Bacterial biofilms in patients with chronic rhinosinusitis: a confocal scanning laser microscopy study

Host-microbe interactions in chronic rhinosinusitis biofilms and models for investigation

Chronic rhinosinusitis (CRS) is a debilitating condition characterized by long-lasting inflammation of the paranasal sinuses. It affects a significant portion of the population, causing a considerable burden on individuals and healthcare systems. The pathogenesis of CRS is multifactorial, with bacterial infections playing a crucial role in CRS development and persistence. In recent years, the presence of biofilms has emerged as a key contributor to the chronicity of sinusitis, further complicating treatment and exacerbating symptoms. This review aims to explore the role of biofilms in CRS, focusing on the involvement of the bacterial species Staphylococcus aureus and Pseudomonas aeruginosa, their interactions in chronic infections, and model systems for studying biofilms in CRS. These species serve as an example of how microbial interplay can influence disease progression and exemplify the need for continued investigation and innovation in CRS research.

Chronic Rhinosinusitis: MALDI-TOF Mass Spectrometry Microbiological Diagnosis and Electron Microscopy Analysis; Experience of the 2nd Otorhinolaryngology Clinic of Cluj-Napoca, Romania

(1) Background: Chronic rhinosinusitis (CRS) represents a wide range of infectious-inflammatory processes affecting, simultaneously, the nose and paranasal sinuses mucosa. The paper presents outcomes of the investigation of CRS microbiological characteristics in a group of 32 patients. (2) Methods: The purulent samples were collected during functional endoscopic sinus surgery. Agar plates were incubated and examined. All types of colonies were identified using Matrix-Assisted Laser Desorption - Ionisation-Time of Flight Mass Spectrometry (MALDI-TOF MS). For scanning electron microscopy, samples were fixed and sputter-coated with 10 nm gold and analyzed using a scanning electron microscope. For transmission electron microscopy, samples were fixed, postfixed, and dehydrated. After polymerization, ultrathin sections were collected on carbon coated copper grids and analyzed with Jeol JEM1010 TEM. (3) Results: Positive microbiological diagnosis was obtained in 62.5% of cases. The most frequent species found are Staphylococcus aureus and Streptococcus constellatus subsp. pharyngis. Corynebacterium aurimucosum and Eggerthia catenaformis were unreported species in CRS until the present. Biofilm was evidenced in 43.7% of sinus mucosa samples. Ciliary disorientation, atrophy, and no ciliated cells were also identified. (4) Conclusion: The microbial factor—pathogen or opportunistic—is one of the most important pathological links in chronic rhinosinusitis. MALDI-TOF MS allows easily and quickly identification of germs.

Bacterial Biofilm and its Role in the Pathogenesis of Disease

Recognition of the fact that bacterial biofilm may play a role in the pathogenesis of disease has led to an increased focus on identifying diseases that may be biofilm-related. Biofilm infections are typically chronic in nature, as biofilm-residing bacteria can be resilient to both the immune system, antibiotics, and other treatments. This is a comprehensive review describing biofilm diseases in the auditory, the cardiovascular, the digestive, the integumentary, the reproductive, the respiratory, and the urinary system. In most cases reviewed, the biofilms were identified through various imaging technics, in addition to other study approaches. The current knowledge on how biofilm may contribute to the pathogenesis of disease indicates a number of different mechanisms. This spans from biofilm being a mere reservoir of pathogenic bacteria, to playing a more active role, e.g., by contributing to inflammation. Observations also indicate that biofilm does not exclusively occur extracellularly, but may also be formed inside living cells. Furthermore, the presence of biofilm may contribute to development of cancer. In conclusion, this review shows that biofilm is part of many, probably most chronic infections. This is important knowledge for development of effective treatment strategies for such infections.

Probiotics Streptococcus salivarius 24SMB and Streptococcus oralis 89a interfere with biofilm formation of pathogens of the upper respiratory tract

Background

Infections of the ears, paranasal sinuses, nose and throat are very common and represent a serious issue for the healthcare system. Bacterial biofilms have been linked to upper respiratory tract infections and antibiotic resistance, raising serious concerns regarding the therapeutic management of such infections. In this context, novel strategies able to fight biofilms may be therapeutically beneficial and offer a valid alternative to conventional antimicrobials. Biofilms consist of mixed microbial communities, which interact with other species in the surroundings and communicate through signaling molecules. These interactions may result in antagonistic effects, which can be exploited in the fight against infections in a sort of “bacteria therapy”. Streptococcus salivarius and Streptococcus oralis are α-hemolytic streptococci isolated from the human pharynx of healthy individuals. Several studies on otitis-prone children demonstrated that their intranasal administration is safe and well tolerated and is able to reduce the risk of acute otitis media. The aim of this research is to assess S. salivarius 24SMB and S. oralis 89a for the ability to interfere with biofilm of typical upper respiratory tract pathogens.

Methods

To investigate if soluble substances secreted by the two streptococci could inhibit biofilm development of the selected pathogenic strains, co-cultures were performed with the use of transwell inserts. Mixed-species biofilms were also produced, in order to evaluate if the inhibition of biofilm formation might require direct contact. Biofilm production was investigated by means of a spectrophotometric assay and by confocal laser scanning microscopy.

Results

We observed that S. salivarius 24SMB and S. oralis 89a are able to inhibit the biofilm formation capacity of selected pathogens and even to disperse their pre-formed biofilms. Diffusible molecules secreted by the two streptococci and lowered pH of the medium revealed to be implied in the mechanisms of anti-biofilm activity.

Conclusions

S. salivarius 24SMB and S. oralis 89a possess desirable characteristics as probiotic for the treatment and prevention of infections of the upper airways. However, the nature of the inhibition appear to be multifactorial and additional studies are required to get further insights.

Electronic supplementary material

The online version of this article (10.1186/s12879-018-3576-9) contains supplementary material, which is available to authorized users.

Causes of higher symptomatic airway load in patients with chronic rhinosinusitis

Background

Chronic rhinosinusitis display a variety of different phenotypes. The symptoms of disease are characterised by various signs and symptoms such as nasal congestion, nasal discharge, pressure sensation in the face and reduced or complete loss of smell.

In a patient population undergoing functional endoscopic sinonasal surgery (FESS) for chronic rhinosinusitis, we wanted to investigate the clinical features and explore if the presence of biofilm, nasal polyps or other disease characteristic could serve as predictor for the symptomatic load. A patient group undergoing septoplasty without disease of the sinuses was included as control.

Methods

The Sinonasal outcome test (SNOT-20), EPOS visual analogue scale (VAS) and the Lund-Mackey CT score (LM CT score) were used to examine 23 patients with chronic rhinosinusitis without nasal polyps (CRSsNP), 30 patient with nasal polyps (CRSwNP) and 22 patients with septal deviation. Tissue samples were collected prospectively during surgery. The cohort has previously been examined for the presence of biofilm.

Results

Patients with CRSsNP and CRSwNP had significantly higher degree of symptoms compared to the septoplasty group (SNOT-20 scores of 39.8, 43.6 and 29.9, respectively, p = 0.034). There were no significant differences in the total SNOT-20 or VAS symptoms scores between the CRSsNP and CRSwNP subgroups. However patients with nasal polyps showed significantly higher scores of symptoms related to sinonasal discomfort such as cough, runny nose and need to blow nose (p = 0.011, p = 0.046, p = 0.001 respectively). Patients with nasal polyps showed a significantly higher LM CT score compared to patients without polyps (12.06 versus 8.00, p = 0.001). The presence of biofilm did not impact the degree of symptoms.

Conclusion

The presence of nasal polyp formations in CRS patients was associated with a higher symptomatic airway load as compared to patients without polyps. These findings suggest that nasal polyps could be an indicator of more substantial sinonasal disease. The presence of biofilm did not impact the degree of symptoms, however, as biofilm seem to be a common feature of chronic rhinosinusitis (89% in this cohort), it is more likely to be involved in the development of the CRS, rather than being a surrogate marker for increased symptomatic load.

Electronic supplementary material

The online version of this article (10.1186/s12901-017-0048-6) contains supplementary material, which is available to authorized users.

Staphylococcus epidermidis and biofilm-associated neutrophils in chronic rhinosinusitis. A pilot study

A key role of bacterial biofilm in the pathogenesis of chronic rhinosinusitis (CRS) with (CRSwNP) and without nasal polyps (CRSsNP) is commonly accepted. However, the impact of some bacterial species isolated from inflamed sinus mucosa on biofilm formation is unclear. In particular, the role of Staphylococcus epidermidis as aetiological agents of CRS is controversial. Moreover, the effect of biofilm formation on neutrophil infiltration and activity in CRSwNP calls for explanation. In this study, biofilms were found in three of 10 patients (mean age = 46 ± 14) with CRS undergoing endoscopic sinus surgery by means of scanning electron microscopy. Unexpectedly, S. epidermidis was the primary isolated bacteria and was also found to be present in all biofilm-positive mucosa specimens, indicating its pivotal role in the pathogenesis of severe chronic infections associated with biofilm formation. We have also measured the activity of myeloperoxidase (MPO), the most abundant neutrophil enzyme, to demonstrate the presence of neutrophils in the samples tested. Our present results show that the level of MPO in CRS associated with biofilm is lower than that without biofilm. It may suggest either a low number of neutrophils or the presence of a type of neutrophils with compromised antimicrobial activity, described as biofilm-associated neutrophils (BAN). Finally, we conclude that further studies with a large number of CRS cases should be performed to establish the association between S. epidermidis and other frequently isolated bacterial species from paranasal sinuses, with the severity of CRS, biofilm formation and the infiltration of BAN.