Urinary Tract Infections Midterm Notes PDF

6 1 URINARY AND RENAL DISORDERS – Urinary Tract Infec.ons A urinary tract infec,on (UTI) is an infec+on that affects any part of the urinary system, including the urethra, bladder, ureters, and kidneys. UTIs...

6 1 URINARY AND RENAL DISORDERS – Urinary Tract Infec.ons A urinary tract infec,on (UTI) is an infec+on that affects any part of the urinary system, including the urethra, bladder, ureters, and kidneys. UTIs can be classified into lower UTIs (affec+ng the urethra and bladder) and upper UTIs (affec+ng the kidneys and ureters). 1. Most Likely Cause The most common cause of UTIs depends on the type and loca+on of the infec+on. Causa,ve Microorganism: o Escherichia coli (E. coli) is the most common causa+ve agent for both lower (cys++s) and upper (pyelonephri+s) UTIs. o Other microorganisms include Proteus species, Enterobacter species, and Klebsiella pneumoniae. o In children, especially during the neonatal period, UTIs may also be linked to congenital renal abnormali+es. 2. Pathophysiology The pathophysiology of UTIs varies depending on whether it is a lower UTI (cys,,s) or an upper UTI (pyelonephri,s). Lower UTI (Cys,,s) 1. Bacterial Invasion: o Bacteria, most oGen E. coli, enter the urinary tract via the urethra and aHach to the bladder's epithelial cells. o The bacteria proliferate, triggering an inflammatory response in the bladder wall. 2. Inflamma,on and Mucosal Injury: o The bladder mucosa becomes inflamed, causing redness, edema, and possible forma+on of pus or exudates. o The inflamma+on s+mulates the detrusor muscle, leading to spasms and symptoms such as urgency and frequency of urina,on. 3. Urine Stasis: o Condi+ons like bladder outlet obstruc+on or incomplete bladder emptying can lead to urine stasis, which allows bacteria to mul+ply and colonize. Upper UTI (Pyelonephri,s) 1. Ascending Infec,on: o Infec+on may spread retrogradely from the bladder to the kidneys via the ureters. o It can also result from hematogenous spread (through the bloodstream). 2. Renal Pelvis Inflamma,on: o Inflammatory mediators and white blood cells (WBCs) infiltrate the renal parenchyma. o This leads to renal edema and poten+ally tubular necrosis, impairing kidney func+on.  2 3. Systemic Manifesta,ons: o Symptoms include fever, chills, back pain, and flank pain, along with signs of a lower UTI. 3. Disease Transmission Transmission: o Person-to-person transmission does not occur. o Instead, UTIs arise from bacteria that are already present in the gastrointes,nal tract (like E. coli), which colonize the perineal area and ascend into the urinary tract. o In children, anatomical abnormali+es (like vesicoureteral reflux (VUR)) allow urine to flow backward from the bladder to the kidneys, facilita+ng infec+on. o In healthcare seQngs, use of urinary catheters can introduce bacteria directly into the urinary system. 4. Risk Factors Risk factors for UTIs are different for lower UTIs (cys,,s) and upper UTIs (pyelonephri,s). Risk factors can be classified as modifiable or non-modifiable. Lower UTI (Cys,,s) Risk Factors Modifiable Risk Factors: o Poor hygiene: Wiping from back to front can introduce fecal bacteria (like E. coli) into the urethra. o Urinary Catheters: Prolonged use of catheters provides a direct route for bacterial entry. o Sexual Ac,vity: Sexual intercourse increases the risk of UTI, especially in women. o Dehydra,on: Low fluid intake results in concentrated urine, which promotes bacterial growth. o Use of spermicides or diaphragms: These can alter the normal vaginal flora, increasing the risk of UTI. Non-Modifiable Risk Factors: o Female anatomy: Females have a shorter urethra, allowing bacteria to reach the bladder more easily. o Postmenopausal changes: Decreased estrogen causes atrophy of the urogenital mucosa, impairing the natural defense against infec+on. o Congenital abnormali,es: Structural defects of the urinary tract (like vesicoureteral reflux (VUR)) predispose individuals to recurrent UTIs. Upper UTI (Pyelonephri,s) Risk Factors Modifiable Risk Factors: o Urinary stasis: Incomplete bladder emptying increases the risk of retrograde infec+on to the kidneys. o Indwelling catheters: Bacteria can travel through the catheter and infect the urinary tract. Non-Modifiable Risk Factors:  3 o Sex: Females have a higher risk of developing pyelonephri+s than males due to shorter urethras. o Vesicoureteral Reflux (VUR): Abnormal backward flow of urine from the bladder into the ureters and kidneys, common in children. o Pregnancy: Hormonal changes and pressure from the growing uterus slow urine flow, leading to stasis. o Diabetes Mellitus: Impaired immune responses and glycosuria (glucose in urine) promote bacterial growth. Summary Table Criteria Urinary Tract Infec,on (UTI) Most Likely E. coli (most common), other bacteria: Proteus, Klebsiella, Enterobacter. Cause Cys,,s: Bacteria adhere to and invade the bladder epithelium, causing mucosal inflamma,on and detrusor spasms. Pyelonephri,s: Bacteria ascend Pathophysiology from the bladder to the kidneys, triggering an inflammatory response in the renal pelvis. Not person-to-person. Bacteria from the gut or perineal area ascend the Transmission urethra. Catheters and Vesicoureteral Reflux (VUR) facilitate bacterial ascent. Modifiable: Poor hygiene, sexual ac+vity, dehydra+on, use of catheters, Risk Factors certain contracep+ves. Non-Modifiable: Female anatomy, postmenopause, congenital defects (like VUR), pregnancy, diabetes.