Why ‘superbugs’ thrive in hospitals
Police Scotland has launched an investigation into the deaths of six patients, including adults and children, believed to have contracted fatal infections at the Queen Elizabeth University Hospital in Glasgow.
The inquiry follows a long-running controversy over hospital-acquired infections at the site, with concerns raised by families and clinicians about water contamination, ventilation systems and wider environmental safety within the hospital.
The hospital has been under scrutiny for several years after campaigners raised questions about possible links between infections and environmental factors within the building. The investigation will examine whether any such factors contributed to the deaths.
Modern hospitals are generally safe places to receive care. But infections remain a risk wherever large numbers of vulnerable patients receive complex treatment.
Hospital-acquired infections (HAIs), also known as nosocomial (meaning originating in hospital) or healthcare-associated infections, are infections patients contract during or after receiving treatment in healthcare settings that were not present when they were admitted.
These infections can occur not only in hospitals, but also in nursing homes, rehabilitation centres, outpatient clinics and dialysis units. They represent a persistent and serious threat to patient safety worldwide. Patients may develop bloodstream infections from contaminated intravenous lines or severe diarrhoeal illness after exposure to resistant bacteria on hospital wards.
Hospital-acquired infections are among the most common adverse events in healthcare globally. They can lead to longer hospital stays, higher costs, disability and death. Across the European Union and European Economic Area combined, surveillance data suggest more than four million patients are affected each year. In the UK, healthcare-associated infections affect hundreds of thousands of people annually and remain a major patient safety concern.
Most hospital-acquired infections are treatable. However, they can become life-threatening when they lead to bloodstream infection or sepsis or occur in already vulnerable patients. Many involve microbes that no longer respond to standard antibiotics.
Read more: Sepsis: why this deadly condition is so hard to diagnose
These infections are especially dangerous for people with weakened immune systems, including older adults, newborn babies and patients undergoing surgery or intensive treatments. Healthcare workers are also at risk because of repeated exposure to infectious patients and contaminated environments.
Causes of HAIs
Hospital-acquired infections can be caused by many microbes, including bacteria, fungi and viruses.
One well-known bacterium is Staphylococcus aureus, which often lives harmlessly on the skin or in the nose but can cause serious infection if it enters the body. A particularly problematic strain is methicillin-resistant S. aureus (MRSA), which has evolved resistance to several commonly used antibiotics.
Read more: Golden staph: the deadly bug that wreaks havoc in hospitals
Another major cause is Clostridioides difficile, which can trigger severe diarrhoea and inflammation of the colon, particularly after antibiotic use disrupts normal gut bacteria. These pathogens have been major concerns for decades because they resist treatment and spread easily in healthcare settings.
Other emerging threats include carbapenem-resistant Enterobacteriaceae, gut bacteria resistant to carbapenems, a class of last-resort antibiotics. These gram-negative bacteria have a cell wall structure that makes them naturally more resistant to many antibiotics and harder to treat. They frequently cause bloodstream infections and urinary tract infections in hospitals.
A growing fungal threat is Candidozyma auris, a drug-resistant yeast that has caused outbreaks worldwide and can survive for long periods on surfaces.
Viruses also play a role. Respiratory viruses such as coronavirus, influenza, respiratory syncytial virus and human metapneumovirus can spread rapidly in wards. Norovirus frequently causes outbreaks of vomiting and diarrhoea because it spreads easily and survives well on surfaces.
Read more: Norovirus: what to know about this bug as northern hemisphere countries face outbreaks
Bloodborne viruses such as hepatitis B, hepatitis C and HIV can spread through contaminated needles, blood products or failures in infection control. Other viruses, including varicella-zoster and measles, have also caused hospital outbreaks.
Hospital-acquired infections spread through multiple routes. Direct contact between patients and healthcare workers is common, as is transmission via contaminated equipment or surfaces when cleaning is inadequate.
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Environmental sources can contribute. Hospital water systems have been linked to outbreaks in some investigations. Surfaces and medical devices such as catheters and ventilators can harbour microbes if not properly sterilised. Research also highlights less obvious routes, including insects carrying resistant bacteria.
Antimicrobial resistance
One of the biggest challenges in tackling hospital-acquired infections is antimicrobial resistance. This occurs when microbes evolve so that medicines designed to kill them become less effective.
Hospitals use large quantities of antibiotics, creating pressure for microbes to develop resistance. Over time this can lead to superbugs that spread quickly, including among frontline healthcare workers. Clear communication about risk and prevention is essential.
Global surveillance indicates that antibiotic-resistant infections in healthcare settings are rising sharply.
Hospital-acquired infections can be fatal, particularly when they lead to bloodstream infection or sepsis. In 2019, antimicrobial resistance was directly responsible for an estimated 1.27 million deaths worldwide.
Outbreaks occur when infection rates rise above expected levels and may begin with a single infected patient, contaminated equipment or environmental sources. Once established, infections can spread quickly between wards.
Preventing hospital-acquired infections requires strict hygiene, sterilisation, environmental cleaning and responsible antibiotic use. Surveillance systems and rapid responses help contain outbreaks early. Improved ventilation, antimicrobial materials and better hospital design may also reduce transmission.
Hospital-acquired infections remain a major global public health challenge because they occur in places meant to heal. No one should enter hospital for treatment and leave with a preventable infection.
Manal Mohammed does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.