UTI

INFECTION OF THE KIDNEY&URINARY TRACT (UT)

الدكتور خلدون ذنون- كلية طب نينوى -المرحلة الرابعة
Objectives
The student have to acquire such knowledge:
1. E.coli is the most common culprit micro-organism.
2. Differentiation between pyelonephritis and cystitis.
3. Abnormalities in the UT predisposes to infection.
4. Urine analysis, culture and sonography are the most important
investigations.
5. Complicated UTI needs further investigations.
6. Managements: fluids, antibiotics, correction of the underlying lesions.
7. Criteria of asymptomatic bacteriuria.
8. Catheter related infection.
9. Effect of UTI on pregnancy and its management.
10. Features of renal tuberculosis.

Infection of the lower UT

Normally bacteria is confined to the lower end of the urethra.
UTI: multiplication of microorganisms in the UT, >105 m.o/ml in midstream urine MSU sample.
Contamination may give high bacterial count but without pyuria.
More common in women, 3% at age 20y. In males it is less common except during 1st year of life & men >60 due to enlarged prostate.
UTI causes (morbidity & may cause renal damage & CRF.


Pathogenesis
Uncomplicated UTI: normal anatomy & physiology of UT, normal renal function, no associated disorder.
Complicated UTI: (risk of infection due to abnormal UT e.g obstruction, calculi, vesico-ureteric reflux, neurological abnormality, indwelling catheter, chronic prostatitis, cystic disease, analgesic nephropathy, and diabetes mellitus.
Out side hospital E.coli cause 75% of UTI, others: proteus, pseudomonas, strep., staph.epidermidis. In hospital: klebsiella, strep. but still faecal E.coli predominate.
In woman, the ascent of m.o in to the bladder is facilitated by the short urethra & the absence of bactericidal secretions.
Instrumentation of the bladder may also introduce m.os.

Clinical features

Abrupt onset 0f frequeucy, dysuria & burning micturition.
Cystitis: suprapubic pain & tenderness.
Slight systemic symptoms, usually without fever.
Cloudy urine, unpleasant odour, gross haematuria may occur.

Investigations

Dipstick estimation of nitrite, leukocyte esterase, and glucose
Microscopy and cytometry of urine for pus cells, RBC, casts, bacteria.
Mid stream urine culture indicated in: recurrent UTI, treatment failure, pregnancy, diabetes, immunecompromised, elderly.
Urine obtained by suprapubic aspiration or from ureter is sterile, presence of any m.o is significant especially if associated with symptoms, in MSU culture count >105 m.o/ml without symptoms is also significant.
U/S or CT: to detect calculi, bladder tumors, size of prostate.
Cystoscopy is helpful in bladder lesion, urethral lesion, BPH, chronic haematuria.
PR.exam. For prostate.
Pelvic exam. for Women with recurrent UTI.


Management
(fluid intake 2L or more /day.
Before treatment do culture & sensitivity. Usually it is not required in healthy woman with single attack of UTI.
Treatment of cystitis and uncomplicated UTI:
First choice: Trimethoprim 200mg/12 hourly. Second choice: amoxicillin 250 mg 8-hourly Nitrofurantoin 50 mg 6-hourly Cephalexin 250 mg 6-hourly Co-amoxiclav 250/125 mg 8hourly Ciprofloxacin 100 mg/12hr for 3days.
Pregnancy: cephalexin and amoxicillin (same dose as above) are safe (. Avoid trimethoprim, sulfa, quinolones & tetracyclines).
Durarion of treatment: 3 days in women, 7 days in pregnancy, 10 days in men
Most E.coli are resistant to ampicillin & amoxicillin.
Treat stones, obstruction, & D.M.
Suppressive antibiotics used continuosly to prevent recurrent symptoms. E.g trimethoprim 100mg/at night, co-amoxiclav 250mg/night. Nitrofurantoin 50 mg at night.
Men & children with recurrent simple UTI should be investigated, in women: no need unless infection is recurrent & severe.
Prophylactic measures in women with recurrent UTI: 1.(Fluid intake at least 2L/day. 2. Regular&complete emptying of the bladder during the day and
before sleep.
3. Good personal hygiene.
4. Emptying of bladder before and after sexual intercourse.

Covert or asymptomatic bacteriuria

More than 105 m.o/ml in MSU without symptoms.
In pregnant women 5%, it is common in those aged over 65.
Treatment is not indicated but investigation & treatment is required in infants & pregnant women.
Urinary tract abnormality should be corrected.


Urethral syndrome
Usually female patient.
Symptoms of urethritis & cystitis.
Urine culture is negative, no m.o.
May be due to organisms not readily cultured by ordinary methods e.g chlamydia, anaerobes..or allergy to toilet preparation & disinfectant, post menopausal atrophic vaginitis.
Antibiotics are not indicated.

Catheter related bacteriuria

It increases the risk of gram ve bacterimia, after 30 days of catheterization bacteriuria occur in most of the patients.
It should not be treated in asymptomatic patient because of antibiotics resistance.
Prevention: sterile methods, closed drainage system, & removal of catheter when not required.

Acute prostatitis

Perineal pain, systemic symptoms, tender prostate.
Positive culture of urine and urethral discharge after prostatic massage.
Treatment: first choice trimethoprim 200mg/12hr for 28 days. Second choice ciprofloxacin 500mg/12hrfor 28 days.

INFECTION OF THE UPPER UT & THE KIDNEY

Due to always ascent of bacteria from bladder and rarely bacteraemia.
75% due to E.coli, others: proteus, klebsiella, strep., & staph.
Complicating factors is commonly present e.g obstruction, reflux, DM, catheter, renal scar, cystic kidney, but in infants & women infection can occur in the absence of such factors.
Renal medulla is particularly susceptable to infection.


ACUTE PYELONEPHRITIS
Pathology: renal pelvis is inflammed, renal parenchymal small abscesses, neutrophil accumulation.

Clinical features

Sudden onset of unilateral or bilateral loin pain that radiate to iliac fossa & suprapubic area.
30% have dysuria due to associated cystitis.
Fever, rigor, vomiting.
Lumbar tenderness & guarding.
Septicaemia & hypotension in severe cases.
Features may be absent in the elderly.
Infants & children may present with fever without localizing symptoms, also may present with convulsion, apathy, abdominal distension & diarrhea, urine should always be examined for pus & m.o in a febrile child.
Acute papillary necrosis may rarely occur, fragments of renal papillae are excreted in urine & may lead to ARF.
Incidence of APN is increased in: DM, chronic UT obstruction, analgesic nephropathy, & sickle cell disease.

Differential diagnosis

Acute appendicitis, diverticulitis, cholecystitis, salpingitis, perinephric abscess.

Investigations

Urine exam.: pus cells, RBC, bacteria, tubular epithelial cells, and casts.
Dipstick estimation of nitrite, leucocyte esterase and glucose in urine.
Mid stream urine culture.
Full blood count, plasma urea, s.creatinine, electrolytes.
Blood culture: fever, rigor, septic shock.
Pelvic exam. in women with recurrent UTI.
PR for men with prostatism.
U/S or CT: to detect obstruction, cysts, calculi, tumors. Done in men after single UTI, child, and women with recurrent UTI.

Management
Diagnosis: clinical features, urine culture, U/S should be performed without delay.
First choice: Co-amoxiclav 500/125 mg 8hr for 10 days.
Ciprofloxacin 500mg 12hr oral for 10 days.
In severe cases, vomiting, septic patient : gentamycin 3-5mg/kg i.v daily for 7-14days, cefuroxime 750mg/8hr i.v for 7-14days.
Oral drugs can be used after initial i.v drugs.
Modify dose of gentamycin & cefuroxime in renal impairment.
Penicillin & cephalosporin are safe in pregnancy, other drugs are avoided.


RENAL TUBERCULOSIS
Secondary to TB in other sites, blood- borne.
Initial cortical lesion & then ulcerate into the pelvis, later bladder, epididymis, seminal vesicles, testis & prostate are involved.
Recurrent heamaturia, pyuria, dysuria, malaise, fever, weight loss, CRF may result.
Urine culture is negative by ordinary methods, so do special cultures on 3 morning urine specimens which give definitive diagnosis in 90%. Urine is acidic.
Cystoscopy may be needed to ascertain extent of lower UT involvement.
IVU: help in the diagnosis, may show calcification & ureteral strictures .
Anti-tuberculous chemotherapy.

UTI in older people

( ( Incidence of asymptomatic bacteriuria.
( ( estrogen & enlarged prostate increases infection.
( UT is a source of bacterimia.
( Incontinence is common presentation.
( In postmenopausal women acute lower UTI may require more than
3 days of antibiotics.
( There is little benefit of treating asymptomatic bacteriuria & may
increase drug side effects & m.o resistance.










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