Discussion
Post-transplant UTIs in kidney transplant patients are important causes
of acute graft dysfunction. Increased morbidity and hospitalization
rates are further major consequences of UTIs in kidney transplant
recipients. Therefore understanding and exploring the UTI details is
very crucial in transplant practice. In our study we found that UTI
incidence in the first year after transplantation was 20.5%. Although
the incidence of UTI in kidney transplant recipients have been reported
ranging between 7%-80% depending on the diagnostic criteria used, our
UTI rate is relatively lower than reported in the other studies where
the first year UTIs are evaluated [1, 4, 14, 15]. In our study a
lower rate of asymptomatic bacteriuria was found. The explanation for
lower rate of ABU may be that a regular screening program was not used
and urine culture studies were only performed in patients with UTI
symptoms or pyuria in urinalysis observed during regular visits. Most
patients with UTI attack presented as LUTI. CUTI incidence was found to
be 34.3%. Three attacks were progressed into bacteremia. The relatively
mild course of UTI attacks might result from early detection and
immediate antibiotic treatment in our cohort.
It has previously been reported that, early (<3 weeks after
transplantation) ureteric stent removal is associated with a lower rate
of UTIs [16,17]. In our center we have not been followed this
approach. Even though, presence of longer duration of ureteral stent was
found in our cohort, we did not find higher rate of UTIs. Other factors
such as, age, a longer duration of indwelling urinary catheter and
presence of urologic complications, stood out as important risk factors
in our patients. Thus, we recommend that patients with risk factors
should be carefully screened for LUTI, CUTI and ABU.
The rates of UTI caused by ESBL-producing organisms were high in our
cohort. More than half of UTI patients were exposed to at least one
episode of UTI with MDROs. According to a recently published study from
Australia, the authors isolated an ESBL-producing organisms in only
3,9% of urine cultures [18]. Bodro et. al. demonstrated that 37%
of bacteria considered as MDROs in kidney transplant recipients’ UTIs
[10]. Nevertheless, there are some studies showing higher rates of
UTI with MDROs in kidney transplant recipients similar to our findings
[19,20]. This finding gave us the opportunity to explore our
infection control methods and came to a conclusion that, prophylactic
use of quinolones up to seven days postoperatively may be responsible
from the high rate of UTIs with MDROs [11]. Changing our method of
prophylaxis was the most important consequence of this study. We stopped
prophylactic use of quinolones in our practice in line with study
results.
There are many studies showing that urinary tract infections are more
common in female recipients [1,4,5]. However, there are also some
studies that did not find any difference with respect to gender [7,
22, 23]. Interestingly, in our study, we showed that recurrent urinary
tract infections with resistant microorganisms are more common in male
transplant recipients. Male recipients also presented more often with
CUTI. Therefore, our data suggest, starting treatment with a
wide-spectrum antibiotic may be warranted for UTI infections in male
transplants since they tend to be caused by resistant microorganisms and
have a tendency to recur. There are studies in both the general
population and the transplant population to support these findings
[24-27]. Urinary outflow obstruction, possible prostatitis, and
inadequate response to antibiotics due to long uroepithelial tissue
compared to women are the mechanisms that explain this situation.
It is important to emphasize that, a UTI caused by ESBL-producing
microorganisms carries an almost three times greater risk of recurrence
[6]. Brakemeir et al reported that recurrence rate of UTI with ESBL
producing bacteria was found to be 54% [21]. Our findings were also
consistent with this previously published data.
These results should be interpreted with caution due to the single
center and retrospective nature of the study and the relatively small
number of patients. The low number of events limits further statistical
analysis for exploring exact effect of male gender on resistant and
recurrent UTIs.
In conclusion, our results shed an interesting perspective on UTI in
kidney transplant recipients. We strongly believe that each center
should explore their own UTI risk factors and causative agents that will
direct them to manage these patients correctly. This study also
highlights the importance of monitoring causative agents of UTIs,
especially in male gender, in order to improve empiric therapy in
transplant practice.