Nocardiosis in Renal Allograft Recipients

Abstract

Introduction: The aim of the study was to study the clinical profile and outcomes of nocardiosis in renal allograft recipients.

Methods: This was a retrospective study of clinical outcomes in consecutive renal allograft recipients with Nocardia infection over a 22-year period (2000-2022) from a tertiary care center in Southern India. The clinical data were obtained from electronic medical records and patient files.

Results: A total of 1970 patients underwent renal transplantation at Christian Medical College, Vellore, India, between January 1, 2000, and December 31, 2022. During this period, 26 patients were diagnosed to have Nocardia infection. Half (50%) of the patients had fever and cough as their initial presentation, 7 (26.9%) patients presented with cutaneous abscesses, 2 (7.6%) patients were incidentally detected to have lung nodules during routine follow-up, 2 (7.6%) patients presented with headache accompanied by fever, and 3.8% had graft abscess. The diagnosis was made by isolating the organism in culture from one or more of the following samples: sputum, blood, pus, or lung biopsy (either computed tomography [CT]-guided or bronchoscopic aspirate culture). Eight patients required bronchoscopy and two patients required CT-guided biopsy for obtaining samples for diagnosis. All patients were similarly managed initially with a reduction of immunosuppression and appropriate antibiotics as per culture sensitivity. All 26 patients responded to induction treatment with meropenem (or imipenem) and trimethoprim-sulfamethoxazole (co-trimoxazole) followed by maintenance treatment with co-trimoxazole. Five (19.2%) out of 26 patients received Minocycline in induction and maintenance treatment regimens as in four patients isolates were resistant and one patient had allergic reaction to Cotrimoxazole. All patients had stable graft function. Two patients succumbed after 2 months of diagnosis with Gram-negative sepsis.

Conclusions: At present, there exists no single serological test to diagnose Nocardia infection in patients. Multiple initially obtained cultures may be negative because of the slow growth of the organism and variable colony morphology. Hence, infected specimens should be obtained by aggressive approaches if the index of suspicion is high. Procedures such as bronchoscopic lavage and aspiration of abscess are invaluable toward making a diagnosis. In our study, eight patients required invasive diagnostic procedures such as bronchoalveolar lavage and CT-guided lung biopsy since initial Gram stain and sputum culture were negative. In conclusion, it is crucial to maintain a high level of suspicion and conduct thorough investigations among post renal transplant recipients. This approach facilitates early diagnosis, prompt initiation of appropriate treatment which helps prevent the spread of disease.

Keywords: Bronchoalveolar lavage; carbapenems; co-trimoxazole; computed tomography; cutaneous nocardiosis; disseminated nocardiosis; minocycline; pulmonary nocardiosis; transbronchial lung biopsy.

Figure 1

(Left side) multiple nodular parenchymal lesions in both lungs. (Right side) peripheral consolidatory mass lesion noted involving the lateral basal segment of the right lower lobe

Figure 2

Multiple, small, well-defined, ring-enhancing lesions of varying sizes in the both cerebral and cerebellar hemispheres with involvement of deep gray matter and midbrain. Lesions show the rim of T2-weighted hypointensity and central hyperintensity with perilesional edema and diffusion restriction

Figure 3

Graft kidney showing 1.6 cm ×1.1 cm ×2.3 cm abscess