Urinary Tract Infection, UTI - Introduction, Epidemiology, Normal Flora
Introduction to Urinary Tract Infection (UTI)
The urinary tract consists of the kidneys, ureters, bladder, and urethra. Its function is to make and process urine. Urine is an ultrafiltrate of blood consisting mostly of water but also consists of nitrogenous wastes, sodium, potassium, chloride, and other analytes. Urine is completely sterile.
Urinary Tract Infection (UTI) is characterized as being upper (U-UTI) or lower (L-UTI) based on the anatomical location of the infection. L-UTI encompasses the bladder and urethra and may affect the urethra (urethritis), the bladder (cystitis), or the case of the male prostate (prostatitis).
The female urethra is comparatively shorter than the male urethra. It also lies in close proximity to the warm, moist, perirectal region, which is teeming with micro-organisms. Because of the shorter urethra, bacteria can reach up to the bladder more easily. Thus, Urinary Tract infections (UTIs) are much more common in females than in males.
Infection in male occurs in males occurs mostly below the age of one or above 60 years- due to enlargement of the prostate complete removal of urine from the bladder is hindered.
Resident micro-organisms of the urinary tract
The urethra has resident microflora that colonizes its epithelium in the distal portion.
Organisms include Lactobacillus, Corynebacterium, and Coagulase-negative Staphylococci (CoNS).
Other potential pathogens include gram-negative aerobic bacilli (primarily Enterobacteriaceae) and on occasion- yeasts, which are also present as transient colonies.
All areas of the urinary tract above the urethra in a healthy human being sterile. But in cases of noninvasive methods for urine collection, the specimen passed through a contaminated milieu must be relayed on.
Thus, quantitative cultures for the diagnosis of Urinary Tract Infection (UTI) have been used to differentiate between contamination, colonization, and infection.
Epidemiology of Urinary Tract Infection (UTI)
Urinary Tract Infection (UTI) is the most common bacterial infection. Approximately, epidemiological studies have confirmed that about 10% of humans will have a UTI at some time during their lives. It is one of the most common nosocomial infections, accounting for as many as 35%.
The incidence of bacteriuria among girls of age 5-17 years is 1-3%. The prevalence of bacteriuria increases as age advances and reaches up to 10-20%. In women having Urinary Tract Infection (UTI) between the ages of 20-40, 50% may become reinfected within 1 year.
Sexual activity also contributes to Urinary Tract Infection (UTI) and increases the chances of bacterial contamination of the female urethra.
Apart from an anatomical perspective, hormonal changes also favor the development of Urinary Tract Infection (UTI) predominantly during pregnancy. These infections can lead to serious infections in both the mother and fetus.
Urinary Tract Infection (UTI) is an important complication of diabetes, renal disease, renal transplantation, and structural and neurologic abnormalities that interferes with urine flow. In 40-60% of renal transplant recipients, the urinary tract is the source of bacteremia. The reoccurrence rate in these patients is about 40%
Urinary Tract Infection (UTI) is the important leading cause of gram-negative sepsis in hospitalized patients. They are also the origin of about half of all nosocomial infections caused by urinary catheters.