UTI in elderly

hey guys, this includes other aspects of UTI in elderly, though my part is oni pathophysio =)


Introduction
Urinary tract infection (UTI) is a common problem in the elderly. Diagnosis, prevention, and treatment can often be complex because clinical manifestations can be atypical and host defenses diminish with age.

Classification
• according to localization: urethritis, cystitis, or pyelonephritis.
• Or, symptomatic, asymptomatic, frequency of occurrence, presence or absence of complications, and whether associated with catheter use
• Recurrent infections: relapse or reinfection UTI
o Relapse UTI: urine is rendered partially or temporarily sterile by antimicrobial therapy, with the subsequent recurrence of bacteriuria from the uneradicated pathogen, generally within 2 weeks of completion of therapy.
o Reinfection UTI: arises >= 4 weeks after the previous infection has been cured; the bacterial strain is often different from the strain that caused the successfully treated prior infection.
• Complicating factors: urinary calculi, abscess formation, and obstructive uropathy.

Epidemiology
• Prevalence of UTI increases in both sexes with age; the female:male ratio is 2:1 in the elderly.
• Annual incidence of symptomatic bacterial UTIs: 10% in the elderly.
• Because many of these infections are recurrent, the percentage of infected patients is lower.

Etiology
• More types of urinary pathogens are isolated from elderly patients with UTI than from younger patients.
• Escherichia coli
o < 70% of bacteriuria in elderly female outpatients with uncomplicated sporadic cystitis
o 40% in patients with indwelling bladder catheters, complicated infections, or nosocomial infections.
• Other Enterobacteriaceae, enterococci, and staphylococci are often found
• Klebsiella sp, especially K. pneumoniae (gram-negative, aerobic)
• Proteus mirabilis, P. vulgaris, P. inconstans, and Morganella morganiiare
o more common in men than in women because these species tend to dominate the normal aerobic preputial flora.
o patients with calculi, because they grow best in an alkaline milieu
o patients with urogenital tumors.
• Proteus sp,M. morganii, and Providencia sp: chronically catheterized.
• Serratia, Enterobacter, Citrobacter, Acinetobacter, and Pseudomonas sp: nosocomial UTIs.
• Resistant gram-negative bacteria other than E. coli and gram-positive bacteria (enterococci, coagulase-negative staphylococci, and group B streptococci)P: recurrent infections
• Enterococcal superinfection often results from frequent use of antibiotics that are inactive against these organisms (eg, quinolones, cephalosporins, sulfonamides).

Pathogenesis
• In the elderly, the female/male ratio of incidence in UTIs narrows, because
o elderly men often have bladder outlet obstruction due to benign prostatic hyperplasia.
o decrease in sexual activity in elderly women
• Severe UTIs, particularly those complicated by septicemia originating from the urinary tract, become more common with age, in part because of more frequent bladder catheterization and instrumentation and possibly because of changes in the immune system.
• Recurrent and complicated infections are also more common because of the higher frequency of predisposing anatomic and pathophysiologic factors, such as prolapse, urolithiasis, and malignancies in the GU tract and uterus.
• Bacteria proliferate in stagnant bladder urine, and clinically important bacteriuria becomes established. A large amount of postvoiding residual urine is most common with a neurologic disorder, bladder outlet obstruction, or urethral stricture. (Normal residual urine: 5 to 20 mL)
• Foreign bodies, most commonly indwelling bladder catheters, also promote bacterial growth.

Signs & Symptoms
• Many patients are asymptomatic.
• Symptoms that may occur include dysuria, urinary frequency, incontinence of recent onset, flank pain, and fever.
• Confusion and delirium are often attributed to UTI, although without high fever or sepsis, uncomplicated UTI is unlikely to cause serious central nervous system dysfunction.

Diagnosis
• The diversity of potential uropathogens mandates that urine cultures be obtained in all elderly persons with suspected UTI.
• Rapid tests can provide a semiquantitative determination of bacteriuria. The best is the nitrite test, in which the conversion of nitrate to nitrite by bacteria in the urine is demonstrated by color change on a dipstick. This test has a high degree of sensitivity and specificity but does not demonstrate bacteriuria caused by Pseudomonas sp, staphylococci, or enterococci, which are incapable of reducing nitrate to nitrite.
• Quantitative urine cultures can be performed in bacteriology laboratories to identify the species involved and determine antibiotic susceptibility.
• Recurrent UTIs: In addition to bacteriologic diagnosis, more testing is often necessary, including quantitation of postvoiding residual bladder urine volume and investigation of the architecture of the upper urinary tract via ultrasound or CT in select cases. Urologic consultation may be sought when obstructive uropathy, calculi, abscesses, or GU tract anatomic abnormalities are suspected. Chronic bacterial prostatitis can also result in relapse UTI in elderly men. The diagnosis is suggested when bacterial colony counts from urine or expressed prostate secretion are at least 10-fold greater than counts from the urethral urine sample. Also, the presence of neutrophils in the prostatic secretions substantiates the diagnosis. In relapse UTI, evaluation should include assessment of bladder anatomy and function (ie, postvoiding residual and voiding cystogram or cystoscopy).





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