With an ageing population, the burden of urinary tract infection in older adults is likely to grow, making the need for improved diagnosis and appropriate management essential to managing the health of older adults. (4) Ased Ali B.Sc.(Hons), MB.ChB, PhD, FRCS(Urol), Consultant Urological Surgeon at Mid Yorkshire Hospitals, explains further – providing a comprehensive overview of lower urinary tract infection in the elderly.

Urinary tract infection (UTI) is broadly defined as an infection of the urinary system involving the lower urinary tract and may include involvement of the upper urinary tracts. (1) The definition of a symptomatic UTI generally requires the presence of urinary tract-specific symptoms in the setting of significant bacteriuria with a quantitative count of ≥10 (5) colony forming units of bacteria per millilitre (CFU/ml) in one urine specimen. (2) Asymptomatic bacteriuria (ABU) is defined as the presence of bacteria in the urine, without clinical signs or symptoms suggestive of a UTI. (2)

Incidence

UTI is one of the most commonly-diagnosed infections in the elderly. It is the most frequently-diagnosed infection in long-term care residents, accounting for over a third of all nursing home-associated infections. (3)

The incidence of UTI is higher in women compared with men across all age groups. In post-menopausal women, the incidence of UTI is estimated at 0.07 per person-year and 0.12 per person-year in older women with diabetes. (5) For men aged 65-to-74 years, the incidence of UTI is estimated to be 0.05 per person-year. (6) Over 10 per cent of women over the age of 65 years report having a UTI within the previous 12 months (7) which increases to almost a third of women over the age of 85 years. (8) Consequently, in both men and women over the age of 85 years, the incidence of UTI increases substantially. A cohort study looking at this older age group found the incidence of UTI in women to be 0.13 per person-year and 0.08 per person-year in men. (9)

ABU is also more common with increasing age in both men and women. In younger women, the estimated prevalence of ABU is one-to-five per cent, increasing to an estimated six-to-16 per cent in women over the age of 65 years. (10) The use of urinary catheters predisposes both men and women to ABU. The risk in catheterised older adults ranges from three to 10 per cent per day of catheterisation, eventually reaching 100 per cent in adults with chronic indwelling catheters. (11)

Risk Factors

Women, both young and elderly, are at greater risk of UTI than men, however, the most consistent and strongest predictor across women of all age groups is having a history of previous UTI. (12) In one study, post-menopausal women with a prior UTI were over four-times more likely to develop a subsequent infection compared with women without a previous diagnosis. (12)

Urinary retention and high postvoid residual (PVR) urine has been postulated to be a risk factor for UTI in older adults. In men, high PVR and urinary stasis as a result of chronic obstruction due to prostatic hypertrophy are thought to be important factors for developing UTI and ABU; however, studies evaluating the association in this population are limited. A study of post-menopausal women in 2011 found that a PVR greater than 200 ml was associated with more frequent urinary symptoms. (13)

Older adults in residential or nursing care are more likely to have functional and cognitive impairments plus more medical comorbidities compared to older adults living in the community. All of these characteristics predispose this population to higher rates of ABU and UTI. (14) The most significant risk factors associated with UTI in long-term care facilities is the presence of a urinary catheter and, similar to community-based older adults, history of prior UTI. (9) Comorbidities, such as stroke and dementia, which may predispose individuals to bowel and bladder incontinence, are also associated with symptomatic UTI and persistent ABU in this population.

Diagnosis

UTI in healthy older women without a urinary catheter or abnormalities of the genitourinary tract is generally regarded as uncomplicated. (1) Diagnosis is usually based on common urinary symptoms suggestive of cystitis including urgency, frequency, dysuria and supra-pubic tenderness.

However, post-menopausal women may also present with non-specific generalised symptoms, such as lower abdominal pain, back pain, chills and constipation. (15) Traditionally, a diagnosis of UTI has required the presence of urinary tract-specific symptoms together with significant bacteriuria denoted by a quantitative count of ≥10 (5)16 CFU/ml in one urine specimen. However, a diagnosis can often be made based on symptoms and signs – a culture is not routinely required. (16)

ABU in women is defined as the presence of two consecutive urine specimens positive for the same bacterial strain in quantities ≥10 (5) CFU/ml, in the absence of any signs or symptoms of a genitourinary tract infection. For men, ABU is defined as a single voided specimen with one bacterial isolate in quantities ≥10 (5) CFU/ml, in the absence of symptoms. (2) For adults with an indwelling urethral, suprapubic or intermittent catheter, ABU is defined as a positive urinary culture for one bacterial isolate in quantities ≥10 (2) CFU/ml, in the absence of symptoms. (19)

In nursing home residents, the diagnosis of symptomatic UTI can be particularly challenging, often due to impaired ability to communicate as a result of cognitive deficits, and chronic genitourinary symptoms (e.g., incontinence, urgency and frequency). Furthermore, when suffering a UTI, long-term care residents are more likely to present with non-specific symptoms, such as loss of appetite, confusion and general decline in function. (17) In the setting of atypical symptoms, clinicians are often faced with the challenge of differentiating a symptomatic UTI from other infections or medical conditions.

To address this issue, a cohort study in nursing home residents attempted to identify clinical features that were predictive of ‘culture-confirmed’ UTI. The most commonly-reported clinical features for suspected UTI in this cohort were change in mental status (39 per cent), change in behaviour (19 per cent), change in character of the urine (i.e., gross haematuria and change in the colour or odour of urine; 15.5 per cent), fever or chills (12.8 per cent) and change in gait or a fall (8.8 per cent). (17) In a multivariable analysis, change in mental status, dysuria and change in character of the urine were significantly associated with culture-confirmed UTI.

The diagnosis of UTI remains a significant diagnostic dilemma for clinicians caring for older adults – fever and localised urinary symptoms should still be the initial trigger for UTI evaluation. The Scottish Antimicrobial Prescribing Group (SAPG) produced a decision aid tool in 2018 to help identify those patients likely to require treatment. (18)

Treatment

The most common organism responsible for causing UTI in both community and healthcare settings is Escherichia coli, followed by other Enterobacteraciae, such as Proteus mirabilis, Klebsiella and Providentia species (found more commonly in catheter-associated UTI). Gram-positive organisms, such as methicillinresistant Staphylococcus aureus (MRSA) and Enterococcus, are also found but less commonly overall, although frequency is increasing in healthcare settings and in adults in long-term care. (19)

With increased emphasis on antibiotic stewardship, careful prescribing of antibiotics has become paramount. The risk of Clostridium difficile diarrhoea and other healthcare-associated infections can be reduced by greater use of targeted, narrow spectrum antibiotics. However, this also increases the necessity for accurate diagnosis and organism identification where possible. Local guidelines based on local resistance patterns and available agents are therefore essential.

The management of uncomplicated symptomatic UTI in women has been the subject of several randomised controlled trials but most exclude the very elderly and focus on younger adults. Current British National Formulary (BNF) and SAPG guidance advocate that Nitrofurantoin and Trimethoprim may be used as the first-line antibiotic in uncomplicated symptomatic UTI in females. (10, 20) Nitrofurantoin is not to be used in those with renal impairment due to the inability to achieve necessary concentrations in the urine and possibility of toxic levels in the plasma. (10) Trimethoprim should only be used if there is low risk of resistance. Second-line treatments are listed as Nitrofurantoin, Fosfomycin and Pivmecillinam. The European Association of Urology (EAU) guidelines no longer include Trimethoprim as first-line treatment and advise usage only in areas where resistance rates for E. coli are less than 20 per cent. (21)

A three-day course of Nitrofurantoin is recommended for women and a seven-day course for men. A Cochrane review of 15 randomised controlled studies examined evidence for duration of antibiotic therapy for uncomplicated, symptomatic lower UTIs in older women (1,644 elderly females) were reviewed and the authors concluded that short course antibiotics of three-to-six days could be adequate for treating uncomplicated UTI in older women. (22) However, for persistent, chronic and recurrent infections, longer courses and or prophylactic courses may be required to remove bacterial persistence. (1, 21, 23)

In catheterised patients with symptoms of UTI, a seven-day course of antibiotics, following local antibiotic guidelines, is recommended in both men and women. (11) The catheter should be removed then replaced if necessary.

For more information, visit Bladder Health UK at www.bladderhealthuk.org or call 0121 702 0820.

References

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