A 62-year-old Nepali, a professional health worker, presented in Grande International Hospital with red erythematous papules near around the previous site of renal transplantation(Fig. 1a). He had lived with diabetes and hypertension for 27 years and had a history of visiting the south-western and south-eastern region of the USA. The renal transplantation was done 6 months ago (6th October 2017). The previous diagnosis was made as cutaneous tuberculosis; in a local hospital, based on clinical presentations and unresolved lesion with a course of antimicrobial therapy (cloxacillin). Simultaneously, the patient had received a course of anti-tubercular therapy for two months. Paradoxically, the lesions continued to progress with pus discharges. A routine culture revealed no bacterial and fungal growth associated with the infection. On clinical examinations, few red erythematous papules with erosions and crusting seen over the site of prior the scar (Fig. 1b); no other systemic abnormality were found to be associated. Hence, the differential diagnosis of actinomycosis, deep mycosis, and rifampicin resistant cutaneous tuberculosis was made.
On histopathological examination, multiple basophilic colonies surrounded by neutrophilic abscesses and granulation tissue with dense infiltration by acute and chronic inflammatory cells were observed. However, the serological marker: HIV, HBsAg, HCV (ELISA) were negative. The Renal function and Liver function were found normal. The level of tacrolimus was assessed 9.0mcg/dl.
As of microbiological approaches, for the detection of an etiologies: right angaled branching, filamentous Acid Fast Bacilli (AFB) was observed on Ziehl-neelson staining (Fig. 2); chalky white adherent colonies were seen on aerobic culture after 72 h of incubation, which turns molar tooth appearance on further incubation (Figs. 3 and 4). Further, identification of the isolate, Nocardia asteroids, was done with standard microbiological culture methods as recommended by American Society for Microbiology, based on phenotypic characteristics, biochemical interpretations, and varied incubation temperature to grow the pathogen; since molecular analysis and sequencing was not accessible in our laboratory setting. Plus, antibiogram of the isolate was determined by modified Kirby-Bauer disk diffusion method on Blood agar against commercially prepared antibiotic disks (HiMedia Laboratories Pvt. Limited, India) in acquiescence with Clinical Laboratory Standards Institute (CLSI). Additionally, the CT scan of lungs and brain was done to rule out the possible disseminated nocardiosis; however, no abnormalities detected. In view of examination and investigations, a diagnosis of primary cutaneous nocardiosis was made on post-renal transplant patient. Subsequently, anti-tubercular therapy was discontinued, and the patient was treated with trimethoprime and sulfamethoxazole as per the drug susceptibility testing.
The patient was treated with trimethoprime and sulfamethoxazole, BACTRIM-DS (PO x BD), 2 double strength oral tablets each containing 800 mg sulfamethoxazole and 160 mg trimethoprim for 3 months.
He has now completed 2 months of treatment; has undergone progressive changes no relapse noted (Fig. 1c); transplant function observed in a good state. He is under regular follow up since then and we found him asymptomatic; however, with limited side effects due to prolonged antimicrobial therapy.