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Asymptomatic Urinary Tract Infection

Asymptomatic Urinary Tract Infection. Edward L. Goodman, MD October 13, 2003. A Common Problem: Prevalence of AB in Ambulatory Persons. Young women: 1-2% Women >60 years: 6-10% Men >65 years: >5% Swedish city At 72 years, 6% men, 16% women VA outpatient men 65-74 years old: 9%

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Asymptomatic Urinary Tract Infection

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  1. Asymptomatic Urinary Tract Infection Edward L. Goodman, MD October 13, 2003

  2. A Common Problem: Prevalence of AB in Ambulatory Persons • Young women: 1-2% • Women >60 years: 6-10% • Men >65 years: >5% • Swedish city • At 72 years, 6% men, 16% women • VA outpatient men • 65-74 years old: 9% • 75-84 years old: 15.3% Nicolle. Inf Dis Clin NA, 1997; 11: 647

  3. Elderly Institutionalized • Prevalence • Men: 15 – 35% • Women: 25 - 50% • Incidence Studies • NH with negative culture on admission • 11% men positive at one year • 23% women at one year • Another study: 10% acquire every 3 months Nicolle IDCNA 1997

  4. So, it’s common- big deal! • We’ve got The Sanford Guide • We can look it up conveniently • Who needs a lecture? • For those of us who can’t read the small print • We’ve got Epocrates • Current house staff were all born with a Palm Pilot™ clutched in their palm! • What’s the big deal – just treat it!

  5. BUT • All antibiotic use ultimately leads to microbial resistance • Resistance results in increased morbidity, mortality, and cost of healthcare; and • Appropriate antimicrobial stewardship should prevent or slow the emergence of resistance among organisms (Clin Inf Dis 1997; 25:584-99.) • Antibiotics are used as “drugs of fear” • (Kunin et al. Ann Int Med 1973;79:555)

  6. Antibiotic Misuse • Surveys reveal that: • 25 - 33% of hospitalized patients receive antibiotics (Arch Intern Med 1997;157:1689-1694) • 22 - 65% of antibiotic use in hospitalized patients is inappropriate (Infection Control 1985;6:226-230)

  7. Consequences of Misuse of Antibiotics • Contagious RESISTANCE • Nothing comparable for overuse of procedures, surgery, other drugs • Morbidity - drug toxicity • Mortality - MDR bacteria harder to treat • Cost

  8. Definitions: Asymptomatic Bacteriuria • “Gold standard” for bacteriuria = >=100,000 CFU/ml voided urine • Applied to Asymptomatic Bacteriuria • Almost always present in acute pyelonephritis • Kass, EH. Trans Assoc. Amer. Phys 69:56, 1956

  9. Definitions: Symptomatic Bacteriuria • Acute cystitis in women: >= 100 CFU/ml • 95% sensitivity; 85% specificity* • Acute pyelonephritis: > 100,000/ml** • (The standard 0.001 ml loop cannot detect <1000 organisms/ml) • *Stamm WE. NEJM 3229:1328, 1982 • **Kass 1956

  10. Infectious Disease Society Consensus Definition • Cystitis: >=10³ cfu/ml • Sensitivity 80%; Specificity 90% • Pyelonephritis: >=10,000 cfu/ml • Can be identified in routine micro labs using 0.001 ml loop • Rubin et al. Clinical Infectious Disease, 1992

  11. Symptoms • Acute: irritation, obstruction or inflammation – correlate with significant bacteriuria • Chronic: incontinence, hesitancy, hematuria – do not correlate with bacteriuria in elderly • In demented: non-specific symptoms such as altered mentation are fairly sensitive for systemic infection

  12. Colonization vs. Infection • Bacteriuria is almost always associated with a host response • Pyuria • Cytokinuria • HENCE, THE TERM COLONIZATION OF URINE IS OBSOLETE. It is infection, asymptomatic or symptomatic

  13. Why So Many Urine Cultures? • Annually 10,400 urine cultures are submitted to the PHD Microbiology Laboratory • Exceeded only by 14,000 blood cultures • At least one third from catheterized patients • Often cath specimens are mislabeled as voided • It is an effort to obtain a clean catch urine from a hospitalized patient • Catheter urine is so convenient to culture! • Nursing preferences play a major role

  14. HCW’s Attitudes and Perceptions • HCW interpret bacteriuria as symptomatic in presence of nonspecific symptoms • Urine cultures are thus ordered for nonspecific changes in patient’s status – part of the “panculture” mentality • Difficulty in eliciting information about symptoms in frail elderly

  15. Attitudes and Perceptions –2 • Physician’s uncertainty about significance and management of positive urine culture • Liability concerns • A positive culture left untreated looks “bad” in the chart • Walker et al. CMAJ 2000; 163 (3): 273

  16. Refrain: Prevalence of AB in Ambulatory Persons • Young women: 1-2% • Women >60 years: 6-10% • Men >65 years: >5% • Swedish city • At 72 years, 6% men, 16% women • VA outpatient men • 65-74 years old: 9% • 75-84 years old: 15.3% Nicolle, Inf Dis Clin NA, 1997

  17. Refrain II: Elderly Institutionalized • Prevalence • Men: 15 – 35% • Women: 25 - 50% • Incidence Studies • NH with negative culture on admission • 11% men positive at one year • 23% % women at one year • Another study: 10% acquire every 3 months Nicolle 1997

  18. Does Rx for AB Help? • All data is from elderly in long term care facilities • Early studies (Platt, NEJM 1982;307:637) suggested AB associated with three fold higher mortality • Therapy had no protective effect • AB seems to be a marker of debility • More recent comparative studies confirm no benefit from Rx and no higher mortality in non Rx

  19. Case Presentation • 91 year old woman admitted from NH with fever, altered mental state and drainage from recent hip incision, no urinary sx • Urine culture from cath inserted in ER: >100,000 Pseudomonas aeruginosa • Diagnosis: “Urosepsis” • BUT

  20. Case continued • Blood and hip aspirate cultures: MRSA • No response to anti-pseudomonas Rx: still confused • Woke up with Vancomycin • Diagnoses: • Infected total hip with secondary bacteremia – MRSA • Asymptomatic bacteriuria - Pseudomonas

  21. Fever and UTI in Elderly Institutionalized • Prospective study • Jan 1, 1989 through Dec 31, 1990 • Two LTCF in Canada • Demographics • M:F 3:1 • Majority >65 years • Catheters 5.7% to 9.3% Nicolle, AJM 1996; 100:71.

  22. Fever and UTI in Elderly Institutionalized • Entry Criteria – Fever • Urine cultures, UA at enrollment and Q4 weeks • Monitored serum antibody • Major Outer Membrane Protein (MOMP) of E coli for all enterobacteriaceae • IgG to other organisms

  23. Fever and UTI in Elderly Institutionalized: Definitions • Fever >38 (100.4) • Sx UTI for non cath required at least 3: • Fever or chills* • New or increased lower tract irritation • New flank or suprapubic pain or tender • Change in character of urine • Worsening mental status* • *our case

  24. Definitions continued • Indwelling catheter: two symptoms • Fever or chills • New flank or suprapubic pain/tender • Change in character of urine • Worsening mental status • Bacteriuria • Non cath >= 100,000/ml of one or two bugs • Condom cath >=100,000 of <3 bugs • Cath: any number

  25. Febrile Morbidity in long term care patients • Prevalence of bacteriuria - 50% • <10% were catheterized • Positive Predictive Value of bacteriuria for clinical UTI – 11% • PPV of bacteriuria for serologic UTI – 12% • <10% of episodes of unexplained fever were attributable to UTI • Nicolle, AJM 1996; 100:71.

  26. To Summarize • Bacteriuria very common in uncatheterized long term care patients • Poor correlation of bacteriuria with symptoms attributable to urinary tract • Bacteriuria rarely explains fever in absence of localizing symptoms • Most treatment for AB is inappropriate

  27. Should AB ever be treated? • Pregnant women • AB Prevalence: 4-7% • Optimal time to screen is 16th week • Symptomatic infection develops in 20-40% of those with AB (1-3% of all pregnancies) • Premature labor in 20-50% with symptomatic UTI • Successful Rx of AB reduces rate of symptomatic UTI by 80-90% • Patterson TF, Andriole VT. Inf Dis Clin NA 1997;11:593-608

  28. When to Rx AB – cont’d • Prior to renal transplant • Prior to invasive urinary procedures • TURP, biopsy prostate • not insertion of catheter (except if valvular heart disease and infected urine) • Unclear before insertion of non urinary prosthesis: heart valve, total hip or knee

  29. Case Presentation 2 • 39 woman, 250 pounds, three previous THR. No urinary sx. • Pre op: “dirty” voided UC: 30k E coli and Klebsiella • Three days of Cefamandole and Tobra starting at time of surgery • 6 weeks later, E coli in hip • Different biotypes and MIC’s

  30. Case 2 - continued • She sued the surgeon alleging negligence for replacing hip in setting of positive urine culture • Defense expert testified • the two organisms were unrelated • the literature didn’t support any increased risk of SSI from asymptomatic UTI*

  31. *Review of literature on urine cultures prior to hip surgery • Lawrence, Kroenke. Arch Int Med 1988; 148:1370-1373 • Chart review 200 consecutive knee procedures • Excluded insertion of prostheses • Criteria for abnormal UA established • 10% UA’s indicated, 90% not • SSI: 1/166 with normal UA; 0/23 with WBC • Overall infection rate 0.5% (95% CI: 0-2.3%)

  32. Literature - continued • Health Technology Assessment 1997; 1:43-47 • No controlled trials on value of routine preop urine testing • Routine preop urine abnormal 1%-34.1% • Leads to change in management in only 0.1%-2.8%! • No good evidence that preop abnormal UA is associated with any postop complication

  33. Case - continued • Plaintiff’s expert stated “An E coli is an E coli is an E coli. Don’t bother me with genetics.” • SHE WON THE CASE!

  34. Catheter Associated UTI • Short term catheter <30 days • Long term catheter >30 days • Prevention of bacteriuria • Prevention of complications of bacteriuria • Avoidance of urethral catheters Warren Inf Dis Clin NA 1997; 11: 609-622

  35. How Significant is Pyuria in Foley Urine? • Definition • Standard: 5 WBC/hpf • Hemocytometer: 10 WBC/µl • Does not correlate with catheter related symptomatic infection. • SHOULD NOT BE USED AS REASON TO OBTAIN FOLEY URINE CULTURE • Tambyah, Maki. Arch Int Med 2000; 160: 673

  36. Short Term Catheter • 15-25% of acute care patients have catheter • Mean/median duration between 2 and 4 days • At 3% to 10% incidence/day, 10% to 30% will develop catheter associated bacteriuria (CAB) during their hospital stay • Warren Inf Dis Clin NA 1997; 11: 609-622

  37. Risk Factors for CAB Platt. Am J Epid 1986; 124: 977 • Duration of catheter • Absence of urinometer • Colonization of drainage back/back flow • Diabetes • No receipt of antibiotics • Female • For other than surgery or output measures • Abnormal serum creatinine • Errors in catheter care

  38. Complications of Short Term Catheter • Most episodes of AB are asymptomatic • Fever or UTI sx in up to 30% • <5% associated with bacteremia • Attributable mortality <15% of bacteremic • Given large number of short term catheters nationwide, up to 15% of nosocomial bacteremias are from UTI

  39. PHD 2001 SurveyData courtesy of Sharon Williamson, MT(ASCP) and Bobby Moore, MT (ASCP) PHD Microbiology Lab • Review Micro Lab Computer for • All patients with positive urinary catheter culture and • Positive blood cultures drawn same day • Exclude urine positive for Staph aureus and Candida since • Literature states these are more likely causes of the bacteriuria rather than the consequence

  40. Cases with same isolate in BC/UC • Total 19 cases • 14 E coli • 2 Proteus mirabilis • 1 had three other urinary isolates as well • 2 Klebsiella pneumoniae • 1 Morganella morganii

  41. Cases with different isolates • 55 total cases • Skin flora in blood: 40 • Seven had 2 + BC for CNS – likely pathogens • 33 had single + BC – unclear significance • Definite pathogens in blood: 16 • Combined definite and likely: 23 cases

  42. Likelihood of Positive Foley Culture As Cause of “urosepsis” • 19/42 (45%) bacteremic episodes in this cohort of catheterized patients were attributable to urine isolate • 23/42 (55%) bacteremic episodes not related to urine isolate – would have been missed if therapy based on urine only!

  43. Conclusion • In an acute care hospital, cannot assume that a positive urine culture from catheterized patient is the cause of a febrile episode • Must always draw blood culture before initiating therapy • Keep an open mind about other sites for fever

  44. Long Term Catheters • Prevalence: more than 100,000 NH patients in USA • Incidence of bacteriuria still 3% to 10%/day • At 30 days, almost 100% prevalence! • 95% polymicrobial • Catheter bugs not the same as bladder bugs at least 25% of the time (biofilm theory)

  45. Complications of Long Term Catheters • Two thirds of febrile episodes in aged LTC attributed to UTI • Incidence: one febrile episode per 100 catheter days • MOST SELF LIMITED (<1 day) • Therapy not usually indicated

  46. Other Complications of LTC • Catheter obstruction • Related to biofilm production • Infection stones • Chronic renal inflammation • Chronic pyelo usually only with obstruction/stones • Urethritis/fistulae, epididymitis, prostatitis • Bladder cancer

  47. Prevention of CA Bacteriuria • Closed catheter system • Remove catheter when possible • Delay onset • Coated catheters largely ineffective • Systemic antibiotics work but ultimately • Adverse effects • Multidrug resistant isolates emerge

  48. Prevent Complications of CA Bacteriuria? • Search out and treat AB? • Prospective trial (Warren JAMA 1982;248:454) • no effect on preventing fever • Marked increase in resistance • DO NOT TREAT CAB except in • epidemics or clusters • High risk patients • Pregnancy, renal transplant, urologic surgery

  49. What about symptomatic UTI in catheterized patient? • Always look for non-UTI explanations as well • Blood cultures • Treat with specific therapy for 10-14 days assuming occult pyelonephritis • Change catheter and obtain new culture before Rx • Clinical and bacteriologic outcomes better • More reliable culture from newly inserted catheter with no biofilm • Raz. J Urol 2000;164:1254

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