Increasingly we are also seeing antibiotic-resistant bacteria from overseas reaching Australia through returning travellers.
https://www.news-medical.net/health/Global-travel-and-antibi...
Antibiotic resistance is also intricately linked to travel health and has many implications for travellers. Overuse of antibiotic medications for ailments such as traveller’s diarrhea has contributed to the spread of antibiotic resistance. In Southeast Asia, for example, ciprofloxacin and other fluoroquinolone antibiotics are no longer effective in treating traveller’s diarrhea since they are resistant to Campylobacter, Escherichia coli, Salmonella, and Shigella bacteria.
In Pakistan, extensively drug-resistant Typhoid Fever is growing since antibiotics such as ampicillin and ciprofloxacin no longer work. Cases have been reported in returning travellers from North America, the UK, Denmark and Australia. Travellers can be at the forefront of antimicrobial resistance – we are sentinels that can provide clues or alert researchers to developments on the ground.
https://www.iamat.org/blog/fighting-back-against-antibiotic-...
I don't think this is an issue, or rather the preferred solution for that seems to be to close borders and keep all the poor people out. Reminding the proponents of this "solution" that e.g. the people immigrating from Africa to the EU to ask for asylum may be carrying diseases that are not found in the Western world is likely to cause a hardening of the anti-immigration and anti-asylum stance, rather than any support for better hygiene in developing nations.
From a national point of view, it's simpler to keep homeless people away from rich peoples' homes than to make sure they don't get sick. So the self-interest argument is not really going to work with people who are already doing fine in their self-interest, they thank you.