Why do patients contract nosocomial infections?

In recent weeks, the death of four patients in Glasgow hospitals – including three babies or children – has been linked to infections contracted during their stay. So, what is the danger of nosocomial infections?

Why do people contract new diseases at the hospital?

By their very nature, hospitals are very busy places for people in poor health. Many of them have already contracted infections in the community.

Patients, visitors and staff are constantly importing bacteria, viruses and fungi into hospitals. The challenge for health workers is how to stop these phenomena of multiplication and spread.

A complicating factor is that hospitalized patients often have a weakened immune system and are less able to fight the disease.

What caused the deadly infections in Glasgow?

Two recently deceased patients at Queen Elizabeth University Hospital – a 10-year-old boy and a 73-year-old woman – were infected cryptococcal fungal infection resembling yeast. The most common form in humans is related to the droppings of pigeons or other birds. It is thought that he entered the hospital's ventilation system after birds entered a machine room near the roof.

Another patient became seriously ill in a separate facility Mucor infection. This is a type of mold that is commonly found in soil or in decomposing organic material, such as food. The infection is usually caused by spore breathing. In this case, it is thought that a leak of water in the patient's room was the source.

Two premature babies died and a third became seriously ill at Princess Royal Maternity Hospital. They were infected with the bacteria Staphylococcus aureus.

It's a common bacterium – about a third of us have it on our skin and it's usually safe. But these so-called "staphylococcal" infections can become serious if the immune system is weakened.

The bacterium is usually transmitted by touch – but it can be transmitted to the air through the loss of skin cells, coughing or sneezing.

How common are these infections?

Infections related to Cryptococcus or Mucor are relatively rare, but Staph infections are much more common.

Staphylococcus aureus about 110 infections each month in Scottish hospitals.

Bacteria, viruses and other microorganisms that cause disease are collectively called pathogens – and there are many. Other varieties common in hospitals are:

• Escherichia coli – better known as E. coli. It is a bacterium found in the intestines of humans and animals. It can be transmitted through contaminated food, contact with animals or poor hygiene. Some strains such as E. coli O157 produce toxins that can make people very sick, but most people get better without medical treatment. Nearly 400 cases a month are reported in Scottish hospitals.

• Clostridioides difficult – formerly known as Clostridium difficile and abbreviated C. diff. A very common type of bacterium, particularly common in the soil, that can cause intestinal infection and diarrhea. This may particularly affect people treated with antibiotics or hospitalized for a long time. Nearly 350 cases are reported each month on average in Scottish hospitals.

What about MRSA?

This is a variant of Staphylococcus aureus that has become resistant to several widely used antibiotics – MRSA actually refers to methicillin-resistant Staphylococcus aureus. The media sometimes speak of "hospital superbug" insofar as it mainly concerns people staying in hospitals.

Indeed, these patients often have wounds or catheters that allow them to enter their body. A weakened immune system makes it more dangerous – and the concentration of inevitable patients in a hospital increases the chances of spread.

MRSA has become a serious problem in recent years, with many experts accusing the abuse of antibiotics – excessive prescription or incomplete treatment – that has allowed these resistant strains of Staph bacteria to multiply.

Does the problem worsen?

Some progress has been made. A decade ago, about 200 Staphylococcus aureus infections were recorded per month in Scottish hospitals.

According to the most recent figures, this figure has fallen to about 110 per month, although most of this improvement occurred between the years and 2012. In addition, infection rates have been stubbornly static.

A major outbreak of C. difficile contributed to 34 deaths between 2007 and 2008 at Vale of Leven Hospital in West Dunbartonshire. An investigation attributed to "serious" personal and systemic failures at the hospital.

But over the next decade, the rate of C. diff infection has steadily declined. For E. coli, the lack of historical data makes it more difficult to identify a trend.

What do hospitals do about it?

In Scotland, there is a national infection control strategy that includes a list of standard 10-point precautions:

• Evaluate patients upon arrival and identify risks
• Hand hygiene – a detailed set of procedures
• Rules of respiratory hygiene and cough
• Protective equipment – gloves, double gloves, aprons, visors, etc.
• Equipment – single-use items, decontamination procedures
• Safe environment – areas must be visibly clean and cleaning procedures in place
• Linen – safe storage and transportation for cleaning, contamination being handled appropriately
• Safe management of blood and body fluid spills
• Safe disposal of waste, including sharps
• Safe work practices, training and reporting incidents

When an outbreak of infection is identified, a plan to combat this scourge is put in place, including a "deep cleansing" of the area.

National Clinic Director for NHS Scotland, Jason Leitch, said nosocomial infection rates were low but remained a "reality of life in our health care system."

"The fact that these are rare events gives us all the more opportunity to learn from these events and aim for zero," he added.

"It would be our hope that Scotland, although world leader in infection control, is still improving."