In a statement, the republic's Ministry of Health (MOH) said the patient, labelled as Case 15,237, had no recent travel history to affected countries or regions.
The 23-year-old female nurse at the National Centre for Infectious Diseases (NCID) reported the onset of symptoms on April 23, and the test results confirmed Covid-19 infection.
Prior to hospital admission, the nurse, who is currently warded at NCID, had mostly been on medical leave and had only gone to work for a few hours, said the ministry.
The MOH said to-date, 1,188 cases of Covid-19 infection had been discharged or were in community isolation facilities, 22 were in critical condition in intensive care unit and 14 had died.
Singapore also identified five more new clusters at 11, Defu Lane 1; 106, International Road; 33, Senoko Way; 17, Shaw Road; and 182, Woodlands Industrial Park E5.
The republic's largest cluster, S11 Dormitory @ Punggol, has a total of 2,436 confirmed cases now.
Singapore reported no imported cases, 11 cases in the community, and 19 Work Permit holders residing outside dormitories.
Meanwhile, about 95% from Wednesday's new cases of 690 involved dorm residents.
The ministry noted that 63% were linked to known clusters, while the rest would be identified pending contact tracing.
Singapore's current tally stands at 15,641 cases. – Bernama