Antibiotic Prophylaxis On UTI Rate After Pediatric Kidney Transplant
Ruthie Su, MD, MS, Jordan Krieger, MD, Michael Semanik, MD, Vinaya Bhatia, MD, Walid Farhat, MD, Ellen Wald, MD.
University of Wisconsin, Madison, WI, USA.
Background: Urinary tract infections (UTIs) are the most common infection and indication for hospitalization after kidney transplant in children. Many institutional protocols employ antibiotic prophylaxis after kidney transplant to decrease UTIs; however, there is no evidence that prophylaxis is effective in this setting. Accordingly, we tested the hypothesis that antibiotic prophylaxis decreases the rate of UTI after kidney transplantation.
Methods: A retrospective cohort study of all kidney transplants performed in persons <18 years old between 1994-2018 at a tertiary care center was conducted. Patients were identified using an IRB-approved institutional transplant database. We reviewed health records of all clinic and hospital admissions up to 10 years following transplantation. We recorded all episodes of UTI, and relevant urinalyses and cultures, symptoms, and preceding antibiotic prophylaxis use. The grade of vesicoureteral reflux (VUR), if known, and etiology of end stage renal disease were recorded. Congenital anomalies of kidney and urinary tract (CAKUT) were defined as diagnoses of posterior urethral valves and reflux nephropathy. Only episodes when the urine culture grew > 50,000 cfu/mL of a single organism were included for analysis. The effects of VUR, antibiotic prophylaxis, and CAKUT on UTI rate were examined using generalized estimating equations with a Poisson link and robust standard errors in SAS v9.0. Joint hypotheses using score statistics tested the overall significance of each effect.
Results: During the study period, 158 patients had 170 kidney transplants at a mean age 10.5 years [SD 5.3 years]. The mean length of follow-up was 7.5 years (SD 3.2 years). During 1,267 person years, there were 175 UTIs. A VCUG to screen for VUR was done in 77% of transplants. On univariate analysis, neither a routine VCUG (p=0.12), nor VUR grade (p=0.62) were associated with different UTI rates. UTIs peaked during the first year after transplant. Antibiotic prophylaxis and CAKUT were associated with higher UTI rates (p=0.004, p=0.06). On multivariate analysis, the effect of prophylaxis was modified by CAKUT status (p=0.047). In the non-CAKUT group, those on prophylaxis had 4.11 times higher UTI rate compared to those off prophylaxis (p=0.01). In contrast, UTI rates were similar between those on vs. off prophylaxis (RR=1.07, p=0.84) in the CAKUT group. Of 175 UTIs, 132 (75%) occurred while on prophylaxis; in 97/132 (73%) cultures, the organism was resistant to prophylactic antibiotic.
Conclusion: Screening for VUR did not reduce UTIs. Antibiotic prophylaxis was associated with a higher UTI rate after pediatric kidney transplantation, especially among those without CAKUT. Urine culture showed high rates of acquired antimicrobial resistance highlighting the importance of developing strategies other than prophylaxis to reduce UTIs after kidney transplantation.
Table. Univariate Analyses of UTI Rates After Pediatric Kidney Transplant
| Variable | # of transplants, 170 total | # of UTI, 175 total | Rate (#uti per year) | Rate Ratio | p-value, chi-square |
| Gender | |||||
| Male | 62 | 99 | 0.13 | 0.87 | 0.5687 |
| Female | 96 | 76 | 0.15 | 1 | |
| Antibiotic Prophylaxis | |||||
| Yes | 157 | 133 | 0.18 | 2.14 | 0.0039 |
| No | 96 | 42 | 0.08 | 1 | |
| Year after transplant | |||||
| 1 | 170 | 51 | 0.31 | ||
| 2 | 157 | 33 | 0.21 | 0.79 per year | 0.0012 |
| 3 | 148 | 27 | 0.18 | ||
| 4 | 141 | 11 | 0.12 | ||
| 5 | 129 | 16 | 0.12 | ||
| 6 | 118 | 7 | 0.06 | ||
| 7 | 111 | 10 | 0.10 | ||
| 8 | 104 | 4 | 0.04 | ||
| 9 | 98 | 2 | 0.02 | ||
| 10 | 91 | 7 | 0.08 | ||
| VCUG | |||||
| Yes | 131 | 158 | 0.16 | 1.77 | 0.1224 |
| No | 39 | 17 | 0.09 | 1 | |
| VUR grade | |||||
| Unknown | 101 | 38 | 0.11 | 1 | 0.6222 |
| 0-1 | 50 | 63 | 0.17 | 1.6 | |
| 2-3 | 67 | 51 | 0.12 | 1.1 | |
| 4-5 | 22 | 23 | 0.21 | 1.96 | |
| CAKUT | |||||
| yes | 71 | 108 | 0.2 | 2.18 | 0.06 |
| no | 99 | 67 | 0.09 | 1 |
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