Classification of asthma severity in children: the importance of symptoms and lung function measures

Abstract

Urinary tract infections are amongst the most common bacterial infections. They can occur in either an uncomplicated host setting, where there is no underlying structural or functional abnormality of the patient's genitourinary tract, or complicated, where there is. For the latter, common predisposing factors are the presence of a foreign body, including urinary catheter, or disruption of normal urinary flow by obstruction or retention. Bacteria vary widely in their ability to successfully invade the urinary tract; the vast majority of such infections being due to a small number of species. The route is usually ascension from the urethra. Certain uropathogenic strains of Escherichia coli are the most proficient as measured by their frequency of being the identified cause. Such strains display a number of virulence factors which enable them to occupy this niche – which with increasing understanding, may promote different methods of treating. Other species are often implicated only in the presence of an underlying urological abnormality. The presence of a urinary catheter, or other urine drainage device, provides a ready scaffold for organisms to develop a biofilm, which in turn shields them from being eradicated successfully. Renal calculi similarly can be linked to biofilm production.