What Are The Most Common Hospital Acquired Infections?

The most common hospital acquired infections include urinary tract infections, respiratory tract infections and sepsis. Also known as healthcare-associated infections (HAI or HCAI), these are unfortunately common, affecting almost 8% of patients in healthcare settings.

HAIs come at a great cost for both patients and the National Health Service (NHS). For individuals, they mean further pain and suffering and sometimes even death. For the NHS, they cause losses of over £2 billion per year in patient management and lost workdays.

These numbers underscore the importance of identifying the most common hospital acquired infections and implementing effective infection prevention and control measures.

Table of Contents

• Respiratory tract infections
• Urinary tract infections
• Methicillin-resistant Staphylococcus aureus (MRSA)
• Clostridium difficile infections
• Escherichia coli
• Surgical site infections
• Bloodstream infections (sepsis)
• What should be done to prevent the most common hospital acquired infections (HAIS)?
• Can I claim compensation for a hospital-acquired infection?

Respiratory tract infections

A 2023 survey of 121 NHS Trusts and independent-sector organisations found that pneumonia and other lower respiratory tract infections were the most common types of hospital acquired infections. These affected 960 (29.6%) of the total number of 3,493 HAIs reported.

• The main types of respiratory HAIs include pneumonia, ventilator-associated pneumonia, and bronchitis.
• These are often caused by bacteria such as Pseudomonas aeruginosa, Streptococcus pneumoniae and Legionella pneumophila.
• Transmission is typically due to poor hand hygiene, contaminated equipment (such as ventilators or surgical instruments) and direct contact with infected patients or healthcare workers.
• As with many infections, elderly patients and those with weakened immune systems and chronic illnesses are most at risk of hospital-acquired pneumonia.

Urinary tract infections

Urinary tract infections (UTIs) are the second most common type of hospital acquired infections, accounting for 17.5% of all HAIs. These infections are caused by microorganisms that enter the urinary tract, often through a catheter or during urological procedures.

• UTIs can affect the kidneys, bladder, urethra, epididymis or the prostate gland.
• These are commonly caused by E. coli, Klebsiella pneumoniae, Enterococcus faecalis, Staphylococcus aureus and Candida spp.
• Most UTIs are mild and treatable, but they can sometimes give rise to complications such as sepsis, permanent kidney damage and repeated infections.
• Complicated cases are usually associated with a weakened immune system, indwelling catheters and exposure to antibiotics.

Methicillin-resistant Staphylococcus aureus (MRSA)

MRSA is a type of Staphylococcus that can be found in the nose and on the skin of many people without causing any problems. However, if it enters the body through wounds or tubes placed during medical procedures, it can lead to severe infections.

MRSA is resistant to common antibiotics, such as penicillin, methicillin and amoxicillin. This makes it harder to treat than other infections and gives it a higher mortality rate. During the 2022/23 period, there were 787 reported cases of MRSA bacteraemia (1.4 per 100,000 population).

• This is a significant decline compared to 4,451 cases in 2007/08, when the rate of infection was 8.6 per 100,000 population.
• Most cases (63%) occurred in the community, while only 37% (295) were hospital-acquired.
• Of the 787 MRSA bacteraemia cases, 147 resulted in deaths within 30 days of diagnosis.

Clostridium difficile infections

Clostridium difficile is the leading cause of infectious diarrhoea and inflammation of the colon. The bacterium is typically found in the intestines, where it usually lives harmlessly, but its spores can be found everywhere and are the most resistant to disinfection.

• In 2022/23, a total of 15,583 cases of Clostridium difficile infections (CDI) were reported by NHS acute trusts, a 9.2% increase from the previous year.
• Most cases (58%) occurred in the community, while 6,499 (42%) were hospital-onset.
• People who have been taking antibiotics, have a weakened immune system or have been staying in the hospital or a care home for a long time are most at risk.
• The risk of CDI is much higher among the elderly – 262 males and 261 females out of every 100,000 people aged 85 years and over had a CDI, compared to only sixteen males and 19 females aged 45 to 64.

Escherichia coli

Escherichia coli (E. coli) can be found in the digestive tract of most people without causing any harm. However, if it gets into other sites, such as cuts or urinary catheter sites, it can cause serious illnesses.

• Hospital-acquired E. coli infections are a significant concern. E. coli causes more than one-third of all bacteraemias in England each year, which have a 30-day mortality rate of 15-20%.
• Of the 42,224 cases of E. coli bacteraemia reported in 2023/24, 8,155 (19.3%) were hospital-onset and most often originated from urinary tract infections.
• The incidence of E. coli bacteraemia has increased from 60.4 per 100,000 population in 2012/13 to 73.8 in 2023/24.

Surgical site infections

Surgical site infections (SSIs) are some of the most common hospital-acquired infections, making up around 14.5% of all HAIs and a 34-226% increase in care costs. These infections develop when germs from the skin or the environment enter incisions made during surgery.

Most of the time, these are harmless and only affect the skin layers, but they can sometimes affect deeper tissues, organs and even surgical implants such as artificial joints and pacemakers.

Bloodstream infections (sepsis)

Sepsis is a life-threatening reaction of the immune system to an infection caused by viruses, bacteria or fungi. This can cause various symptoms, including fever, chills, a fast heartbeat and difficulty breathing. In some cases, it might only resemble the symptoms of the flu.

• If infections are not adequately treated, sepsis can damage the body’s own tissues and organs and cause multiple organ failure and cardiac arrest.
• The UK Sepsis Trust estimates that 245,000 people are affected and 48,000 die from sepsis in the UK each year, many of whom are patients in intensive care units.
• Globally, sepsis causes 11 million deaths annually.
• In hospital settings, it is most commonly caused by E. coli, Streptococcus, MRSA, C. difficile and Klebsiella spp.

What should be done to prevent the most common hospital acquired infections (HAIS)?

Healthcare associated infections are a major cause of morbidity, mortality and significant costs for the NHS. Infection control measures are crucial to enhancing patient safety and minimising associated costs. These include:

• Strict hand hygiene – regular hand disinfection with soap and water or alcohol-based hand sanitisers.
• Environmental hygiene – regular cleaning and sterilisation of patient rooms, operating theatres, medical equipment and all surfaces throughout the hospital.
• Personal protective equipment (PPE) – use sterile gloves between rooms and patients, as well as masks and gowns when there is a risk of infection.
• Screening and cohorting – identify and isolate patients with infections to prevent spread.
• Antibiotic stewardship – prescribe antimicrobial medicine with care to reduce antibiotic resistance.

Can I claim compensation for a hospital-acquired infection?

Healthcare providers have a legal duty to prevent the spread of infections to patients. If you developed a hospital infection as a direct result of healthcare negligence, you may be eligible to make a hospital-acquired infection compensation claim.

Examples of negligence that could lead to a claim include:

• Failure to clean or sterilise equipment properly.
• Poor hand hygiene or failing to use PPE correctly.
• Ignoring signs of infection or delaying diagnosis and treatment.
• Failing to isolate infectious patients.
• Inadequate management of infectious waste.

To find out if you have a valid medical negligence claim, call 0800 470 0474 today or request a call back, and you will receive a free consultation with a specialist personal injury lawyer.

Last edited on 1st Sep 2025

With over 15 years’ experience in the legal sector, Nicholas Tate (LLB Hons, LLM in Health Law) has extensive experience across all areas of personal injury and medical negligence claims.