Comment on "Orbital Actinomycetoma with cranial extension: A rare case report".

Dear Editor;

A spectacular case report was recently published by Fadalla et al. under the title “Orbital Actinomycetoma with cranial extension: A rare case report” [1]. Actinomycetoma is identified as a chronic subcutaneous infection caused by aerobic Actinomycetes; Nocardia brasiliensis, Actinomadura madurae, as well as Streptomyces somaliensis are considered to bethe most frequent microorganisms which are isolated form this disease [2]. Nevertheless, a better way of managing actinomycetoma should be defined by identification of bacterial species, drug susceptibility testing, as well as location of infection [3]. We describe some constructive points to enrich the current rare report.

Aerobic Actinomycetes is heterogeneous group of actinomycetes including Actinomadura, Gordona, Nocardia, Rhodococcus, Mycobacteria, Streptomyces, and Tsukamurella that have similar features such as colony morphology or gram-staining. Accurate identification of aerobic actinomycetes involves performing various biochemical assays, high performance liquid chromatography (HPLC), matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry, and molecular methods is required [4]. However, the authors have been identified Streptomyces somaliensis using histopathology staining. The histopathological identification of the causative organism has been described in the literature as a valid method [5], [6], [7]; but histopathological staining was not able to identified Streptomyces spp. to the species level. Actinomycetoma should be identified using both histopathological staining and microbiological methods to be accurate as well as informative.

To validate the microbiological results, the performance of repetitive culture results (at least two positive culture) for confirmation of Streptomyces somaliensis infection could be more reliable for this cases. However, details of culture or microbiological identification were not mentioned in this report.

According to the guidelines of the American Thoracic Society (ATS), aerobic actinomycete isolates should be identified at the species level for proper diagnosis, optimal treatment, and epidemiological purposes [8], [9]. Streptomyces has an exclusive drug susceptibility pattern. Though, did not attain accomplish drug susceptibility testing for this Streptomyces spp. and there is no data regarding follow-up result. The recommendation of blind treatment with multiple antibiotics could contribute in emergence of drug-resistant Streptomyces isolates. Thus, drug-susceptibility testing is necessary as antimicrobial stewardship strategy for reduction of antimicrobial resistance burden. Nevertheless, the authors rectified that the patient was referred to a Mycetoma center for medical treatment and follow up. According to the literatures, the main therapy in such this case was surgical as well as antibiotic therapy [10]. It is more appealing that details of treatment processes and follow-up outcomes would be suggested for management of further similar cases.

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Author contribution

Ali Beheshti Namdar contribue in review and editing.

Saeed Sahebi contribue in review and editing.

Masoud Keikha contribue in conceptioal, study design, review of the litratures, writing the draft and revision.

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Not applicable for this study.

Declaration of competing interest

There is no conflict of interest.