October: NHS trust is rated 'good' in glowing report by watchdog <br />Now: Catalogue of failings in care and hygiene is revealed

Poor standards of care at an accident and emergency unit in one of the country's flagship hospitals may have contributed to the unnecessary deaths of over 400 patients, an official NHS investigation has concluded. Dirty equipment and an absence of leadership contributed to a death rate almost 40 per cent above the national average among emergency admissions to the 770-bed Basildon and Thurrock University Hospitals NHS Foundation Trust, inspectors said.

The unit had blood stains on the floor, dirty curtains, stinking mattresses and soiled equipment; nurses who failed to monitor, feed and give drugs to patients correctly; and a rate of pressure sores almost twice the national average. Instead of the national four-hour maximum waiting time for A&E, the trust was operating a 10-hour waiting time.

The Care Quality Commission, the independent NHS inspectorate, which published the findings yesterday, said it had "lost confidence" in the management of the trust, after repeated requests to address the problems had failed to deliver results. It has referred the trust to Monitor, the foundation trust regulator, for action. It is the second time in six months that a foundation trust, a flagship NHS medical institution granted control of its own finances on the strength of its performance, has been found to be delivering sub-standard care suspected of causing hundreds of deaths.

In March, the Healthcare Commission – the CQC's predecessor – exposed a similar scandal at Mid-Staffordshire NHS Foundation Trust, where monitoring of mortality rates showed between 400 and 1,200 more deaths had occurred than the national average in the three years to 2007-08.

The Basildon NHS Trust, which has a £250m annual budget and treats 90,000 A&E patients a year, was one of the first in the country to achieve foundation status in 2004. In October it was rated "Good" overall on the quality of care in the NHS performance ratings for 2008-09, published by the CQC, after scoring "Excellent" the previous year.

Yesterday, a month after the 2008-09 ratings were published, the CQC dramatically revised that assessment with a catalogue of failings including persistently high death rates, poor care, inadequate arrangements for children, poor nursing, breaches of infection control, and poor leadership.

An unannounced spot check of the A&E department revealed half of the curtains surrounding cubicles were soiled, some of them with blood, 11 out of 12 trolley mattresses were stained and two had a "foul odour", suction machines for clearing airways were "dirty and dusty", and reusable equipment was not being "effectively decontaminated" between patients.

Cynthia Bower, CQC chief executive, said: "We want to act swiftly at Basildon to nip problems in the bud, working closely with other regulators ... We believe that effective action will now take place as a result of this joint regulatory action.

"Our work has uncovered serious failings. The trust has high mortality rates for emergency admissions and we have found evidence of significant problems in different parts of the organisation. The trust has taken our concerns seriously but improvements are simply not happening fast enough. Our confidence in the management's ability to deliver on commitments and to turn the situation around has been severely dented. We have shared our concerns with Monitor, which is now using its formal powers to accelerate improvement."

The CQC said the death rate for all emergency admissions to the trust was 6.1 per cent, 39 per cent higher than the 4.4 per cent national average and equivalent to an extra 400 deaths. "There has been no evidence to show sustained improvement so far this year," it said.

Arrangements for monitoring patients in the A&E waiting room were inadequate. Patients had little privacy, with curtains separating cubicles, and many being cared for on trollies round the edges of the major injuries area or, in busy times, in the centre of it. It was not clear who had the overall view of what was happening in the department. The trust was given an official warning last month because of its failure to maintain a "clean and appropriate" environment in A&E. The notice required it to take immediate action to address infection control problems by 30 November.

Further concerns were raised about people with learning disabilities after the deaths of four people under the trust's care. The cases were referred to the CQC by the charity Mencap. The commission said it was reviewing information from the trust giving assurances that action had been taken and lessons learned.

"Analysis of board meeting minutes suggests it spent little time discussing and challenging information in relation to poor quality of care for patients. The trust board must assure itself that quality of care remains at the top of its agenda."

Shadow Health Secretary Andrew Lansley said: "I am extremely disturbed by this news and the effect that these shocking conditions may have had on patients. It is unforgivable if any lives have been needlessly lost."