232. Genomic Evidence for Dissemination of Mycobacterium marinum in an HIV Patient with Multifocal Cutaneous Disease

Abstract

BackgroundHematogenous dissemination has been proposed to explain multifocal cutaneous disease caused by Mycobacterium marinum in certain patients. Treatment duration for disseminated disease is often months longer than for skin infection alone. However, distinguishing multiple independent inoculation events from dissemination has relied primarily on clinical judgement. Additionally, whether temperature-sensitive non-tuberculous mycobacteria such as M. marinum are indeed capable of invading the vascular space at core body temperature is debated. Here we used whole-genome sequencing (WGS) of serial isolates from a single patient with multifocal cutaneous M. marinum infection to distinguish dissemination of a clonal strain from multiple inoculation events.MethodsA 35-year-old male with HIV (CD4 of 66 cells/µL) presented with a two-month history of a non-healing M. marinum wound on his left elbow (isolate MM0). This was followed a month later after initiation of antiretroviral therapy by a second M. marinum lesion on the right heel (MM1) without history of repeat inoculation, and increased swelling and erythema of the wound on the left arm (MM2) consistent with paradoxical immune reconstitution inflammatory syndrome. A PacBio genome was generated for MM0 and short read Illumina genomes were generated for MM1 and MM2.ResultsAll isolates were found to be closely related, with MM1 and MM2 distinguished from MM0 by one and five single-nucleotide variants (SNVs), respectively. Given the substantial genetic heterogeneity among environmental M. marinum strains, such close relatedness of these isolates suggests common origin, and provides strong evidence for dissemination of a clonal strain in this patient. The SNVs included a frameshift mutation in the purT gene, which encodes a formate-dependent phosphoribosylglycinamide formyltransferase involved in de novo purine synthesis, and missense mutations in atsA and the DNA methylase hsdM. All isolates grew at 35°C, compared with the optimal growth temperature of 30°C typically observed for M. marinum, suggesting thermotolerance permissive for dissemination.ConclusionThese results demonstrate the potential role of WGS for providing supportive evidence of disseminated infection with M. marinum.Disclosures All authors: No reported disclosures.