Mucosal Biofilms Research Articles

Longitudinal Analyses of Gut Mucosal Microbiotas in Ulcerative Colitis in Relation to Patient Age and Disease Severity and Duration

Bacteria belonging to the normal colonic microbiota are associated with the etiology of ulcerative colitis (UC). Although several mucosal species have been implicated in the disease process, the organisms and mechanisms involved are unknown. The aim of this investigation was to characterize mucosal biofilm communities over time and to determine the relationship of these bacteria to patient age and disease severity and duration. Multiple rectal biopsy specimens were taken from 33 patients with active UC over a period of 1 year. Real-time PCR was used to quantify mucosal bacteria in UC patients compared to 18 noninflammatory bowel disease controls, and the relationship between indicators of disease severity and bacterial colonization was evaluated by linear regression analysis. Significant differences were detected in bacterial populations on the UC mucosa and in the control group, which varied over the study period. High clinical activity indices (CAI) and sigmoidoscopy scores (SS) were associated with enterobacteria, desulfovibrios, type E Clostridium perfringens, and Enterococcus faecalis, whereas the reverse was true for Clostridium butyricum, Ruminococcus albus, and Eubacterium rectale. Lactobacillus and bifidobacterium numbers were linked with low CAI. Only E. rectale and Clostridium clostridioforme had a high age dependence. These findings demonstrated that longitudinal variations in mucosal bacterial populations occur in UC and that bacterial community structure is related to disease severity.

A mucosal model to study microbial biofilm development and anti-biofilm therapeutics

Biofilms are a sessile colony of bacteria which adhere to and persist on surfaces. The ability of bacteria to form biofilms is considered a virulence factor, and in fact is central to the pathogenesis of some organisms. Biofilms are inherently resistant to chemotherapy and host immune responses. Clinically, biofilms are considered a primary cause of a majority of infections, such as otitis media, pneumonia in cystic fibrosis patients and endocarditis. However, the vast majority of the data on biofilm formation comes from traditional microtiter-based or flow displacement assays with no consideration given to host factors. These assays, which have been a valuable tool in high-throughput screening for biofilm-related factors, do not mimic a host–pathogen interaction and may contribute to an inappropriate estimation of the role of some factors in clinical biofilm formation. We describe the development of a novel ex vivo model of biofilm formation on a mucosal surface by an important mucosal pathogen, methicillin resistant S. aureus (MRSA). This model is being used for the identification of microbial virulence factors important in mucosal biofilm formation and novel anti-biofilm therapies.

Kinetic analysis and evaluation of the mechanisms involved in the resolution of experimental nontypeable Haemophilus influenzae-induced otitis media after transcutaneous immunization

Transcutaneous immunization (TCI) is a simple and needle-free method with which to induce protective immune responses. Using a chinchilla model of nontypeable Haemophilus influenzae (NTHI)-induced otitis media (OM), we examined the efficacy afforded by TCI with a novel chimeric immunogen called ‘chimV4’ which targets two critical adhesins expressed by NTHI, outer membrane protein P5 and the majority subunit of NTHI Type IV pilus, PilA. Experimental OM was first established in cohorts of animals, and then TCI performed via a therapeutic immunization regime by rubbing vaccine formulations on hydrated pinnae. The kinetics of resolution of established experimental disease was evaluated by clinically-relevant assessments of OM, bacterial culture of planktonic and adherent NTHI within the middle ear and gross examination of the relative amount of NTHI mucosal biofilms within the middle ear space. Within seven days after primary TCI, a significant reduction in the signs of OM, significantly fewer NTHI adherent to the middle ear mucosa and significant resolution of mucosal biofilms was detected in animals that received chimV4+ the adjuvant LT(R192G-L211A), compared to animals administered LT(R192G-L211A) alone or saline by TCI (p<0.05) with eradication of NTHI within an additional seven days. The mechanism for rapid disease resolution involved efflux of activated dermal dendritic cells from the pinnae after TCI, secretion of factors chemotactic for CD4+ T-cells, induction of polyfunctional IFNγ- and IL-17-producing CD4+ T-cells and secretion of host defense peptide within the middle ear. These data support TCI as a therapeutic intervention against experimental NTHI-induced OM and begin to elucidate the host response to immunization by this noninvasive regimen.

Mastoid Biofilm in Chronic Otitis Media

We designed a study to determine the role of mastoid mucosal biofilm in chronic otitis media (COM). Biofilm formation has been found in several chronic airway infections. COM is associated with chronic, recalcitrant infection of the mastoid mucosa, and surgery often is required. COM patients were divided into 2 groups: one with chronic suppurative otitis media (CSOM) and one with cholesteatoma presence. All COM patients had mastoid involvement in a preoperative computed tomographic scan. The control group consisted of patients undergoing cochlear implantation, with no previous history of chronic otitis media. Mastoid mucosa samples were harvested during mastoidectomy. The samples were studied with multiplex-polymerase chain reaction and with CSLM using BacLight Live/Dead stain. Routine bacterial culture was performed in selected cases. A total of 29 COM patients underwent mastoidectomy. Mastoid mucosal biofilm formation could be found in 19 (66%) of these patients. In the control group, there were 11 cases of cochlear implantation, and 1 patient (9%) presented mastoid mucosal biofilm. In the cholesteatoma group, there were 17 patients, of which, 14 (82%) presented biofilm, whereas in the CSOM group, 5 (42%) of 12 patients presented biofilm. The correlation between COM and biofilm was statistically significant (Fisher's exact test, p = 0.003), as was the correlation between cholesteatoma and biofilm, in comparison with the CSOM group (Fisher's exact test, p = 0.046). Mastoid mucosal biofilm could be seen in patients with COM with or without cholesteatoma. The role of mastoid biofilm in the development of cholesteatoma should be studied further.

Adenotonsillar Disease

Adenotonsillar disease (adenoiditis and recurrent tonsillitis) is a prevalent otolaryngologic disorder aetiologically based on chronic inflammation triggered by a persistent bacterial infection. These bacteria, mostly Staphylococcus aureus, Haemophilus sp., and Streptococcus sp., persist predominantly intracellular and within mucosal biofilms. The recurrent or chronic inflammation of the adenoids and faucial tonsils leads to chronic activation of the cell-mediated and humoral immune response, resulting in hypertrophy of the lymphoid tonsillar tissue. This hypertrophic tissue is the cause for the prominent clinical symptoms: obstruction of the upper airways, snoring, and sleep apnea for adenoiditis or sore throat, dysphagia and halitosis for recurrent tonsillitis. Treatment strategies should target the persisting bacteria within their biofilm or intracellular shelter. Macrolide antibiotics like clarithromycin are able to modulate the immune system and to interfere in bacterial signaling within biofilms. Clindamycin, quinupristin-dalfopristin, and oritavancin are intracellular high active compounds. Surgical removal of the hypertrophic tissue by modern procedures like laser tonsil ablation, eliminates not only a mechanical obstacle of the airways, it removes also the basis for the aetiologic cause, the "biofilm carrier". This review summarizes the role of bacterial persistence in mucosal biofilms for the aetiology, diagnosis and treatment of adenotonsillar disease and relevant patents.

Giardia duodenalis: A model of pathogen‐mediated disruptions in the human microbiota in leading to the development of chronic gastrointestinal disease

Giardia duodenalis is a key pathogen causing post‐infectious Irritable Bowel Syndrome (PI‐IBS) symptoms. Underlying mechanisms are unknown, but disruptions in species distribution of the intestinal microbiota in IBS patients have been reported. The intestinal microflora exists in biofilm communities, and the effects of enteropathogens on this phenotype, in the context of PI‐IBS, remain obscure.AimTo study effects of Giardia on the structure, species, and pathogenic profile of microflora biofilms.MethodsRepresentative intestinal mucosal biofilms were cultured from human colonic mucosal biospy samples.ResultsGiardia enhances the presence of Clostridiales spp. in microflora biofilms. Giardia promotes planktonic growth in microflora biofilms by disrupting normal polysaccharide production. Giardia‐exposed biofilms induce higher levels of enterocyte apoptosis than ones incubated with control biofilms.ConclusionGiardia exposed biofilms exhibit altered structure and species composition in human microflora biofilms, and promote enterocyte apoptosis, highlighting detrimental effects of a pathogen‐modified microflora in the bowel. Supported by NSERC

Tumor necrosis factor‐α receptor expression correlates with mucosal changes and biofilm presence in chronic rhinosinusitis with nasal polyposis

Biofilms might play a potential role in the pathogenesis and high recurrence rate of chronic rhinosinusitis with nasal polyposis (CRSwNP). Biofilm persistence has been thought to correlate with epithelial damage, subepithelial inflammatory cell infiltration, and tumor necrosis factor-α receptor (TNFR) expression in CRSwNP. Case-control experimental study. A total of 36 patients with CRSwNP undergoing endoscopic sinus surgery were analyzed. The negative control group consisted of eight patients undergoing septoplasty for nasal obstruction without CRSwNP. The nasal polyps and inferior turbinate mucosa samples applied as negative controls were processed by hematoxylin-eosin (HE) and Gram staining and TNFR-I and TNFR-II-specific immunofluorescent assay. Biofilm was detected in 29 of 36 patients with CRSwNP and in none of the eight negative controls. Staining by HE showed strong correlation with the results of Gram staining protocol. In the biofilm-positive cases, TNFR-I and TNFR-II displayed homogeneous pattern of significantly increased epithelial expression compared to the biofilm-negative nasal polyps. In cases of biofilm absence, the expression pattern of TNF-α receptors was characterized by increased TNFR-II-specific immunoreaction. It was found that biofilm detectability corresponded to the integrity of nasal epithelium and to the dominant inflammatory cell type of the subepithelial layer. Persisting biofilms might increase the epithelial sensitivity against TNF-α that result in epithelium destruction. Coexistence of biofilms and increased TNFR expression might explain the inflammatory mucosal changes, functional disorders, and therapy resistance featuring CRSwNP.

In VitroStreptococcus pneumoniaeBiofilm Formation andIn VivoMiddle Ear Mucosal Biofilm in a Rat Model of Acute Otitis Induced byS. pneumoniae

ObjectivesStreptococcus pneumoniae is one of the most common pathogens of otitis media (OM) that exists in biofilm, which enhances the resistance of bacteria against antibiotic killing and diagnosis, compared to the free-floating (planktonic) form. This study evaluated biofilm formation by S. pneumoniae on an abiotic surface and in the middle ear cavity in a rat model of OM.MethodsIn vitro biofilm formation was evaluated by inoculation of a 1:100 diluted S. pneumoniae cell suspension in a 96-well microplate. Adherent cells were quantified spectrophotometrically following staining with crystal violet by measurement of optical density at 570 nm. The ultrastructure of pneumococcal biofilm was assessed by scanning electron microscopy (SEM). For in vitro biofilm study, S. pneumoniae cell suspensions containing 1×107 colony forming units were injected through transtympanic membrane into the middle ear cavity of Sprague Dawley rats. The ultrastructure of middle ear mucus was observed by SEM 1 and 2 weeks post-inoculation.ResultsThe in vitro study revealed robust biofilm formation by S. pneumoniae after 12-18 hours of incubation in high glucose medium, independent of exogenously supplied competence stimulating peptide and medium replacement. Adherent cells formed three-dimensional structures approximately 20-30 µm thick. The in vivo study revealed that ciliated epithelium was relatively resistant to biofilm formation and that biofilm formation occurred mainly on non-ciliated epithelium of the middle ear cavity. One week after inoculation, biofilm formation was high in 50% of the treated rats and low in 25% of the rats. After 2 weeks, biofilm formation was high and low in 25% and 37.5% of rats, respectively.ConclusionThe results imply that glucose level is important for the S. pneumoniae biofilm formation and S. pneumoniae biofilm formation may play important role in the pathophysiology of OM.

Synergistic Interaction between Candida albicans and Commensal Oral Streptococci in a Novel In Vitro Mucosal Model

Candida albicans is a commensal colonizer of the gastrointestinal tract of humans, where it coexists with highly diverse bacterial communities. It is not clear whether this interaction limits or promotes the potential of C. albicans to become an opportunistic pathogen. Here we investigate the interaction between C. albicans and three species of streptococci from the viridans group, which are ubiquitous and abundant oral commensal bacteria. The ability of C. albicans to form biofilms with Streptococcus oralis, Streptococcus sanguinis, or Streptococcus gordonii was investigated using flow cell devices that allow abiotic biofilm formation under salivary flow. In addition, we designed a novel flow cell system that allows mucosal biofilm formation under conditions that mimic the environment in the oral and esophageal mucosae. It was observed that C. albicans and streptococci formed a synergistic partnership where C. albicans promoted the ability of streptococci to form biofilms on abiotic surfaces or on the surface of an oral mucosa analogue. The increased ability of streptococci to form biofilms in the presence of C. albicans could not be explained by a growth-stimulatory effect since the streptococci were unaffected in their growth in planktonic coculture with C. albicans. Conversely, the presence of streptococci increased the ability of C. albicans to invade organotypic models of the oral and esophageal mucosae under conditions of salivary flow. Moreover, characterization of mucosal invasion by the biofilm microorganisms suggested that the esophageal mucosa is more permissive to invasion than the oral mucosa. In summary, C. albicans and commensal oral streptococci display a synergistic interaction with implications for the pathogenic potential of C. albicans in the upper gastrointestinal tract.

Efficacy of Using a Hydrodebrider and of Citric Acid/Zwitterionic Surfactant on a Staphylococcus Aureus Bacterial Biofilm in the Sheep Model of Rhinosinusitis

Biofilms in chronic rhinosinusitis (CRS) patients are associated with recalcitrant disease patterns. Citric acid/zwitterionic surfactant (CAZS) has been shown to have significant efficacy at in vitro biofilm eradication. Unique hydrodebrider systems have been shown to have effective antibiofilm efficacy. The aim of this study was to evaluate the efficacy of the CAZS/hydrodebrider treatment on Staphylococcus aureus biofilms in the sheep model of CRS. Forty-two sheep frontal sinuses were inoculated with S. aureus, followed by 7 days of biofilm growth. Sinuses were randomized to one of nine treatment groups: control, hydrodebrider with saline or CAZS (killed on day 0 or day 7 posttreatment), CAZS, or saline flush (killed on day 0 or day 7 posttreatment). Confocal scanning laser microscopy (CSLM) was used to confirm extent of biofilm reduction. Samples of each sinus were taken, assessing cilia morphology using electron microscopy. A mean of 37.22 ± 9.65% of control (no treatment) CSLM images taken showed biofilms. Both CAZS flush and CAZS/hydrodebrider treatments showed initial improvements in biofilms but biofilm regrowth followed treatment, 14.74 ± 9.58% to 18.91 ± 12.14% and 15.60 ± 13.92% to 24.70 ± 3.66%, respectively (p > 0.05). Saline/hydrodebrider treatments showed a nonsignificant improvement in biofilm treatment, which was maintained, 18.34 ± 11.85% to 12.04 ± 10.28% (p > 0.05). Cilial morphology grade was significantly worse in the CAZS treatment groups (p < 0.05). CAZS solution (with and without a hydrodebrider system) can significantly adversely affect cilia morphology. The hydrodebrider system, when combined with saline, may be a useful treatment adjunct for mucosal biofilms.

Middle Ear Irrigations Decrease the Density of Mucosal Biofilms in an Animal Model of Acute Otitis Media

Objective: Bacteria in biofilms are extremely resistant to antibiotics. Recurrent acute otitis media appears to be a disease related to biofilm formation. The goal of this study is to determine if middle ear irrigations with saline or baby shampoo could eradicate mucosal biofilms in a chinchilla model of acute otitis media. Method: After a baseline ABR, middle ears of 10 chinchillas were inoculated with Haemophilus influenzae. On day 5, the ears were irrigated with saline or 1% baby shampoo using a syringe or hydrodebrider. A final ABR was obtained before the animals were euthanized and middle ear mucosa were harvested for SEM analysis. Results: Biofilm formation on middle ear mucosa in chinchillas was in nonuniform distribution. SEM analysis by a blinded microscopist showed a statistically significant decrease in biofilm densities of middle ear mucosa after normal saline or 1% baby shampoo irrigations when compared with nonirrigated ears using Wilcoxon/Kruskal-Wallis Tests ( P &lt; .01). No statistically significant difference in biofilm densities between normal saline and 1% baby shampoo irrigations was seen. The hearing thresholds on auditory brainstem responses (ABR) at frequencies 16 kHz, 4 kHz, 1 kHz, and 500 Hz were unchanged two days after normal saline or 1% baby shampoo irrigations. Conclusion: Middle ear irrigations with 1% baby shampoo or normal saline lead to a statistically significant decrease in biofilm densities. One percent baby shampoo or normal saline are non-ototoxic and can be safely used for middle ear irrigations. Future work in our laboratory will study the effect of a hydrodebrider prototype.

Quantitative analysis of in vivo mucosal bacterial biofilms

Quantitative assays of mucosal biofilms on ex vivo samples are challenging using the currently applied specialized microscopic techniques to identify them. The COMSTAT2 computer program has been applied to in vitro biofilm models for quantifying biofilm structures seen on confocal scanning laser microscopy (CSLM). The aim of this study was to quantify Staphylococcus aureus (S. aureus) biofilms seen via CSLM on ex situ samples of sinonasal mucosa, using the COMSTAT2 program. S. aureus biofilms were grown in frontal sinuses of 4 merino sheep as per a previously standardized sheep sinusitis model for biofilms. Two sinonasal mucosal samples, 10 mm × 10 mm in size, from each of the 2 sinuses of the 4 sheep were analyzed for biofilm presence with Baclight stain and CSLM. Two random image stacks of mucosa with S. aureus biofilm were recorded from each sample, and analyzed using COMSTAT2 software that translates image stacks into a simplified 3-dimensional matrix of biofilm mass by eliminating surrounding host tissue. Three independent observers analyzed images using COMSTAT2 and 3 repeated rounds of analyses were done to calculate biofilm biomass. The COMSTAT2 application uses an observer-dependent threshold setting to translate CSLM biofilm images into a simplified 3-dimensional output for quantitative analysis. Intraclass correlation coefficient (ICC) between thresholds set by the 3 observers for each image stacks was 0.59 (p = 0.0003). Threshold values set at different points of time by a single observer also showed significant correlation as seen by ICC of 0.80 (p < 0.001). COMSTAT2 can be applied to quantify and study the complex 3-dimensional biofilm structures that are recorded via CSLM on mucosal tissue like the sinonasal mucosa.

Inherent Differences in Nasal and Tracheal Ciliary Function in Response to Pseudomonas aeruginosa Challenge

Sinonasal mucosal biofilms are recognized as contributors to the pathogenesis of chronic rhinosinusitis (CRS). Attachment of bacteria to the sinonasal surface is an initial step in biofilm formation. A critical defense against this occurrence is mucociliary clearance (MCC). To ascertain whether the ciliary component of MCC is uniform throughout the airway we compared ciliary beat frequency (CBF) in the murine nasal septum and trachea at baseline and after challenge with Pseudomonas aeruginosa, a common pathogen of CRS. Murine septal and tracheal air-liquid interface cultures were evaluated for basal and stimulated CBF after exposure to control or conditioned media from Pseudomonas. Additionally, the attachment of Pseudomonas to nasal and tracheal cultures was assessed after pretreatment with control or conditioned media. Basal CBF is significantly slower in primary nasal airway cultures compared with tracheal airway cultures. Tracheal airway cultures show resistance to Pseudomonas secreted ciliotoxins not evident in nasal septal cultures. Furthermore, after challenge with viable Pseudomonas, significantly more bacteria attach to the nasal cultures compared with the tracheal cultures. Using primary murine nasal and tracheal airway cultures we show inherent differences in cilia function and increased susceptibility of the upper airway to attachment by Pseudomonas. Understanding the differences between upper and subglottic airway mucociliary clearance should lead to novel approaches in the management of upper airway infection.

Role of Bcr1-Activated Genes Hwp1 and Hyr1 in Candida Albicans Oral Mucosal Biofilms and Neutrophil Evasion

Candida albicans triggers recurrent infections of the oropharyngeal mucosa that result from biofilm growth. Prior studies have indicated that the transcription factor Bcr1 regulates biofilm formation in a catheter model, both in vitro and in vivo. We thus hypothesized that Bcr1 plays similar roles in the formation of oral mucosal biofilms and tested this hypothesis in a mouse model of oral infection. We found that a bcr1/bcr1 mutant did not form significant biofilm on the tongues of immunocompromised mice, in contrast to reference and reconstituted strains that formed pseudomembranes covering most of the tongue dorsal surface. Overexpression of HWP1, which specifies an epithelial adhesin that is under the transcriptional control of Bcr1, partly but significantly rescued the bcr1/bcr1 biofilm phenotype in vivo. Since HWP1 overexpression only partly reversed the biofilm phenotype, we investigated whether additional mechanisms, besides adhesin down-regulation, were responsible for the reduced virulence of this mutant. We discovered that the bcr1/bcr1 mutant was more susceptible to damage by human leukocytes when grown on plastic or on the surface of a human oral mucosa tissue analogue. Overexpression of HYR1, but not HWP1, significantly rescued this phenotype. Furthermore a hyr1/hyr1 mutant had significantly attenuated virulence in the mouse oral biofilm model of infection. These discoveries show that Bcr1 is critical for mucosal biofilm infection via regulation of epithelial cell adhesin and neutrophil function.

The small intestine: A critical linkage in pathophysiology of cardiac cachexia

The small intestine: A critical linkage in pathophysiology of cardiac cachexia

The effect of PDT on H. influenzae biofilm in vivo

Biofilm formation has been demonstrated for many mucosal pathogens such as Haemophilus influenzae . The presence of mucosal biofilms with chronic otitis media with effusion (COME) suggests that bacteria do not clear by antibiotics. Aim: To test the effect of photodynamic therapy (PDT) on H. influenzae induced biofilm in vivo. Methods: Gerbils were divided into control (C), HI group, Laser (L), PS, PDT A, and PDT B groups. The C group received no treatment. HI group was injected with 20μl (10 8 CFU/ml) of H. influenzae into the bullae and formation of biofilms in the bullae was obtained by 5 days. For L group, 120 J/cm 2 (100 mw × 20 min) of 632 nm LD laser was irradiated by a fiber inserted into the bullae 5 days after the H. influenzae injection. For PS group, photofrin 40μl (1mg/ml) were injected into the bullae 5 days after the H. influenzae injection. PDT A group received photofrin 1 mg/ml and LD laser 120 J/cm 2 that were administered into the bullae 5 days after the H. influenzae injection. PDT B group received photofrin 2 mg/ml and laser 150 J/cm 2 5 days after the H. influenzae injection. The mucosal tissues in bullae were examined by H/E staining, and SEM. Results: The C group showed normal mucosa of bullae. The HI, L, and PS groups have shown well formed biofilm. Twenty five percent of the PDT A group and 50 % of the PDT B group have shown completely or partially resolved biofilm. Conclusion: The results of this study demonstrated that PDT appears to be effective to treat experimental H. influenzae induced biofilms in vivo. Clinical implication: PDT may be an alternative to antibiotic treatment on otitis media with biofilm formation.

C-C Chemokines, RANTES and Eotaxin in Allergic Rhinitis

and sensitivity); subjects also performed daily nasal nebulization of mometasone and the antibiotic, along with saline pressure hydrotherapy, for a period of 6 weeks. Clinical outcome was assessed using the Lund-Kennedy symptom and endoscopic appearance scores. Biofilm disruption was assessed ex-vivo using the traditional Colony Forming Units (CFUs) bacterial assay technique and semi-quantitative real-time PCR (rt-PCR). Mucosal epithelial barrier changes were evaluated histologically. RESULTS: There was a statistically significant difference in the patients’ Lund-Kennedy symptom and endoscopic appearance scores after 6 weeks of rhinotopic therapy. There was also statistically significant difference in CFUs mucosal bacterial count and in microbial and organisms virulence genes presence, indicating mucosal biofilm disruption. Changes indicating mucosal barrier remodeling were observed by H&E histology. Nasoendoscopic-guided cultures performed one month following rhinotopic therapy, showed resolution of the pathogenic organism(s) in 14/23 patients (60.8%). No significant clinical adverse effects were experienced. CONCLUSION: Gel rhinotopic therapy is a promising treatment strategy for refractory chronic rhinosinusitis, and has the potential to cause mucosal biofilm disruption.

Quantitative assessment of the human gut microbiome using multitag pyrosequencing.

Recent advances in molecular techniques have now made it possible to interrogate the human microbiome in depth to better understand the interactions with the host organism and its role in diseases. We now report the utility of Length Heterogeneity Polymerase Chain Reaction (LH-PCR) to survey samples and a proprietary Multitagged Pyrosequencing (MTPS) methodology to interrogate the gut microbiome in healthy and disease states. We present an overview of our studies demonstrating the application of these molecular-biology techniques to an example disease state such as Inflammatory Bowel Disease (IBD). The findings show that there is a core mucosal bacterial microbiome (i.e., a mucosal biofilm) that is distinct from the luminal microbiome in health, and that the mucosal microbiome appears to be dysbiotic in IBD. We propose that the mucosal microbiome forms a synergistic and stable interaction with the host immune system, while the lumen microbiome varies based on diet or other environmental factors. We define this composite ecosystem of the human microbiome and human host as the Human Metabiome.

Characterization of Mucosal Candida albicans Biofilms

C. albicans triggers recurrent infections of the alimentary tract mucosa that result from biofilm growth. Although the ability of C. albicans to form a biofilm on abiotic surfaces has been well documented in recent years, no information exists on biofilms that form directly on mucosal surfaces. The objectives of this study were to characterize the structure and composition of Candida biofilms forming on the oral mucosa. We found that oral Candida biofilms consist of yeast, hyphae, and commensal bacteria, with keratin dispersed in the intercellular spaces. Neutrophils migrate through the oral mucosa and form nests within the biofilm mass. The cell wall polysaccharide β-glucan is exposed during mucosal biofilm growth and is more uniformly present on the surface of biofilm organisms invading the oral mucosa. We conclude that C. albicans forms complex mucosal biofilms consisting of both commensal bacterial flora and host components. These discoveries are important since they can prompt a shift of focus for current research in investigating the role of Candida-bacterial interactions in the pathogenesis of mucosal infections as well as the role of β-glucan mediated signaling in the host response.

Biofilms correlate with T H1 inflammation in the sinonasal tissue of patients with chronic rhinosinusitis

Objective Determine the prevalence of bacterial biofilms in surgical chronic rhinosinusitis (CRS) patients and characterize the inflammatory response associated with biofilm CRS. Study Design Cross-sectional. Setting Tertiary care academic center. Subjects and Methods Sinonasal mucosa and peripheral blood were collected from 60 CRS patients. Mucosal biofilms were demonstrated by scanning electron microscopy. Leukocyte subpopulations were determined by flow cytometry. Cytokines were identified with a luminex-based assay on the lysate of homogenized tissue or plasma. Results Of the 60 samples, 17 were determined to be positive for the presence of biofilms. Oral steroid–naive CRS patients with biofilm demonstrated a local T H1 inflammatory response with significantly elevated levels of interferon-γ (INF-γ), granulocyte colony-stimulating factor, macrophage inflammatory protein-1 β, and neutrophils in the sinonasal mucosa. No differences were present at the systemic level. Conclusion Sinonasal bacterial biofilms correlate to a T H1 skewed local but not systemic inflammatory response in CRS. This difference is abrogated by the use of oral steroids.