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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/10761/1684

Data: 20-feb-2015
Autori: Scillato, Marina
Titolo: Clinical Application of S.salivarius 24SMBc in the Prevention of Recurrent Otitis Media in Paediatric Age
Abstract: ABSTRACT (English) Introduction. Much attention has recently been devoted to the analysis of the oral microbiota to develop a bacteriotherapy focused on prevention and/or treatment of upper respiratory tract infections. The oral cavity harbours some beneficial bacterial species such as Streptococcus salivarius which is considered the predominant 'safe' colonizer, capable of fostering more balanced, health-associated oral microflora, interfering with potential pathogens. This antagonist activity is often mediated by competition for nutriments, better adhesion to target cells and release of bioactive agents such as bacteriocins. In our laboratory, we characterized one strain, S.salivarius 24SMBc, isolated from healthy children which showed excellent inhibitory activity against S.pneumoniae and S.pyogenes and potent capacity of adhesion to HEp-2 cells. These properties encouraged us to evaluate a possible application of S.salivarius 24SMBc as an oral probiotic for children with recurrent otitis media. Material and methods. We sequenced the S.salivarius 24SMBc genome by pyrosequencing to verify the presence of virulent factors and to look for genes encoding bacteriocins that inhibit the growth of the pathogens previously described. Then, we included S.salivarius 24SMBc in a clinical trial protocol conducted on 17 healthy adult volunteers to evaluate its safety for the human host and its ability to colonize and persist in the upper respiratory tract. The presence of S.salivarius 24SMBc in rhinopharynx tissue was determined after different time intervals from nasal administration by molecular identification, antagonism test to evaluate BLIS production and RAPD-PCR to distinguish S.salivarius 24SMBc s genotype from other S.salivarius strains. The following phase for the assessment of the colonization of S.salivarius 24SMBc in the upper respiratory tract of children and its efficacy to reduce the number of episodes of otitis media (OM), was realized through a paediatric randomized, placebo-controlled, double-blind trial. This study enrolled 120 otitis prone children and included phenotypic and molecular identification of S.salivarius 24SMBc and pathogenic strains of OM from the biological samples. Moreover, the level of colonization of our strain was determined by qPCR using a specific genomic target to identify S.salivarius 24SMBc. Results and conclusion. Genome annotation showed that S.salivarius 24SMBc is free of streptococcal virulent factors. The results of clinical trials demonstrated the absence of adverse effects for the human host and a good capability of S.salivarius 24SMBc to colonize the human rhinopharynx tissue. Prophylactic administration of S.salivarius 24SMB to children with a history of recurrent OM reduces episodes of this disease as well the incidence of infection by some causative pathogens such as S.pneumoniae and S.pyogenes. Therefore, S.salivarius 24SMBc appears a competitive nasopharyngeal - localized strain with a good potential for use as an oral probiotic to prevent OM in paediatric subjects.
InArea 06 - Scienze mediche

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