1. No category

Australian and New Zealand Continence Journal
© Continence Foundation of Australia
Peer reviewed article
Long-term urinary catheter-associated
urinary tract infection (UTI)
Abstract
This paper reviews the literature on the current management of symptomatic urinary tract infections (UTIs) in those with long-term
urinary catheters. Long-term is defined as being in situ for more than 1 month. The discussion refers to published guidelines and
relevant clinical trials.
As bacteriuria is universal in people with long-term urinary catheters, diagnosis of symptomatic UTIs is made chiefly by the presence
of clinical symptoms, which usually include fever. Urine culture is then performed in order to direct an appropriate antibiotic choice.
Urinary catheter change at the time of initiating treatment is likely to lead to earlier clinical improvement, and a more accurate
assessment of infecting organisms when a culture is taken via the new catheter. Antibiotic treatment should be for as short a time as
possible, 5-7 days, to reduce the selection of resistant microorganisms. Regular catheter change and newer catheter materials have not
been proven to reduce the incidence of symptomatic UTIs in those with a long-term urinary catheter in situ.
Key words: urinary tract infection, urinary catheter, antibiotics, urinalysis.
Introduction
The purpose of this article is to present what is a current
Urinary tract infections (UTIs) were studied extensively in the
1980s; this led to the development of evidence-based guidelines
for treatment in those with normal urinary tracts 1, 2. Since that
time, further areas have been elucidated by excellent trials, such
as the treatment of UTIs in pregnancy and in those in long-term
evidence-based management strategy for those with long-term
catheter-associated UTIs.
Literature review methodology
Material for this article was identified by searches of Medline,
care facilities 2, 3, and also whether treatment of asymptomatic
Cochrane Reviews and references from relevant original articles
bacteriuria is appropriate 4, 5.
published in English between 1994 and 2004. Search terms
included catheter, urinary catheter, urinary tract infection, and
Studies on the prevention of UTIs in patients with a urinary
were combined with the terms review and guidelines.
catheter have mainly addressed those with short-term urinary
catheterisation (usually less than 14 days) in recent years 6. In
respect to long-term urinary catheterisation, various clinical
issues have been investigated – such as presentation, diagnosis
and treatment of symptomatic UTIs – focussing on particular
groups, including the institutionalised elderly and those with
spinal cord lesions
7, 8
.
This has resulted in a number of
recommendations regarding long-term urinary catheter-related
UTIs, but many areas remain to be clarified by further studies 3.
Dr Miriam Paul
Bacterial urinary tract colonisation
and persistence
Following insertion of a urinary catheter, bacteria spread to the
bladder and establish persistence there, with subsequent
intermittent invasion leading to symptomatic UTIs. A long-term
urinary catheter is defined as: one that is required for more than
a month; is most commonly used either to manage incontinence,
particularly in women; or as an intervention for bladder outlet
obstruction with retention, more commonly in men 7, 9.
Microbiologist and Infectious Diseases Physician
Douglass Hanly Moir Pathology
MacQuarie Park, NSW
Tel: (02) 9855 5312
E-mail: [email protected]
A normal bladder has very effective defences against transient
This paper was developed from the author’s presentation at the
organisms to the bladder. Initially, the urethra will become
Continence Foundation of Australia 12th National Conference,
colonised, then organisms ascend to cause bladder colonisation 9.
Manly, 2004. The author is employed part-time as a pathologist
These colonising perineal organisms usually consist of normal
by a laboratory that performs urine cultures
bowel flora such as Enterococcus, Escherichia coli and other
bacteriuria, with most organisms being removed by the next
urination.
Unfortunately, inserting an indwelling urinary
catheter bypasses many of these host defences, allowing access of
Gram-negative bacilli, skin flora such as coagulase-negative
4
Vol. 11, No. 1 • Autumn 2005
Australian and New Zealand Continence Journal
© Continence Foundation of Australia
Staphylococci and Candida 9. In women, colonising organisms
can include normal vaginal flora such as Group B
Streptococcus 9. Colonising organisms may also include hospitalassociated organisms with which the person has come in contact
such as methicillin resistant Staphylococcus aureus (MRSA).
Prevention of symptomatic UTIs in
catheterised persons
Various measures have been suggested to prevent the
development of urinary catheter-associated bacteriuria but, apart
from the closed drainage system, to date, none have been proven
Closed urinary catheter drainage systems have been successful in
to be effective. Periurethral topical antibiotics have not been
greatly reducing access of organisms to the bladder via the
shown to prevent the development of urinary catheter
lumen of the catheter, with the result that most ascending
bacteriuria 11. Prophylactic antibiotics have been found to delay
colonisation now occurs via the external surface of the
the development of bacteriuria in short-term catheterised
catheter . However, with closed drainage systems, detaching the
patients, but eventually resistant organisms colonise the urinary
collection tube from the catheter can allow organisms entry into
catheter 9. In the long-term catheterised patient, urine sterility
the system, as can contamination of the emptying tube of the bag
cannot be maintained with antibiotics 9. Routine urinary catheter
with a dirty container 6.
change has not yet been proven, in any study, to reduce the
6
incidence of UTIs in people with long-term urinary catheters 7.
In all urinary catheterisation, the catheter balloon prevents
complete emptying of the bladder, causing a small volume of
While published recommendations for the timing of urinary
residual urine to accumulate, thus providing a suitable medium
catheter change are few, it is reasonable that catheters not
for persistence and multiplication of organisms once they have
associated with complications be left in place for 12 weeks 8.
entered the urinary bladder. The development of persistent
Antibiotic prophylaxis at the time of urinary catheter change is
bacteriuria occurs at a rate of 3-10% per day following urinary
not recommended as, despite a 4-10% incidence of transient
catheterisation, with all urinary catheters becoming colonised
bacteraemia associated with the procedure, symptomatic
after 1 month in situ . This persistence of bacteria in the urine
infection is uncommon 12.
of catheterised patients is termed ‘asymptomatic bacteriuria’ or
antimicrobial agents has been shown to be ineffective in
more correctly ‘asymptomatic UTIs’, as there is evidence of a
preventing UTIs 8.
host response involved implying a degree of tissue invasion
urethral catheterisation, has been suggested as an alternative, as
rather than mere surface colonisation 3.
the abdominal skin carries less of a bacterial load than the
7
Organism factors also facilitate bacterial persistence in the
bladder, most notably those properties that promote their
adherence to the bladder uroepithelial lining and catheter
surface.
A biofilm forms on the surface of the catheter,
consisting of glycocalyx slime and minerals 10.
periurethral area.
Routine catheter irrigation with
Suprapubic catheterisation, compared to
However, this option has not been well
studied in terms of UTI incidence in a long-term catheterised
group and no conclusions can be drawn 13, 14.
In an attempt to reduce bacterial adhesion, materials such as
This biofilm
Teflon and silicon have been used in catheter construction, but
facilitates bacterial attachment and provides protection from
no reduction in UTI incidence has been shown 9. In individual
normal host defences. In particular, there is a blunting of the
patients, however, more frequent routine catheter change and a
host antibody and neutrophil response which might normally
silicon catheter may reduce urinary catheter blockage if this is
eradicate bacteria. Bacterial persistence occurs initially in the
the cause of their recurrent UTIs.
bladder but may extend to the kidneys, with biofilm being
Chronic renal
Antimicrobial impregnated or silver-coated urinary catheters
inflammation has commonly been found at autopsy of those with
have had variable success in preventing UTIs in those
long-term urinary catheters, but actual chronic pyelonephritis
catheterised for less than 14 days, with silver alloy coated
with scarring is much less frequent, occurring mainly in people
catheters particularly showing some promise 15.
with renal stones .
insufficient evidence to comment on the use of these urinary
formed in the renal pelvis or tubules 7.
7, 9
There is
catheters in long-term catheterised patients, but there is some
Long-term catheters are usually colonised by two to five
concern regarding silver toxicity from prolonged use 6, 8.
different organisms 7. These organisms are replaced by other
organisms regularly, and can change as frequently as every 2
Future options for reducing symptomatic UTIs lie particularly
weeks . Some organisms are more persistent as they adhere
in the development of alternatives to permanent indwelling
better to the uroepithelium, particularly E. coli and Providencia
catheters, such as urethral stents and condom drainage for males.
stuartii . Over time, more antibiotic-resistant organisms may be
Intermittent catheterisation is thought to be associated with a
selected, particularly by the use of multiple antibiotic treatment
lower rate of symptomatic UTIs, although no definitive study
courses.
has been performed 8.
7
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Vol. 11, No. 1 • Autumn 2005
Vaccines against the common UTI
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Australian and New Zealand Continence Journal
© Continence Foundation of Australia
pathogens such as E. coli are being developed but, while these are
note, the risk of death is 60 times higher in febrile catheterised
very promising in people with normal urinary tracts, it remains
patients with UTIs than in those who are afebrile 9.
to be seen whether they will be effective when there is a urinary
Laboratory findings
catheter in situ 11.
When a clinical diagnosis of symptomatic UTIs has been made,
Symptomatic UTIs in the long-term catheterised
urine microscopy and culture provides useful information to
Progression from an asymptomatic infection to symptomatic
direct appropriate antibiotic therapy. Examination of urine in
UTIs can be related to a number of factors. Catheter obstruction
patients with a urinary catheter frequently shows pyuria due to
is the most common cause of symptomatic UTIs, with fever eight
mechanical irritation so the presence of white cells is unhelpful
times more common in those with obstruction than with a patent
urinary catheter 7. Obstruction leads to increased residual urine
in the bladder in which colonising organisms multiply.
Obstruction is often caused by a combination of precipitated
crystals, biofilm, Tamm-Horsfall protein (antibacterial mucus
normally made in the kidneys) and bacteria 9.
in diagnosing symptomatic UTIs 18. However, conversely the
absence of white cells on urinalysis or microscopy has excellent
negative predictive value and is useful as evidence against UTIs,
suggesting than an alternative source of the patient’s current
symptoms should be sought 3.
Diagnosis of UTIs cannot be based purely upon culture as
Of particular note, urinary colonisation with Proteus species
may lead to obstructive problems as the organism produces the
enzyme urease 9. This catalysis of the breakdown of urea into
ammonia and the subsequent alkaline urine allows the
development of a precipitate of struvite and apatite crystals. A
similar process may cause kidney and bladder stones.
Obstruction does not necessarily lead to UTIs if the catheter is
almost all catheter urine specimens will grow organisms. When
obtaining a specimen of urine for diagnostic purposes, it is
important to realise that a urine sample taken from a urinary
catheter reflects organisms present in the biofilm on the
catheter, and not solely the organisms that are actually present in
the bladder. A greater variety of organisms plus higher numbers
of these organisms will be isolated from the colonised catheter
compared to a sample taken from the bladder when a new
changed as soon as obstruction occurs 3.
catheter is inserted 7. Thus catheter culture samples are not
Catheter trauma also contributes to the development of
necessarily representative of the actual organism causing an
symptomatic UTIs by causing mechanical uro-epithelial
episode of symptomatic UTIs. Preferably a urine sample should
damage, facilitating invasion of organisms into deeper tissue 14.
be taken from a newly inserted urinary catheter at the time of
symptomatic UTI diagnosis to determine what organisms are
Clinical presentation
present in the bladder.
Symptomatic UTIs in catheterised patients may be overdiagnosed, with non-specific signs such as delirium in an elderly
Treatment
mistakenly attributed to infection from a urinary source 16, 17.
Ideally the urinary catheter should be changed every time a
Purely lower UTI symptoms such as dysuria are uncommon and
symptomatic UTI is diagnosed and treated. The disadvantages
periurethral infection as a cause of these symptoms, particularly
of changing the urinary catheter are a 4-10% rate of transient,
in men, should be excluded by examining the urethral meatus for
usually asymptomatic bacteraemia associated with the
discharge and checking for epididymitis or prostatitis . Bladder
procedure, plus potential mechanical trauma involved and
spasms may cause symptoms if the catheter is blocked but this
financial costs 9.
7
cause should be obvious on examination.
A study of aged nursing home patients looking at catheter
Symptoms of UTIs such as gross haematuria or loin pain
replacement prior to starting treatment of symptomatic UTIs
consistent with pyelonephritis, or persistent fever with no other
found that inserting a new urinary catheter in addition to
obvious source, correlate with acute symptomatic urinary
treating with antibiotics led to clinical improvement after 3 days
infection 7, 9. In patients with a long-term urinary catheter, fever
in 93% versus 41% of patients without catheter change,
occurs at a rate of 0.7-1.2 fevers per 100 days of catheterisation .
although all had a similar clinical outcome eventually 19. There
However, the majority of these fevers only last 1 day and settle
was also a lower rate of symptomatic relapse 4 weeks after
without treatment, leaving approximately 30% of fevers with no
treatment cessation in those who had urinary catheter
obvious source that are actually due to symptomatic UTIs .
replacement 20.
Elevated peripheral blood white cell count and, in some patients,
replacement when the catheter has been in situ for more than 7
positive blood cultures, also support the diagnosis of
days 7. If the catheter is not being replaced, a sample of urine
symptomatic UTIs compared to asymptomatic bacteriuria . Of
should be aspirated from the catheter port.
7
7
16
6
This has led to a recommendation for
Vol. 11, No. 1 • Autumn 2005
Australian and New Zealand Continence Journal
© Continence Foundation of Australia
Antibiotic treatment of UTIs in people who have a urinary
men with relapsing infection with the same organism, a 4 week
catheter in situ in the long-term is aimed at symptom relief
antibiotic course of treatment should be considered for possible
rather than eradication of bacteriuria and thus should be for as
occult prostatitis.
short a time as possible, usually 5-7 days . This is because a
trimethoprim as few antibiotics penetrate the prostate well 2.
3
longer antibiotic course will still not sterilise the urine for any
prolonged time and may lead to bacteriuria with more resistant
microorganisms.
Options include ciprofloxacin and
Urine culture following resolution of UTI symptoms and
cessation of antibiotic is not recommended in patients with a
long-term urinary catheter as it is likely to still show bacteriuria
In mildly symptomatic patients with only a low-grade fever, it is
and does not influence further management 3.
appropriate to wait for urine culture results to enable an
appropriate antibiotic to be chosen. Once susceptibilities are
Conclusion
available, a suitable oral antibiotic can be prescribed from
UTIs are a common cause of morbidity in people with a long-
trimethoprim 300mg daily, cephalexin 500mg twice daily,
term urinary catheter in situ.
amoxicillin plus clavulanate 500/125mg twice daily or
closed drainage system, have yet been proven to be effective in
nitrofurantoin 50mg four times a day 2.
preventing UTIs in this group of patients. Diagnosis of UTIs
Empiric antibiotics
should be started immediately in those with severe symptoms
No measures, apart from the
should be based on symptoms, particularly fever.
such as rigors or hypotension; for these people, a broadspectrum antibiotic should be chosen to cover a wide range of
Urinary catheter change is recommended prior to starting
potential infecting organisms such as ciprofloxacin (not
treatment of symptomatic UTIs as symptoms resolve more
recommended for children) or intravenous gentamicin
rapidly and there is a lower rate of symptom recurrence in the
5mg/kg/day as a single daily dose plus ampicillin 1g 6-hourly .
following 4 weeks. A urine sample should be taken from the new
2
catheter for culture and subsequent antibiotic treatment directed
For severely unwell patients in whom gentamicin is
by the result. Antibiotic treatment should be given for 5-7 days
contraindicated,
or
to reduce the risk of acquisition of resistant microorganisms
intramuscularly may be used, but this has no activity against
colonising the urinary tract. Further clinical trials of preventive
Pseudomonas 2. On occasion when the patient is known from
measures regarding UTI in long-term catheterised persons are
past urine cultures to be persistently colonised with a
required to assist in formulating management strategies.
ceftriaxone
1g
daily
intravenously
microorganism that is resistant to the latter antibiotics, the
empiric initial antibiotic used should be one that the organism is
References
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antibacterial substances in the urinary tract. It also leads to
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achieve as it requires dietary modification as well as the
administration of agents such as ascorbic acid or methionine.
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