1. When to Test and When to Treat… High Yield Clinical Concepts: Asymptomatic Bacteriuria
Robert Redwood MD, MPH
Emergency & Preventive Medicine Physician
April 12, WHA Journal Club #1

2. Conflict of Interest Disclosure
Robert Redwood MD, MPH has no real or apparent financial relationships to report.

3. Aims and Outline Background on Antimicrobial Stewardship
Deep dive on Asymptomatic Bacteriuria
Case Discussions: To treat or not to treat?

4. Treat or not? CASE #1
43yoF with old spinal cord injury and indwelling catheter p/w vomiting, but no other symptoms, UA strongly positive.

5. What is asymptomatic bacteriuria?
An “asymptomatic urinary tract infection”
an isolation of bacteria in an appropriately collected urine sample from an individual without signs or symptoms referable to a urinary infection
Nicolle LE et al. Clin Infect Dis. 2005;40(5):

6. Epidemiology of asymptomatic bacteriuria
Health women: 2-5%
Pregnant women: 2-11%
Diabetic women: 7-9%
Elderly: nursing home: 5-50%
Varies widely because prevalence of ASB corresponds to level of functional impairment
Spinal cord injury: 50%
Long-term catheter: 100%
80% discordance between recommended practices and actual practices
Nicolle LE et al. Clin Infect Dis. 2005;40(5):

7. Why is it important to stop treating asymptomatic bacteriuria?
35% of US Ecoli strains are resistant to ciprofloxacin
CDiff more than doubled from 65.6 to per 100,000 population from 1991 to 2003
1 in 8 will have antibiotic associated diarrhea
0.3% rate of antibiotic related ADEs
J Pharm Pract Oct; 26(5): 464–475.
BMC Infect Dis. 2015; 15: 545.

8. Treat or not? CASE #2
Healthy 33yoF G1P0 is in OB clinic for 8wk US w/o symptoms, second urine culture grows E.Coli.

9. Core Principles of AMS
Antimicrobials exert selective pressure on pathogens
Top 3: Meat industry, vets, human medicine
Worldwide: 700,000 annual deaths attributable to nosocomial-resistant organisms
US: 2,049,442 illnesses and 23,000 deaths / yr
Sequelae of AMR costs the US $21-$34 billion with million additional patient-days in the hospital
Right dx, right drug, right dose, right duration

10. Oh…and there’s this 1980’s: 16 new abx 1990’s: 10 new abx
Only 5 of 572 pharmaceutical companies have active antibacterial discovery programs

11. Oh…and then there’s this
Superbug resistant to every antibiotic available in US kills Nevada woman January 13, 2017 “It was tested against everything that’s available in the United States… and was not effective” Dr Alexander Kallen, a medical officer with the CDC who first reported the discovery of the superbug
carbapenem-resistant enterobacteriaceae

12. Treat or not? CASE #3
21yoF is suicidal with strongly positive UA on psych clearance labs. No symptoms. Accepting MD requests abx prior to acceptance.

13. Brief history of how we got to where we are today?
Quantitative urine culture for the microbiological diagnosis of UTI (1957)
Pregnant women with ASB frequently went on to develop pyelonephritis
Treatment of ASB started in this group and was extrapolated to other groups without clear evidence
The conceptual framework for clinicians was that asymptomatic bacteriuria was consistently harmful in all populations and warranted antimicrobial treatment.
That is quite simply WRONG

14. The three times it ok to screen for and treat asymptomatic bacteriuria
Once in early pregnancy
only treat if two positive cultures
Pre-urologic procedure (usually TURP)
Post-renal transplant
Although growing body of evidence against this
Pregnancy: We usually treat with single microscopy which is wrong
TURP: We often treat ALL TURP patients without even getting a UA or urine culture…this is wrong
Infect Dis Clin North Am Jun;17(2):367-94

15. Treat or not? CASE #4
65yoF w/o symptoms grows pseudomonas on pre-op screening urine culture before TKA.

16. The low-hanging fruit: Clinical scenarios where asymptomatic bacteriuria is commonly treated (incorrectly)
Catheter myths: Foul smelling, dark, or sediment in foley catheter bag
Convenience screening (“The patient peed doc, should I send a UA?”
Contaminated sample incorrectly treated empirically or incorrectly sent for culture
“Positive UA” on medical clearance for psych or jail (ED)
Blaming altered mental status on ASB (ED, ICU, LTCF)

17. Treat or not? CASE #5
11yoF with periumbilical abd pain has 4+ WBCs on UA w/o bacteriuria. No other urinary symptoms.

18. How to stop treating asymptomatic bacteriuria in 6 easy steps
Recognize the problem
Recognize high-risk populations
Do not screen for ASB
Recognize when a UA or Ucx is being sent for the wrong reasons
Diagnose UTIs with sophistication
Free-text the REAL diagnosis

19. Treat or not? CASE #6
89yoF presents to the ED with no urinary symptoms and AMS. Cath UA strongly positive.

20. 1. Recognize the problem
Up to 80% of ASB patients are given antibiotics (against IDSA guidelines)
At best we’re doing this wrong 20% of the time
Nicolle LE et al. Clin Infect Dis. 2005;40(5):

21. 2. Recognize populations with high likelihood of having ASB
Indwelling catheter
Spinal cord injury
Urologic procedure
Long term care resident
Diabetic female
Pregnant female
Its not a long list

22. 3. Do not screen for asymptomatic bacteriuria
Each and every time you send a UA, have a good reason for doing so
RN initiated UA protocols should emphasize symptoms
Beware order sets
Beware reflex culture orders on a urinalysis order
If a UA was ordered to evaluate for non-infectious symptoms (i.e. proteinuria) and it appears to a “UTI”, do not act on results and do not send it for culture

23. 4. Recognize when a UA or Ucx is being sent for the wrong reasons
Foley catheter without flank pain, fever, or sepsis
Foul smelling urine = UTI
Dark urine = UTI
Foul smelling urine or change in urine appearance does not correlate with infection. It is usually related to hydration status.
Screening, reflex orders, convenience, incidental
J Emerg Med. 2016;51(1):25-30. 

24. 5. Diagnose UTIs with sophistication
Urinary symptoms = UTI.
Between 34% and 50% of women presenting with urinary symptoms do not have a UTI. Concentrated urine causes dysuria mimicking a UTI.
WBCs = UTI.
Pyuria is inflammation within the genitourinary tract and is measured as WBCs in the urine. It is a common accompaniment of asymptomatic bacteriuria and should not influence decisions about antimicrobial therapy.
Leukocyte esterase and/or nitrites = UTI.
Not so fast, leukocyte esterase suggests pyuria and nitrites suggest bacteria--either of these could be present in asymptomatic bacteriuria, so clinical context (i.e. symptoms) really matters.
J Emerg Med. 2016;51(1):25-30. 

25. 5. Diagnose UTIs with sophistication (cont.)
Positive culture always means UTI.
A good specimen has <5 epithelial cells per low-power field. A "positive" culture is meaningless if the sample was contaminated.
UTI is a common cause of altered mental status in the elderly.
Actually it is an uncommon cause and this type of anchoring bias can work against us in terms of uncovering the true cause of our patient's altered mental status. Before you think UTI, think of more common (and also more subtle) etiologies like medication reactions, sundowning, dehydration or sensory impairment.
Once resistant, always resistant.
Previous resistance does not predict future resistance; however, previous susceptibility is likely to predict future susceptibility.
J Emerg Med. 2016;51(1):25-30. 

26. 6. Free-text the REAL diagnosis
Being precise is a tenet of good medical practice
EHRs sometimes lead to oversimplification
If Asymptomatic Bacteriuria is not on the diagnosis menu, add it

27. Theory vs. Reality: Treating probable asymptomatic bacteriuria
If you have a diagnostic uncertainty and choose to treat probable ASB…
Consider watch and wait prescription
If possible, wait for culture results, then call patient to RE-confirm symptoms
If admitting, consider 24 hour “tincture of time”
Choose nitrofurantoin, bactrim, or 1st gen cephalosporin if appropriate
Inform patient of your uncertainty and risks / benefits

28. Treat or not? CASE #7
35yoF presents to the clinic with dysuria and frequency for 1d. UA is strongly positive, but >5 squamous epithelial cells/hpf.

29. Not all bugs are bad bugs
“Transient bacteriuria is common
in healthy young women”
Clin Infect Dis (2005) 40 (5):
N Engl J Med , 2000, vol. 343 (pg. 992-7)
J Infect Dis , 1982, vol. 146 (pg. 579-83)
JAMA , 1980, vol. 243 (pg. 134-9)