Though the tissue remained culture negative after 6 weeks, PCR again confirmed the presence of MH. He recommenced antibiotic therapy of clindamycin, ciprofloxacin and rifampicin without dapsone Romidepsin cost and improvement in arthralgia was noted at review 2 weeks later. It

is anticipated that he will need life-long antibiotic suppression. This case highlights the difficult diagnostic and therapeutic implications of atypical infections in transplant patients. MH infections have been described in renal, heart, liver and bone marrow transplant recipients.[3] We believe this is the first reported case of MH presenting atypically with intra-nasal lesions and subsequent disease relapse at a new anatomical site with skin and presumably synovial involvement. Clinical features of MH in this population are wide-ranging, with reported pyomyositis with abscesses, tenosynovitis, septic arthritis, osteomyelitis, pneumonitis, septicaemia and skin lesions varying from nodules, papules, cysts to tender discharging ulcers.[3, 4] It is likely that cell-mediated immunity plays a significant role in

the clinical evolution of the disease and outcome, with low levels of absolute CD4 count associated with worse outcomes including disseminated disease and death.[3] The presence of MH metastatic infection raises the possibility of over-immunosuppression Napabucasin cell line in this patient. The occurrence of early rejection meant a reduction in immunosuppression was approached cautiously. Although culture remains the gold standard for diagnosis, MH is notoriously fastidious and slow growing requiring temperatures of 30–32°C and does not culture on routine Mycobacterium media. Given the difficulty of detection of this organism it is likely that this infection has been under recognised and under reported in the literature.

Diagnosis for optimal detection of MH includes acid fast staining, culturing at two temperatures with iron-supplemented media and molecular Ribonucleotide reductase detection using PCR.[2] Treatment with multiple active agents was commenced based on a small series which found 100% of sixteen MH isolates were sensitive to ciprofloxacin and clarithromycin and 94% rifampicin sensitive. Treatment with at least two agents is recommended, as resistance has been described using clarithromycin, azithromycin, rifampicin and amikacin in NTM infections.[3, 5] Further complicating the management in transplant recipients is the interaction of immunosuppressive agents, particularly tacrolimus and cyclosporine and rifamycins such as rifampicin. The dose of calcineurin inhibitors often needs to be increased three to five fold with close monitoring of drug levels due to the induction of enzyme cytochrome P450. Transplant patients treated with rifampicin based regimens for Mycobacterium tuberculosis have been associated with an increased risk of allograft rejection and loss.[6] There is currently no consensus with respect to duration of therapy.