Should we screen for occult bacterial infection before kidney transplant? Balancing stewardship and patient safety

Recommendations on pre-transplant screening for bacterial infection and asymptomatic bacteriuria (ASB) in kidney transplantation (KT) are limited. We evaluated whether pre-KT screening cultures (prior-KT-SC) predict early post-KT infections and inform perioperative antimicrobial strategies.

We conducted a historical cohort of asymptomatic KT recipients (2017-2022) who had blood and urine cultures collected ≤48 hours before surgery. The outcomes were surgical site infection (SSI) and urinary tract infection (UTI) caused by the same organism isolated on prior-KT-SC within 30 days post-KT.

Among 996 KTs (986 patients), prior-KT-SC were positive in 225 (22.6%): 86 blood (8.6%) and 152 urine (15.3%), including 48 ASB (≥10⁵ CFU/mL). The most frequent bloodstream isolate was Staphylococcus epidermidis (41; 40.2%), while Gram-negative bacilli accounted for 48% of bloodstream isolates. From 185 urine isolates, E. faecalis (26.5%) and E. coli (21.1%) predominated; 16 patients harbored multidrug-resistant organisms (MDRO). Among recipients with positive prior-KT-SC, 17 (7.6%) developed a post-KT infection caused by the same organism. UTI risk increased with prior-KT-SC showing MDRO (p = 0.02) and with pre-KT ASB (p = 0.007). Protective factors for UTI were amikacin prophylaxis (p = 0.04), deceased donor (p = 0.02) and glomerulonephritis as end-stage kidney disease (p = 0.006). Positive prior-KT-SC were not associated with SSI. Risk factors for same-organism post-KT infection included ESBL-Enterobacterales (p = 0.004), multiple positive cultures sites (p = 0.04) and combined transplant (p = 0.01).

Pre-KT screening showed frequent blood culture contamination but also detected asymptomatic bacteremia. ASB increased the risk of 30-day UTI. These findings support screening in asymptomatic patients, while highlighting the need for cautious interpretation.