The pathogenic track to urinary tract

URINARY TRACT INFECTIONS

Ibrahim Al-Orainey,FACP,FRCP(Lond)

Professor of medicine

Faculty of Medicine, King Saud University

Urinary tract infections

• Asymptomatic bacteriuria

• Acute cystitis

• Acute pyelonephritis

Uncomplicated / complicated UTI

Epidemiology of UTI

• UTI is more common in females.(1-2% of young nonpregnant women)

• 40% of females will have a symptomatic UTI in their life time.

• In men: prevalence is 0.04%.• Incidence of UTI increases in old age.

(10% of men & 20% of women)

Risk factors for UTI

• in females:pregnancy, spermicidal contraceptives,

diaphragm, estrogen deficiency, diabetes.

• In males:lack of circumcision, prostatic hypertrophy, use of condom catheter.

• in both :old age , obstruction, vesicoureteric reflux, instrumentation, neurogenic bladder, renal transplantation.

Infecting organisms

E.coli ProteusKlebsiella PseudomonasEnterobacter EnterococciStaphylococci Candida

Pathogenesis of UTI

Host defences:• Urinary bladder is usually resistant to

bacterial colonisation.• Bacteria accessing the bladder are

eliminated by: - flushing mechanism - urine inhibitors (PH, osmolality, urea)

- uroepithelial defences (cytokines,PMNs) - Tamm- Horsfall protien

Pathogenesis of UTI

Organism features:• Most E.coli causing UTI belong to O,K and H

serotypes.• Uropathogenic E.coli virulence factors:

- Have fimbria (for adherence).- Secrete hemolysin & aerobactin.- Resist serum bacterical action.- Have higher K capsular antigen.

• Adherence is important in other bacteria.

Pathogenesis of UTI

• Periutheral area & urethra are colonised by bacteria.

• Bacteria enter bladder in susceptable host.• Adherence properties enable pathogens to

colonise bladder.• Pathogens attach to uroepithelial mucosa

secretion of cytokines recruitment of PMNs inflammation.

• Pathogens may ascend through ureter to kidney pyelonephritis.

Clinical presentation of UTI

Asymptomatic bacteriuria:• Common in females & elderly.• 25% develop symptomatic UTI .• 25% clear spontaneously.• Spontaneous cure & reinfection are common.

Cystitis:• Frequency, dysurea , urgency.• Suprapubic discomfort +/- tenderness.• Fever is often absent.

Clinical presentation of UTI

Acute pyelonephritis:• Fever, abdominal pain, vomiting.• Dysuria ,frequency, flank or loin pain.• Flank or loin tenderness.• In elderly: symptoms are often atypical.• Bacteremia is common.

Acute pyelonephritis

Acute pyelonephritis

Special situations

Special situations

UTI in pregnancy:• Asymptomatic bacteriuria occurs in 4-8%.• Of these: 25% develop acute pyelonephritis.• Pyelonephritis in pregnancy predisposes to:

- premature delivery.- low birth weight infant.- increased newborn mortality.

Special situations

Catheter associated UTI :• Bacteriuria occurs in 10-15% of cathed pts. • All chronicly cathed pts. develop bacteriuria.• Organisms: E.coli, Proteus, Klebsiella, Serratia

Pseudomonas, Enterococci, Candida.

• Antibiotic resistance is common.• Symptoms are often absent or minimal.• Intermittent cathing reduces infections.

Diagnosis of UTI

• Urine dipstick:- leukocyte esterase- nitrite

• Urine microscopy:-WBCs, WBC casts, RBCs- Bacteria ( 1 bact/hpf = significant )

Diagnosis of UTI

Urine culture:• Significant bacteriuria= 100K cfu/ml• symptoms: 1 +ve cuture = infection• Symptoms: 10K cfu/ml = propable infection• Asymptomatic: 2 +ve cultures = infection• False negative : antibiotics, antiseptics, urethral

syndrome,TB kidney, diuresis.

Natural history of UTI

• Treatment of uncomplicated UTI leads to complete resolution and cure.

• Recurrences occur in some patients usually within 2-3 monthes of initial infection.

• Frequent recurrences usually occur in clusters followed by long remissions.

• Recurrent uncomplicated UTI does not lead to chronic renal impairment or failure.

• Recurrent complicated UTI may lead to renal failure.• UTI may accelerate progression of underlying renal

disease.

Treatment of UTI

Acute pyelonephritis:• Mild infections are treated orally.

(fluoroquinolones,co-trimoxazole,cefuroxime)• Moderate - severe infections – parenteral trt.

(aminoglycosides,ceftriaxone,aztreonam,tazocin)• Therapymarked decline in bact.count after 48hrs.• Persistant fever, +ve blood culture after 3 days of

therapy..R/O obstruction, abscess.• After defervescence..change to oral therapy to

complete 2 weeks.• In males look for a predisposing cause.• FU urine cultures 2 weeks after end of therapy.

Treatment of UTI

• Cystitis:• young females: 3 days of oral therapy

(fluoroquinolone,cotrimoxazole,cefuroxime,augmentin)

• In females: symptoms x 7 days or history of previous infection 7 days

therapy.• In males : oral therapy for 7-10 days.

Treatment of UTI

Asymptomatic bacteriuria• No urgency to treat – confirm by 2 cultures.• Treatment is indicated in :

- Pregnancy- Children with VU reflux- Urinary obstruction

• Treatment is not indicated in :- Young nonpregnant women without

structural abnormalities- Elderly patients

Structural abnormalities should be corrected

Treatment of UTI

• Relapse of infection:• Relapse may be due to :

- renal invovement- structural abnormalities- chronic bacterial prostatitis

• Relapses need to be treated for 2 weeks.• Obstuction should be corrected .• If uncorrectable obstruction: treatment is prolonged

for 4-6 weeks or as required.• The latter group needs FU by monthly cultures and

annual assessment of kidneys.• In males R/O chronic prostatitis.

Treatment of UTI

Recurrent UTI:• Infrequent symptomatic UTI : treat attacks.• In females, reinfections may be related to sexual

activity – attacks may be reduced by: - avioding use of spermicidal contraceptives - voiding after intercourse - post coital single dose therapy

• If no precipitating factors – long term prophylaxis.• Long term prophylaxis is also indicated for frequent

asymptomatic infection in:- Children with VU reflux - Patients with obtructive uropathy

What is the prognosis ?

So I learned something ,how about you ?

وقل رب زدني علما

صدق الله العظيم

Confused..I did not understand any thing,did you?