Linda Hirst, CQC deputy director of operations in the north, said leaders at the care home were working on an improvement plan at the time of the inspection but it was too early to see any progress.
Ms Hirst said: “When we inspected Addison Court, it was disappointing to see a significant deterioration in the level of care being provided.”
She said incidents were not always investigated quickly enough to keep people safe.
“For example, falls in the home had increased significantly between June and July, but nothing had been done to check why and to put preventative measures in place to keep people safe,” she said.
There was an increase in agency staff employed at Addison Court but they told inspectors they did not know people’s needs well enough.
One member of staff had not received an induction and did not know how to support people in distress, the CQC said.
Medicine were not safely managed and records showed that some doses had been missed with no explanation. One missed dosage was for a “critical” medicine to treat Parkinson’s disease.
The home’s accident analysis failed to explore trends such as “unexplained bruising” on residents.
Ms Hirst said some positive areas of care were seen. This included the care home having a “welcoming and spacious” environment that had been adapted for the needs of residents living with dementia.