You are presented with a paragraph from a COVID-19 literature. Classify the topics of this piece of text by choosing from the following categories:

- Epidemic Forecasting: The content relates to predictions about the spread of COVID-19.
- Treatment: The paragraph discusses therapeutic methods or medication for COVID-19.
- Prevention: The content covers measures to prevent the spread of COVID-19.
- Mechanism: The paragraph explains the biological mechanisms of the virus.
- Case Report: The content is a report of a COVID-19 case.
- Transmission: The paragraph discusses how COVID-19 is transmitted.
- Diagnosis: The content is about diagnosing COVID-19 in individuals.

Your classification should be provided as an element within a JSON array. The array should be formatted with topics enclosed in double quotes and separated by commas, following the JSON format, for example: ["Topic1", "Topic2", ...]. Include all applicable topics within the array. Your output should be a valid JSON array, and no additional text should be included in your response.

Article:

We report a 60-year-old male who was transferred to our hospital for the operation because of refractory ulcerative colitis (UC). He was diagnosed to be infected with COVID-19 for SARS-CoV-2 PCR test positive at the time of transfer. We determined emergency operation because his general condition was poor such as malnutrition and ADL decline due to exacerbation of UC and air embolization by central venous catheter removal. He underwent subtotal colectomy with a sigmoid mucous fistula and ileostomy. He was well postoperatively. This is a first case report in Japan who underwent an operation for UC with COVID-19 infection.
["Case Report"]