Urinary tract infections

Urinary tract infections

 

A high fluid intake and complete bladder emptying assist antimicrobial therapy of urinary tract infections (UTI).

Acute cystitis

 

A high fluid intake and complete bladder emptying assist antimicrobial therapy of urinary tract infections (UTI).

Escherichia coli and Staphylococcus saprophyticus are the commonest causative organisms, although other members of the Enterobacteriaceae may be responsible. Some patients require investigation to exclude an underlying abnormality when cystitis is confirmed by a positive urine culture. These patients are males of any age, females under 5 years and premenarcheal females with recurrent UTI.

 

 

Acute cystitis: nonpregnant women

 

 

Any of the following regimens can be expected to cure the majority of acute uncomplicated lower UTI in nonpregnant women. Single-dose therapy is not as reliable as multiple dose therapy in preventing relapse. However, in remote communities treatment with nitrofurantoin 200mg orally as a single dose has been found useful. Amoxycillin is only recommended if susceptibility of the organism is proven.

1	trimethoprim 300 mg orally, daily for 3 days
	OR
2	cephalexin 500 mg orally, 12-hourly for 5 days
	OR
3	amoxycillin+clavulanate 500+125 mg orally, 12-hourly for 5 days
	OR
4	nitrofurantoin 50 mg orally, 6-hourly for 5 days.

 

Fluoroquinolones should not be used as first-line drugs as they are the only orally active drugs available for infections due to Pseudomonas aeruginosa and other multiresistant bacteria.

If resistance to all the above drugs is proven, a suitable alternative is

norfloxacin 400 mg orally, 12-hourly for 3 days.

 

Treatment failures are usually due to a resistant organism, an unsuspected underlying abnormality of the urinary tract or re-infection with a similar organism.

If relapse occurs, pyelonephritis should be considered and treatment given for 10 to 15 days.

Acute cystitis: pregnant women

 

 

Prescribers should consider the category of risk posed by the use of the particular antibiotic during pregnancy, see Drugs and their categories in pregnancy and breastfeeding.

1	cephalexin 500 mg orally, 12-hourly for 10 days (category A)
	OR
2	nitrofurantoin 50 mg orally, 6-hourly for 10 days (category A)
	OR
3	amoxycillin+clavulanate 500+125 mg orally, 12-hourly for 10 days (category B1).

 

Urine culture should be repeated after treatment. Amoxycillin (without clavulanate) (category A) is only recommended if susceptibility of the organism is proven.

 

Acute cystitis: men

 

 

An underlying urinary tract abnormality is common and there is often associated infection of the posterior urethra, prostate or epididymis. All males with an UTI should be investigated to exclude an underlying abnormality which determines the duration of antibiotic therapy, see for example Prostatitis.

If there is no underlying abnormality, use

1	trimethoprim 300 mg orally, daily for 14 days
	OR
2	cephalexin 500 mg orally, 12-hourly for 14 days
	OR
3	amoxycillin+clavulanate 500+125 mg orally, 12-hourly for 14 days
	OR
4	nitrofurantoin 50 mg orally, 6-hourly for 14 days.

Acute cystitis: children

 

 

When UTI is confirmed by a positive urine culture, clinical examination for high fever and renal tenderness and investigation are required to exclude pyelonephritis and/or an underlying abnormality for males of any age, females under 5 years and premenarcheal females with recurrent UTI.

Fluoroquinolones should be avoided in children unless deemed necessary on microbiological grounds.

1	cephalexin 12.5 mg/kg up to 500 mg orally, 12-hourly for 5 days
	OR
2	trimethoprim 6 mg/kg up to 300 mg orally, daily for 5 days
	OR
3	amoxycillin+clavulanate 12.5+3.1 mg/kg up to 500+125 mg orally, 12-hourly for 5 days
	OR
4	trimethoprim+sulfamethoxazole 4+20 mg/kg up to 160+800 mg orally, 12-hourly for 5 days.

 

After the initial infective episode, antibiotic prophylaxis (nitrofurantoin or trimethoprim) should be commenced immediately after cessation of the treatment course until such time as urinary tract imaging has been done.

 

Acute pyelonephritis

 

Attempts should be made to define or exclude any underlying anatomical or functional abnormality. The antibiotic susceptibilities of organisms cultured from patients with underlying abnormalities of the urinary tract are often difficult to predict and as therapy may need to be prolonged, high-dose, and often parenteral, it is most important that adequate urine cultures are performed.

Acute pyelonephritis is common in pregnancy where the special problems associated with antibiotic use will need to be considered, see Drugs and their categories in pregnancy and breastfeeding.

 

Mild cases may be treated by oral therapy alone.

1	cephalexin (child: 12.5 mg/kg up to) 500 mg orally, 6-hourly for 10 days
	OR
2	amoxycillin+clavulanate (child: 22.5+3.2 mg/kg up to) 875+125 mg orally, 12-hourly for 10 days
	OR
3	trimethoprim (child: 6 mg/kg up to) 300 mg orally, daily for 10 days.

 

If resistance to all the above drugs is proven or the causative organism is Pseudomonas aeruginosa, use

ciprofloxacin 500 mg orally, 12-hourly.

 

Ciprofloxacin should be avoided in children unless deemed necessary on microbiological grounds.

Treatment should be continued for a total of 10 days. A follow-up urine culture after the conclusion of therapy is advised.

 

For severe infection with suspected sepsis or vomiting, parenteral treatment should be given initially, substituting oral therapy as soon as possible, guided by antibiotic sensitivity results.

	amoxy/ampicillin (child: 25 mg/kg up to) 1 g IV, 6-hourly
	PLUS
	gentamicin (child <10 years: 7.5 mg/kg ; >=10 years: 6 mg/kg) 4 to 6 mg/kg IV, daily (adjust dose for renal function, see Monitoring of aminoglycosides).

 

In patients hypersensitive to penicillin, gentamicin alone will usually suffice.

If the use of an aminoglycoside is undesirable, eg in the elderly, in the presence of significant renal failure or following a previous adverse reaction, as a single drug, use

1	cefotaxime (child: 50 mg/kg up to) 1 g IV, 8-hourly
	OR
1	ceftriaxone (child: 50 mg/kg up to) 1 g IV, daily.

 

Treatment should be continued for a total of 10 to 14 days, the greater part of which may be oral or in an established outpatient IV antibiotic therapy program, guided by antibiotic sensitivity results. A follow-up urine culture at the conclusion of therapy is advised.

Recurrent urinary tract infections

 

 

 

Recurrent infections occur either as relapse of a previously treated infection or because of re-infection. In female patients, instruction on perineal hygiene (especially related to defecation or intercourse) and micturition after intercourse may assist in preventing re-infection. In postmenopausal women, intravaginal oestrogen significantly reduces recurrent infections, see Hormone replacement therapy. In males underlying prostatitis is common.

For the treatment of an episode of recurrent urinary tract infection, one of the antibacterial drugs specified under acute cystitis, should be continued for 10 days; in selected patients self-initiated treatment is an option.

In women of child-bearing age the category of risk posed by the use of any antimicrobial during pregnancy should be considered, see Drugs and their categories in pregnancy and breastfeeding.

 

Prophylaxis instituted after successful treatment can reduce or prevent subsequent attacks and may be continued for 3 to 6 months or in some cases longer. Appropriate prophylactic therapy can be given either continuously (usually at night) or intermittently (eg within 2 hours after sexual intercourse).

1	nitrofurantoin (child: 1 to 2.5 mg/kg up to) 50 mg orally, at night , or in adult females within 2 hours of sexual intercourse
	OR
2	cephalexin (child: 12.5 mg/kg up to) 250 mg orally, at night
	OR
3	trimethoprim (child: 2 mg/kg up to) 150 mg orally, at night.

 Asymptomatic bacteriuria

 

 

The treatment of asymptomatic bacteriuria is a controversial issue and there is evidence that different patient groups require different management.

Treatment is advised for asymptomatic bacteriuria in patients known to have a urinary tract abnormality and those undergoing genitourinary instrumentation, surgery or intermittent catheterisation.

In neonates and preschool children, asymptomatic bacteriuria should be treated and investigations for vesicoureteric reflux or other anatomical abnormalities should be undertaken, see Acute cystitis, children.

In pregnant women, asymptomatic bacteriuria should be treated because of the risk of developing pyelonephritis, see Acute cystitis, pregnant women.

In men under 60 years of age, asymptomatic bacteriuria should be treated and patients should be investigated for the presence of chronic prostatitis, which requires prolonged therapy, see Chronic prostatitis.

In school-age children, nonpregnant women and those over 60 years of age, asymptomatic bacteriuria probably does not require treatment if the urinary tract is normal.

Asymptomatic bacteriuria in patients with long-term indwelling catheters does not usually require treatment, see Catheter-associated bacteriuria and urinary tract infections.

Catheter-associated bacteriuria and urinary tract infections

 

Bacteriuria and pyuria alone are common and not indications for treatment. Generally, treatment should only be given if the patient shows signs of systemic infection (eg fever, rigors), or if the patient has risk factors (eg neutropenia, transplantation, pregnancy), or prior to urological surgery. Cultures should be taken only at that time. There is no role for routine urine cultures. Systemic infection is often due to catheter blockage.

There are two important rules for the management of long-term indwelling catheters:

·            Blockage can be prevented by encouraging the patient to drink adequate fluids and by changing the catheter regularly.

·            A poorly functioning or obstructed catheter must be changed immediately.

Permanent removal of the catheter whenever possible is the greatest contribution towards cure.

Prolonged or sequential courses of antibiotics given for catheter-associated bacteriuria whilst the catheter remains in situ tend to select for organisms resistant to many antibiotics. For similar reasons, local irrigation with antibiotics should not be used. Antibiotics should not be routinely administered at the time of catheter change.

 Candiduria

 

 

The presence of Candida in the urine is common, particularly in association with indwelling urinary catheters, and does not necessarily indicate renal tract infection. Antifungal therapy is not usually indicated and should not be initiated without consultation.

Candiduria may also occur in association with infection of the upper urinary tract and/or systemic candidiasis. In such instances, systemic treatment with antifungal drugs is recommended as for candidal sepsis, see Severe sepsis, Candida species.