1992 Volume 36 Issue 8 Pages 803-813
Pili were detected using electron microscopy in clinical isolates of Shigella flexneri which had been continuously subcultivated in liquid media. Morphologically, the pili appeared as thin, flexible, cylindrical structures of up to 2-5μm in length and about 3-5nm in diameter. Two strains showed mannose-resistant (MR) hemagglutination to fresh fowl erythrocytes (type 4), and one to tannic acid-treated horse erythrocyte (type 3) pili. These pili are novel and different from the mannose-sensitive (MS) type 1 pili described by Duguid and Gillies.