiple Upper Respiratory Tract Pathogens

Microbiology Spectrum ◽

10.1128/spectrum.00778-21 ◽

2021 ◽

Author(s):

Sanjay V. Menghani ◽

Angela Rivera ◽

Miranda Neubert ◽

James R. Hagerty ◽

Lourdes Lewis ◽

...

Keyword(s):

Antibiotic Resistance ◽

Streptococcus Pneumoniae ◽

Respiratory Tract ◽

Dependent Manner ◽

Upper Respiratory Tract ◽

Coccidioides Posadasii ◽

Content Type ◽

Upper Respiratory

With the rise of antibiotic resistance, approaches that add new antimicrobials to the current repertoire are vital. Here, we investigate putative and known copper ionophores in an attempt to intoxicate bacteria and use ionophore/copper synergy, and we ultimately find success with N , N -dimethyldithiocarbamate (DMDC). We show that DMDC has in vitro efficacy in a copper-dependent manner and kills pathogens across three different kingdoms, Streptococcus pneumoniae ( Sr. pneumoniae ), Coccidioides posadasii , and Schistosoma mansoni , and in vivo efficacy against Sr . pneumoniae .

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