Superbugs and the Road to Antimicrobial Resistance: A Case Study from Ecuador

There’s more to developing drug resistant bacteria than simply taking antibiotics. Antibiotic resistance is a growing problem worldwide that needs to be addressed on multiple fronts including human and veterinary medicine. Research recently concluded in Ecuador suggests that environment and social context may play a major role in the development and spread of antibiotic drug resistance and the rise of microbial “superbugs”.

For five years, a team led by University of Michigan School of Public Health researcher Professor Joseph Eisenberg studied 21 northern Ecuadoran communities of variable driving distance to the nearest major city. Although all villages had approximately identical antibiotic usage, antibiotic-resistant E. coli was found to be more prevalent in villages situated along roads leading to the city than in rural villages far from roads. Antibiotic resistance was highest among villagers with the shortest drive to the nearest city. Among other findings, this study illustrates the need for water and sanitation improvements to keep pace with advances in transportation infrastructure. According to the researchers, in the area studied, villagers primarily consume untreated surface source water and sanitation facilities are inadequate.

The study, titled “In-roads to the spread of antibiotic resistance: regional patterns of microbial transmission in northern coastal Ecuador,” confirms previous research that shows roads are associated with the spread of diseases. It also demonstrates that roads favor the spread of antibiotic resistance.

The study identifies two important factors in the promotion of antibiotic resistant bacteria:

1. When a rural community has access to roads, people can move into and out of the community easily, introducing new strains of resistant bacteria.
2. Where water quality and sanitation are poor, pathogens are easily spread.

According to a report on the study posted on Science NOW, a mathematical model developed by the researchers traces how antibiotic usage affects the flow of resistant bacteria in villages in northern Ecuador:

The more antibiotics villagers in this study took, Eisenberg and colleagues calculated, the more likely they were to transfer the resistant E. coli to their close neighbors. When people take antibiotics, the resistant bacteria become the dominant strains in their guts and the ones they transmit, Eisenberg says. So, in communities in which the antibiotics flow freely, villagers tend to swap resistant gut [bacteria] frequently, especially because sanitation tends to be poor—latrines are few and far between, and community members usually draw their drinking water directly from freshwater streams.

The World Health Organization estimates 884 million people, mostly in rural areas, still depend on unimproved water sources. Globally, the sanitation situation is even direr: 2.6 billion people lack improved sanitation facilities, including over 1.1 billion people with no access to toilets or sanitation facilities of any kind.

Drinking water disinfection, such as household point-of-use chlorination systems, and improved sanitation could help mount a roadblock to the spread of antimicrobial resistance in rural areas of Ecuador and other developing communities. It’s just one more good reason to share life-saving safe water and sanitation technologies.
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ⁱThe authors attribute relatively uniform antibiotic use in the study area to the presence of both governmental and non-governmental organizations that deliver medical care, including antibiotics, throughout the region. It is also possible that antibiotics can be purchased over the counter without a prescription.
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Ralph Morris, MD, MPH, is a Physician and Preventive Medicine and Public Health official living in Bemidji, MN.