A female patient, 56, received medical treatment from Bang Len Hospital for cough on March 27 but she did not inform the doctors that she was at risk of being infected with Covid-19.
Her daughter later told the doctors on March 28 that she had made contact with another Covid-19 patient and the hospital found that she was infected.
The hospital ordered 14 days self-quarantine for the 24 personnel who had made contact with the patient.
Bang Len Hospital decided to close its outpatient ward for 30 days to sanitise the zone and will only accept emergency cases.
Nakhon Pathom has 15 cases of Covid-19 but only 11 remain in the hospitals.