Urinary Tract Infections and Renal Involvement In Systemic Disorders

Urinary Tract Infections

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* The prevalence of UTI in women is about 3% at the age of 20, increasing by about 1% in each subsequent decade. In males UTI is uncommon, except in the first year of life and in men over 60, in whom urinary tract obstruction due to prostatic hypertrophy may occur.

Definitions

UTI may be asymptomatic (subclinical infection) or symptomatic (disease). Uncomplicated UTI refers to acute cystitis or pyelonephritis in nonpregnant outpatient women without anatomic abnormalities or instrumentation of the urinary tract; complicated UTI is a catch-all term that encompasses all other types of UTI.
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Aetiology and risk factors

* Urine is an excellent culture medium for bacteria. In women, the ascent of organisms into the bladder is easier than in men; the urethra is shorter and absence of bactericidal prostatic secretions may be relevant. Sexual intercourse may cause minor urethral trauma and transfer bacteria from the perineum into the bladder.

Risk factors for urinary tract infection

* Incomplete bladder emptying: Bladder outflow obstruction, Gynaecological abnormalities, Neurological problems, VUR. Foreign bodies: Urethral catheter or ureteric stent Loss of host defences: e.g. Diabetes mellitus

Organisms causing UTI in the community include

* Escherichia coli derived from the gastrointestinal tract (about 75% of infections) Proteus Pseudomonas species Streptococci Staphylococcus epidermidis.


Clinical assessment
* Asymptomatic bacteriuria Symptomatic acute urethritis and cystitis Acute pyelonephritis Acute prostatitis Septicaemia (usually Gram-negative bacteria).

Asymptomatic Bacteriuria (ABU)

A diagnosis of ABU can be considered only when the patient does not have local or systemic symptoms referable to the urinary tract. The clinical presentation is usually that of a patient who undergoes a screening urine culture for a reason unrelated to the genitourinary tract and is incidentally found to have bacteriuria.
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Cystitis

The typical symptoms of cystitis are dysuria, urinary frequency, and urgency. Nocturia, hesitancy, suprapubic discomfort, and gross hematuria are often noted as well. Unilateral back or flank pain is generally an indication that the upper urinary tract is involved. Fever is also an indication of invasive infection of either the kidney or the prostate.
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Pyelonephritis

Mild pyelonephritis can present as low-grade fever with or without lower-back. Severe pyelonephritis can manifest as high fever, rigors, nausea, vomiting, and flank and/or loin pain. Symptoms are generally acute in onset.
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Prostatitis

Acute bacterial prostatitis presents as dysuria, frequency, and pain in the prostatic, pelvic, or perineal area. Fever and chills are usually present, and symptoms of bladder outlet obstruction are common. Chronic bacterial prostatitis presents more insidiously as recurrent episodes of cystitis, sometimes with associated pelvic and perineal pain. Men who present with recurrent cystitis should be evaluated for a prostatic focus.
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Investigations

* In an otherwise healthy woman with a single lower urinary tract infection and no indications of a complicated infection, urine culture prior to treatment is not mandatory. Definitive diagnosis rests on the combination of typical clinical features with findings in the urine. Neutrophils are usually present in the urine in symptomatic infections.



* In asymptomatic patients, > 105/ml organisms is usually regarded as significant. Urine dipstick tests can be used to test for UTI. One tests for nitrite-most urinary pathogens can reduce nitrate to nitrite. Another tests for leucocyte esterase, suggesting the presence of neutrophils. If either test is positive, UTI is probable; if they are both negative, UTI is unlikely. The detection of bacteria in a urine culture is the diagnostic "gold standard" for UTI

* Indications

Investigation
All patients
Culture of MSU, or urine obtained by suprapubic aspiration
All patients
Microscopic examination or cytometry of urine for white and red cells
All patients
Dipstick examination of urine for nitrite and leucocyte esterase
All patients
Dipstick examination of urine for blood, protein and glucose
Infants; children; adults with acute pyelonephritis or prostatitis
Full blood count
Infants; children; acute pyelonephritis; recurrent UTI
Plasma urea, electrolytes, creatinine
Fever, rigors or evidence of septic shock
Blood culture

* Women with recurrent UTI

Pelvic examination
Men (to examine prostate)
Rectal examination
To identify obstruction, cysts, calculi Infants, children, men after single UTI Women who have (1) acute pyelonephritis; (2) recurrent UTI after antibiotic treatment; (3) UTI or asymptomatic bacteriuria in pregnancy
Renal ultrasound or CT
Alternative to ultrasound, particularly to image the collecting system after voiding
Intravenous urogram (IVU)
Selected infants and children; to look for reflux and renal scars
Micturating cysto-urethrogram (MCU) or radioisotope study to identify and assess severity of vesico-ureteric reflux or impaired bladder emptying
Patients with haematuria or a suspected bladder lesion
Cystoscopy

Management

* Antibiotics are recommended in all cases of proven UTI . Treatment for 3 days is the norm and is less likely to induce antibiotic resistance than more prolonged therapy. Trimethoprim is the usual choice for initial treatment. Nitrofurantoin, quinolone antibiotics such as ciprofloxacin and norfloxacin, and cefalexin are also generally effective.

Pyelonephritis

* High rates of TMP-SMX-resistant E. coli in patients with pyelonephritis have made fluoroquinolones the first-line therapy for acute uncomplicated pyelonephritis. Whether the fluoroquinolones are given orally or parenterally (7-day course of therapy) depends on the patient's tolerance for oral intake. In general, the treatment of complicated, previous episodes of pyelonephritis, or recent urinary tract manipulations should be guided by urine culture results.


* Rarely, acute pyelonephritis is associated with papillary necrosis. Fragments of renal papillary tissue are passed per urethra and can be identified histologically. They may cause ureteric obstruction and, if this occurs bilaterally or in a single kidney, may cause acute renal failure. Predisposing factors include diabetes mellitus, chronic urinary obstruction, analgesic nephropathy and sickle-cell disease.


* The differential diagnosis of acute pyelonephritis includes Acute appendicitis, Diverticulitis, Cholecystitis and Salpingitis.

UTI in Pregnant Women

Nitrofurantoin, ampicillin, and the cephalosporins are considered relatively safe in early pregnancy.
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Prophylactic Measures To Be Adopted By Women With Recurrent Urinary Infection

* Fluid intake of at least 2 liters/day. Regular complete emptying of bladder. If vesico-ureteric reflux is present, practice double micturition (empty the bladder then attempt micturition 10-15 minutes later). Good personal hygiene. Emptying of the bladder before and after sexual intercourse. Cranberry juice may be effective.

* In women, recurrent infections are common and further investigation is only justified if infections are frequent (three or more per year) or unusually severe. Men and children with recurrent infections, and patients with signs of pyelonephritis or systemic infection should also be investigated. Recurrent UTI, particularly in the presence of an underlying cause, may result in permanent renal damage, whereas uncomplicated infections rarely (if ever) do so.

Asymptomatic Bacteruria

* This is defined as > 105/ml organisms in the urine of apparently healthy asymptomatic patients. Approximately 3% of non-pregnant adult women and 5% of pregnant women have asymptomatic bacteriuria. It is increasingly common in those aged over 65. Up to 30% of patients will develop symptomatic infection within 1 year. In infants and pregnant women, treatment is required and investigation is indicated. Where the urinary tract is abnormal, asymptomatic bacteriuria is also more significant and may require intervention.

Catheter Related Bacteruria

* In patients with a urethral catheter, bacteriuria increases the risk of Gram-negative bacteraemia fivefold. However, bacteriuria is common, and almost universal during long-term catheterisation. Treatment is usually avoided in asymptomatic patients as this may promote antibiotic resistance. Careful sterile insertion technique is important, and the catheter should be removed as soon as it is not required.

Prognosis

Cystitis is a risk factor for recurrent cystitis and pyelonephritis. ABU is common among elderly and catheterized patients but does not in itself increase the risk of death. In the absence of anatomic abnormalities, recurrent infection in children and adults does not lead to chronic pyelonephritis or to renal failure.
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Prognosis

In the presence of underlying renal abnormalities (particularly obstructing stones), infection as a secondary factor can accelerate renal parenchymal damage. In spinal cord–injured patients, use of a long-term indwelling bladder catheter is a well-documented risk factor for bladder cancer. *

Renal Involvement In Systemic Disorders

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The kidneys may be directly involved in a number of multisystem diseases or secondarily affected by diseases of other organs. Involvement may be at a pre-renal, renal (glomerular or interstitial) or post-renal level.
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DIABETES MELLITUS

Steady state from Micro- Macroalbuminuria- Frank Nephrotic syndrome. Few patients require renal biopsy to establish the diagnosis. Management with ACE inhibitors and other hypotensive agents to slow progression
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HEPATIC-RENAL DISEASE

IgA nephropathy is more common in patients with liver disease. Severe hepatic dysfunction may cause renal failure (hepatorenal syndrome). Patients with severe hepatic failure are often difficult to treat by dialysis and have a poor prognosis.
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PULMONARY-RENAL DISEASE
Presentation is with renal and respiratory failure. Goodpasture's disease and small-vessel vasculitis can cause this presentation.
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MALIGNANT DISEASES

Cancer may affect the kidney in many ways: Primary malignancy. Glomerulonephritis: especially membranous nephropathy. Hypercalcaemia. Uric acid crystal formation in tubules: usually in tumour lysis syndromes. Light chains in myeloma and amyloidosis. Antibodies in cryoglobulinaemia
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TB of urinary tarct

Is the result of blood-borne infection (secondary to tuberculosis elsewhere). Calcification in the kidney and stricture formation in the ureter are typical. Neutrophils are present in the urine but routine urine culture may be negative ('sterile pyuria'). Anti-tuberculous chemotherapy follows standard regimes. Surgery to relieve urinary tract obstruction or to remove a very severely infected kidney may be required.
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SYSTEMIC VASCULITIS

Medium- to large-vessel vasculitis: only causes renal disease when arterial involvement leads to hypertension or renal infarction.
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Small-vessel vasculitis

This causes a focal inflammatory glomerulonephritis, characteristically in some patients causes pulmonary hemorrhage. The most important causes of this syndrome, microscopic polyangiitis and Wegener's granulomatosis. Treatment of the primary types of small-vessel vasculitis with cyclophosphamide and corticosteroids is life-saving. Vasculitis may also be seen in rheumatoid arthritis, SLE and cryoglobulinaemia
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SYSTEMIC LUPUS ERYTHEMATOSUS (SLE)

Haematuria and proteinuria but minimally impaired or normal renal function, is common in SLE. Haematuria, hypertension, variable renal impairment, accompanied by heavy proteinuria that often reaches nephrotic levels. Many patients go into relative remission from SLE once ESRF has developed. This may be because ESRF itself is an immunosuppressed state.
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SLE
Patients with ESRF caused by SLE are usually good candidates for dialysis and transplantation. Although it may recur in renal allografts, the immunosuppression required to prevent allograft rejection usually controls SLE too.
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PREGNANCY

Physiological adaptations includes: Peripheral vascular resistance declines, Blood volume, cardiac output and GFR increase, and There is usually a reduction in plasma creatinine and urea values in the first trimester.
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Pregnancy and renal disease

Pyelonephritis is more common during pregnancy, perhaps because of dilatation of the urinary collecting system and ureters, so asymptomatic bacteriuria should be treated. Proteinuria caused by glomerular disease is always exacerbated. Pre-existing renal disease increases the fetal and maternal risk involved in pregnancy. During pregnancy, therapy should not usually be stopped,
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Pre-eclampsia and related disorders

Pre-eclampsia is traditionally defined by the triad of oedema, proteinuria and hypertension. Pre-eclampsia presents progressively, increasing risks to mother and fetus which can be reversed almost immediately by early delivery. Proteinuria and hypertension in the first trimester of pregnancy suggest pre-existing renal disease.
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Pre-eclampsia and related disorders

Clinical syndromes: Eclampsia: severe hypertension, encephalopathy and fits DIC Thrombotic microangiopathy: may also occur post-partum (post-partum haemolytic uraemic syndrome) Acute fatty liver of pregnancy 'HELLP' syndrome: haemolysis, elevated liver enzymes, low platelets (thrombotic microangiopathy with abnormal liver function)
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Pre-eclampsia and related disorders

Clinical signs: Hypertension Proteinuria Oedema
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Pre-eclampsia and related disorders
Management: The only effective management for pre-eclampsia is delivery. Aspirin remains controversial. If life-threatening complications are not present and the baby is immature, corticosteroids may be given to induce maturation of fetal lungs, and delivery postponed while mother and baby are closely observed. Magnesium sulphate reduces the incidence of eclamptic convulsions. Maternal acute renal failure may occur in most of these syndromes, and may result from cortical necrosis (irreversible infarction of the renal cortex).
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