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Asymptomatic Urinary Tract Infection

Asymptomatic Urinary Tract Infection. Edward L. Goodman, MD FACP, FIDSA, FSHEA October 12, 2009. Nicolle et al IDSA Guidelines for Asymptomatic Bacteriuria. Clin Inf Dis 2005;40:643-54. So, it’s common- big deal!. We’ve got The Sanford Guide We can look it up conveniently

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Asymptomatic Urinary Tract Infection

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  1. Asymptomatic Urinary Tract Infection Edward L. Goodman, MD FACP, FIDSA, FSHEA October 12, 2009

  2. Nicolle et al IDSA Guidelines for Asymptomatic Bacteriuria. Clin Inf Dis 2005;40:643-54

  3. 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, Hopkins-abxguide.com • Current house staff were all born with an IPhone™ clutched in their hands! • What’s the big deal – just treat it! • A whole lecture on this?

  4. 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

  5. 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

  6. 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

  7. 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

  8. 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is almost always associated with a host response • Pyuria • Cytokinuria • HENCE, THE TERM COLONIZATION OF URINE IS OBSOLETE.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

  9. 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

  10. 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

  11. 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

  12. 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

  13. 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

  14. 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

  15. 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.

  16. 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

  17. 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

  18. 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

  19. 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.

  20. 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

  21. 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

  22. Nicolle et al IDSA Guidelines for Asymptomatic Bacteriuria. Clin Inf Dis 2005;40:643-54

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

  24. 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 (the first of the 2nd generation cephalosporins) and tobramycin starting at time of surgery • 6 weeks later, E coli found in infected hip • Different biotypes and MIC’s

  25. 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*

  26. *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%)

  27. 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

  28. Case - continued • Plaintiff’s expert stated “An E coli is an E coli is an E coli. Don’t bother me with genetics.” • SHE RECEIVED A SETTLEMENT! • Given more time, I would be happy to expound on medical legal issues

  29. 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

  30. 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

  31. 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

  32. 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

  33. 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 (0.75% of symptomatic patients with short term foley) • Given large number of short term catheters nationwide, up to 15% of nosocomial bacteremias (symptomatic or not) are from UTI

  34. 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

  35. 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

  36. 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

  37. 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! • Recall Case #1 • Pseudomonas AB from foley; MRSA in blood

  38. 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

  39. 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)

  40. 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

  41. 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

  42. Prevention/delay of CA Bacteriuria • Closed catheter system • Remove catheter when possible* • Delay onset • Coated catheters largely ineffective • Systemic antibiotics work but at the cost of ultimately causing • Adverse effects • Multidrug resistant isolates emerge

  43. 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

  44. 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

  45. What about Candiduria? • 10% of positive urine cultures in referral hospitals yield candida sp. • Symptomatic candiduria should be treated • What about catheter associated candiduria? • Short term eradication with 14 days fluconazole • No effect on candiduria two weeks after therapy • No effect on mortality Sobel. Clin Inf Dis 2000; 30:19

  46. Incidentally • 10/1/08 CMS announced that treatment for hospital acquired UTI would not be compensated • Should we screen new admissions for bacteriuria? • If we do • They will be treated! • There will be increased MDR organisms including MRSA • C diff will emerge • THR Chief Quality Officers Council has agreed that we WILL NOT ROUTINELY SCREEN FOR AB ON ADMISSION

  47. Thanks to the following persons for their assistance: • Sharon Williamson, MT (ASCP) • Bobby Moore, MT (ASCP) • Tammy Chung, Pharm.D • Carla Philmon, Pharm.D • Teri Smith, Pharm.D • Judith Marshall, R. Ph

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