|Year : 2021 | Volume
| Issue : 3 | Page : 139-140
Actinomycetoma caused by Nocardia brasiliensis successfully treated with antibiotics: A case report
Yi-Teng Hung1, Ting-Shu Wu2, Yu-Han Hsueh1, Hsuan-Ning Wang1, Pei-Lun Sun3
1 Department of Dermatology, Chang Gung Memorial Hospital Linkou Bracnh, Taoyuan, Taiwan
2 Division of Infectious Diseases, Chang Gung Memorial Hospital Linkou Branch; College of Medicine, Chang Gung University, Taoyuan, Taiwan
3 Department of Dermatology, Chang Gung Memorial Hospital Linkou Bracnh; College of Medicine, Chang Gung University, Taoyuan, Taiwan
|Date of Submission||28-Feb-2021|
|Date of Decision||15-May-2021|
|Date of Acceptance||08-Jun-2021|
|Date of Web Publication||28-Jul-2021|
Dr. Pei-Lun Sun
No. 5, Fushin Street, Guishan Dist., Taoyuan City 33305
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Hung YT, Wu TS, Hsueh YH, Wang HN, Sun PL. Actinomycetoma caused by Nocardia brasiliensis successfully treated with antibiotics: A case report. Dermatol Sin 2021;39:139-40
|How to cite this URL:|
Hung YT, Wu TS, Hsueh YH, Wang HN, Sun PL. Actinomycetoma caused by Nocardia brasiliensis successfully treated with antibiotics: A case report. Dermatol Sin [serial online] 2021 [cited 2021 Dec 6];39:139-40. Available from: https://www.dermsinica.org/text.asp?2021/39/3/139/322490
Mycetoma, including actinomycetoma (caused by bacteria) and eumycetoma (caused by fungi), is a chronic infection of the subcutaneous tissues and the overlying skin caused by traumatic implantation of microorganisms. Mycetoma has a characteristic clinical triad: Firm swelling on the lesion, draining sinuses, and discharge of grains comprising either fungi or bacteria., Mycetoma may cause limb deformity, amputation, and even death if left untreated. It is extremely rare in Taiwan, and the diagnosis and treatment experience are scarce. Herein, we report a case of actinomycetoma caused by Nocardia brasiliensis that responded well to systemic antimicrobial treatment.
A 26-year-old otherwise healthy female had a blunt trauma by hitting into a telephone pole on her right knee in 2014 and resulted in a small-crusted wound. This wound remained unchanged for years but became a large infiltrative plaque gradually after seawater activity at a sand beach in October 2019. The lesion was left untreated until 3 months before her visit to our emergency department and subsequent referral to the outpatient clinic of department of dermatology. Physical examination showed a large bulging plaque with multiple progressive coalescing nodules, abscesses, draining sinuses, and powdery materials discharged through draining sinuses on her right knee [Figure 1]a. The powdery materials were identified to be granules of thin filamentous materials through microscopy. Histopathological examination revealed hyperkeratosis, marked acanthosis, and mixed inflammatory cell infiltrates composed of neutrophils, eosinophils, lymphocytes, plasma cells, and histiocytes in the dermis with one granule with Splendore-Hoeppli phenomenon [Figure 2]a. On pus and tissue biopsy culture, the growth of the bacterium identified as N. brasiliensis by matrix-assisted laser desorption ionization-time of flight mass spectrometry and further confirmed by partial 16S ribosomal RNA sequence was observed. The colonies on chocolate agar were yellowish and rugose [Figure 2]b. Cultures for mycobacteria and fungi were negative. Plain radiography showed only soft-tissue swelling without remarkable bone deformity.
|Figure 1: (a) Actinomycetoma on right knee. (b) Resolution during follow-up after 21-week treatment of amoxicillin-clavulanate.|
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|Figure 2: (a) Histopathology revealed hyperkeratosis, acanthosis, mixed inflammatory cell infiltrates and one sulfur granule with Splendore-Hoeppli phenomenon (H and E stain, ×200). (b) The yellowish and rugose colonies of Nocardia brasiliensis on chocolate agar.|
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Oral antibiotics of cefadroxil (1 g/day), amoxicillin-clavulanate (2 g/day), and trimethoprim-sulfamethoxazole (160 mg/800 mg twice daily) were administered sequentially for 2 months at outpatient clinics. Trimethoprim-sulfamethoxazole was discontinued due to drug eruption after a 2-week course. Then, the patient was hospitalized and received intravenous imipenem (2 g/day) and amikacin (800 mg/day) for 2 weeks; this was switched to amoxicillin-clavulanate (3.6 g/day) for 1 week according to the antimicrobial susceptibility results from the Thermo Scientific™ Sensititre™ RAPMYCOI AST panel (TREK Diagnostic Systems Ltd.). After discharge, oral amoxicillin-clavulanate (2 g/day) was administered for 5 months; the lesion subsided gradually [Figure 1]b.
While treating mycetoma, it is essential to distinguish between actinomycetoma and eumycetoma. The colors of fungal grains are often black or pale, while those of actinomycetes are yellow, red, or white., Eumycetoma grains are Gram-negative with larger sized 2–5 μm-wide septate hyphae, while actinomycetoma grains are Gram positive, 0.5-1-μm-wide filaments. This simple grain examination could help in defining the nature of infection and choosing either antibacterial or antifungal treatment before the culture reports are obtained.
In Taiwan, there are only ten published cases of mycetoma including seven actinomycetoma (including this case) and three eumycetoma cases. Among the actinomycetoma cases, three were caused by N. brasiliensis, three by Nocardia asteroids, and one by Nocardia otitidiscaviarum., Among the eumycetoma cases, one was caused by Pyrenochaeta romeroi and two by Scedosporium apiospermum. N. brasiliensis infection manifests differently from those of other Nocardia species, usually associated with a primary cutaneous infection. In Taiwan, N. brasiliensis is the most prevalent species causing cutaneous nocardiosis and accounts for 43% of actinomycetoma in our review. The susceptibility profiles of Nocardia spp. to antimicrobials showed that N. brasiliensis was sensitive to amoxicillin-clavulanate, amikacin, linezolid, trimethoprim-sulfamethoxazole, moxifloxacin, tobramycin, and gentamicin and resistant to cefepime, imipenem, cefoxitin, doxycycline, ciprofloxacin, levofloxacin, clarithromycin, azithromycin, ampicillin, clindamycin, and vancomycin. N. brasiliensis displayed a distinct antimicrobial susceptibility pattern from other Nocardia species showing high sensitivity to amoxicillin-clavulanate and low sensitivity to carbapenem antibiotics. A study on antimicrobial susceptibility testing of N. brasiliensis strains from patients with cutaneous nocardiosis in Taiwan found that the local strains were susceptible to trimethoprim-sulfamethoxazole, amikacin, gentamicin, and piperacillin-tazobactam, and resistant to erythromycin and oxacillin; the susceptibilities to imipenem, clindamycin, vancomycin, tetracycline, and ciprofloxacin were inconclusive and showed a great range of minimum inhibitory concentrations. The antimicrobial susceptibility for N. brasiliensis isolates in our case is similar to that in previous studies., Therefore, amoxicillin-clavulanate, amikacin, linezolid, and trimethoprim-sulfamethoxazole may remain effective in treating mycetoma caused by N. brasiliensis in Taiwan.
In conclusion, we presented a rare case of actinomycetoma caused by N. brasiliensis with a characteristic triad of mycetoma. Proper isolation and identification of the causative agent along with antimicrobial susceptibility testing is mandatory to choose appropriate antibiotics. Early diagnosis and treatment could avoid devastating outcomes such as bone destruction.
This study was approved by the institutional review board of Chang Gung Medical Foundation (approval number: 202100199B0; approval date: 2021.02.22). The patient consent was waived by the IRB.
Financial support and sponsorship
Conflicts of interest
Dr. Pei-Lun Sun, an editorial board member at Dermatologica Sinica, had no role in the peer review process of or decision to publish this article. The other authors declared no conflicts of interest in writing this paper.
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[Figure 1], [Figure 2]