1e:T409,

Abstract

Escherichia coli is a Gram-negative bacterium that colonizes the human intestine and virulent strains can cause severe diarrhoeal and extraintestinal diseases. The protein SslE is secreted by a range of pathogenic and some commensal E. coli strains. It can degrade mucins in the intestine, promotes biofilm maturation and it is a major determinant of infection in virulent strains, although how it carries out these functions is not well understood. Here we examine SslE from the E. coli Waksman and H10407 strains and reveal that it has a novel and dynamic structure. In response to acidification within mature biofilms we show how SslE forms a unique functional aggregate that interacts with cellulose and regulates the distribution of exopolysaccharides in macrocolony biofilms. Our data indicates that the spatial organization of SslE polymers and local pH are critical for biofilm maturation and SslE is a key factor that drives persistence of SslE-secreting bacteria during acidic stress.1f:T41e,PERCUTANEOUS needle biopsy of the lung, first reported in 1883 when bacteria were taken from pneumonia patients by aspiration biopsy,¹was later applied to solid lung tumors and favorable results have been reported sporadically since,^2-4although the method was generally avoided out of fear of complications. In 1940, Tripoli and Holland⁵suggested using the Vim-Silverman needle in biopsying lung tumors, but it was not until 1954 that this technique was used in studying a small series of three patients.⁶Since then, interest in this diagnostic procedure has risen and the reports have been encouraging.^7-13This study describes the results of percutaneous lung biopsy in 62 patients with various pulmonary lesions.

Materials and Methods

All patients in the study were hospitalized either at the University of Arkansas Medical Center or the associated Little Rock Veterans Administration Hospital. The study covers patients with a variety of pulmonary lesions, including solitary lung masses

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