Browsing by Author "Subtil, Joao"
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- Biofilm-forming bacteria on the pharyngeal tonsil in a pediatric populationPublication . Rodrigues, João; Reis, Lucia; Subtil, Joao; Jordão, LuísaObjective: The main goal of this study is to evaluate the existence of a link between biofilm assembly on pharyngeal tonsil and the incidence of recurrent infections within a paediatric population. Methods: Nasal and pharyngeal tonsils scrubs as well as a biopsies of pharyngeal tonsils tissue were collected (n=70) and processed for bacterial identification using standard microbiologic methods. Bacteria were identified at the species level using a VITEC apparatus. Another pharyngeal tonsil biopsies were processed for electron microscopy. Initially, a screening for the presence of biofilms was performed using scanning electron microscopy (SEM) being the positive samples further processed for transmission electron microscopy (TEM). Biofilm assembly assay ability in vitro was evaluated by the microtiter-plate test. The assay was performed at 37ºC in Muller-Hinton broth for different periods of time. Results: As expected a vast number of bacterial species were identified in the samples. The majority were aerobic and a balance between Gram negative and positive bacteria was observed. A good correlation between the floras of the three samples from the same patient was found. The presence of biofilms pharyngeal tonsils was assessed by SEM. The data collected so far suggest that in at least 30% of the samples biofilms were present. In vitro all the microorganisms evaluated were able to assemble biofilms. Conclusion: Biofilm formation can be part of the mechanism involved both in onset and propagation of infections. Further studies must be performed to validate the thesis that pharyngeal tonsils function as a reservoir for microorganisms.
- Prospective observational study of adenoidal biofilms in a paediatric population and their clinical implicationsPublication . Subtil, Joao; Bajanca-Lavado, Maria Paula; Rodrigues, Joao; Duarte, Aida; Reis, Lucia; Nogueira, Isabel; Jordão, LuisaINTRODUCTION: Adenoids are nasopharyngeal lymphoid tissue with a relevant role in host defence against infection of upper respiratory tract. Nevertheless, adenoids are also a reservoir of microorganisms that can cause infections of upper respiratory tract and otitis particularly in children. OBJECTIVE: Evaluate and compare the association between biofilm assembly on adenoids and the incidence of recurrent infections in a paediatric population submitted to adenoidectomy by either infectious or non-infectious indication. METHODS: Scanning electron microscopy was used to assess biofilms on adenoid surface; biofilm assembly in vitro was monitored by crystal violet assay; antibiotic susceptibility was assessed following EUCAST guidelines; Hinfluenzae capsular typing was performed by PCR. RESULTS: Biofilms were present in 27.4% of adenoid samples and no statistical difference was found between infectious and non-infectious groups. In vitro, the most clinically relevant bacteria, H.influenzae, S.aureus, S.pyogenes, S.pneumoniae and M.catarrhalis, were mostly moderate biofilm assemblers (71.7%). 55.3% of these bacteria were intermediate/resistant to at least one of the tested antibiotics. No association was found between the ability to assemble biofilms in vitro and the presence of biofilms on adenoids nor antibiotic resistance. All H.influenzae were characterized as non-typeable. CONCLUSION: The presence of biofilms on adenoid surface was independent from clinical sample background. Bacterial ability to assemble biofilms in vitro cannot be used to predict biofilm assembly in vivo. The lack of correlation between biofilm formation and infectious respiratory diseases found contributes to question the relevance of biofilms on the pathogenesis of infectious diseases.