ABSTRACT
Objective:To investigate clinicopathological features of swimming pool granuloma.Methods:From January 2018 to January 2021, 56 patients with swimming pool granuloma were collected from Tianjin Academy of Traditional Chinese Medicine Affiliated Hospital, and their clinical and pathological characteristics were retrospectively analyzed.Results:Among the 56 patients, 16 were males and 40 were females, with an average age of 60.84 years. The most common exposure type among these patients was handling of infected fishes or seafood by aquaculture workers and residents in daily cooking (31/56) , the average incubation period was 4.58 weeks, and the average time to diagnosis was 3.19 months. All skin lesions were located at the upper extremities, mainly manifesting as erythema and papular nodules, and sometimes as pustules, ulcers, granulomas or verrucous plaques. Eleven patients presented with solitary skin lesions, 36 with sporotrichoid skin lesions, and 6 with bilateral sporotrichoid lesions. Histopathologically, infectious granulomas were observed in all patients except 4 without specific changes, and 37 presented with characteristic exudative necrosis, with varying amounts of fibrinoid exudative or necrotic elements in the center, and a large number of neutrophils, histiocytes and multinucleated giant cells infiltrating inside or around it. Sequences of Mycobacterium marinum were identified in all 56 cases by metagenomic DNA sequencing of pathogenic microorganisms. Conclusion:In Tianjin area, swimming pool granuloma mostly affected elderly females, handling of infected fishes or seafood was the main type of exposure, and skin lesions were histopathologically characterized by exudative necrotic granulomas.
ABSTRACT
Mycobacterium marinum is an atypical mycobacterium (ATM) and is an uncommon cause of skin and soft tissue infections associated with contact with contaminated water. Diagnosis is often delayed when only a conventional identification method is used. PCR amplification and direct sequencing is recently available method for rapid identification of ATM. We report a case of M. marinum infection identified by PCR and sequencing. A 56-year-old female was referred for multiple erythematous nodules on both forearms which appeared two months ago. Skin biopsy showed suppurative granulomatous inflammation, and AFB culture showed nontuberculous Mycobacteria. PCR and sequencing were performed, and the obtained sequences were compared to the database using BLAST. The sequences of 16S rRNA and rpoB could not differentiate between M. marinum and M. ulcerans, showing 100% homology to both. Identification was possible using the sequences of the tuf and hsp65 genes, showing both 100% homology to M. marinum, while 99.8%, 99.7% to M. ulcerans. The patient was treated with clarithromycin, rifampicin, and ethambutol for 6 months.