Curious case of cutaneous Mycobacterium abscessus complicated by paradoxical reaction

Dear Sir, Mycobacterium abscessus is a drug-resistant microorganism involved in skin and soft tissue infections.[1] Treatment outcomes are dependent on the location and extent of disease, host immune system and antibiotic susceptibility status.[2] Paradoxical reaction manifests as worsening of existing lesions following the initiation of anti-mycobacterial therapy, due to an exaggerated inflammatory response.[3] We present a rare case of cutaneous M. abscessus complicated by paradoxical reaction in an immunocompetent patient, demonstrating the complex relationship between bacterial antibiotic resistance and host immune system. Recognising paradoxical reaction prevented further unnecessary surgeries, especially in the setting of 'worsening' clinical condition despite adequate treatment. A 46-year-old Chinese woman with diabetes mellitus presented with a posterior neck carbuncle and underwent saucerisation. Tissue culture revealed methicillin-sensitive Staphylococcus aureus, and she was treated with augmentin. She underwent rotation flap coverage of the neck wound, but recurrent wound dehiscence [Figure 1] occurred, with tissue culture growing M. abscessus sensitive to azithromycin. Infectious disease specialist started the patient on azithromycin and clofazimine. She was readmitted a month later for left posterior neck swelling. Computed tomography (CT) neck showed irregular rim-enhancing fluid collections in the left neck [Figure 2]. She underwent multiple wound debridement [Figure 3] with negative tissue cultures, but postoperative CT neck still revealed persistent multiloculated abscesses. The patient also presented with right supraorbital swelling, but CT scan did not indicate orbital cellulitis. Human immunodeficiency virus test was negative. She was treated with prednisolone 30 mg/day for paradoxical reaction. She completed 6 weeks of intravenous amikacin and cefoxitin. Oral clofazimine and azithromycin were continued for 6 months with 2 months of tapering prednisolone. The neck wound healed by secondary intention.Figure 1: Cutaneous Mycobacterium abscessus presents with superior and inferior wound dehiscence after rotation flap coverage.Figure 2: (a) Coronal CT image shows fluid collections on the left side of the neck involving the left superficial parotid. (b) Axial CT image shows inferior extension to the left supraclavicular region.Figure 3: Photograph shows multiple cutaneous tunnelling wounds over infra-auricular and superior posterior neck.Factors suspicious for M. abscessus are delayed wound healing, recurrent wound dehiscence and poor response to typical antibiotics.[4] It is difficult to treat M. abscessus because of its rapid growth, multidrug resistance and complex antibiotic regimes, which increase the risk of treatment non-compliance.[5] The Infectious Diseases Society of America recommends clarithromycin or azithromycin with parenteral antibiotics (cefoxitin plus amikacin/imipenem) for a duration of 4–6 months.[4] A review of cutaneous non-tuberculous mycobacterium infection over a 10-year period in Singapore[6] revealed a majority of them were caused by M. abscessus.[7,8] Paradoxical reaction is the worsening of existing lesions[9] after anti-mycobacterial therapy, due to an exaggerated host cell-mediated immunity. It should be considered if there is unexplained worsening infection not attributed to drug toxicity, multidrug resistance, bacterial superinfection, drug allergy or non-compliance.[10] Complementary findings include the lack of response to antibiotic augmentation, modestly elevated inflammatory markers, negative repeat mycobacterial wound cultures and clinical improvement with corticosteroids. In conclusion, we present a rare case of cutaneous M. abscessus infection, complicated by paradoxical reaction in an immunocompetent patient, treated with surgical debridement, long-term antibiotics and steroids. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.