Biofilms in pediatric respiratory and related infections

Emerging concepts and directed therapeutics for the management of asthma: regulating the regulators

Asthma is a common, heterogeneous and serious disease, its prevalence has steadily risen in most parts of the world, and the condition is often inadequately controlled in many patients. Hence, there is a major need for new therapeutic approaches. Mild-to-moderate asthma is considered a T-helper cell type-2-mediated inflammatory disorder that develops due to abnormal immune responses to otherwise innocuous allergens. Prolonged exposure to allergens and persistent inflammation results in myofibroblast infiltration and airway remodelling with mucus hypersecretion, airway smooth muscle hypertrophy, and excess collagen deposition. The airways become hyper-responsive to provocation resulting in the characteristic wheezing and obstructed airflow experienced by patients. Extensive research has progressed the understanding of the underlying mechanisms and the development of new treatments for the management of asthma. Here, we review the basis of the disease, covering new areas such as the role of vascularisation and microRNAs, as well as associated potential therapeutic interventions utilising reports from animal and human studies. We also cover novel drug delivery strategies that are being developed to enhance therapeutic efficacy and patient compliance. Potential avenues to explore to improve the future of asthma management are highlighted.

Biofilm distribution on tympanostomy tubes: An ex vivo descriptive study

BACKGROUND

Tympanostomy tube (TT) insertion is a common procedure in children with otitis media with effusion. Post-TT otorrhea (PTTO) is a frequent post-operative complication. Biofilms are involved in chronic PTTO cases.

OBJECTIVE

To describe and qualitatively analyze the geometry and sites prone to biofilms on removed TTs, relatively to their position in the ear, past medical/surgical history and PTTO presence.

METHODS

Biofilms presence and topographic distribution on TTs were ex vivo evaluated by using scanning electron microscope, confocal microscope and stereo-microscope.

RESULTS

Forty-eight TTs from 30 children were analyzed. Indications for removal were: 71% due to retained TTs (average time from insertion: 24.4 ± 15.1 months), 23% due to chronic PTTO, and 6% due to TT obstruction/dysfunction. Different types of bacterial biofilms were detected on all TTs, regardless the time from their insertion nor their types. Biofilms were observed more on the perpendicular junction and on the internal lumen, and more biofilm colonies were detected on the medial part, facing the middle ear mucosa. TTs removed from children with PTTO exhibited more biofilm colonies when compared to their peers. Of the 16 children who underwent adenoidectomy concomitantly with TT insertion, 10 (62%) children were sent for TT removal due to retained TTs, and 6 (38%) children due to chronic PTTO (p = 0.03).

CONCLUSION

Descriptive analysis of biofilm topographic distribution demonstrated adhesions on specific TT areas: perpendicular junctions and the internal lumen. Such "prone zones" may be the future target areas for changes in TT geometry or can be specifically coated with anti-biofilm materials.

Acute otitis media with spontaneous tympanic membrane perforation

The principal aim of this review is to present the current knowledge regarding acute otitis media (AOM) with spontaneous tympanic membrane perforation (STMP) and to address the question of whether AOM with STMP is a disease with specific characteristics or a severe case of AOM. PubMed was used to search for all studies published over the past 15 years using the key words "acute otitis media" and "othorrea" or "spontaneous tympanic membrane perforation". More than 250 articles were found, but only those published in English and providing data on aspects related to perforation of infectious origin were considered. Early Streptococcus pneumoniae infection due to invasive pneumococcal strains, in addition to coinfections and biofilm production due mainly to non-typeable Haemophilus influenzae, seem to be precursors of STMP. However, it is unclear why some children have several STMP episodes during the first years of life that resolve without complications in adulthood, whereas other children develop chronic suppurative otitis media. Although specific aetiological agents appear to be associated with an increased risk of AOM with STMP, further studies are needed to determine whether AOM with STMP is a distinct disease with specific aetiological, clinical and prognostic characteristics or a more severe case of AOM than the cases that occur without STMP. Finally, it is important to identify preventive methods that are useful not only in otitis-prone children with uncomplicated AOM, but also in children with recurrent AOM and those who experience several episodes with STMP.

Nasopharyngeal microbiota composition of children is related to the frequency of upper respiratory infection and acute sinusitis

BACKGROUND

Upper respiratory infections (URI) and their complications are a major healthcare burden for pediatric populations. Although the microbiology of the nasopharynx is an important determinant of the complications of URI, little is known of the nasopharyngeal (NP) microbiota of children, the factors that affect its composition, and its precise relationship with URI.

RESULTS

Healthy children (n = 47) aged 49-84 months from a prospective cohort study based in Wisconsin, USA, were examined. Demographic and clinical data and NP swab samples were obtained from participants upon entry to the study. All NP samples were profiled for bacterial microbiota using a phylogenetic microarray, and these data were related to demographic characteristics and upper respiratory health outcomes. The composition of the NP bacterial community of children was significantly related prior to the history of acute sinusitis (R (2) = 0.070, P < 0.009). History of acute sinusitis was associated with significant depletion in relative abundance of taxa including Faecalibacterium prausnitzii and Akkermansia spp. and enrichment of Moraxella nonliquefaciens. Enrichment of M. nonliquefaciens was also a characteristic of baseline NP samples of children who subsequently developed acute sinusitis over the 1-year study period. Time to develop URI was significantly positively correlated with NP diversity, and children who experienced more frequent URIs exhibited significantly diminished NP microbiota diversity (P ≤ 0.05).

CONCLUSIONS

These preliminary data suggest that previous history of acute sinusitis influences the composition of the NP microbiota, characterized by a depletion in relative abundance of specific taxa. Diminished diversity was associated with more frequent URIs.

Ciprofloxacin plus erythromycin or ambroxol ameliorates endotracheal tube-associated Pseudomonas aeruginosa biofilms in a rat model

BACKGROUND AND OBJECTIVE

Pseudomonas aeruginosa is a multi-drug resistant bacterium, with its biofilm-growing mucoid (alginate-producing) strains being particularly resistant. As atomized drug administration is a common practice in pediatric patients, we compared the effect of inhalational therapy with erythromycin plus ciprofloxacin, with that of ambroxol plus ciprofloxacin, against biofilm producing strains of P. aeruginosa.

RESULTS

Both combined treatment regimens were associated with a significant reduction in bacterial counts in endotracheal (ET) tubes and lungs, as compared to that observed with ambroxol and erythromycin monotherapies (P<0.05). Ciprofloxacin plus ambroxol appeared to have a higher efficacy than ciprofloxacin plus erythromycin, both in lowering bacterial counts (P<0.05) and in disrupting the structural integrity of biofilm. Histopathological changes in the lungs were milder in the two combined treatment groups, as compared to that in groups treated with single drugs.

CONCLUSION

Erythromycin or ambroxol in combination with ciprofloxacin could eliminate P. aeruginosa biofilms. When combined with ciprofloxacin, ambroxol outperformed erythromycin in eradicating P. aeruginosa biofilm.

Role of biofilm in children with recurrent upper respiratory tract infections

Recurrent respiratory tract infections (RRTIs) are very common in children and a major challenge for pediatricians. In the last few years, bacterial biofilms have been linked to RRTIs and antibiotic resistance, and have raised serious concerns regarding the therapeutic management of recurrent middle ear diseases, chronic rhinosinusitis, and recurrent pharyngotonsillitis. This paper aims to review the new insights into biofilm-related upper respiratory tract infections in children and possible therapeutic strategies. It focuses on the clinical implications for recurrent disease and on studies in pediatric patients. Analysis of the literature showed that the involvement of bacterial biofilm in recurrent upper airway tract infections is an emerging problem that may lead to serious concerns about infection control. Despite the large amount of research within this field, detailed insight into the complex structure of bacterial biofilms and the ultrastructural and biochemical mechanisms responsible for its evasion of the immune system and resistance to treatments is currently lacking. In the future, additional emphasis should be placed on biofilm management as a component of therapeutic strategies. This goal can be attained by finding feasible methods for detecting biofilms in vivo and identifying effective methods for administering treatments that eradicate preexisting bacterial biofilms or hinder bacterial adhesion to respiratory cells.

Pediatric chronic rhinosinusitis

Pediatric chronic rhinosinusitis is a multifactorial inflammatory and infectious disorder. It likely reflects a dysfunction at the site of the interaction between host and environmental factors in the nose and sinuses. Our limited understanding of this common childhood disease makes it difficult to diagnose and to treat effectively. This review focuses on the scope of manifestations particular to the pediatric form of the disease, diagnostic challenges, and epidemiologic data. The normal development of sinuses in children, the role of inflammation, and biofilm and immune responses in the pathophysiology of chronic rhinosinusitis in pediatric patients are discussed. Predisposing and comorbid factors contributing to this disorder or associated with it are described. The current investigational and therapeutic approaches are presented, including recommendations for imaging and medical and surgical therapy. Various aspects of the disease that are still subject of controversy are underscored. Advice for what constitutes a reason to involve a multidisciplinary collaboration in the care of a child with chronic rhinosinusitis is provided.

Topographic distribution of biofilm-producing bacteria in adenoid subsites of children with chronic or recurrent middle ear infections

OBJECTIVES

Bacterial biofilms have been found in the adenoids of children with recurrent acute otitis media (AOM) and persistent otitis media with effusion (OME). However, the possible difference in biofilm-producing bacteria (BPBs) between the adenoid surface at the nasopharyngeal dome (ND) and near the ostium of the eustachian tube (ET) has not been investigated. This study aimed to assess the difference in BPBs between adenoid biopsy specimens of the ND and those taken near the pharyngeal ostium of the ET in children with chronic adenoiditis with recurrent AOM and/or persistent OME.

METHODS

We collected adenoid biopsy specimens from the ND and ET during transoral endoscopic adenoidectomy to assess BPB by means of spectrophotometric analysis.

RESULTS

We collected 135 adenoid biopsy specimens from 45 children. BPBs were detected significantly (p = 0.04) more frequently in the ET samples than in the ND samples, mainly Staphylococcus aureus. Although the prevalence of S aureus was slightly greater in the ND samples, and that of Streptococcus pneumoniae and Moraxella catarrhalis was slightly greater in the ET samples, these differences were not statistically significant.

CONCLUSIONS

The fact that BPBs were significantly more frequently located near the ostium of the ET suggests that the adenoids are a reservoir for bacteria and indicates that hypertrophic adenoids (particularly hypertrophy near the ostium of the ET) play a role in recurrent AOM and/or OME.

Recurrences in chronic tonsillitis substained by tonsillar biofilm-producing bacteria in children. Relationship with the grade of tonsillar hyperplasy

OBJECTIVES

It has been suggested that bacterial biofilms are involved in chronic tonsillar disease, but there is a lack of strong evidence concerning their etiopathogenic role in childhood chronic tonsillar infections. The aim of this study was to assess the presence of biofilm-producing bacteria (BPB) in tonsillar bioptic specimens taken from children with recurrent exacerbations of chronic hyperplastic tonsillitis, and to evaluate the possible relationship between them and the patients' demographic and clinical characteristics.

METHODS

22 children (68.2% males; median age 6.5 years, range 3-13) with recurrent exacerbations of chronic hyperplastic tonsillitis were included. The presence of tonsillar BPB was assessed by means of the spectrophotometric analysis of tonsillar bioptic specimens taken during tonsillectomy between episodes of tonsillar infection.

RESULTS

BPB were found in 50.0% of the 44 tonsillar specimens, and Staphylococcus aureus was the most frequent pathogen (81.8%). There was a significant relationship (p=0.02) between the grade of tonsillar hyperplasy (GTH) and the presence of tonsillar BPB, with an increased relative risk (RR=4.27, standard error=2.57, p<0.01) of tonsillar BPB development in children with GTH scores of >2.

CONCLUSIONS

The findings of this study: (1) confirm the presence of tonsillar BPB in children with recurrent exacerbations of chronic tonsillar infections; (2) suggest that GTH is an important indicator of the presence of tonsillar BPB; and (3) raise the question as to whether tonsillar biofilm is a causative factor or just a consequence of recurrent exacerbations of chronic hyperplastic tonsillitis.

Nasopharyngeal biofilm-producing otopathogens in children with nonsevere recurrent acute otitis media

OBJECTIVE

Bacterial biofilms have been detected in biopsies of the adenoid and middle ear mucosa of otitis-prone children and children with chronic middle otitis media. However, the invasiveness of biopsy makes it unsuitable for routine clinical practice, especially in pediatrics. This study aimed to investigate nasopharyngeal biofilm-producing otopathogens (BPOs) of nasopharyngeal swabs (NPS) in children with a history of nonsevere recurrent acute otitis media (RAOM) and healthy controls.

STUDY DESIGN

A cross-sectional study with planned data collection.

SETTING

University of Milan.

SUBJECTS AND METHODS

Transoral NPS were taken from infants and children aged 10 months to 11 years with nonsevere RAOM or healthy controls without adenoid hypertrophy. Nasopharyngeal colonization by otopathogens was assessed by means of microbiological cultures and standard bacterial identification, as well as nasopharyngeal BPOs by means of spectrophotometric analysis.

RESULTS

The study involved 113 children (56.6% males; median age 40 months; range, 10-132 months): 58 with a history of nonsevere RAOM (51.3%) and 55 controls (48.7%). Otopathogens were significantly more frequently detected in the RAOM group (24/58, 41.4%) than in controls (8/55, 14.5%; P = .003); the main pathogens were respectively Haemophilus influenzae (12/24, 50.0%) and Streptococcus pyogenes (3/8, 37.5%). Nasopharyngeal BPOs were more frequently isolated in the RAOM group (17/58, 29.3%) than in controls (6/55, 10.9%; P = .02). H influenzae (12/17, 70.6%) was confirmed as the main pathogen in the RAOM group.

CONCLUSION

The presence of nasopharyngeal BPOs is an important factor favoring RAOM; it is therefore useful investigating biofilms even in children with nonsevere recurrences of AOM without adenoid hypertrophy.

Comparison of two minimally invasive techniques for treating chronic rhinosinusitis in the pediatric population

OBJECTIVE

To compare two minimally invasive techniques for the treatment of chronic rhinosinusitis in young children.

BACKGROUND

Chronic rhinosinusitis (CRS) is a common diagnosis in young children. Maxillary sinus aspiration & irrigation with adenoidectomy (MSI) followed by an extended course of oral antibiotics has been shown to be an alternative to functional endoscopic sinus surgery. However, since MSI is not performed under direct visualization, it has inherent risk. This study analyzes the techniques of MSI and endoscopically guided middle meatus cultures & antral biopsy with adenoidectomy (EGC) in the (1) diagnosis of bacterial infection by culture, (2) time to resolution using double antibiotic therapy, and (3) associated morbidity of the two procedures.

METHODS

The medical records at Wayne State University, Department of Otolaryngology Head & Neck Surgery were reviewed from 2004 to 2010. All children who presented with CRS who underwent MSI or EGC were included in this retrospective case series.

RESULTS

Patients presented with a history of cough, nasal discharge, and congestion. The mean age was 3.7 years. Symptom duration prior to treatment was 7.4 months in the 64 patients who underwent MSI and 9.1 months in the 46 patients who underwent EGC. MSI identified bacteria in 80% of patients compared to 73% in EGC patients (p=0.45). The MSI group underwent antibiotic treatment for 8.7 weeks and achieved symptom resolution in 8.7 weeks compared to 6.9 weeks and 4.9 weeks respectively in the EGC group (p=0.08 and 0.01). However, if patients presented with snoring or cough, time to resolution of symptoms was significantly lower in patients undergoing EGC versus MSI (p=0.02 and p=0.01, respectively). One patient who underwent MSI experienced epistaxis requiring nasal packing, and two patients had pseudoproptosis following irrigation that resolved spontaneously shortly thereafter. No complications were reported in the EGC group.

CONCLUSION

EGC is an effective treatment for young children with CRS. EGC and MSI are equally effective in obtaining diagnostic cultures. EGC decreases time to symptom resolution, and it lowers the risk of complication when compared to MSI.

Nasal cytology: the "infectious spot", an expression of a morphological-chromatic biofilm

The purpose of this study was to describe some "morphological-chromatic" patterns (i.e. spots of cyan colour) identified during the study of nasal cytology in patients with both bacterial and fungal infectious rhinological disorders. These peculiar aspects strongly suggest the presence of a microscopic biofilm. We retrospectively examined 1,410 nasal cytology specimens from subjects who underwent clinical-instrumental investigations (history, ENT visit, nasal endoscopy and nasal cytology) from January to August 2010. The control samples were represented by 30 subjects not suffering from infectious rhinological diseases. The presence of particular spots of "cyan" was found in colour in 107/1,410 rhinocytograms (7.6%), within which bacterial colonies and/or fungal spores were found. We called these coloured spot formations "infectious spots" (IS). The positivity to periodic acid Schiff (PAS) staining confirmed the polysaccharide nature of the coloured spots and allowed us to relate them to biofilms. This study demonstrates, for the first time, that nasal cytology performed by optical microscope can play an important role in detecting biofilms.

Emerging knowledge of regulatory roles of D-amino acids in bacteria

The d-enantiomers of amino acids have been thought to have relatively minor functions in biological processes. While l-amino acids clearly predominate in nature, d-amino acids are sometimes found in proteins that are not synthesized by ribosomes, and d-Ala and d-Glu are routinely found in the peptidoglycan cell wall of bacteria. Here, we review recent findings showing that d-amino acids have previously unappreciated regulatory roles in the bacterial kingdom. Many diverse bacterial phyla synthesize and release d-amino acids, including d-Met and d-Leu, which were not previously known to be made. These noncanonical d-amino acids regulate cell wall remodeling in stationary phase and cause biofilm dispersal in aging bacterial communities. Elucidating the mechanisms by which d-amino acids govern cell wall remodeling and biofilm disassembly will undoubtedly reveal new paradigms for understanding how extracytoplasmic processes are regulated as well as lead to development of novel therapeutics.

A biofilm exists on healthy mucosa of the paranasal sinuses: a prospectively performed, blinded, scanning electron microscope study

OBJECTIVES

Based on our hypothesis that biofilm is nothing else but normal, otherwise abundantly colonised mucosal mucous blanket, the aim of this study was to check out whether bacterial biofilm exists exclusively at the diseased mucosal surfaces or at healthy mucosa of paranasal sinuses as well.

DESIGN

Prospective and blinded.

SETTING

Tertiary academic hospital.

PARTICIPANTS

The patients suffering from the diseases not related to the chronic inflammation of the paranasal sinuses. Mucosal tissue samples from healthy sphenoid sinuses were taken from 48 patients who underwent pituitary gland surgery and from ethmoidal sinuses mucosa of the 17 patients who underwent endonasal endoscopic orbital decompression because of Graves' disease.

MAIN OUTCOME MEASURES

The samples were submitted blindly along with similar samples from patients with chronic rhinosinusitis to two scanning electron microscope experts. In all samples the looked for the main signs of biofilm presence of: the 'towers', rod-shaped bacteria and water channels.

RESULTS

Signs of biofilm presence were found in 45 out of 48 pituitary gland surgery patients (94%) and in all of 17 EEOD patients (100%).

CONCLUSIONS

Our study showed the presence of the biofilm at the surface of the healthy mucosa of the paranasal sinuses. This suggests that perhaps so called bacterial biofilm is nothing else but regular respiratory mucosal blanket, a part of the mucociliary system itself, containing a great number of bacteria.