[1606] Pyelonephritis in Renal Allografts – Biopsy or Cultures?

Anna Bracewell, Uday Nori, Joan-Miquel Balada, Tibor Nadasdy, Anjali Satoskar. Ohio State University Wexner Medical Center, Columbus, OH

Background: We recently encountered four patients with severe allograft dysfunction requiring dialysis in the early post-transplant period with biopsy findings of acute pyelonephritis, but repeatedly negative urine culture results. Despite antibiotics, recovery was slow. Two of them lost their grafts within a year. We retrospectively reviewed our renal allograft biopsies with histologic features of acute pyelonephritis to study degree of correlation between biopsy diagnosis and urine culture results.
Design: We found 53 patients with biopsy diagnosis of acute (with or without chronic) pyelonephritis over a 7 year period.
Results:

Table 1. Patients with biopsy features of pyelonephritis over 7 years.
 Culture positive (n)Culture negative (n)Total
Total351853
Biopsy in 1st year post-transplant221436
Graft loss within 1 year of biopsy6/22 (27%)1/14 (7%)7/36
Biopsy after 1 year post-transplant13417
Total graft loss15/35 (42%)4/18 (22%)19/53


In 10/35 culture positive patients, the urine culture turned positive only after the biopsy (after up to 4 months), in 25/35 patients, positive culture results were available before or on the day of the biopsy. Besides the common urinary pathogens, Staphylococcus epidermidis (n=3), Serratia spp. (n=1), Providencia spp (n=1), Citrobacter spp (n=1), Candida spp (n=5), were found in culture. Mycoplasma spp was positive on urine PCR in one patient. In 14 patients, the colony count was less than 105 CFU/ml (5000 to 10,000 CFU/ml), but these were treated as infection. 7 of these 14 recovered graft function (one after Prednisone), 4 had graft loss within one year and three survived with increased serum creatinine. Of the 18 culture negative patients, 5 had subsequent acute rejection episode within the same month, one failed, one patient died and three recovered. Mean baseline serum creatinine of 1.6 mg/dl before biopsy increased to 2.2 mg/dl one year after biopsy in culture positive patients; there was no change (1.8 mg/dl to1.77 mg/dl) in culture negative patients. Graft loss was higher in culture positive group (Table 1). Biopsy findings were similar in both groups.
Conclusions: Low colony counts, isolated low virulence bacterial strains are not uncommon in urine cultures from renal allografts and can be clinically significant. Repeat urine cultures are warranted as culture positivity may occur late during the course. Differential diagnosis of pyelonephritis and acute rejection in transplant setting is difficult and there is currently no single gold standard for confirmation.
Category: Kidney (does not include tumors)

Monday, March 4, 2013 1:00 PM

Poster Session II # 226, Monday Afternoon

 

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