Characterization of Bordetella pertussis clinical isolates biofilms by FT-IR spectroscopy

NATALIA CATTELAN; LAURA ARNAL; ALEJANDRA BOSCH; OSVALDO YANTORNO

Berlin

Congreso; 9th Internacional Workshop FT-IR Spectroscopy in Microbiological and Medical Diagnostics; 2013

Robert Koch Institute

Whooping cough is a highly contagious infectious disease of the upper respiratory tract caused by the Gram-negative pathogen Bordetella pertussis [1]. Despite widespread and efficient vaccination, in the last two decades there has been a worldwide resurgence of pertussis [2, 3]. The resurgence of the disease has been associated to various factors including suboptimal vaccines, waning immunity and pathogen adaptation to persist in vaccinated populations. Although traditionally known as a severe childhood disease recently, an increased incidence in adolescents and adults was reported. In the later groups the disease symptoms are mild or even not manifested, consequently, the infected individuals become silent carriers of the pathogen, facilitating its circulation in the population [4]. One proposed hypothesis to explain the survival and continued persistence of B. pertussis in human host is that this organism may adopt a biofilm lifestyle during respiratory infection as a strategy to survive and persist in their host [5]. The aim of this study was to get insights into the phenotypic diversity of B. pertussis local clinical isolates and a reference strain (B.p. Tohama I). We analyzed the ability of 11 circulating isolates to grow as biofilm and compared their chemical composition with Bp Tohama I strain biofilm by FT-IR spectroscopy. No differences were found when we analyzed the phenotypic diversity of the isolates after 48 h of culturing on Bordet-Gengou agar at 36 ºC by FT-IR spectroscopy. Nevertheless, when the biofilm formation ability of these bacteria was assessed with the crystal violet method, all clinical isolates showed a significantly greater capacity to form biofilms, compared to the reference strain. Moreover, a semi-quantitative FT-IR analysis of the bands assigned to proteins (Amide II), carbohydrates and lipids showed a relative increase in protein content for the biofilms of clinical isolates. This is in accordance with proteomics results showing the increased expression of several genes associated to biofilm growing conditions. Overall, our results suggest a higher capability of clinical isolates than the reference strain to adopt the biofilm lifestyle, reinforcing the hypothesis that biofilm lifestyle can be considered as an ?evolution trait? adopted by B. pertussis to persist in their host.