Pharmacy Clinic
Urinary Tract Infection
UTI is the presence of microorganisms in the urine that cannot be accounted for by contamination, and have the potential to invade the tissues of
the urinary tract and adjacent structures

Lower tract infections such as cystitis, involve the bladder and manifest with symptoms of dysuria, frequency, urgency, and occasionally suprapubic
tenderness

Uncomplicated UTIs are not associated with structural or neurologic abnormalities that may interfere with the normal flow of urine or the voiding
mechanism

Recurrent UTIs are characterized by multiple symptomatic episodes with asymptomatic periods occurring between these episodes. These infections
may be due to reinfection or relapse

Reinfections are caused by a new organism and account for the majority of recurrent UTIs

Relapse represents the development of repeated infections caused by the same initial organism

Etiology and Pathogenesis

Gram-negative aerobic bacteria cause most bacterial UTIs
A few UTIs are acquired hematogenously, but about 95% occur when bacteria ascend from a colonized vaginal introitus and urethra to the bladder
and, in the case of acute uncomplicated pyelonephritis, up the ureter to the kidney

Community-acquired infections
Escherichia coli is the most common bacterium isolated and accounts for about 80%
Staphylococcus saprophyticus for about 10%

Hospitalized patients

E. coli accounts for about 50% of cases
The gram-negative species Klebsiella, Proteus,

Enterobacter, and Serratia for about 40%
The gram-positive bacterial cocci

Enterococcus faecalis and Staphylococcus sp (saprophyticus, aureus) for 10%

The nosocomial incidence of bacteremia attributed to UTI is about 73/100,000

Abnormalities of the urinary tract
Structural abnormality or obstruction increase the possibility of infection;
Renal stones
Congenital obstruction of the ureter or urethra
Prostatic enlargement
Vesicoureteric reflux; in which failure of the valves at the junction of the ureters and bladder allows urine to reflux towards the kidneys when the
bladder contracts

UTIs can be acquired via 3 routes;
Ascending pathways
Hematogenous pathways (blood borne)
Lymphatic pathways

Ascending pathways
In females; the short length of the urethra make the colonization happens. Bacteria enters the bladder through the urethra
In the bladder, the organisms multiply quickly and can ascend the ureters to the kidney

Hematogenous pathways
As a result of dissemination of organisms from a distant primary infection in the body

Factors determine the development of infection;
Size of the inoculum
Virulence of the microorganism; their ability to adhere to urinary epithelial cells. Also hemolysin, a cytotoxic protein produced by bacteria that lyses
a wide range of cells including erythrocytes, polymorphonucear leukocytes, and monocytes. Aeobacin, which facilitates the binding and uptake of
iron by E.coli
Competency of the natural host defense mechanisms. High urea concentration in the urine and PH inhibits bacterial growth

Urethritis: Bacterial infection of the urethra occurs when organisms that gain access to it acutely or chronically colonize the numerous periurethral
glands in the bulbous and pendulous portions of the male urethra and the entire female urethra

Cystitis: Bacterial infection of the bladder in men is usually complicated and generally results from ascending infection of the urethra or prostate or
occurs secondary to urethral instrumentation
In women, sexual intercourse usually precedes uncomplicated cystitis

Prostatitis: Chronic bacterial prostate infection is the most common cause of recurrent UTI in men due to reintroduction of infection into the bladder

Acute pyelonephritis: The term pyelonephritis refers to bacterial infection of the kidney parenchyma and not tubulointerstitial nephropathy unless
UTI is documented
About 20% of community-acquired bacteremias in women are attributed to pyelonephritis
Pyelonephritis is uncommon in men with a normal urinary tract
In patients who have recurrent infections and no structural abnormalities, the normal host defense mechanisms may be decreased

In 30 to 50% of women with a normal urinary tract, pyelonephritis occurs by the ascending route despite the dynamics of urine flow and the
interference of the vesicoureteral junction. Cystitis alone or anatomic defects may produce reflux. This tendency is greatly enhanced when
peristalsis is inhibited (eg, during pregnancy, by obstruction, by endotoxins of gram-negative bacteria). Although obstruction (strictures, calculi,
tumors, prostatic hypertrophy, neurogenic bladder, VUR) predisposes to infection, most women with pyelonephritis have no demonstrable functional
or anatomic defects of the urinary tract. Pyelonephritis or focal abscess may be due to hematogenous UTI, which is infrequent and usually results
from bacteremia with virulent bacilli (eg, Salmonella organisms, S. aureus). Pyelonephritis is very common in girls or in pregnant women after
instrumentation or bladder catheterization.
The kidney usually is enlarged due to inflammatory PMNs and edema. Infection is focal and patchy beginning in the pelvis and medulla and
extending into the cortex as an enlarging wedge. Chronic inflammatory cells appear within a few days, and medullary and subcortical abscesses
may develop. Parenchymal tissue between foci of infection is common. Arteries, arterioles, and glomeruli are considerably resistant to infection.
Papillary necrosis may be evident in acute pyelonephritis associated with diabetes, obstruction, sickle cell disease, or analgesic nephropathy.
Although acute pyelonephritis is frequently associated with renal scarring in children, similar scarring in adults is not detectable in the absence of
reflux or obstruction.

Symptoms and Signs

Urethritis: Onset is gradual, and symptoms are mild. Men with urethritis usually present with urethral discharge, which is purulent when due to N.
gonorrhoeae and whitish mucoid when nonspecific. Women usually present with dysuria, frequency, and pyuria



Cystitis: Onset is usually sudden. Cystitis usually produces frequency, urgency, and burning or painful voiding of small volumes of urine. Nocturia,
with suprapubic and often low back pain, is common. The urine is often turbid, and gross hematuria occurs in about 30% of patients.

Prostatitis: Acute bacterial prostatitis is characterized by chills, fever, urinary frequency and urgency, perineal and low back pain, varying symptoms
of obstruction to voiding, dysuria, nocturia, and sometimes gross hematuria. The prostate gland is tender, focally or diffusely swollen, and
indurated.
Chronic prostatitis is more occult than acute prostatitis; the patient usually presents with recurrent bacteriuria or variable low-grade fever with back
or pelvic discomfort.

Acute pyelonephritis: Typically, symptom onset is rapid and characterized by chills, fever, flank pain, nausea, and vomiting
Symptoms of lower UTI (eg, frequency, dysuria) occur concomitantly in about 1/3 of patients
If abdominal rigidity is absent or slight, a tender, enlarged kidney may sometimes be palpable
Costovertebral tenderness is generally present on the infected side. In children, symptoms often are meager and less characteristic.

Chronic pyelonephritis: Symptoms and signs (eg, fever, flank or abdominal pain) are often vague and inconsistent. In xanthogranulomatous
pyelonephritis, presenting symptoms may include flank pain, fever, malaise, anorexia, and weight loss. A unilateral renal mass can usually be
palpated on physical examination.

The cornerstone is to be able to demonstrate significant numbers of microorganisms present in an appropriate urine specimen to distinguish
sample contamination from infection

Urinalysis must be done
Microscopic examination using gram stain
Then look at the criteria for defining significant bacteriuria