Great apes are susceptible to many infectious diseases in humans, but important weapons against bacterial pathogens could soon become blunted: The analysis of fecal samples reveals that even wild chimpanzees in Tanzania already carry antibiotic-resistant bacteria. The source of this resistance is likely the contamination of rivers with residues of these drugs.
Whether Covid-19, colds or diarrhea: great apes are also susceptible to many of our infectious diseases. These affect chimpanzees, gorillas and the like in some cases even worse than we do. So far, antibiotics have been the means of choice against bacterial pathogens in both humans and great apes. In the meantime, however, human medicine is increasingly fighting against pathogens that have already become resistant to common antibiotics. These occur above all when the bacteria in our body or the environment often come into contact with these drugs.
Resistance genes also in chimpanzee faeces
Michele Parsons from Emory University in Atlanta and her colleagues in Gombe National Park in Tanzania have now investigated whether and to what extent wild chimpanzees are affected by antibiotic resistance. To do this, they analyzed around 400 samples of faeces from humans, pets and farm animals, as well as baboons and chimpanzees in and around the national park for genes that cause resistance to sulfonamides and tetracyclines. These two classes of antibiotics are used in this area against diarrhea, cholera and other human infections. The researchers also tested river water for the resistance genes.
It turned out that many wild animals in the national park already carry resistant bacteria. The scientists were not only able to detect genes for sulfonamide resistance in around 75 percent of human fecal samples, but also in around half of the chimpanzee and just under 35 percent of the baboon samples. In the domestic and farm animal samples, more than 15 percent were affected, with dogs making up the largest group of resistance carriers at around 70 percent, which the researchers explained, among other things, with their close relationship with humans.
Spread over the water
These results suggest that resistance to commonly used antibiotics is not only spreading among the pathogens in the human environment, but also penetrating into the habitats of wild animals. The more frequently an antibiotic is used, the more the corresponding resistance genes are spread in the environment. It is fitting that the genes for tetracycline resistance in the chimpanzees in Gombe National Park were significantly less common than those against sulfonamides. In humans it was around 15 percent, in animals only about five on average. The researchers attribute this to the fact that tetracycline is prescribed and consumed less often by the population because of its higher price and poor availability.
The evaluations also provided information about the possible pathways for the resistance genes to spread: In the streams shared by humans, pets and wild animals, genes for sulfonamide resistance were found in around 20 percent of the samples. On the other hand, there were little differences between two groups of chimpanzees, one of which is in the immediate vicinity of human settlements, while the other lives deeper in the forest with little contact with humans or human surroundings. “These results suggest that antibiotic-resistant germs spread from humans to non-human primates by finding their way into local waters,” says Parson’s colleague Thomas Gillespie. “People bathe and wash in the streams and contaminate the water with drug-resistant bacteria that wild chimpanzees and baboons drink from.”
A problem for humans and animals
As the researchers point out, the spread of antibiotic resistance is a problem for both humans and animals in the region: “The majority of the people in our sample had bacteria that are resistant to the sulfonamide drugs they are taking,” reports Gillespie. “In this way, they spend their money on a drug that does not help them get healthy.” In addition, excessive ingestion of such active ingredients promotes the development and spread of more and more resistances. For the animal world, this means that they too are increasingly exposed to the risk of resistant germs. However, if they become ill, this can also be disadvantageous for humans: “After drug-resistant bacteria have spread to chimpanzees, they can develop further in chimpanzees and then spread to humans again,” explains Gillespie.
This is why Parsons and his team are now calling for infectious diseases to be viewed more closely in an evolutionary and ecological framework. This could help people in the vicinity of the national park to live next to each other with primates and other wild animals in such a way that as few pathogens as possible are exchanged between the species. The research results should support the development of interventions in the future: At the local level, more guidelines are needed for the correct use of antibiotics, says Gillespie. It is also important to improve hygiene when washing in the streams in the area, as well as the disposal of human waste, adds the researcher.
Source: Emory Health Sciences, Article: Pathogens, doi: 10.3390 / pathogens10040477