Recurrent Subcutaneous Abscess from Co-Infection with Prototheca wickerhamii and Mycobacterium haemophilum: mNGS Misdiagnosis as Leprosy.

Abstract

Prototheca wickerhamii (P. wickerhamii) and Mycobacterium haemophilum (M. haemophilum) are both opportunistic pathogens that could cause infections in immunocompromised populations. However, these infections rarely occur in individuals with normal immunity. We reported a 39-year-old immunocompetent man presented with recurrent subcutaneous abscess on fingers who developed a co-infection of P. wickerhamii and M. haemophilum. To our knowledge, this is the first reported co-infection involving P. wickerhamii and M. haemophilum. The diagnosis was complicated by mNGS misidentifying M. haemophilum as Mycobacterium leprae (M. leprae) (98% sequence similarity) and overlooking P. wickerhamii. This case underscores the critical need to correlate mNGS results with clinical features and use complementary diagnostic methods to avoid errors. The combination of traditional and molecular methods can improve diagnostic accuracy.