Kidney Matters - Issue 16 Spring 2022

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primarily an infection of the bladder and the lower
urinary tract, and is usually resolved with a short
course of antibiotics. Pyelonephritis is an infection of
the transplanted or the native kidneys, and can cause
severe illness very quickly,” comments Ms Rhana Zakri.
Rhana is a consultant transplant surgeon at Guy’s
and St Thomas’ NHS Foundation Trust and runs a
specialist transplant UTI clinic.
UTIs not only have a serious impact on quality of life
and health of the individual patient, but may also
affect the lifespan of the transplanted kidney. Rhana
explains:
“While we would not necessarily worry about a single
treated UTI, we want to avoid recurrent episodes,
as they can lead to pyelonephritis. If these episodes
are repeated over several years, they may affect
the function of the kidney transplant and may also
affect its survival. At present it is unclear if recurrent
UTIs per se cause rejection or whether rejection
causes recurrent UTIs due to the higher doses of
immunosuppression needed to treat rejection.”
Why are UTIs common after a kidney
transplant?
A combination of risk factors related to the
transplanted kidney (allograft factors) and factors to
do with the individual patient (host factors) explain
why UTIs are common in kidney transplant patients.
Rhana says: “Most transplanted kidneys reflux urine
from the bladder into the kidney when voiding. By
itself, this doesn’t cause a problem if the urine is not
infected and the bladder is emptied regularly, but
cystitis can very quickly progress to pyelonephritis
because of the reflux and potentially cause scarring to
the kidney.
“Reflux makes it all the more important to not only
maintain a good fluid intake but also perform regular
(say, three hourly) double voids (see Table 2, below).
This can be difficult in certain jobs; for example, lorry
drivers and taxi drivers are at risk of UTIs if they limit
their drinking because they cannot use the toilet when
they need to,” she adds.
Kidney transplant patients are treated with medication
that suppresses the immune system, making it more
difficult to fight UTIs. These immunosuppressants
include mycophenolate, which can have
gastrointestinal side effects, including diarrhoea or
constipation that can increase the risk of UTIs.
Kidney transplant patients may have other host risk
factors, such as diabetes, that are associated with a
greater likelihood of UTIs. Postmenopausal woman
or women with a hysterectomy are similarly prone to
UTIs because low oestrogen levels mean that ‘good’
Lactobacilli bacteria, which usually lower the pH of the
vagina, do not flourish, giving way to the possibility of
gut bacteria multiplying and potentially causing UTI.
UTIs are more common in women than in men, both
in kidney transplant recipients and in the general
population. The main reason is differences in
anatomy: in women the vagina, entrance to the urethra
and anus are sited close together, so that bacteria like
E. coli transfer more easily from the anus.
“This is why a UTI in a man should be regarded as
‘complicated’ because there is more likely to be an
underlying cause. For example, his prostate may have
grown larger and is preventing him from emptying his
bladder properly. Quite often, men may not realise this
is happening until they get a UTI,” says Rhana.
How should UTIs be diagnosed?
It can be difficult for doctors to diagnose a UTI in a
transplant patient because immunosuppression may
mask typical symptoms; for example, a transplanted
kidney has lost its nerve supply so it may not feel
tender or painful. Instead, kidney transplant patients
may report feeling simply tired or feverish or have
smelly/cloudy urine, and can become ill very quickly.
The first step to diagnosis is a dipstick and midstream
urine (MSU) to check for the growth of bacteria.
This can be performed by your GP. The second
investigation is a flowrate with postvoid residual
volume (PVR) to see how well the patient voids and
judge how much urine is left behind in the bladder.
This is more likely to be initiated by your kidney doctor
or transplant urologist.
A more specialist investigation is a DMSA scan, a
nuclear medicine scan that looks for scarring in the
transplanted kidney. “Management will be tailored
to the result of this scan. The patient may have a
number of these scans over the years to look for
progression of scarring. It is an indication of the
severity of the UTI, and that perhaps more aggressive
intervention is needed to prevent loss of graft
function,” comments Rhana.
Issue 16 | Spring 2022