Urinary Tract Infections

Optimal therapy for urinary tract infection is based on results of susceptibility tests following culture of the causative organisms.

Acute uncomplicated Cystitis

This includes patients with asymptomatic bacteriuria.

These infections are typically community-acquired and are usually caused by Escherichia coli (90%), Staphylococcus saprophyticus (5%), or other Enterobactericeae (5%).  Mixed infections are rare.  In view of the high prevalence of resistance to ampicillin and cotrimoxazole, some authorities recommend amoxycillin-clavulanate, an oral first-generation cephalosporin (e.g. cephalexin), or a quinolone (ciprofloxacin, enoxacin, ofloxacin etc) as the empiric agents of choice.  However, others advocate the use of either ampicillin or cotrimoxazole for uncomplicated UTI since these antibiotics frequently achieve concentrations in urine in excess of the MICs of resistant strains.  This may explain why an uncomplicated UTI may apparently respond to an antibiotic even when the pathogen is judged resistant by laboratory tests.  Quinolones should be avoided during pregnancy.  A 3-day regimen achieves the best results in patients with uncomplicated UTI.  This is considered as effective, costs less, and causes fewer side effects than 7-day regimens.  One-day regimens are associated with higher recurrence rates.   The antibiotics listed below are in order of cheapest to more expensive drugs.

          Ampicillin or amoxycillin 250 mg 8 hourly for 3 days (50 mg/kg/day in children)
                           OR
Cotrimoxazole 1 double strength tablet 12 hourly for 3 days (8 mg/kg/day TMP + 40 mg/kg/day SMX)
                           OR
Enoxacin 400 mg 12 hourly for 3 days
                           OR
Fosfomycin 3 g orally stat dose
                           OR
Amoxycillin-clavulanate 1 tablet containing 250 mg amoxycillin 8 hourly for 3 days
                           OR
Ciprofloxacin 250 mg 12 hourly for 3 days
                           OR
Cephalexin 500 mg 12 hourly for 3 days (25 - 50 mg/kg/day in children)
                           OR
Ofloxacin 200 mg 12 hourly for 3 days
                           OR
Norfloxacin 400 mg 12 hourly for 3 days.

Single dose therapy is no longer favoured. 

In pregnancy, consider a 7-day regimen of ampicillin, amoxycillin, cotrimoxazole (not in 3rd trimester), amoxycillin-clavulanate or cephalexin.

Acute pyelonephritis

This is caused by the same range of pathogens as uncomplicated cystitis, except that Staphylococcus saprophyticus is a rare cause of pyelonephritis.

Pre- and post-treatment (10 - 14 days after discontinuation of treatment) cultures are strongly advised.

Treatment with appropriate antibiotics for 2 weeks is usually sufficient.   The initial route of antibiotic administration (oral vs parenteral) and setting of treatment (outpatient vs inpatient) depends on the severity of the illness (mild to moderate vs moderate to severe), overall clinical condition, patient reliability and compliance, whether there is nausea and/or vomiting, and whether the patient is pregnant.  Suggested empiric regimens include:

Mild-to-moderate illness:

Oral antibiotics:      Enoxacin 400 mg 12 hourly for 14 days
                                                            OR
                                    Ciprofloxacin 250 mg 12 hourly for 14 days
                                                            OR
                                    Amoxycillin/clavulanate 1 tablet containing 250 mg      
                                    amoxycillin 8 hourly for 14 days.

Severe illness and possible urosepsis: Parenteral therapy (e.g. ciprofloxacin OR amikacin with or without ampicillin OR a second- or third-generation cephalosporin) until the fever abates, then oral therapy (as for mild-to-moderate illness) for a total of 14 days.

Pregnancy: Hospitalisation is recommended.  Ceftriaxone (OR cefotaxime) OR amikacin IV until the fever abates, then oral therapy with amoxycillin-clavulanate OR cephalexin OR cefuroxime axetil for a total of 14 days.

Recurrent urinary infections

Continuous prophylactic antibiotic therapy should be considered in women with more than 3 UTI’s/year.  Antibiotics are given on a thrice-weekly basis and the choice of antibiotic is based on previous sensitivity results, and costs.

Postcoital prophylaxis if UTI is related to coitus:  Single dose of norfloxacin 400 mg OR ciprofloxacin 250 mg OR amoxycillin/clavulanate 1 tablet OR cephalexin 500 mg OR nitrofurantoin 100 mg OR trimethoprim 100 mg after coitus.  Micturition to empty the bladder completely shortly after coitus should be strongly advocated.

Prevention of catheter-associated UTI:  Administration of antimicrobials is not of value in preventing colonisation/infection in patients with indwelling catheters.  Furthermore, this has been shown to promote the selection of resistance.

Urinary tract infections in children

In general, children with urinary tract infections without obstruction or vesicoureteric reflux, have a very good prognosis.  In the presence of obstruction (e.g. urethral valves), severe destruction of renal parenchyma can occur.  Ultrasonography and voiding cystourethrography are therefore recommended in all boys after the first episode of urinary infection and in preschool girls at least after the second infection, in order to detect remediable causes timeously.

Prostatitis

Acute:      Ciprofloxacin 500 mg 12 hourly OR ofloxacin 300 mg 12 hourly OR norfloxacin 400 mg 12 hourly OR cotrimoxazole 1 DS   tablet twice daily.
These antibiotics are given for 2 - 4 weeks.
Urine culture is necessary in the initial workup, and 10 – 14 days after completion of treatment.

Chronic:   Antibiotic as above for 4 weeks.  If there is no response after 4 weeks, the same antibiotic should be given for 12
                    weeks.