Hospitals in Northern Ireland have dramatically improved their performance on hygiene and dealing with infection.
Staff at major acute hospitals, delivery suites for pregnant women and psychiatric wards have made significant progress, the regulator said.
Inspections of acute hospitals revealed 90% complied with standards compared with 10% a year ago.
Hospitals which met standards included: the Royal Belfast Hospital for Sick Children; the Mater Hospital; Daisy Hill Hospital; The Ulster Hospital; and Tyrone County Hospital.
Glenn Houston, Regulation and Quality Improvement Authority (RQIA) chief executive, said: "Good infection control and hygiene practices are key to reducing the risk of healthcare-associated infection, and building public confidence in our health and social care services."
A public inquiry into a C. difficile outbreak two years ago has concluded.
An independent panel last month reviewed cases in Northern Trust hospitals between June 2007 and August 2008 and established that 31 people died from the outbreak.
Mr Houston said since 2009 significant improvements had been made across all services.
In acute hospitals compliance rates rose from 10% of areas inspected in 2009 to almost 90% this year. There were similar levels of compliance in maternity delivery suites and acute psychiatric admission wards.
The RQIA said there is still scope for further improvement and urged a continued focus on sustained performance on hygiene and infection prevention and control.