King Kong Pox: A Case of Severe Mpox and Bartonella Co-infection in a Patient Living With Human Immunodeficiency Virus (HIV)

Mpox, formerly monkeypox (MPXV), is a zoonotic virus that has emerged globally in recent times, disproportionately affecting immunocompromised individuals, particularly people living with human immunodeficiency virus (HIV) (PWH). PWH with advanced HIV and low CD4 counts are at higher risk for severe, prolonged courses and sometimes fatal Mpox infections, which may often be complicated by bacterial superinfections and opportunistic co-infections. We present a case of Mpox in a PWH with an initial CD4 count of 2 cells/μL and a high HIV viral load, who had worsening disease despite treatment with tecovirimat, raising the question of persistent/resistant Mpox. Further investigations revealed co-infections with <i>Bartonella</i> and <i>Cytomegalovirus</i> (CMV), adding to the case's complexity. He initially presented with high-grade fever, and multiple, large necrotic lesions were noted on his face, scalp, left hand and knee, back, rectum, and genitalia. The patient was initiated on treatment with IV tecovirimat, oral brincidofovir, and vaccinia immunoglobulin (VIGIV). Anti-retroviral therapy (ART) was rapidly re-initiated. His hospital stay was further complicated by a superimposed extended-spectrum beta-lactamase (ESBL) <i>Escherichia coli</i> abscess underlying his necrotic left knee lesion. While admitted, he completed a two-week course of IV tecovirimat, three doses of brincidofovir, and a single dose of VIGIV with gradual improvement and no new lesions. This case demonstrates the potential for Mpox to have a prolonged and extensive course with widespread necrotic ulcers in the setting of HIV despite treatment. It is critical to have timely diagnosis and treatment of both Mpox and underlying HIV, alongside management of co-infections for improving disease outcomes.