Urinary Tract Infection in the Elderly

UTI is the most common infection in the elderly, and is especially frequent in debilitated and institutionalised individuals; it is the commonest source of bacteraemia in older adults.

Uncomplicated UTI occurs in a structurally and functionally normal tract; complicated UTI occurs with obstruction, stones, catheters, neurogenic bladder, renal impairment, immunosuppression or male sex — most UTI in older people is complicated.

Catheter-associated UTI (CA-UTI) and urosepsis are the two forms with the greatest mortality.

Obstructive uropathy is the key mechanism — prostatic hypertrophy in men, prolapse and cystocele in women, stones and strictures in both.

Non-obstructive factors: vaginal and urethral atrophy, puddling of urine from bed rest, bladder catheterisation, incomplete emptying with a raised post-void residual, and faecal incontinence.

Host factors: diabetes, immunosenescence with reduced cell-mediated and humoral immunity, malnutrition, dementia and functional dependence.

Phagocytic function and the complement system appear unaltered in ageing; the defect is largely mechanical and mucosal rather than immunological.

E. coli remains the commonest organism, but the frequency of Gram-negative bacilli other than E. coli increases with age — Proteus, Klebsiella, Pseudomonas, Serratia — along with Enterococcus and, in catheterised patients, polymicrobial flora.

Proteus mirabilis is urease-producing and causes alkaline urine, struvite stones and catheter encrustation.

If Staphylococcus aureus is grown from urine, take blood cultures — it usually reflects bacteraemic seeding of the kidney rather than ascending infection.

In India, ESBL-producing Enterobacterales are widespread, with high resistance to fluoroquinolones and third-generation cephalosporins, and rising carbapenem resistance in hospital-acquired infection.

Classical dysuria, frequency and urgency may be absent; presentation is often atypical — confusion or delirium, functional decline, falls, anorexia, incontinence, or unexplained fever.

Fever may be blunted or absent; conversely, in the very old a febrile response is more likely to indicate bacterial rather than viral illness. Absence of leucocytosis does not exclude bacterial infection.

Acute unexplained functional deterioration should alert the physician to a potential acute infectious process.

Nevertheless, non-specific symptoms alone should not be attributed to UTI unless other causes have been excluded — this is the central diagnostic discipline in geriatric practice.

Acute pyelonephritis presents with fever, rigors, loin pain and vomiting; in the elderly it may present simply as collapse or sepsis.

Send a properly collected specimen: clean-catch midstream, or a fresh condom-catheter specimen in incontinent men after cleaning; catheterised patients should have the sample taken from a freshly changed catheter, never from the drainage bag.

Dipstick negative for both nitrites and leucocyte esterase makes cystitis very unlikely; a positive dipstick alone does not establish infection in an older patient.

Treatment principles: choose according to the organism isolated and local resistance patterns; empirical cover should account for the higher frequency of Gram-negative organisms, and renal function must be considered and monitored, particularly with aminoglycosides.

Typical regimens: nitrofurantoin 100 mg twice daily for 5–7 days (avoid if eGFR <45 mL/min) or fosfomycin 3 g single dose for lower UTI in women; 7 days for men; 7–14 days for pyelonephritis with an aminoglycoside or third-generation cephalosporin initially, stepped down by culture; carbapenem or a beta-lactam/beta-lactamase inhibitor for ESBL infection.

Fluoroquinolones should be avoided in older adults where possible — tendon rupture, aortic aneurysm, QT prolongation, delirium, hypoglycaemia and C. difficile.

Supportive care: hydration, review of drugs, treatment of constipation, catheter removal, delirium prevention, and early mobilisation. Investigate for obstruction, stone or abscess if fever persists beyond 72 hours.

Prevention: adequate fluid intake, vaginal oestrogen, avoidance of unnecessary catheterisation, prompt catheter removal, bladder emptying strategies, and not treating asymptomatic bacteriuria.