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Antibiotic Resistance On the Rise in China; May Go Global

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“Antimicrobial resistance is now recognized as one of the most serious global threats to human health in the 21st century.”

Scientists working in the UK and China recently released a report in the Lancet Journal on plasmid-mediated colistin resistance mechanism MCR-1 in animals and human beings in China. The study looks at the effects of colistin, a polymixin antibiotic. In the past, polymyxin resistance has involved chromosomal mutations but has never been reported via horizontal gene transfer. Horizontal gene transfer refers to the transfer of genes between organisms in a manner other than traditional reproduction. Co-author Jian-Hua Liu, a professor specializing in antimicrobial resistance in animals, says the results are “extremely worrying” because the polymyxins were “the last class of antibiotics in which resistance was incapable of spreading from cell to cell.”

The researchers have identified a new form of resistance, to the very last-ditch drug colistin—and that it is present in both meat animals and people, probably comes from agricultural use of that drug, can move easily among bacteria, and may already be spreading across borders. Researchers found MCR-1 in 20 percent of sampled pigs and 15 percent of sampled raw meat from markets. It was also found in 16 of 1,322 patients at two Chinese hospitals. The bacteria with MCR-1 have spread to Laos and Malaysia – and probably beyond.

The MCR-1 gene that creates this resistance is contained on a plasmid, a small piece of DNA that is not part of a bacteria’s chromosome. Plasmids move freely around the bacterial world, hopping from one bacterium to another; in the past, they have transported resistance DNA between bacterial species, facilitating resistance’s rapid movement around the globe. According to the authors’ prediction, this gene will be able to do that as well.

The researchers found that in 2011, more than 5% of Escherichia coli isolates from retail chicken and pork meat from China tested positive for the colistin (polymyxin E) resistance gene MCR-1. By November 2014, the last date for which data are available, the percentage of positive isolates had increased to approximately 25%.

Professor Timothy Walsh, who collaborated on the study, says:

“The rapid spread of similar antibiotic-resistant genes such as NDM-1 suggests that all antibiotics will soon be futile in the face of previously treatable gram-negative bacterial infections such as E.coli and salmonella.

“Our investigations in China found that MCR-1 is already prevalent in E.coli samples found in live animals and meat products, and in a small number of human cases.”

Thus, not only have microbes now achieved resistance to polymyxin, but the resistance is spreading quickly.

Attention is now being focused on the widespread use of “last line” antibiotics in animals. The overuse has mainly been in China, where the agricultural industry has been largely unregulated. Whether it’s due to ignorance of what drug dosages are necessary, or due to mere irresponsibility, the damage has been done.

The report urges governments, regulators and online firms to clamp down on unlicensed sales of antibiotics. According to a recent WHO poll, 83% of Chinese believe that farmers should give fewer antibiotics to livestock. But additionally, humans need to understand when drugs are or are not necessary. Antibiotics can only be obtained by a doctor’s prescription in first world countries like the US and UK, but it is relatively commonplace in many lower income countries for the drugs to be purchased over the counter. Apart from overly prescribed or overly used medications, another problem is patients stopping their dosages when they feel better without completing the cycle, not understanding that the infection may still remain and that it can strengthen without completing their doctors instructions.

Comp Pro Med is aware of the emerging threat that such a scenario presents if the gene proliferates to a global level. That is why our staff is dedicated to programming the most efficient laboratory information systems available, with the most benefits to labs working against the tide of this future epidemic.

Before, when people became infected, there was always a last line of defense: harsh, aggressive antibiotics called polymyxins. But health experts warned that the day would come when that defense could fall, when we would enter a “post-antibiotic era” in which it would become increasingly difficult to treat even common cuts and diseases like strep and pneumonia. Operations that are routine today, like knee replacements and caesarean sections, would be more dangerous due to untreatable infection.

According to another recent study, author Ramanan Laxminarayan and his team of researchers posit that if antibiotic resistance increases by just 30% in the United States, the tougher-to-treat bacteria could cause 6,300 more deaths a year and 120,000 more infections in patients undergoing either chemotherapy for cancer or the 10 most common surgical procedures. This complicates the issue of treatment altogether and would change the face of medicine across the world.

Labs and hospitals around the country are aware that in the future they may have to combat stronger bacterial infections. That is why lab systems with the ability to capture all the myriad detail in a formal microbiology workup such as Polytech are so important. Upgrading lab systems that are accurate and reliable will be all the more important in the face of this threat.

Since MCR-1 is a resistance gene that is carried on a plasmid, a swappable circle of DNA that can be easily passed between bacteria, this means that like previous plasmid-borne resistance genes, this one is likely to go global.

While curtailing the use of colistin in farm animals would be a sensible move, it’s possible that it won’t make a difference. The team that discovered the gene, led by Yi-Yun Liu at the South China Agricultural University in Guangzhou found that bacteria seem to hang on to the plasmid even when the antibiotic isn’t being used, suggesting this is a problem that’s unlikely to go away.

In a linked comment for the study published in the Lancet journal, David Paterson and Patrick Harris from the University of Queensland in Brisbane, Australia, wrote that, “The links between agricultural use of colistin, colistin resistance in slaughtered animals, colistin resistance in food, and colistin resistance in human beings are now complete.”