Hyperbiofilm Formation by Bordetella pertussis Strains Correlates with Enhanced Virulence Traits

Abstract

Pertussis, or whooping cough, caused by the obligate human pathogen is undergoing a worldwide resurgence. The majority of studies of this pathogen are conducted with laboratory-adapted strains which may not be representative of the species as a whole. Biofilm formation by plays an important role in pathogenesis. We conducted a side-by-side comparison of the biofilm-forming abilities of the prototype laboratory strains and the currently circulating isolates from two countries with different vaccination programs. Compared to the reference strain, all strains examined herein formed biofilms at high levels. Biofilm structural analyses revealed country-specific differences, with strains from the United States forming more structured biofilms. Bacterial hyperaggregation and reciprocal expression of biofilm-promoting and -inhibitory factors were observed in clinical isolates. An association of increased biofilm formation with augmented epithelial cell adhesion and higher levels of bacterial colonization in the mouse nose and trachea was detected. To our knowledge, this work links for the first time increased biofilm formation in bacteria with a colonization advantage in an animal model. We propose that the enhanced biofilm-forming capacity of currently circulating strains contributes to their persistence, transmission, and continued circulation.

Structural Analysis of Bordetella pertussis Biofilms by Confocal Laser Scanning Microscopy

“…Based on these results, biofilm formation has been proposed by us and others as a possible strategy adopted by B. pertussis to infect, persist and continually circulate in the community (Cattelan et al ., 2016). Consistent with this hypothesis, we found that currently circulating strains from Argentina and USA produce significantly higher levels of biofilms when compared to a laboratory reference strain and colonize the mouse nose and trachea at higher numbers than the prototype laboratory strain (Cattelan et al ., 2017). These results also provide evidence that hyperbiofilm growth is a strategy employed by circulating organisms to infect and survive inside their host.…”

“…Biofilms of B. pertussis form on a variety of artificial surfaces and under static, shaking, and fluid flow conditions (Mishra et al ., 2005; Sloan et al ., 2007; Serra et al ., 2011). Microscopic evaluation of these biofilms shows that this bacterium produces irregularly shaped microcolonies separated by fluid channels, embedded in an exopolymeric matrix composed by extracellular DNA (eDNA), proteins and polysaccharides (Parise et al ., 2007; Sloan et al ., 2007; Serra et al ., 2008; Conover et al ., 2011; Nicholson et al ., 2012; Ganguly et al ., 2014; Cattelan et al ., 2017). In addition to forming biofilms in the laboratory setting, B. pertussis forms multidimensional organ-adherent biofilms on the nose and trachea during experimental infections of mice.…”

“…In particular, confocal laser scanning microscopy (CLSM) is frequently used because it allows visualization of architectural complexities of intact and hydrated biofilms. In this protocol, we describe how to grow and process samples of B. pertussis biofilms, as demonstrated in our recent publication (Cattelan et al ., 2017). …”

Bacterial Biofilm and its Role in the Pathogenesis of Disease

“…In both a nose and a trachea model, distinct architectural features adherent to ciliated epithelium were observed; in the form of mats, towers or pillars for B. bronchiseptica, and clusters and macrocolonies for B. pertussis. Furthermore, Cattelan et al observed an association between increased biofilm formation by B. pertussis and higher levels of bacterial colonization in the nose and trachea of mice [183]. Direct observations of B. pertussis biofilm in humans have not been reported, but abundant extracellular Bordetellae were observed in respiratory tissue samples from 15 infants who had died from confirmed B. pertussis pneumonia [184].…”

Chemical Synthesis and Immunological Evaluation of a Pentasaccharide Bearing Multiple Rare Sugars as a Potential Anti‐pertussis Vaccine

“…[6,7] Several major factors contribute to the rise of the pertussis infections.These include that some current circulating B. pertussis strains are deficient in the production of certain vaccine targets resulting in probable escape from vaccine-induced immunity. [8,9] Furthermore,the current acellular vaccine does not prevent infections and the immunity induced can only last ashort time. [10][11][12] Therefore,there is an urgent need for an ew generation of anti-pertussis vaccines.…”