It Comes From Prehistorical Bacteria?
For the past decades, the development of antibio-resistance is becoming a major concerns for human health. We are estimating that antibio-resistance is responsible currently for the death of 700,000 persons world-wide. It is already the 5thcause of death after Cancer (8 millions), Diabetes, Diarrheal diseases and road traffic accidents but it may become the first with an estimated 10 millions deaths by the year 2050.
Antibiotic resistance has not been created by humans misuse of antibiotics. It started long before the discovery of the penicillin by Fleming. Antibiotics and corresponding resistances are produced by microorganisms in their competition for survival against other organisms.
We found some resistances genes to β-lactam antibiotics from the Alaskan soil that has no known exposure to synthetic antibiotics. Antibio-resistance has been identified as well in the deep ocean, amazon forest, in the artic ice cap or in wild animals like flamingo or reindeer without any exposure to synthetic antibiotics.
Moreover, evolutionary analyses showed that the Alaskan β-lactamases are distinct from previously reported β-lactamases. It was suggested that diverse resistance genes have evolved even in the absence of selective pressure, and that β-lactamases of Alaskan soil might be closely related to ancestral enzymes.
But the balance between the distribution of these natural resistances was up to recently restricted to a geographical area where they were ‘developed’ with little opportunities to become world threat.
When the pharmaceutical industry starts enabling an intensive use of antibiotics, we exaggerated the exposure of antibiotics to various reservoirs of resistance and start creating selection of ‘bad’ bacteria. By concentrating population in cities for humans and in farms for animals, we favored the transmission; transmission of resistant genes between bacteria and transmission of resistant bacteria between individuals and animals.
Through the re-circulation of human and animal waste, we contributed to the contamination of our environmental soil around cities. Not surprisingly, the feces and wastewater from livestock farm had the highest level of total resistance gene abundance. A study run by Li B. and Yang Y. on animal fecal resistomes demonstrated that antibiotic resistance genes were enriched more in adult chickens than in chicks. An opposite trend was observed in pigs. Human resistomes were more similar to the pig resistomes than chicken resistomes.
The most appropriate place for selecting and transmitting these resistances is an animal intestine. This is the place where the largest quantity of antibiotics and bacteria are exposed to each other. Many studies revealed that antibiotic treatments directly affect the diversity of bacterial composition. An increase of the resistance genes in the microbiome was also observed after antibiotic treatments. Several studies compared resistomes from different geographical areas. It turn out that Americans and North Europeans showed the lowest prevalence of resistant genes. Southern Europeans and Japanese had higher concentration but still lower than Chinese population who demonstrates the highest risk of antibio-resistance. The conclusion of these studies must be correlated to each country practice regarding the use of antibiotics namely self-medication and excess of antibiotics use in livestock.
Through intensive farming for the past 50 years, our industry is the funnel where concentrate antibio-resistant genes to create super-bacteria. But there are still a reservoir of resistance genes in the wild that did not take part yet to that selection process. With global warming, the situation could get worse. When melting the North and South pole ice could free some new resistance genes that could get the current situation out of control.
There are multiple reasons to get our livestock industry more disciplined in using antibiotics wisely. There are now on the market some innovative products to replace antibiotics to get rid of pathogenic bacteria without promoting the selection of resistance. With sufficient sense of responsibility from our industry’s opinion leaders, we should be able to accelerate the move away from intensive use of antibiotics.
But this article makes us realize as well that global warming is still hiding some unknown but terrible disturbance with some consequences on human health.