‘ENT’ and eye infections

This chapter discusses ear, nose, throat, and eye infections. Many different bacterial species normally colonize the mouth. Host defense mechanisms, including those associated with the ciliated epithelium in the nose and sinuses, lysozyme in saliva, and IgA and other immunoglobulins in mucous secretions or serum, may help reduce the incidence of infections because of respiratory pathogens. The normal mouth flora probably contributes to the prevention of attachment of exogenous pathogens to the mucosa. Nevertheless, certain respiratory pathogens are sometimes carried asymptomatically in the mouth or nose of healthy individuals. Upper respiratory tract infections are extremely common in infants and young school children. An average preschool child is said to have about six upper respiratory tract infections a year. Most of the infections are of viral etiology and occur in winter. Bacterial infections are also very common in young children. The eustachian tubes in infants are relatively wider and more horizontal than in adults; this might partly explain the greater incidence of acute otitis media in infants as the causative organisms may spread directly from the throat to the middle ear via the eustachian tube. Older children and adults usually have good immunity to a wide range of respiratory pathogens, but the common cold continues to be prevalent in these age groups. Sinusitis frequently occurs in adults and children.