Could cockroaches be aiding the spread of antimicrobial resistance?
Research suggests that cockroaches – and perhaps other species – could be spreading antimicrobial resistance via the bacteria living on and within them.
- 8 January 2024
- 3 min read
- by Linda Geddes
Cockroaches tend to be unwelcome visitors at the best of times, but a new study suggests that these insects – and perhaps other social species – may be contributing to the spread of antimicrobial resistance (AMR) through their microbiomes.
"While cockroaches might not replicate the complexities of human or mammalian microbiomes, they offer a tractable, relevant and efficient system for studying the dynamics of AMR transmission, especially in the context of densely populated urban environments."
AMR occurs when bacteria, viruses, fungi and parasites no longer respond to antimicrobial substances used to prevent or treat infections, and its growth poses a significant threat to global health. While the development of AMR is a natural process, driven by the accumulation of genetic changes in microbes over time, the process is accelerated by the misuse and overuse of antimicrobials in humans, animals and plants.
Another potential contributor could be the sharing of antimicrobial resistance genes between bacteria living as part of the microbiome of other creatures . But few studies have explored this possibility in live animals until now.
Amalia Bogri and colleagues at the Technical University of Denmark picked cockroaches because they carry a diverse microbiome and many species live in dense groups with frequent contact between individuals – similar to densely reared farm animals, or humans living in urban environments.
"While cockroaches might not replicate the complexities of human or mammalian microbiomes, they offer a tractable, relevant and efficient system for studying the dynamics of AMR transmission, especially in the context of densely populated urban environments," the researchers said.
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To investigate, they added tetracycline – an antibiotic used to treat several kinds of bacterial infections – to the diet of Pycnoscelus surinamensis cockroaches, a highly sociable species that lives in closely-knit groups.
They later saw an increase in the abundance of tetracycline resistance genes among bacteria living in the guts of the treated cockroaches.
Next, they allowed an untreated population of cockroaches to mix with the tetracycline-treated ones. Following these interactions, the untreated cockroaches also displayed elevated resistance to tetracycline , as did bacteria living in the soil of their enclosures – with the level of resistance depending on the extent and frequency of interaction between treated and untreated cockroaches.
The research, published in mSystems, suggests that the many microorganisms living on and inside cockroaches, and perhaps other creatures , could be helping the spread of antimicrobial resistance genes within the microbiomes of populations .
Cockroaches and other arthropods may also be aiding the spread of AMR in healthcare settings more directly . According to separate research published in Nature Microbiology in 2021, approximately 20% of cockroaches, ants, flies, moths and spiders at a hospital in northern Pakistan were found to be carrying bacteria resistant to the "last-resort" antibiotic, carbapenem, while 80% of them were carrying bacteria with genes that confer resistance to many common antibiotics. This could imply that such creatures play a role in the spread of resistant bacteria within hospitals, including to patients, the researchers said, potentially suggesting that insects and spiders should be removed from health care environments.
