Anatomical level of infection
Cystitis, urethritis, pyelonephritis, prostatitis
Grade of severity of infection
Uncomplicated and complicated UTIs, urinary tract-driven sepsis, septic shock
Underlying risk factors
Prostatic hypertrophy, permanent catheterisation, incontinence, high motor dependency
Recurrent infections, multiresistant bacteria, antibiotic abuse
ASB is very common in older people: 10.6–16% in older women and 3.6–19% in older men living in the community and up to 50% in older women and up to 40% in older men living in long-term care facilities . Its presence does not necessarily indicate acute illness and is not, on its own, an indication for treatment . Symptomatic UTI requires the presence of new urinary tract symptoms (such as frequency, urgency, dysuria, new incontinence, haematuria, or costovertebral or suprapubic tenderness) together with a urine culture with an identified urinary pathogen (Fig. 16.1) . It represents 5% of all ED visits made annually by older adults in the United States, with a prevalence of 16.5% in a cohort of community-dwelling older women . However, diagnosis becomes problematic when a patient, usually a frail older adult, is unable to provide a clear history of acute urinary symptoms and/or present with nonspecific symptoms such as acute functional decline, confusion (delirium), or generalised weakness.
16.2 Symptoms of UTI
In adult patients, symptoms, signs, and laboratory findings focus on the anatomical level and the degree of severity of the infection (Table 16.2). The risk factor analysis contributes to define any additional therapeutic measure required (i.e. drainage).
Anatomical localisations of UTI and classical related symptoms
Urethra and bladder: lower urinary tract infection (LUTI)
• Dysuria or frequency with or without fever and chills
• Tenderness over the bladder
• Lower back pain
• Urgency, spasm after voiding
• Cloudy urines, haematuria
• Generally acute onset
Kidney: upper urinary tract infection (UUTI) or pyelonephritis
• Loin pain, flank tenderness
• Fever > 38°C
• Rigours or other manifestations of infection
• Pain in the lower back, perirectal area, and testicles
• High fever and chills
• Swelling of the prostate with possible obstruction
• Urinary retention, which can cause abscesses or seminal vesiculitis
• Symptoms of UTI and systemic symptoms
• Presence of bacteria in the blood diagnosed by blood culture
Older people with UTI can present with these classical symptoms, but often, particularly when they have communication barriers, typical symptoms may be absent, masked, or impossible to ascertain. In this case, the predominant clinical expression could be lethargy or agitation (i.e. hypoactive or hyperactive delirium), fever or hypothermia (sepsis), hypotension and tachycardia (septic shock), acute functional decline (or fall), generalised weakness, and so on .
In older adults, the diagnosis of UTI should be always based on a full clinical assessment. The very high prevalence of asymptomatic bacteriuria (with positive dipstick test) together with the high prevalence of atypical presentations or inability to provide a clear history of acute urinary symptoms in older patients (especially in the presence of indwelling catheter holders) risks overdiagnosis and consequent overtreatment. Potentially unnecessary use of antibiotics leads to increased resistance of the common uropathogens, specifically the emergence of multidrug-resistant ESBL-producing Escherichia coli and Klebsiella species. Additionally, overuse of antibiotics increases the risk of antibiotic-related complications such as increasing number of MRSA infections and clostridial diarrhoea, as well as unnecessary costs. There is also an opportunity cost in terms of missed diagnoses—incorrect interpretation of urine dipstick testing can lead to the true diagnoses being missed and delays in treatment.
16.2.1 Asymptomatic Bacteriuria
ASB is defined as the presence of bacteria in the urine in quantities of 105 colony-forming units per millilitre (cfu/mL) or more in two consecutive urine specimens in women or one urine specimen in men, in the absence of clinical signs or symptoms suggestive of a UTI . It is more common in diabetic older patients, while it is constant in indwelling catheter holders and very frequent in incontinent women. The prevalence of ASB is estimated to be between 6 and 10% in women older than 60 years and approximately 5% in men older than 65 . In institutionalised adults the incidence of bacteriuria is even higher, with estimates ranging from 25 to 50% for women and 15 to 35% for men. Table 16.3 shows the prevalence of bacteriuria in different countries and ages. Although ASB increases the risk of symptomatic UTI, it should not be treated except in those patients undergoing invasive genitourinary procedures .
Prevalence of asymptomatic bacteriuria according to age in different countries 
A common clinical scenario is an older patient, maybe living in a residential home, who is referred to the ED with a history of increasing confusion, being unable to provide clear associated symptoms. The patient could have dark and offensive smelling urine; the dipstick test is positive for leucocyte esterase and nitrites. A urine culture is sent (and will be positive), UTI is diagnosed, and antibiotic treatment is started. However, fever or other indices of systemic inflammation (hypothermia, CRP, raised white cell count) or genitourinary tract infection are lacking; other sources of infection (pneumonia, diverticulitis, endocarditis, etc.) have not been ruled out; and alternative diagnoses of acute confusion have not been adequately taken into account. For example, the patient could have recently started codeine for knee pain, and this could be the cause of increasing confusion, constipation, reduced fluid intake with consequent dehydration, and change in the character of urine that is chronically bacteriuric. An apparently simple and well-managed clinical case becomes a misdiagnosis and a missed diagnosis of the true cause of delirium . Moreover, unnecessary antibiotic treatment may frequently cause harm (rash, drug interactions, development of antibiotic resistance, and disruption of intestinal microbiome) .
16.2.2 Symptomatic Urinary Tract Infection
In older patients the symptoms and signs of UTI may be atypical and difficult to distinguish from other urinary diseases. Older adults with UTI are more likely to present to the ED with altered mental status rather than fever or classic urinary symptoms; however, when present, acute dysuria is more specific for UTI than urinary frequency or urgency . Atypical presentations also abound in older patients with pyelonephritis, but fever and chills are more consistently present . Another important symptom of UTI could be the pain in the suprapubic area, the flank, or the back, which in the non-cooperative patient could be suggested by agitation, irritability, and increased confusion (delirium) with increased incidence of falls. Even if incontinence could be a risk factor for UTI, it may also represent a symptom of the disease. When UTI evolves into sepsis or septic shock, typical symptoms—like hypotension, tachycardia, tachypnoea, anorexia, respiratory distress, and abdominal tenderness—may occur but can be delayed or onset abrupt.
As mentioned above, the simple evidence of cloudy or malodorous urine is not sufficient to start an antimicrobial treatment, as it could be due to epithelial cells or mucus, dehydration, or poor hygiene, while the evidence of haematuria could be due to different causes, such as cancer or medication. In older patients also fever may be absent or late in onset, or they could be hypothermic with sepsis. When present, fever is the most important sign, but it is important to exclude other sources of infection.
The vast majority of UTI are due to infection by Escherichia coli, Proteus mirabilis, Klebsiella pneumoniae, Enterococcus, Pseudomonas, and Staphylococcus spp. [12, 13]. Older patients have a lower incidence of Escherichia coli and a higher incidence of polymicrobial infections [12, 13]. In community-living postmenopausal women, E. coli is the most common urinary isolate, accounting for 75–82% of UTIs [12, 13]. Gram-positive organisms including Enterococcus and Staphylococcus accounted for 4.5% and 4.1% of cases, respectively [12, 13]. Klebsiella sp. was the second most common (12%) followed by Enterococcus faecalis (8%) [12, 13]. It is postulated that the postmenopausal state changes the vaginal microbial environment of older women, which together with worsening of incontinence and disability, and greater exposure to antibiotics, leads to change the profile of uropathogens causing UTI in community-dwelling and institutionalised women [12, 13]. In nursing homes the microbiology of UTI changes according to the presence of a long-term catheter [12, 13].
16.3.1 Antimicrobial Resistance
Multidrug-resistant organisms (MDROs) are increasing over time, due to the widespread and frequently inappropriate use of antibiotics for UTI . Although MDROs are more common in healthcare settings, the prevalence of resistant urinary pathogens in community populations is also growing . Figure 16.1 shows the antimicrobial resistance in E. coli-positive urinary cultures in a North Italian environment, with a high prevalence of older people . These data suggest that it is important to know the epidemiology and antibiotic sensibility in each environment, setting, and geographical location, to be able to conduct a correct education of doctors to use antibiotics that are effective and that are not increasing resistances, which vary widely among Europe.