An everyday tragedy: treating asymptomatic bacteruria with antibiotics


Act 1 of a common tragedy that sets the scene for antibiotic resistance – an elderly female resident of a nursing home complains of minor dysuria or perhaps just has urine that appears cloudy or smelly. The nurse collects some urine and performs a urinalysis that shows presence of white cells and nitrite.  The urine is sent to pathology where microscopy shows > 100 WC per 10^9/L and a pure growth of E. coli.

The result returns and prompts a call from the nurse to the local community General Practitioner(GP) for the patient- the GP provides a phone order for cephalexin course to treat the patient who by now has no further dysuria nor other symptoms.    Acts 2, 3 and 4 repeat the same cycle over successive months.

Finale – Klebsiella pneumoniae grown that exhibits this multi-resistant antibiogram (FOT represents fosfomycin):

Urine antibiogram

Epilogue – the GP wisely calls the clinical microbiologist to discuss the result. It is confirmed that the patient has minimal symptoms and is systemically well.  No antibiotic treatment is given. The patient is advised to use citrate salts to alleviate dysuria when it recurs and to consider the use of topical oestrogen cream applied to the vaginal introitus as a preventative strategy.

A new Australian Choosing Wisely campaign that builds on a similar foreign venture ( National Prescribing Service)  encourages doctors and patients to question unnecessary interventions. Inappropriate use of antibiotics to treat asymptomatic bacteruria is a major contributor to antibiotic overuse. Asymptomatic bacteruria is when a significant number of uropathogenic bacteria are present in the urine with no or minimal accompanying symptoms such as burning and frequency.

Bacteriuria is extremely common in elderly men and women. It is frequently associated with pyuria and abnormal urinalysis.  Testing of urine from patients with minimal symptoms is NOT indicated. Minor lower tract UTIs are almost always self-limited in any case and are best treated with symptomatic measures in the first instance.

Recurrent symptomatic UTIs in older people should prompt a number of considerations, particularly if pyelonephritis or bacteraemic infection recurs (complicated cases). These include:

  • presence of underlying prostatitis (men)
  • presence of anatomical problems (women) such as uterine or urethral prolapse
  • whether a trial of topical oestrogen is indicated (women)
  • unnecessary exposure to indwelling catheters or mis-management of catheter systems

The overuse of antibiotics for asymptomatic bacteruria  is costly, and is a major cause of antimicrobial resistance and post antibiotic C. difficile infection.

A common initial step towards urinary antibiotic resistance misadventure – the urinalysis test: 

Urinalysis

(Presence of nitrite merely indicates the presence of a species of Enterobacteriaceae (eg. E. coli that are able to reduce nitrate to nitrite. Other causes of UTI like Streptococcus do not lead to a positive nitrite result.)

About mdjkf

Microbiologist and Infectious Diseases Physician
This entry was posted in A/m stewardship, Cautionary tales, Module-Urinary tract infection and tagged . Bookmark the permalink.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s