Podcast #158 - EM ID: Asymptomatic Bacteriuria versus UTI with Dr. Gompf

For this round of EM ID, Patrick Bafuma interviews Dr. Sandra Gompf who specializes in infectious disease and has Gompf's ID Pearls.  They focus primarily on delirium, indwelling Foley catheters, and callbacks.

What do we do about cultures and what about callbacks?

• Be concerned for Klebsiella, staph, and strep even if asymptomatic.  
• If it’s a blood culture growing any Gram negative bacillus or Staphylococcus aureus or Enterococcus, and the patient did NOT have UTI or pyelonephritis symptoms, that patient needs further evaluation for an occult focus of infection.  They may require admission.
• Note that a urine culture that grows S. aureus in the absence of a bladder catheter should also raise suspicion for a deep focus like endocarditis. Catheters commonly become colonized, sometimes with S. aureus. But if there’s no catheter, it may be a disseminated hematogenous infection to the kidneys.  Get a follow-up blood culture.
• If the patient was seen for UTI symptoms, and a blood culture grows a Gram negative bacillus, verify that 1. The organism in urine is the same, and 2.  It’s susceptible to the antibiotics prescribed. If both are true, and the patient is improving clinically, no need for further evaluation or testing.  We used to insist on repeating blood cultures for Gram negative bacteremia, but there is recent data showing that if we know the source is an uncomplicated pyelonephritis and the patient is getting better, there is no need to do that. 

Common blood contaminants include:

• Coagulase negative Staphylocci except S. lugdunensis
• Bacillus species
• Corynebacterium species except C. jeikeium or “JK”
• Strep viridans species/mitis if asymptomatic

Gram negative bacillus, staph aureus, and yeast SHOULD NOT be assumed to be contaminants!

Do you treat the “asymptomatic” men differently than women?

• First let’s discuss asymptomatic bacteruria (ASB). Both normal men and women may be have asymptomatic bacteriuria and pyuria over time, often starting in their 40s.
  
• Menopausal women lose estrogens, which causes dryness and atrophy of the perineal tissues, and disrupts Lactobacillus colonization.
  
• Lactobacilli produce H2O2 and a low pH that protects against pathogens.
  
• Men begin to experience hormonal and prostate changes that obstruct urine flow and predispose them to UTIs.
  
• Studies show that treating ASB clears bacteria temporarily at best, and usually does NOT work.
  
• Antibiotics DO NOT sterilize urine.
  
• They act on the metabolic process of actively replicating bacteria during infection.
  
• They reduce the uncontrolled volume of bacteria so the immune system can take care of the rest. 
  
• Treating ASB does NOT reduce development of UTI or morbidity/mortality of UTI, BUT it significantly increases adverse reactions, allergies, and C. difficile. as well as resistance.
  
• When you bathe a colony of bacteria in antibiotics, they switch on resistance genes to it. So when an infection takes hold, it’s going to be harder to treat. 

Bottom line on asymptomatic bacteruria (ASB)

• Do NOT get “test of cure” cultures as it leads to a vicious cycle of test - treat - test - treat again. 
• Essentially, do not get cultures on those without symptoms or those responding to treatment of UTI.

Exceptions to not treating ASB

• Pregnancy - ASB is assoc w preterm labor and poor outcomes.
• Before urologic procedures that may cause bleeding, especially kidney and prostate procedures as they are more likely to lead to sepsis. 
  
• Side note: pre-operative urine cultures & treatment do not reduce post-operative UTI or surgical site infection. 

Should we culture everyone?

• Obtaining cultures are important for the local antibiogram.
  
• If we do NOT culture, do we end up biasing towards a “sicker” or more resistant antibiogram and use less than ideal agents because of it? (ie, macrobid works 95% of time for outpatient UTIs, but if we only cx the admitted patients, our local antibiogram may show that macrobid only works 70% of the time and we may use other abx)
  
• Labs doing reflex-only cultures appears to make more sense as there is recent evidence that doing so cuts unnecessary antibiotics without affecting quality of care since you would get only the meaningful pathogens that are causing the most disease.
• In low risk patients such as UTI in a young woman without previous UTIs, it is appropriate to treat with nitrofurantoin or TMP-SMX without a culture as the resistance or failure is very low in this case, and it saves the patient $20-$60 or a co-pay for the labs. If anything, these cultures may skew the antibiogram to “too healthy” because of these patients.
• On the opposite end of the spectrum, older women w UTI usually will need a culture. 
  
• Men are more likely to be complicated. In a young man, think STDs like gonorrhea/chlamydia more than UTI. In older men send a culture. Also look for underlying voiding problems, kidney stones, diabetes, etc, that need addressing.

Treatment of symptoms with NSAIDs or phenazopyridine (Pyridium or AZO)?

• Generally recommended to treat with acetaminophen to avoid nephritis or allergic reactions.
  
• NSAIDS and Pyridium also mask some of the symptoms and the idea is that you want the patient to be able to tell if they are not improving.

Colonization and indwelling catheters

• Within days the patient will be colonized even with great care.
  
• Most Staph seeding the spine actually comes from elsewhere such as endovascular infection, bad teeth, or abscess somewhere else. Gram negative bacillus is more likely to seed the spine from urine or gut. 
  
• The only time to treat for UTI is when a patient is symptomatic such as suprapubic tenderness, malaise, elevated temp, etc.

Delirium and UTIs

• If the patient is NOT acutely delirious on exam, just demented, increase hydration as tolerated. These patients forget to drink, then they get constipated, or do get a UTI. People do not realize they may need to offer food and drink frequently. 
  
• If patient has clearly and acutely declined in the last few days, may be newly incontinent, not eating/drinking, no symptoms/signs of viral or respiratory infection, it’s reasonable to check for UTI. That’s the patient who probably should be admitted, too. Harder to manage a delirious loved one at home, may not swallow pills, etc.

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