Antibiotic-resistant bacteria found in wild birds are of similar composition to those of human origin
Stop what you are doing and look up for just a second, you might be able to see some wild birds such as ravens, rooks, and crows flying across the blue sky.
While you might marvel at their freedom from any troubles in the human society, the truth is their health and ours often influence each other.
One example of such influence is the presence of antibiotic-resistance bacteria, also known as superbugs 2, in wild birds.
What are Antibiotic-Resistant Bacteria?
Antibiotics hinder bacterial infections either killing or preventing their growth. Ever since the discovery of the first antibiotic (Penicillin) in the 1920s, and further developed for mass production, treating previously untreatable infections become just a cakewalk.
However, the existent overuse of antibiotics promotes natural selection among bacteria.
As vulnerable bacteria are killed, the surviving bacterium, with more space to replicate, develop a mutated gene enabling resistance from antibiotic attacks. This gene is a part of a plasmid, small circular DNA molecules, present in all bacterial cells. With a distinctive capacity, the plasmid can be transferred between bacterial cells through cell-to-cell contact. Over time, equipped with the unique gene, an antibiotic-resistant bacterial population is spawned 3.
Vancomycin-Resistant Enterococcus faecium: A Ticking Time Bomb
One example of antibiotic-resistant bacteria is vancomycin-resistant Enterococcus faecium (VREfm), evolved from the gastrointestinal commensal E. faecium 4, 5. Occasionally pathogenic, E. faecium infections were treated by vancomycin, an antibiotic which has been commonly used since the 80s 7. Decades ago, doctors began noticing an increasing number of patients unresponsive to vancomycin, leading to the unsettling discovery of varieties of VREfm.
Limited available treatments and the risk of transferring
resistance to other types of bacteria, make the rapidly spreading
VREfm a ticking time bomb
Why Should We Study VREfm in Wild Birds?
With animals being the most common source for a human to get infected by bacteria such as VREfm (60% of all cases), 75% of which are of wildlife origin. That is why Dr. Veronika Oravcová (Prof. Ivan Literak’s group) and the fellow researchers in CEITEC, along with scientists from Portugal and Spain, are studying the plasmids of VREfm found in wild birds.
By comparing the VREfm plasmids from human and wild-bird origins, they are trying to answer the question, are wild-birds the reason behind the dissemination? 1
|Enterococcus faecium (Source: Dr. Oravcová)|
Ranging from Canada and the US to Europe and specifically, the Czech Republic, researchers collect 75 VREfm samples from ravens, crows, and rooks.
Using Multilocus Sequence Typing (MLST), a genetic structure-analyzing technique 8, the sequence of plasmid samples from wild birds and human are compared. “We observe that plasmids from wild birds hold similar genetic arrangement as plasmids of human origin collected from hospitals,” said Dr. Oravcová.
Most importantly, previous studies on human-harboring VREfm identified the antibiotic-resistant gene as Tn1546 7, uniquely analogous to VREfm samples from wild birds, exhibited by Dr. Oravcová.
The conclusion is that a major source of widespread VREfm in wild birds which potentially disseminated globally is of human origin from clinical settings, such as hospitals and questionable over-prescriptions from family doctors.
Vicious Cycle between Human and Wild Birds
While the result of Dr. Oravcová’s research identifies the linkage between VREfm from wild birds and clinical settings, one may ask “Since wild birds don’t visit the hospitals and get vancomycin prescriptions, how exactly do VREfm and other antibiotic-resistant bacteria from human spread onto wild bird?”
Although yet unclear, there are various hypotheses.
Firstly, with wild birds eating from trashes which includes poorly-managed human wastes, such as used utensils, leftovers, and medical tools, allows them to come in contact with antibiotic-resistant bacteria.
Secondly, agriculture is a possible culprit: World Health Organization (WHO) states, over 80% of antibiotic usage in many countries is from the agriculture industry 9, mainly to facilitate the growth of livestock. Besides us who can obtain antibiotic-resistance through consuming livestock, wild birds can receive antibiotic residuals from livestock-produced wastes, aside from consuming the plants grown on the ranches.
Apart from the local dispersion, wild birds can spread the antibiotic-resistant bacteria all over the globe through migration, “for example, some rooks originally reside in Russia during the summer, and migrate to the Czech Republic during the winter, which promotes spreading of antibiotic-resistant bacteria between the two countries,” alerts Dr. Oravcová.
|Dr. Veronika Oravcová|
Before It Is Too Late...
The reckless overuse of antibiotics has led to an antibiotic-resistance crisis worldwide. So far, antibiotic-resistant bacterial infections are recorded in 22 countries affecting 500 000+ people 10. Even though the pharmaceutical industry seeks for better antibiotics, it is still far-fetched 11.
Beside further investigations, stricter regulations of antibiotic use are desperately needed 12.
The agriculture industry ought to stop exploiting antibiotics to stimulate the growth of healthy livestock. The EU has forbidden unreasonable use of antibiotics on livestock since 2006 13, paving a path for the rest of the world to walk. Management of antibiotics in a clinical setting requires control; it demands identification of the pathogen preceding the treatment.
The reckless overuse of antibiotics has led to a worldwide
While governments educating the citizens about antibiotic resistance, we, the patients, should be more vigilant. With >70% of bacterial infections are treatable alternatively 14, 1 in 3 antibiotics prescribed is unnecessary 15.
Regular exercises can help strengthen our immune systems
(Credit: Jenny Hill on Unsplash)
Don’t underestimate your White Blood Cells. By taking better care of your immune-system, antibiotics will be less needed, routing a better fight against antibiotic-resistance.
Written by Sophia Man and Somsuvro Basu
Publication date: 29.03.2019