Infecções do trato urinário por Escherichia coli Uropatogênica: uma revisão

Abstract

The Urinary Tract Infections (UTI) are one of the most frequent bacterial infections affecting humans, being the second most common infection in the general population. From the clinical aspect, the UTI can be divided into cystitis and pyelonephritis. When symptomatic, the clinical features of UTI may be characteristic for the diagnosis, including dysuria, urinary frequency, back pain, fever and chills, urinary urgency, nocturia, and cloudy urine. However there are those asymptomatic and also those that are recurrent, clinical entities that need special attention in the diagnosis and treatment. The quantitative urine culture is a very important test for the laboratory diagnosis of a UTI since it indicates the presence of infection, allows the identification of the organism causing the infection and the study of their antimicrobial susceptibility. The great majority of UTI is caused by Escherichia coli, a bacterium belonging to the family Enterobacteriaceae, whose normal habitat is the gastrointestinal tract of humans and animals of hot blood. Because of its virulence factors and conditions associated with Escherichia coli these bacteria can be divided into Escherichia coli Uropatogênica (UPEC), Escherichia coli Enteropatogênica (EPEC), Escherichia coli Enterotoxigênica ETEC, Escherichia coli Enterohemorrágica (EHEC), Escherichia coli Enteroinvasiva (EIEC) e Escherichia coli Enteroagregativa (EAEC). UPEC is considered the main causative agent of UTI and accounts for approximately 80% of them, as shown by studies conducted in different regions of Brazil and other countries. The known virulence factors of UPEC are: adhesins, iron acquisition systems, toxins and capsular polysaccharides. These factors make the microorganism capable of fixing the cells and tissues of host surfaces and allow these bacteria to escape the host's immune system. Currently, as preconized by the Conselho Federal de Medicina, the treatment of the great majority of UTI is accomplished using the following drugs: sulfamethoxazole + trimethoprim, quinolones and fluoroquinolones, betalactams and Nitrofurantoina.