Healthcare Hygiene magazine December 2019 | Seite 10

infection prevention
By Barbara DeBaun, MSN, RN, CIC
Screening for Asymptomatic Bacteriuria:
A Dangerous Intersection
It
was a dark and stormy specimen. You know the story.
It begins with a well-meaning nurse who notices that
the urine in the patient’s urinary drainage bag is dark in color.
When the urine is drained from the bag, the nurse notes
that the urine is not only concentrated but smelly. More
likely than not, this nurse will collect a sample of the urine
and request an order for urinalysis and culture. The nurse
has seen this before and is confident the patient’s symptoms
suggest a urinary tract infection.
Another twist on the story is the patient who presents in
the emergency department (ED) and whose daughter or son
insists that “When mom gets like this, it’s always a urinary
tract infection.” Sound familiar?
Asymptomatic bacteriuria (ASB) is the presence of one
or more species of bacteria growing in the urine at specified
quantitative counts (≥10 5 colony forming units (CFU/mL
or ≥10 8 CFU/L regardless of whether there is presence of
pyuria or signs/symptoms that are attributable to an urinary
tract infection.
What do we know about ASB?
• Present in >30 percent of nursing home patients and
100 percent of those who are chronically catheterized
• 23 percent to 50 percent of antibiotic days for UTI are
unnecessary treatment of ASB
• ASB is a benign condition that generally does not
require treatment
Urine culturing misadventures often begin when a patient
with a low pre-test probability of having a UTI is tested for
one. It may start when a physician orders a urinalysis and
culture on a patient who is unlikely to have a UTI, or in the
scenario previously described, when a nurse obtains the
specimen first and requests the order later. The integrity
of the specimen including technique for obtaining and
transporting it will impact the result.
Despite our best efforts, we still hear of urine samples
being obtained directly from urinary catheter drainage bags. It
is not unusual for a urine sample to be considered low priority
for transfer to the lab therefore overgrowth of bacteria may
result. The downstream impact of this includes additional
work for the laboratory, increased costs for the pharmacy,
and a negative impact on antimicrobial stewardship. Infection
preventionists are tasked with reporting hospital onset
catheter associated urinary tract infections (CAUTI) and are
likely reporting cases that are not true infections despite
meeting the NHSN case definition. Financial penalties and
impact on reimbursement are impacted by a substandard
culture of culturing. The ultimate negative impact of culturing
patients for an infection that is probably not likely, is that
patients receive antibiotics that are not necessary.
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The Infectious Diseases Society of America (IDSA) recently
issued a clinical practice guideline for the management of
asymptomatic bacteriuria. These 2005 guidelines recom-
mended that only pregnant women and those scheduled to
have an invasive urologic procedure be screened for ASB. The
updated guidelines provide additional guidance on children
and specific adult populations such as those with neutropenia,
solid organ transplants, and surgery that does not involve the
urological tract. Much has been learned about the impact
of testing for ASB in these settings therefore the IDSA has
provided guidance that will ultimately impact antimicrobial
prescribing and the emergence of antimicrobial resistance.
An all-too-common practice is for practitioners to test
a patient who has been admitted to an acute-care hospital
with an indwelling catheter. The temptation to screen may
be based upon the pressure to “capture on admission” or
prove that the patient was already “infected” at the time of
admission. The IDSA strongly advises against screening or
treating ASB. As the screening of patients admitted with a
catheter are likely to present in the ED, it is critical to partner
with the ED providers and nurses so they are aware of the
negative impact of performing urine screening in patients
who are unlikely to have a UTI.
An additional strong recommendation is to avoid
screening patients who are scheduled to undergo elective
nonurological surgery for ASB. This is an area where the IP
has tremendous opportunity to impact and drive change.
Pre-operative order sets commonly include “urinalysis” and
it may be “because we have always done it and we’re afraid
to stop doing it.” We must have critical conversations with
our surgical partners to discuss the impact of ASB screening
to assure them that the risk of testing may outweigh the
benefits. A patient scheduled for a knee replacement will
be far better off if s/he is not treated with an antibiotic
for ASB. There are no data to support the benefit of urine
screening for nonurological surgical patients, however there
is an abundance of data to connect antimicrobial therapy
with negative downstream effects such as multi-resistant
organisms and C. difficile infection.
Our laboratory “culture of culturing” practices that
discourage the screening of patients who have a low
probability of having a UTI directly impact antimicrobial
prescribing practices and patient outcomes. This requires
a partnership that connects the dots between laboratory
stewardship and antimicrobial stewardship so that antibiotics
are only prescribed when they should be. 
Barbara DeBaun, MSN, RN, CIC, is an improvement advisor
for Cynosure Health.
december 2019 • www.healthcarehygienemagazine.com