The diagnosis is based on quantitative culture of a cleancatch mid-stream specimen of urine. Details on the collection of urine samples are given. Once collected, samples must be sent to the laboratory immediately or refrigerated pending despatch in order to prevent further multiplication of bacteria. More than 100000 of the same organism per millilitre of urine indicates bladder infection (,significant bacteriuria’). Lower counts may be accepted as evidence of infection in patients passing large volumes of urine. If in doubt, urine must be obtained by suprapubic bladder aspiration, when any growth of a uropathogenic organism is evidence of infection. Pyuria is not a constant feature of UTI and its absence does not exclude the diagnosis. Dipstick tests for nitrite have a high false-negative detection rate.
Excretion urography is not indicated in women with one or two isolated episodes of UTI if post-treatment urinalysis, including microscopy and urine culture, are normal. If there are further attacks or if post-treatment urinalysis is abnormal, excretion urography should be performed to identify or exclude anatomical or functional abnormalities predisposing to or complicating infection, e.g. impaired bladder emptying.
Excretion urography should be carried out in all males and children following a first proven episode of bacteriuria to identify complicating factors.
Meu is indicated in children with abnormal excretion urograms and may be required to evaluate abnormal bladder emptying at any age. Otherwise it is of no value in the management of UTI.
ystoscopy in patients with known UTI has a very limited role. It is indicated only to investigate abnormal bladder or ureteral emptying, or haematuria in bacteriuric women over the age of 40 years, since bladder cancer becomes more common with age. It is more appropriately performed in abacteriuric frequency or dysuria to exclude bladder lesions such as carcinoma or interstitial cystitis (Hunner’s ulcer).
Single isolated attack
Pretreatment urine cultures are desirable.
IF SYMPTOMS ARE MILD, symptomatic treatment with potassium citrate mixture (10 ml three times daily) can be given pending the result of urine culture. IF SYMPTOMS ARE SEVERE, treatment with 3-5 days of amoxycillin (250 mg three times daily), nitrofurantoin (50 mg three times daily) or trimethoprim (200 mg twice daily) should be started immediately without waiting for the result of urine culture. A high (2 litres daily) fluid intake should be encouraged during treatment and for some subsequent weeks. Urinalysis, microscopy and culture should be repeated 5 days after treatment. ‘Single-shot’ treatment with 3 g of amoxycillin or 1.92 g of co-trimoxazole can be used for patients with bladder symptoms of less than 36 hours duration who have no previous history of
IF THE PATIENT IS ACUTELY ILL with high fever, loin pain and tenderness (acute pyelonephritis), intravenous ampicillin or amoxycillin (1 g 6-hourly) or intravenous gentamicin (2-5 mg kg-l daily in divided doses) should be given switching to a further 7 days’
treatment with oral therapy as symptoms improve. Intravenous fluids may be required to achieve a good urine output.
In patients presenting for the first time with high fever, loin pain and tenderness, urgent renal ultrasound examination is required to exclude an obstructed pyonephrosis. If this is present it should be drained by percutaneous nephrostomy.
Pretreatment and post-treatment urine cultures are mandatory to confirm the diagnosis and identify whether recurrent infection is due to relapse or reinfection. IN RELAPSE, a search should be made for a cause, e.g. stones or scarred kidneys, and this should be eradicated if possible, for example by the removal of stones. Intense or prolonged treatment-intravenous or intramuscular aminoglycoside for 7 days or oral antibiotics for 4-6 weeks-is required. If this fails, long-term antibiotics are required.
REINFECTION implies that the patient has poor defence systems; such patients must undertake prophylactic measures:
• A 2-litre daily fluid intake
• Voiding at 2-3 hour intervals with double micturition if reflux is present
• Voiding before bedtime and after intercourse
• Avoidance of bubble baths and other chemicals In bath water
• Avoidance of constipation, which may impair bladder emptying
Evidence of impaired bladder emptying on excretion urography requires urological assessment. If UTI continues to recur, treatment for 6-12 months with low-dose prophylaxis (trimethoprim 100 mg, co-trimoxazole 480 mg, or cephradine 250-500 mg) is required; it should be taken last thing at night when urine flow is low. Intravaginal oestrogen therapy has been shown to produce a reduction in the number of episodes of UTI in elderly women.
Urinary infections in the presence
of an indwelling catheter Colonization of the bladder by a urinary pathogen is common after a urinary catheter has been present for more than a few days. Because antibiotic treatment while the catheter is in place is thought to encourage the development of resistant organisms, antibiotic treatment is only recommended if the patient has symptoms or evidence of systemic infection. There may be a place for antibiotic treatment prior to catheter removal, as catheter-introduced infections are often slow to clear spontaneously. Bladder stones may form in patients with long- erm indwelling catheters, further complicating the situation.
Infection by Candida sp. is a frequent complication of prolonged bladder catheterization. Treatment should be . reserved for patients with evidence of invasive infection or those who are immunosuppressed, and should consist of removal or replacement of the catheter and possibly intravesical antifungals.
• Bacteriuria in pregnancy.
The urine of pregnant women must always be cultured as 2-6% have asymptomatic bacteriuria. Failure to treat this may result in severe symptomatic pyelonephritis later in pregnancy, with the possibility of premature labour. Asymptomatic bacteriuria, particularly in the presence of previous renal disease, may predispose to pre-eclamptic toxaemia, anaemia of pregnancy, and small or premature babies. Therefore bacteriuria must always be treated and be shown to be eradicated. Reinfection may require prophylactic therapy. Tetracycline drugs must be avoided in pregnancy, as should trimethoprim in the first trimester and sulphonamides in the third.
Bacterial prostatitis is a relapsing infection which is difficult to treat. It presents as perineal pain, recurrent epididymo-orchitis and prostatic tenderness, with pus in expressed prostatic secretion. Treatment is with drugs that penetrate the prostate-trimethoprim, tetracylines or ciprofloxacin-for 4-6 weeks. Long-term low-dose treatment may be required.
Renal carbuncle is an abscess in the renal cortex caused by a blood-borne Staphylococcus, usually from a boil or carbuncle of the skin. It presents with high swinging fevers, loin pain and tenderness, and fullness in the loin. The urine shows no abnormality as the abscess does not communicate with the renal pelvis, more often extending into the perirenal tissue. Staphylococcal septicaemia is common. Diagnosis is by ultrasound or CT scanning. Treatment involves antibacterial therapy with flucloxacillin and surgical drainage.
Tuberculosis of the urinary tract
Tuberculosis of the urinary tract should still be kept in mind in patients presenting with frequency, dysuria or haematuria, particularly in the Asian immigrant population of the UK. Cortical lesions result from haernatogenous spread in the primary phase of infection. Most heal, but in some, infection persists and spreads to the papillae, with the formation of cavitating lesions and the discharge of mycobacteria into the urine. Infection of the ureters and bladder commonly follows, with the potential for the development of ureteral stricture and a contracted bladder. Rarely, cold abscessses may form in the loin. In males the disease may present with testicular or epididymal discomfort and thickening.
Diagnosis depends on constant awareness, especially in patients with sterile pyuria. Excretion urography may show cavitating lesions in the renal papillary areas, commonly with calcification. There may also be evidence of ureteral obstruction with hydronephrosis. Diagnosis of active infection depends on culture of mycobacteria from early-morning urine samples. The urogram may be normal in diffuse interstitial renal tuberculosis when diagnosis is made by renal biopsy. Some patients present with small unobstructed kidneys when the diagnosis is easy to miss.
The treatment is as for pulmonary tuberculosis Renal ultrasonography or excretion urography should be carried out 2-3 months after initiation of treatment as ureteric strictures may first develop in the healing phase.
This is an uncommon chronic interstitial infection of the kidney, most often due to Proteus spp., in which there is fever, weight loss, loin pain and a palpable enlarged kidney. It is usually unilateral and associated with staghorn calculi. CT scanning shows up intrarenal abscesses as lucent areas within the kidney. Nephrectomy is the treatment of choice; antibacterial treatment rarely, if ever, eradicates the infection.
This is a rare condition in which plaques of abnormal inflammatory tissue grow within the urinary tract in the presence of urinary infection. The histological appearances are characteristic. It is thought that the condition is caused by an acquired inability of macrophages to kill phagocytosed bacteria. Cholinergic agonists and ascorbic acid may improve macrophage function; ciprofloxacin penetrates the macrophage well and is the antibiotic of choice. Prolonged treatment may be needed~ Viral renal infections Viruses are commonly present in the urine in a wide range of common viral infections, but very few viruses cause significant renal disease. Secondary immune complex glomerulonephritis may result from chronic viral infections; for instance, membranous nephropathy complicating hepatitis Band cryoglobulinaemic mesangiocapillary glomerulonephritis complicating hepatitis C infection. The role of cytomegalovirus in renal disease is unclear. Haemorrhagic fever with renal syndrome is the name given to a spectrum of diseases caused by Hanta viruses; renal failure may be severe, and is caused by an acute haemorrhagic interstitial nephritis. Human immunodeficiency virus infection is associated both with focal glomerulosclerosis and with haemolytic uraemic syndrome, but the pathogenesis of these complications remains uncertain.