Urinary Tract Infections
Section snippets
Asymptomatic bacteriuria
Asymptomatic bacteriuria (ASB) is the presence of 100,000 microorganisms per milliliter of urine without clinical symptoms.5 Usually no treatment is needed. Screening for ASB is not recommended for nonpregnant women,6 elderly living in the community,7 diabetic women,8 institutionalized elderly,9 or persons with spinal cord injuries.9 However, screening with treatment of positive cultures is recommended for pregnant women in the first trimester.5, 6, 7
Uncomplicated UTIs
An uncomplicated UTI is diagnosed in patients with cystitis symptoms who have normal urinary tract anatomy, no fever, no kidney disease, and no contributing medical problems such as diabetes, neurogenic bladder, or renal stones.5, 10, 11 Characteristic symptoms of cystitis include dysuria, urgency, increased frequency, pyuria, and bacteriuria on urinalysis, and sometimes suprapubic pain, fullness, and hematuria.5, 6 No long-term adverse effects have been seen on renal function or increased
Acute pyelonephritis
Acute pyelonephritis is an infection of the kidney that starts either from ASB or from an ascending bladder infection.6 Pyelonephritis can develop from an uncomplicated UTI; however, it is more commonly seen in the setting of obstruction, urinary tract malformations, urolithiasis, or pregnancy.6 Typical symptoms include flank pain, chills, fever (>38°C), nausea or vomiting, and costovertebral angle tenderness. Common symptoms of cystitis also can be present, especially dysuria, increased
Recurrent UTI
Recurrent UTI is defined as at least three episodes of symptomatic uncomplicated UTI with one or more documented positive cultures in 12 months,6, 12 without complicating factors. A relapse is infection with the same organism as the previous UTI.5 A reinfection is when the initial UTI is treated, the patient becomes asymptomatic with a negative culture in between, and then develops symptoms again, or when the second infection is caused by a second organism.5, 6 American College of Obstetricians
Men
Only 20% of UTIs occur in men. Male UTI rates increase dramatically with age, and most are complicated by prostate pathology.1 Men at low risk with a first UTI may be treated using a 3-day course with a first-line agent.14 Low-risk men are defined as under age of 45, with no prostatitis, urethritis, obstructive symptoms, or hematuria.14 Urological evaluation is recommended in adolescents, men with febrile UTI, pyelonephritis, recurrent infections, or when complicating factors are suspected.9
Nosocomial UTIs
There has been a recent interest in prevention of catheter-associated UTI (CAUTI) in the hospital setting, since the Centers for Medicare and Medicaid Services (CMS) identified this as one of six unacceptable diagnoses for payment if UTI was not present on admission.24, 25 As of 2009, a CAUTI is one that occurs in a patient who had an indwelling urethral catheter at the time of or within 48 hours of the event.26 A previous definition included those with a catheter within 7 days of the event.16
Pediatric patients
Infants and children diagnosed with UTIs more often present to emergency rooms than outpatient clinics.48 In any setting, prompt identification, treatment, and follow-up of pediatric UTIs are key to preventing long-term complications.
When considering whether a UTI is the cause of unexplained fever in infants or children, physicians should assess pretest probability, using prevalence data by age, gender, race, and for male patients, circumcision status. A meta-analysis by Shaikh and colleagues49
Immunosuppressed patients
There is sparse literature on UTIs in immunosuppressed hosts, perhaps because opportunistic infections are more likely to manifest in other organ systems.71 Viruses such as BK virus, adenovirus, and cytomegalovirus are a relatively commonly cause of UTIs, particularly hemorrhagic cystitis, in the immunocompromised.72 UTIs are common in renal transplant patients, particularly in the first 3 months after transplantation.73 An international guideline includes the following recommendations for
Patients with spinal cord injury
Urologic complications are a primary source of morbidity and until recently were the leading cause of death for the estimated 260,000 Americans living with spinal cord injury (SCI).75 Factors leading to UTIs in SCI patients are impaired voiding, stone formation secondary to acute bone loss, and altered sensation and symptoms. Variables linked to development of UTI in spinal cord injured patients are prior history of UTI, higher degree of functional impairment, and lack of exercise.76Table 1
Seniors
UTIs occur frequently in the elderly, and contribute significantly to morbidity and mortality. UTIs are a principal cause of falls in nursing home patients,91 especially those with dementia.92 UTIs frequently complicate acute medical conditions such as stroke.93 A clear association exists between UTI and acute coronary syndrome, suggesting that systemic inflammation may even precipitate coronary ischemia.94
Several factors make the diagnosis of UTIs in the elderly challenging. ASB is highly
Diabetic patients
ASB is common in diabetic patients. Although diabetics with ASB have higher rates of developing symptomatic UTIs, there is no good evidence that antibiotic treatment of ASB reduces UTI rates, as recolonization occurs rapidly.103 Nicolle states succinctly: “Bacteriuria is benign, and seldom permanently eradicable.”104 The United States Preventive Services Task Force does not recommend screening for ASB in diabetic patients.8
However, a UTI in a diabetic patient is considered a complicated UTI.
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