Asymptomatic Bacteriuria Treatment in Singapore

This temporary form occurs when bacteria briefly colonise the urinary tract but clear spontaneously without treatment. Common in young, healthy individuals, transient ASB typically resolves within days to weeks. The bacteria present usually reflect contamination or temporary colonisation that the body’s immune system effectively manages without intervention.

Persistent ASB involves continuous bacterial colonisation lasting months or years without causing symptoms. This type is more common in elderly individuals and those with underlying urological abnormalities. The same bacterial strain typically remains present across multiple urine cultures, indicating stable colonisation rather than repeated new infections.

Patients with indwelling urinary catheters almost universally develop bacterial colonisation within 30 days of catheter placement. This represents biofilm formation on the catheter surface rather than true tissue infection. Management focuses on appropriate catheter care and removal when possible rather than antibiotic treatment.

The primary cause of asymptomatic bacteriuria is bacterial colonisation of the urinary tract without triggering an inflammatory response. Common bacteria include Escherichia coli (E. coli), which accounts for about 80% of cases, followed by other organisms like Klebsiella, Proteus, and Enterococcus species. These bacteria typically originate from the intestinal tract and colonise the periurethral area before ascending into the bladder. The bacteria establish a balanced relationship with the host without causing tissue invasion or immune activation.

• Age over 65 years
• Female gender (shorter urethra facilitates bacterial ascension)
• Pregnancy (hormonal changes and anatomical pressure)
• Diabetes mellitus (altered immune function and glucose in urine)
• Urinary tract abnormalities (stones, strictures, enlarged prostate)
• Recent urological procedures or instrumentation
• Indwelling catheters or frequent catheterisation
• Neurogenic bladder conditions
• Post-menopausal status (decreased oestrogen affects vaginal flora)
• Immunosuppression from medications or medical conditions
• Previous recurrent urinary tract infections
• Sexual activity in younger women

By definition, asymptomatic bacteriuria presents with no symptoms. Patients feel completely well and have no urinary complaints. The condition is discovered incidentally during routine urine testing for other purposes, such as pre-operative screening, pregnancy checks, or annual health examinations.

• No burning sensation during urination
• No increased frequency or urgency
• No lower abdominal or pelvic pain
• No fever or chills
• No blood in urine visible to the naked eye
• No cloudy or foul-smelling urine
• No back or flank pain
• No nausea or vomiting

If symptoms appear, the condition is no longer classified as asymptomatic bacteriuria but as a urinary tract infection requiring different management. Any development of urinary symptoms, fever, or systemic illness warrants immediate medical evaluation.

The absence of symptoms distinguishes ASB from urinary tract infections. Regular monitoring helps ensure the condition remains asymptomatic and doesn’t progress to symptomatic infection.

The gold standard for diagnosing asymptomatic bacteriuria is urine culture. A clean-catch midstream urine sample is collected to minimise contamination. The laboratory grows and identifies bacteria present, determining the colony count and antibiotic sensitivity. For women, two consecutive positive cultures with the same organism are required for diagnosis, while men need only one positive culture due to lower contamination risk.

Basic urinalysis provides initial screening but cannot definitively diagnose ASB. It may show bacteria, white blood cells, or nitrites suggesting bacterial presence. These findings must be confirmed with culture, as contamination and other factors can cause false positives.

Confirmation through repeat testing is essential before considering treatment. This helps distinguish true colonisation from contamination and transient bacteriuria. Samples should be collected at least 24 hours apart using proper technique to ensure accuracy.

For patients with persistent ASB or risk factors for complications, additional tests may include kidney function tests, imaging studies like ultrasound or CT scan to evaluate for structural abnormalities, and post-void residual measurement to assess bladder emptying. These investigations help identify underlying conditions that might influence management decisions.

For healthy individuals, observation without antibiotics is the preferred approach. Regular urine cultures every 3-6 months help ensure the condition remains stable. This strategy avoids unnecessary antibiotic exposure, reducing risks of resistance and side effects while allowing the body’s natural defences to maintain balance with colonising bacteria.

Antibiotic therapy is recommended only for pregnant women and patients undergoing urological procedures with mucosal bleeding risk. Pregnant women receive treatment to prevent complications like pyelonephritis and premature delivery. Treatment typically involves 3-7 days of pregnancy-safe antibiotics like amoxicillin or cephalexin, with follow-up cultures to ensure clearance.

Patients scheduled for urological surgery involving mucosal trauma, such as transurethral resection of the prostate or ureteroscopy, receive antibiotics immediately before the procedure. This prevents bacteraemia and post-operative infections. The antibiotic choice depends on culture sensitivity results, administered as a single dose or short course.

Addressing predisposing factors helps reduce bacterial colonisation. This includes optimising diabetes control, treating prostatic enlargement, removing unnecessary catheters, and managing post-menopausal vaginal atrophy with topical oestrogen. Improving these conditions may spontaneously resolve ASB without direct antimicrobial treatment.

Some patients benefit from cranberry supplements or juice, which may prevent bacterial adhesion to bladder walls. Probiotics, particularly lactobacillus strains, might help maintain healthy urogenital flora. While evidence for ASB specifically is limited, these interventions are safe and may reduce recurrence in susceptible individuals.

For catheterised patients, focus shifts to proper catheter care rather than treating bacteriuria. This includes maintaining closed drainage systems, ensuring adequate hydration, regular catheter changes according to protocol, and removing catheters as soon as clinically appropriate. Antibiotic treatment is reserved for symptomatic infections only.

Maintaining adequate fluid intake helps flush bacteria from the urinary system. Aim for 2-3 litres of water daily unless fluid restrictions apply. Regular voiding every 3-4 hours and complete bladder emptying reduce bacterial multiplication. Women should wipe from front to back and urinate after sexual intercourse to minimise bacterial introduction.

Optimal control of diabetes through diet, exercise, and medications reduces infection susceptibility. Post-menopausal women may benefit from vaginal oestrogen therapy to restore protective flora. Addressing constipation prevents bacterial overgrowth in the rectum, a common source of urinary colonisation.

Minimise catheter use duration and opt for intermittent catheterisation over indwelling catheters when possible. Proper insertion technique and maintenance protocols reduce contamination risk. Consider alternatives like external collection devices or prompted voiding programmes for incontinence management.

Evidence supports cranberry products for prevention in women with recurrent colonisation. Probiotic foods like yoghurt may help maintain healthy bacterial balance. Limiting bladder irritants such as caffeine, alcohol, and spicy foods might reduce inflammation that facilitates bacterial adhesion.