Orbital Cellulitis Due to Mycobacterium abscessus

Dear Editors, Orbital cellulitis is a potentially dangerous infection of soft tissue located within the eye socket. Ocular tissues may get infected with microorganisms, following external ocular trauma, iatrogenic procedures on the eye, or due to spreading rhinosinusitis.[1] The common organisms implicated include bacteria such as Staphylococcus aureus and Streptococci species and fungi such as Mucorales and Aspergillus species.[2] Here, we report a rare case of orbital cellulitis due to non-tuberculous mycobacteria (NTM), Mycobacterium abscessus. A 65-year-old elderly woman, a homemaker, reported at our center with complaints of pain, redness, swelling, diminution of vision, and purulent discharge from her right eye [Figure 1]. Her records indicated a case of inferior retinal detachment with a retinal break at 6 o’clock and diagnosed 5 years back. She underwent combined vitrectomy and scleral buckling surgery for the same. She was on regular follow-up and was managed with topical antibiotics. Five months before the current referral, she underwent posterior sub-Tenon triamcinolone acetonide injection in the right eye at a private center for complaints of red eye.Figure 1: Photograph of the Orbital cellulitis of the right eye of the patientClinical examination revealed a case of buckle exposure with orbital cellulitis of the right eye. She was managed with buckle explant surgery right eye and irrigation of the subconjunctival cavity with 0.5% povidone-iodine. Postoperatively, broad spectrum antibiotic cover was provided in the form of injection ceftazidime 1 g intravenous (IV) 12 hourly, and injection metronidazole 500 mg IV 8 hourly. Topical antibiotic cover was initiated with tobramycin and moxifloxacin–dexamethasone eye drops. Intraoperative specimen from the right eye was submitted for microbiology. Multiple smears were prepared on glass slides for staining and the buckle tissue was cultured on blood agar and MacConkey agar. Gram-stain smear showed slender, nonfilamentous, and faintly staining Gram-positive bacilli with a background of numerous polymorphonuclear cells, whereas Ziehl–Neelsen stain revealed slender, evenly staining, pink, acid-fast bacilli [Figure 2]. Growth on routine 5% sheep blood agar showed tiny, smooth, dome-shaped, translucent, and nonhemolytic colonies after 48 h of incubation. Furthermore, growth on MacConkey agar showed smooth, tiny (1 mm), dome-shaped lactose-fermenting colonies.Figure 2: Ziehl–Neelsen-stained smear showing numerous acid-fast bacilli with polymorphonuclear leukocytes in the backgroundOwing to the acid-fast nature of bacilli, a GeneXpert Mycobacterium tuberculosis (MTB)-Rif (Cepheid diagnostics), a cartridge-based nucleic acid amplification assay for MTB was performed on the isolate, which turned out to be negative. The isolate was further analyzed by Matrix Associated Laser Desorption Ionization–Time of Flight (MALDI-ToF) mass spectrometry technology, which identified it as M. abscessus. After the microbiological diagnosis of M. abscessus orbital cellulitis, antibiotics were changed to injection meropenem 1 g IV 8 hourly, injection amikacin 750 mg IV once a day, and tablet azithromycin 500 mg per oral once a day for 3 weeks. Additional work-up for pulmonary infection with NTM was noncontributory. She responded well to the treatment and was discharged after 3 weeks. This case highlights a rare cause of orbital cellulitis due to nontuberculous mycobacterium (NTM), M. abscessus.[3] Unlike MTB, M. abscessus is a rapid grower characterized by growth on solid media within 7 days.[4] This bacterium is ubiquitous in soil and water and can cause a wide spectrum of skin and soft-tissue infections. Infections due to NTM are difficult to identify and cause a significant delay in diagnosis. MALDI-ToF is an established modality for prompt diagnosis of M. abscessus.[5] It is resistant to many antibiotics and disinfectants, thus difficult to treat.[4,6] Combination therapy of IV amikacin with third-generation cephalosporin or carbapenem (imipenem) and an oral macrolide has been recommended by the American Thoracic Society.[7] Although the source of infection in our case could not be identified, infection with M. abscessus is usually caused by contaminated injections or through invasive procedures employing contaminated equipment, warranting regular checks on sterilization procedures in OT. M. abscessus infection can also occur after accidental injury where the wound is contaminated by soil.[8] M. abscessus infections are an increasing threat to public health due to their multidrug resistance. Prompt diagnosis plays an important role in the management of diseases due to M. abscessus. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given her consent for her images and other clinical information to be reported in the journal. The patient understands that her name and initials will not be published and due efforts will be made to conceal her identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.