P-fimbriae, bacterial adhesion, and pyelonephritis.

Everyday observations usually seem self evident and are often not given the attention they merit. Examples are the fact that I haemolytic streptococci cause sore throat but not pneumonia; gonococci cause urethritis but not urinary tract infection (UTI) (which Escherichia coli do); and bacteria like Neisseria gonorrhoea and Bordetella pertussis that cause human disease are often harmless in animals. Bacterial adherence may play a role in this 'tropism'. In nature bacteria often stick to surfaces like stones, leaves, and roots. Epithelial cell surfaces make no exception. Bacteria belonging to the 'normal' flora as well as pathogens may adhere by hydrophobic or electrostatic bonds, or both, of an 'unspecific' nature, or through a specific interaction between bacterial adhesins and epithelial cell receptors.'-5 The ability of pathogens to adhere to mucous membranes is now recognised as a potential factor in virulence.