By the time nurses realised it was too late, the blackened skin at the base of Jamesina Mackenzie's back had turned putrid and soft to the touch.

A bedsore on her heel was two centimetres wide, while one on her left hip had rotted her flesh to the bone. According to one doctor, you could see the hip joint moving through the wound.

Other signs made it clear these septic wounds had triggered a blood infection. The slightest touch would trigger considerable pain. Jamesina's dry mouth indicated obvious dehydration. She was muddled and confused – very different from the intelligent and fiercely independent woman her relatives knew.

The home itself, which had changed ownership the previous March, had cut staff hours, and a complaint that patient care was suffering had been upheld by the industry regulator. In April, the home was briefly banned from accepting new residents until changes were made. On May 8, a plan for tackling Jamesina's bedsores was drawn up, but there's little evidence it was followed.

Nine days after the full scale of Jamesina's wounds were discovered, she died of septicaemia – infection of the blood – in hospital. The fatal accident inquiry which followed said she was "powerless" to do anything about her sores and reliant on staff for help. Had the treatment plan been adhered to, it concluded, there was "every chance" of survival.

If the events that led to Jamesina's death were unique, the disease that killed her is anything but. Evidence uncovered by a Sunday Herald investigation reveals a large spike in blood infection deaths in Scottish care homes.

Over the past five years the number of care home deaths from septicaemia, also known as sepsis, has risen by 50%, according to reports gathered by the Care Inspectorate. The figures, obtained by the Sunday Herald under Freedom of Information laws, are based on reports compiled after deaths by care home staff rather than death certificates.

In 2008, septicaemia was included among the causes of death in 109 incidents. By 2012, that number reached 165 following steady rises in the intervening years.

A breakdown of the deaths indicated a worrying link. The vast majority of homes with the highest death counts were reprimanded by the care home regulator in the same period. They scored inadequate marks on quality and had dozens of complaints upheld against them. Criticisms were made over issues of incontinence, tissue damage and hygiene – all key in the prevention of blood infection.

Reacting to the revelations, charities and MSPs across the political divide are now calling on the Government to launch an immediate investigation into the increase in deaths and the apparent link to poor care. About 37,000 elderly people are currently in Scottish care homes.

Kirsty Yanik of Alzheimer Scotland said: "The statistics relating to septicaemia indicate that a number of care homes are simply not providing respectful and dignified care delivered by understanding and appropriately trained staff. Care homes that fail to meet these basic standards are also failing to recognise the fundamental human rights of people with dementia."

Margo MacDonald, Independent MSP for Lothians and an activist on care, said financial pressures could be taking a toll: "We know care homes have been up against it. Money's tight. They have been cutting back, first on materials and then personnel. That creates the possibility of infections being passed round very quickly in a community such as a care home.

"The Government needs to look at the figures, to see if it's a pattern confined to one area or one type of home. If it's widespread throughout the sector and across all the price ranges, that's a worry. Because people are dying it makes this urgent."

Green MSP Alison Johnstone said "the rational response to this increase is investigating what can be done to prevent these situations from happening" and called for hygiene records of care homes to be made more public to "help drive up standards".

Noting that most Scottish care homes perform well, he added: "If septicaemia is recorded as an underlying health condition when someone dies, it is often one of many complex medical factors. Our job is not just to inspect but to improve, so when a care home performs poorly we work intensively to bring it up to scratch."

Scottish Care, the body which represents care-home operators, said it collaborates closely with health experts on hygiene and wound management. "We believe the picture has been one of steady improvement," a spokesperson said. "However, any highlighting of possible areas of concern is something we take very seriously. Scotland's older people deserve the best possible care."

A spokesman for Wyvis House said management had changed and improvements been made since 2009 but declined to provide a statement.

It is four years since Jamesina died. Her relatives, to whom the Highlands-born vet moved to be near in her retirement, remember her fierce independence. "She was a very strong-willed character. A very clever, religious woman," recalled her niece, Jane Barker. "She didn't complain too much. She kept things to herself."

Yet for weeks she lay in that bed on Wyvis House's first floor, in the dementia wing despite not having dementia, her independence replaced by dependence, "reliant" on staff for treatment.

Underperforming homes must be "named and shamed", her niece said. But there was a note of resignation when she heard more residents had been killed by blood infections since her aunt's death.

"I hope they would have learned by now," she said. "Surely they've learned from it? Surely?"

THE CARE HOMES THAT FAILED THE VULNERABLE

There is an overlap between care homes reporting the highest number of deaths from septicaemia and those reprimanded by the industry regulator in the same period.

Out of the 15 homes which recorded five or more deaths from septicaemia, 12 received inadequate marks on quality or complaints upheld by the regulator.

Marks from the Care Inspectorate are given after inspections and complaints are completed, in the following four categories: care and support, environment, staffing and management.

A score of one or two out of six is considered inadequate. Last year, around 5% of inspections led to a score of two or below.

Complaints are looked into by the inspectorate before being upheld. All the comments here relate to requirements and recommendations following complaints and date from between 2008 and 2012.

l Buckreddan Care Centre, Kilwinning

10 deaths; 2 bad marks; 5 complaints

Ordered to change procedures on bedsores within two weeks after complaint about approach to tissue damage. Told every at-risk resident must be given an individual care plan for bedsores.

l Four Hills Care Home, Glasgow

10 deaths; 1 bad mark; 1 complaint

Given 48 hours to ensure all necessary actions are taken to reduce risk of pressure sores developing. Also told to make sure residents are being given enough water and food.

l Suncourt Nursing Home, Troon

9 deaths; 3 bad marks; 5 complaints

Repeated criticism of infection controls. Given 24 hours to ensure single-use medical equipment wasn't used on more than one resident. Staff told to learn appropriate hand-washing procedures. Criticism of approach to incontinence, malnutrition and dehydration.

l Lochduhar, Dumfries

9 deaths; 3 bad marks; 1 complaint

Widespread staff retraining ordered with immediate effect after December 2010 complaint, including pressure sore management. Check procedures for malnutrition and dehydration.

l Hillview Care Home, Clydebank

7 deaths; 0 bad marks; 12 complaints

Reprimanded for approach to death and dying in 2012 – told to ensure staff respect the dignity of residents. Ordered to make sure staff have skills to support residents with issues relating to personal hygiene, oral hygiene, continence and skin damage.

l Briery Park, Thornhill, Dumfries-shire

7 deaths; 2 bad marks; 1 complaint

Given a month to ensure healthcare issues raised by residents are reported to senior staff after a complaint in November 2010. Told to ensure monitoring of water and food intake of residents who spend lots of time alone in their rooms.

l Riverside Nursing Home, Aberdeen

6 deaths; 1 bad mark; 1 complaint

Told to make sure no resident is restrained unless it is the only practicable means of protecting their welfare. Also given 24 hours to properly implement procedures on the safe administration of medication.

l Garioch Care Home, Inverurie

5 deaths; 3 bad marks; 1 complaint

Ordered to make sure all areas are "free from offensive odours" and carpets by the entrance can be kept clean. Told to ensure staff show they understand how to deal with tissue damage, including identifying risks.

l Castlegreen, Edinburgh

5 deaths; 5 bad marks; 4 complaints

Criticised over infection controls. Told to update staff advice on uniforms – ensure they are washed, dried and stored adequately. Change of approach on dressing wounds recommended.

l Abercorn House Care Home, Hamilton

5 deaths, 7 bad marks; 5 complaints

Advised to ensure personal hygiene needs of residents are met by noting preferences. Given 24 hours to ensure that medical help is sought when health of resident deteriorates. Told to keep records of how much water residents are drinking.

l Braeside House, Edinburgh

5 deaths; 2 bad marks; 1 complaint

Ordered immediately to make sure resident needs direct staff practice and that relatives are informed when there are significant changes of health. Concerns over hydration and medication issues upheld.

l Erskine Edinburgh Home

5 deaths; 6 bad marks; 3 complaints

Told to immediately ensure staff can meet the needs of incontinent residents and that nutrition plans provide individualised information for carers to act. Approach to nutrition and medication repeatedly criticised.

Deaths listed are those in which the causes of death included septicaemia. All figures come from the Care Inspectorate. Incidents of poor performance do not necessarily reflect overall performance across this period or quality of care today.

HOW DO WE STOP IT?

By Dr Ron Daniels, chair of the UK Sepsis Trust

I t makes entirely logical sense that care homes with the worst ratings for hygiene and general satisfaction would see the most care-home associated infections, and therefore sepsis. I would say there is a direct causal relationship between hygiene levels, basic infection control principles and sepsis in care homes.

It is about the culture of staff. Those that have the desire to regularly wash their hands, clean their uniforms and care for patients' basic hygiene will see lower rates of infection. In organisations that have lower ratings, the staff approach to these issues is likely to be poorer and the management vigilance lower, so they are going to see higher numbers of health-care associated infections.

Septicaemia, also known as sepsis, arises when the body's response to an infection causes inflammation. That inflammation then injures the body's own tissues and organs by triggering the immune system to launch an attack on the patient.

The warning signs are severe shivering, very severe pains in muscles and joints, racing heart beats, shallow, rapid breathing, a reduction in the need to pass water and changes in skin colour.

In care homes common triggers for septicaemia are skin infections, such as bedsores, urinary tract infections, and pneumonia. Prevention is important, but so is spotting the early signs of sepsis.

Part of the rise may be due to better reporting. But I do wonder whether the change in the economic climate has led to efficiency drives at some homes. In many this won't compromise quality but in some it inevitably will.

The regulator of care homes should ensure there is a national educational programme in wound and infection management and the recognition and treatment of sepsis. It should become an essential part of training for all medical staff

Unless we address the situation as a matter of urgency with improved training and with minimum standards in hygiene, wound care and sanitation, then we will continue to see more and more deaths occurring.