Bacteria from the Enterobacter species in a petri dish. Image: © Creative Vault/Stock.adobe.com
Researchers believe the new discovery could improve treatments and clear Enterobacter infections more efficiently, leading to less deaths.
A new study from Queen’s University Belfast (QUB) has shown how the antibiotic-resistant bacteria Enterobacter can hide in human cells without alerting the body’s immune system.
According to the study, which was published in The Journal of Infectious Diseases yesterday (3 March), Enterobacter can hide inside macrophages – a type of white blood cell in blood and tissue which is the first line of defence against microbes.
By hiding inside these cells, the bacterium lies dormant and does not stimulate any inflammatory responses, allowing it to escape the action of the few antibiotics that remain available for treating the infection.
Enterobacter species are described by the researchers as “opportunistic, multidrug-resistant Gram-negative bacteria associated with morbidity and mortality worldwide”.
Enterobacter infections are considered serious and can be quite dangerous, even with appropriate treatment. Examples of Enterobacter infections include wound infections, urinary tract infections, gastroenteritis, meningitis, pneumonia and septicemia.
The bacteria is included in the World Health Organization’s (WHO) Bacterial Priority Pathogens List 2024, a list of bacterial pathogens of public health importance. Enterobacter is also listed as one of the most resistant pathogens in the list.
“Despite extensive information on antibiotic resistance by Enterobacter species, very little is known about how these bacteria cause infection,” explained the study’s lead researcher Prof Miguel A Valvano, who is chair of Microbiology and Infectious Diseases at the Wellcome-Wolfson Institute for Experimental Medicine at QUB.
“Our new study has bridged this knowledge gap by showing for the first time that antibiotic-resistant isolates of Enterobacter species can survive inside human macrophages without being killed.”
The researchers believe that this breakthrough could help develop new ways to treat infected patients and clear Enterobacter infections more efficiently, leading to less deaths.
“The demonstration that Enterobacter isolates can hide inside macrophages has important clinical implications for the treatment of infected patients since antibiotics cannot reach the intracellular bacteria and the macrophages cannot easily remove them,” added Valvano.
Antimicrobial resistance (AMR) is described by the WHO as one of the top global public health and development threats, and it is estimated that bacterial AMR was directly responsible for 1.27m global deaths in 2019 and contributed to 4.95m deaths.
According to the WHO, the misuse and overuse of antimicrobials – such as antibiotics – in humans, animals and plants are the main drivers in the development of drug-resistant pathogens. While this is a serious issue for societies and communities across the world regardless of wealth and development, the WHO says that drivers and consequences of AMR are exacerbated by poverty and inequality, and low- and middle-income countries are most affected.
Last year, QUB and University of Limerick researchers discovered a new species of bacteria that is resistant to antibiotics at University Hospital Limerick.
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