Non-tuberculous mycobacteria (NTM) are acid-fast bacilli other than Mycobacterium tuberculosis (TBC). These organisms are ubiquitous in the environment and person-to-person transmission is considered an unlikely source. They can cause disease in both immunocompetent and immunosuppressed patients. Extrapulmonary NTM infections can occur due to breaches in the skin or soft tissues or due to several nosocomial factors. The diagnosis and differentiation of mycobacteria are carried out mainly through cultures and rapid molecular methods such as Real-Time Polymerase Chain Reaction (PCR), which in its multiplex format manages to rule out or confirm several molecular targets in a single reaction, speeding up thus the medical decision making.
Clinical case: 33-year-old male patient, related living donor kidney transplant, due to terminal chronic renal failure secondary to lupus nephritis. Immunosuppressive scheme: tacrolimus, prednisone, and mycophenolate. With a personal history of acute renal failure due to ureteral obstruction that required graft reimplantation to the native ureter. He was admitted for fever with chills for 9 days of evolution, lumbar pain in the right flank, and diarrhea. Inflammatory parameters were increased in blood and there were no isolates in cultures. He received empirical ceftriaxone and due to clinical improvement, he was discharged. The next day, he was re-admitted to the hospital due to the persistence of symptoms. Altered parameters in blood: Leukocytes 12.7 k/ul, erythrocyte sedimentation rate 93 mm/h, C-reactive protein 9.62 mg/dl, Creatinine 3.56 mg/dl and LDH 269 U/L. Lumbar and abdominal CT scan: severe hydronephrosis in the right native kidney. A nephrostomy was performed. Blood culture: development of mycobacteria. PCR negative for mycobacteria in peripheral blood, but positive NTM in nephrostomy collection; also, discarding TBC by the same multiplex PCR. Treatment with ethambutol and clarithromycin was started. Radical nephrectomy of the right native kidney was performed, and histopathological analysis reported lesions consistent with uropyonephrosis/exacerbated chronic pyelonephritis.
NTM infections in kidney transplants are uncommon, but when they do occur, the differentiation of NTM from TBC is of great clinical importance since it defines the isolation of patients in special rooms of health centers and the study of patient contacts. For that purpose, the implementation of molecular techniques has improved the diagnosis and differentiation of mycobacteria quickly and specifically concerning traditional culture. In our case, a multiplex PCR was used to detect targets of the genus Mycobacterium, the TBC complex, and the TBC species.
Although NTM infections in kidney transplant have been described, to our knowledge we describe the first case of infection caused by NTM in the native kidney of a renal transplant recipient, diagnosed by multiplex PCR.