A recent study by the Translational Genomic Research Institute (TGen), published in the online journal mBio, reveals that a strain of MRSA, a bacterium which is untreatable by the use of antibiotics, is now not only found in livestock, but also in humans.
The strain MRSA CC398, which is a strain of methicillin-resistant Staphylococcus aureus, also known as a Staph infection, is believed to have probably started in humans, spread to livestock, and is back infecting humans. It is believed to have become antibiotic resistant while in the animals.
Scientists used the menthol of whole genome sequencing, an advanced technology which lays out billions of molecules of DNA with unbelievable detail, to find the origin of MRSA CC98.
For this study, scientists from 20 different establishments worked together to analyze 89 genomes from animals and humans from 4 continents and 19 different countries.
They believe that the transfer of the Staph, from humans to livestock, was responsible for the bacterium becoming resistant to antibiotics, specifically tetracycline, then methicillin – two of the most common drugs used to treat Staph infections.
The researchers comment:
“Our results strongly suggest that food animals-associated MRSA CC398 originated in humans as MSSA (methicillin-susceptible S. aureus)
They state that the microbe, when it was in the animals, turned resistant to the tetracycline and methicillin, due to the constant use of the antibiotics.
The study’s lead author, and Director of the TGen’s Center for Food Microbiology and Environmental Health, Dr. Lance Price, said:
“Our findings underscore the potential public health risks of widespread antibiotic use in food animal production. Staph thrives in crowded and unsanitary conditions. Add antibiotics to that environment and you’re going to create a public health problem.
Retracing the evolutionary history of MRSA CC398 is like watching the birth of a superbug – it’s simultaneously fascinating and disconcerting. MRSA CC398 was discovered less than a decade ago and it appears to be spreading very quickly. “
Dr. Paul Keim, an author of the study, Director of TGen’s Pathogen Genomics Division, a Regents Professor of Biology at Northern Arizona University, and Director of NAU’s Center for Microbial Genetics and Genomics, commented:
“The most powerful force in evolution is ‘selection’ And, in this case, humans have supplied a strong force through the excessive use of antibiotic drugs in farm animal production.
We can’t blame nature or the germs. It is our inappropriate use of antibiotics that is now coming back to haunt us. The good news is that this study clearly shows the way to change evolution and remove this and other similar threats to our health.”
Head of the Microbial Genomics and Antimicrobial Resistance at the Technical University of Denmark, head of both the World Health Organization’s Collaborating Centre for Antimicrobial Resistance among Foodborne Pathogens, and of the European Union (EU) Reference Laboratory for Antimicrobial Resistance, Dr. Frank M. Aarestrup, said:
“Given its rapid emergence and trajectory of increasing important in humans, the evolutionary history of MRSA CC398 has relevance for the epidemiology of MRSA and global health.”
Dr. Robert Skov, M.D, the study’s Senior Microbiologist, concluded:
“Further analyses are required to estimate the number of independent genetic events leading to the methicillin-resistant sub lineages, but the diversity of the (MRSA) subtypes is suggestive of strong and diverse antimicrobial selection associated with food-animal production.”
Written By Christine Kearney