785. Treatment of Mycobacterium immunogenum Skin and Soft Tissue Infections: A Case in a Peritoneal Dialysis Patient.
Session: Poster Abstract Session: Tuberculosis and Other Mycobacterial Infections
Thursday, October 4, 2018
Room: S Poster Hall
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  • Background: Mycobacterium immunogenum is a somewhat recently identified species of rapidly growing non-tuberculous mycobacteria, genetically related to Mycobaterium abscessus and Mycobacterium chelonae. Resistance patterns of rapidly growing non-tuberculous mycobacterium species can make them difficult to treat. This is particularly true of M. immunogenum, in part due to the infrequency of reported cases of human infection and limited data to guide therapy.

    Methods: We present here a case of Mycobacterium immunogenum skin and soft-tissue infection at the site of insertion of a peritoneal dialysis catheter in a patient with end-stage renal disease. He initially presented with nodular subcutaneous lesions around his catheter site that progressed through oral antibiotics. This led to sampling which confirmed the diagnosis of M. immunogenum. We conducted a review of the literature to identify previously reported cases of M. immunogenum, including skin and soft-tissue infections, and used this data to guide management.

    Results: We reviewed 11 reports (cases and case series) of Mycobacterium immunogenum in the literature. Susceptibilities often take weeks to return, and so empiric therapy is based on case series, and then later adjusted based on susceptibilities. Patients received combined antimicrobial regimens with durations of two weeks to twelve months, with variable outcomes. Several required surgical debridement, as was the case with our patient. His PD catheter was removed and he was treated empirically with amikacin, azithromycin, and tigecycline intravenous induction. His ultimate long-term regimen was later switched to azithromycin, clofazimine and tedizolid due to side effects and the eventually available susceptibility profile.

    Conclusion: The treatment of Mycobacterium immunogenum remains a challenge due to the relative scarcity of data to guide treatment, and consequent lack of systemic approach to therapy. Most reported cases involve the use of a macrolide, often in combination with an aminoglycoside or a fluoroquinolone. Several started with intravenous induction, followed by transition to oral therapy on the order of weeks to months. Others also require surgical debridement. More data is required to develop a standardized approach to the treatment of M. immunogenum.

    Walid El-Nahal, MD1, Abhishek Shenoy, MD1, McCall Walker, MD1, Tushar Chopra, MD2, Greg Townsend, MD3, Scott Heysell, MD, MPH3 and Joshua Eby, MD3, (1)Department of Medicine, University of Virginia Health System, Charlottesville, VA, (2)Division of Nephrology, University of Virginia Health System, Charlottesville, VA, (3)Division of Infectious Diseases and International Health, University of Virginia Health System, Charlottesville, VA


    W. El-Nahal, None

    A. Shenoy, None

    M. Walker, None

    T. Chopra, None

    G. Townsend, None

    S. Heysell, None

    J. Eby, None

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