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Urinary Tract Infections

Urinary Tract Infections. Meral Sönmezoğlu Division of Infectious Diseases Yeditepe University Hospital. Learning objectives UTI’s. Epidemiology Pathogenesis Risk Factors Types of cystitis Evaluation Therapy. Urinary System. Based on: Mader, S., Inquiry Into Life , McGraw-Hill.

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Urinary Tract Infections

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  1. Urinary Tract Infections Meral Sönmezoğlu Division of Infectious Diseases Yeditepe University Hospital

  2. Learning objectives UTI’s • Epidemiology • Pathogenesis • Risk Factors • Types of cystitis • Evaluation • Therapy

  3. Urinary System Based on: Mader, S., Inquiry Into Life, McGraw-Hill

  4. Anatomy of the Kidney Based on: Mader, S., Inquiry Into Life, McGraw-Hill

  5. Nephron Based on: Mader, S., Inquiry Into Life, McGraw-Hill

  6. Urine moves from the collecting ducts through the kidney pelvis to the ureter Based on: Mader, S., Inquiry Into Life, McGraw-Hill

  7. Urine moves from the kidneys, through the ureters to the bladder and finally through the urethra Based on: Mader, S., Inquiry Into Life, McGraw-Hill

  8. Epidemiology UTI’s • UTIs are the second most common cause for prescription of antibiotics • Most infections are limited to the lower urinary tract • 30 times more likely in young women than young men • Incidence in men rises dramatically after age 50

  9. Women may have more UTIs than men because: • they have a shorter urethra, allowing quicker access to the bladder • the urethral opening is nearer the anus • intercourse may result in UTIs in women Based on: Harvard Medical School Family Health Guide

  10. Relative frequency of nosocomial (hospital-acquired) infections

  11. Pathogenesis UTI’s Bacteria travel: • Ascending route via the urethra 95% • Hematogenous (kidney-> bladder) • Endocarditis • Tuberculosis • Direct (connection bowel-bladder)

  12. Bacterial factors • Inoculum size • Virulence • Adherence • E. coli adhere to urothelial cells • Proteus, Providencia adhere to lumen of catheter material

  13. Virulence Host factors Infection No infection

  14. Host defense mechanisms • Mechanical • Dilution and flow of urine • Length of urethra • Interference • Normal bacteria flora (meatus) • Chemical • Osmolality and pH of urine • Prostatic fluid • Anti-adherence mechanisms in bladder • Urinary immunoglobulins • Mucosal antibacterial activity

  15. Risk factors UTI’s (I) • Alteration/introduction of bacteria • Antibiotics • Spermicides • Vaginal atrophy (age) • Sex • Insertive rectal sex • Inserting toys • Patient education: • Void after intercourse, • Proper wiping, front to back once

  16. Urinary stasis Neurologic bladder Reflux into the ureters (pregnancy) Obstruction Congenital anatomical abnormalities Prostate hypertrophy (age) Stones, tumor Diabetes mellitus Glycosuria Foreign materials Stones Stents Catheters Risk factors UTI’s (II)

  17. Pathogenesis of cystitis

  18. UTI’s • Uncomplicated cystitis • Risk factors • Complicated UTI’s • When to look for causes • Interpret UA, dipstick, urine cx • Asymptomatic bacteriuria • Catheter-related issues • Prudent use of antibiotics

  19. Types of urinary tract problems • Asymptomatic bacteriuria • Dysuria • Cystitis • Acute uncomplicated cystitis • Recurrent cystitis • Complicated UTI • Pyelonephritis • UTI’s in men, pregnant women, children • Prostatitis • Other • Catheter associated UTI • Candida in urine • Sterile pyuria

  20. Definitions (I) • Asymptomatic bacteriuria: • isolation of a specified quantitative count of bacteria • in an appropriately collected urine specimen • obtained from a person without symptoms or signs referable to urinary infection • Acute uncomplicated UTI (cystitis): • symptomatic bladder infection • characterized by frequency, urgency, dysuria or suprapubic pain • in a woman with a normal genitourinary tract

  21. Definitions (II) • Acute nonobstructive pyelonephritis: • renal infection • characterized by costovertebral angle pain • often with fever • sometimes with bacteraemia • Complicated urinary tract infection: • may involve the bladder or kidneys • symptomatic urinary infection • in individuals with functional or structural abnormalities of the urinary tract

  22. What can the laboratory do with a sample of urine? • Urinalysis • Microscopy • Dipstick • Quantitative culture • Specialized cultures (TB, fungi)

  23. Urine dipstick • Leukocyte esterase: rapid screening test for detecting pyuria • Patients with symptoms and negative LE should have a urine microscopic examination for pyuria • Urinary nitrite • Nitrite is formed when bacteria reduce the nitrate that is normally found in the urine • False negatives common, but false positives are rare

  24. The whys and how's of urinary tract organism quantification • Bladder urine is sterile • Distal urethra is not sterile • How can we differentiate: • bladder bacteria (pathogens) from • urethral bacteria (contaminants)?

  25. What is a positive culture? • Classic definition: > 105 cfu/ml • With symptoms: > 103 cfu/ml • 90% chance of actual infection

  26. Etiologic agentsCommunity acquired-UTI • E. coli (25%) • Enterococcus spp (16%) • P. aeruginosa (11%) • Candida spp. (8%) • K. pneumoniae (7%) • Enterobacter spp. (5%) • Proteus mirabilis (5%)

  27. Community-Acquired UTI E.coli S.epi & gm - enterics Enterococcus Proteus S.saprophyticus K.pneumoniae

  28. Microscopy • A true UTI is accompanied by • Pyuria • >10 leukocytes/mm³ of uncentrifuged urine • unless catheter in place • Lack of epithelial cells • >5/ mm³ indicates contamination • Only one bacterial species (monoculture) • >105 cfu • Do not culture urine unless • Indicated AND • Abnormal UA

  29. Dysuria • Dysuria can be caused by • Vaginitis -no pyuria and <102 cfu/ml) • Candida • Trichomonas • atrophy of vaginal tissues • Urethritis –pyuria and <102 cfu/ml, gradual • Chlamydia • Neisseria gonorrhoeae • Cystitis – pyuria and >103 cfu/ml, onset abrupt

  30. Asymptomatic bacteriuria - why screen? • Screening of asymptomatic people for bacteriuria is only appropriate to prevent adverse events • In pregnancy (Gp B strep) • Prior to urologic surgery • Undesirable outcomes associated with therapy: • Antimicrobial resistance • Adverse drug effects • Costs • C. difficile associated disease

  31. Asymptomatic bacteriuria-Healthy, premenopausal women • Bacteriuria increases risk for symptomatic UTI • Not associated adverse outcomes • Treatment of asymptomatic bacteriuria • neither decreases frequency of symptomatic infection • nor prevents further episodes of asymptomatic bacteriuria • Screening for and treatment of asymptomatic bacteriuria is not indicated

  32. Asymptomatic bacteriuria - Pregnant women • 20-30 fold increased risk of pyelonephritis during pregnancy • More likely to experience premature delivery and to have low birthweight infants • Treatment of bacteriuria decreases above risks • Screen for bacteriuria by urine culture at least once in early pregnancy and treat for 3-7 days if positive

  33. Asymptomatic bacteriuria -Elderly institutionalized subjects • No decrease in rate of • symptomatic infection • improvement in survival • chronic GU symptoms with Abx therapy • Screening and treatment of asymptomatic bacteriuria in elderly institutionalized residents of long-term care facilities not recommended

  34. Asymptomatic bacteriuria –Patients with indwelling catheters • Antimicrobial therapy not associated with decrease in rate of symptomatic infection • High incidence of recurrence, usually with more resistant organisms • Asymptomatic bacteriuria or funguria should not be screened for or treated in patients with indwelling urethral catheter

  35. Symptoms Dysuria, frequency, urgency Initial and terminal hematuria Suprapubic discomfort Low-grade fever may occur Exclude other causes STD Vaginitis Diagnosis Dipstick or microscopy Nitrite positive Positive LE/WBC (>10 WBC’s) Culture Not routinely necessary Carefully obtained clean catch 104-5 cfu/ml 1 bacterial species only Acute uncomplicated UTI (cystitis)

  36. Acute uncomplicated UTI (cystitis) • Bacteria • E. coli in 80-90% • Staph. saprophyticus in 5-15% • Proteus and Klebsiella species • Adult female • No anatomic/functional/immunologic abnormalities • Non-pregnant

  37. Acute uncomplicated UTI -Therapy • Resistance varies • 30% resistant to amoxicillin • 1-20% to nitrofurantoin • 5-15% to TMP-SMX • Recommend: course of • TMP-SMX as first choice (3 days) • Fluoroquinolone as second (3 days) • Nitrofurantoin (7 days) • Does not penetrate in kidney

  38. Recurrent Cystitis • Relapse: same organism in <2 weeks • Suggests uneradicated focus • Abx resistance • Non compliance • Reinfection - may be same or different organism: Interval >2 weeks • Hygiene/wiping • Post-coital • Vaginal atrophy • Post-void residual (prolapse)

  39. Management: Recurrent UTI • Patient-initiated therapy: multiple 3 day courses of antibiotics to be started by the patient at onset of sx • Post-menopausal women: symptomatic relief with topical estrogen -helps to “normalize” protective flora

  40. Further Studies / Referral • Renal US- least invasive • VCUG- beststudy to detect vesico-urethral reflux • CT / MRI • IVP • According to Fihn, NEJM (July 17,2003), imaging studies are not necessary unless there are other sx ie. hematuria.

  41. Complicated UTI(Everyone/everything else) • Child, male, pregnant female • Kidney involvement, 2nd bacteraemia • Abnormality • Anatomy, function, immunology • Urologic procedure • Catheterization • Unusual or resistant organisms

  42. Acute pyelonephritis • Usually E. coli • Obtain urine culture • If hospitalized obtain blood cultures • Mostly an ascending infection • Disease severity • Mild • Life threatening urosepsis

  43. Acute pyelonephritis -Therapy • Mild to moderately ill patients • TMP-SMX (bactrim) amox/clav, cefuroxime or fluoroquinolone • Patients usually improve in 48-72 hours • Treat for 1-2 weeks • Severely ill patients • Ampicillin + aminoglycoside • IV therapy until patient afebrile for 48-72 hours • Treat for 2 weeks • If fever persists and all children and men: • Renal US, CT or MR ± IVP • Look for perinephric abscess • Exclude urinary obstruction

  44. Cystitis in males • Young men (rare in men under 50) • Anatomic abnormalities • Anal insertive sex, toys • Older men • Calculi • Enlarged prostate (obstruction) • Chronic prostatitis • Organisms differ • E. coli accounts for 40-50% • Proteus and Providencia species accounting for next most frequent cause • Most common cause of relapsing UTI is chronic bacterial prostatitis

  45. UTI’s in males (other than pyelonephritis) • Urethritis (STI’s) • Gonorrhea • Chlamydia • Ureoplasma • Prostatitis • Same organisms as above • For older males (in addition to above): • Gram negative rods • Enterococci

  46. Acute prostatitis • Fever, chills • Dysuria, pain • Marked local tenderness • Excellent penetration by most antibiotic classes-easily cured • Complications • Prostatic abscess • Chronic prostatitis

  47. Chronic prostatitis • Chronic pain • Dysuria • Recurrent “UTI’s” – same organism • Poor antibiotic penetration-difficult to treat • Biofilm • Calculi • Preferred agents • Fluoroquinolones • TMP-SMX

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