More than 100 people who died at hospitals in south-west London in the last three years were carrying deadly super bugs, figures show.
C. difficile was the cause of death in 14 cases
At St George's NHS Trust 95 people had C. difficile listed on their death certificate and the bug was cited as a cause of death for 14 of those.
A further 21 people died where MRSA was listed as a related cause.
The trust's chief executive David Astley said the rates of C. difficile and MRSA had been cut in the last year.
Mr Astley said while each case of a hospital-acquired infection was a serious incident, to put it in context, the trust treated 64,000 inpatients last year.
He also said that as a large teaching hospital it took patients with complex illnesses and injuries, sometimes from other hospitals across south-east England.
"These seriously ill patients are particularly vulnerable to infection and this is factor which should be taken into account."
The trust said there had been no cases of MRSA since 2006 and the number of cases of C. difficile had been cut from 55 in October 2006 to 20 last month.
Mr Astley said: "Through monitoring mortality, we have been able to report death rates which other hospitals may not have had available.
"Our rates are comparable with the national average where C. difficile is known to have a mortality rate of between 6% and 12%.
"Through keeping a watchful eye on this we can take quick and appropriate action should rates begin to rise, but also learn from what we are doing well to help bring the rates down further."