Antibiotic Tolerability in Nocardia Infection Among Kidney Transplant Recipients: A Multicenter Cohort Study.

Abstract

Background: Nocardia infection is a rare but severe complication in kidney transplant (KT) recipients, with high morbidity and mortality. Data on antibiotic tolerability in this population are scarce.

Methods: We conducted a retrospective, multicentric study across six Spanish transplant units to analyze clinical characteristics, treatment strategies, and antibiotic tolerability in KT patients diagnosed with Nocardia infection.

Results: Twenty-six cases of Nocardia infection were identified, predominantly in elderly male patients with significant comorbidities and a high immunosuppressive burden. Pulmonary involvement was the most common presentation, although extrapulmonary manifestations also occurred. Only 36% of infections occurred within the first posttransplant year. Most patients received initial combination therapy, followed by prolonged treatment-primarily with trimethoprim-sulfamethoxazole (TMP-SMX) or linezolid. However, antibiotic tolerability was poor: TMP-SMX was discontinued in 80% of cases due to adverse effects, mainly hyperkalemia, metabolic acidosis, and acute kidney injury. Linezolid was withdrawn in 90% of patients because of myelotoxicity. Tedizolid, used in 38.4% of cases, showed better tolerability, with only 20% of treatment discontinuation and no relapses reported during follow-up. Overall, mortality during treatment reached 30.8%, mainly due to infectious causes.

Conclusions: This is the largest series of Nocardia infection in KT recipients in Spain and the first to specifically evaluate antibiotic tolerability. TMP-SMX and linezolid were poorly tolerated, reinforcing the need for alternative strategies. Tedizolid showed a favorable safety profile and may be considered a promising first-line option in high-risk patients. Further prospective studies are needed to confirm these findings and support guideline development.