Transcript Document
Superbugs: Yesterday's solutions often wind up as today's problems Mohammad Riazul Islam, PhD Scientists find new superbug spreading from India A new superbug from India could spread around the world -- in part because of medical tourism -- and scientists say there are almost no drugs to treat it. Researchers said they had found a new gene called New Delhi metallobeta-lactamase, or NDM-1, in patients in South Asia and in Britain. U.S. health officials said there had been three cases so far in the United States -- all from patients who received recent medical care in India, a country where people often travel in search of affordable healthcare. NDM-1 makes bacteria highly resistant to almost all antibiotics, including the most powerful class called carbapenems. Experts say there are no new drugs on the horizon to tackle it. With more people traveling to find less costly medical treatments, particularly for procedures such as cosmetic surgery, Timothy Walsh, who led the study, said he feared the new superbug could soon spread across the globe. What is Superbug Gene can be transferred between bacteria in horizontal fashion by conjugation, transduction or transformation; thus a gene for antibiotic resistance which had evolved via natural selection may be shared. Many antibiotic resistance gene resides on plasmids, facilitating their transfer. If a bacterium carries several antibiotic resistance genes it is called multiresistant or informally a SUPERBUG or super bacteria Mechanism of antibiotic resistance Origin of Antibiotic Resistance The widespread use of antibiotics both inside and outside of medicine is playing a significant role in the emergence of resistant bacteria. (Super bug) In most of the developing countries antibiotics that are sold most often without prescription include Tetracycline, Amoxycillin, Ofloxacin and Ciprofloxacin Why bacteria become resistant against antibiotics? Bacteria have existed on Earth for at least three billion years. In this time they have evolved complex strategies to adapt to different habitats and compete with other bacteria for every available niche. One strategy involves attacking rivals with chemical weapons - which we call antibiotics. Logically, any bacterium attacking a competitor needs to protect itself and its species from its own antibiotics. Resistance genes have also evolved in bacteria which do not produce antibiotics, but compete with those that do. Resistance is often provided by a protein produced by a single gene. The gene is small and self-contained, making it easy to move through a gene pool from bacterium to bacterium. This ease of movement is significant because of the clever ways bacteria use to swap genes. Horizontal gene transfer has the power to drive the spread of resistance genes when bacteria are faced with antibiotics, disinfectants or other pollutants in waste from towns, cities and agriculture. Is pollution driving antibiotic resistance? “Pollution from sewage sludge, animal slurry, disinfectants and fabric softeners may be linked to the rise in bacteria resistant to the most powerful antibiotics”, says William Gaze. Antibiotics and other chemicals that could drive antibiotic resistance enter rivers and soils in many ways. Industry uses larges volumes of detergents and disinfectants - including quaternary ammonium compounds (QACs) - known together as biocides. Nearly all domestic cleaning products and shampoos also contain QACs. They wash out in large volumes with the waste water from factories and homes. QAC resistance genes are significant because they are often located with antibiotic resistance genes on the same piece of DNA, so exposure to one will co-select for the other. Cont….. Farmers spread millions of tonnes of sewage sludge and animal slurry on UK land every year. Sewage sludge contains antibiotics, resistant bacteria and biocides. In addition, animal slurry harbours veterinary antibiotics. All this eventually flows or seeps into the soil and water. The number of bacteria on Earth has been estimated by scientists from the University of Georgia as five million trillion trillion - if each bacterium were a penny, the stack would reach a trillion light years. Because this huge number of bacteria can freely exchange genes that have evolved over billions of years it is not too surprising that new genes giving resistance to clinical antibiotics appear soon after an antibiotic is introduced. But what is surprising is that it is not just antibiotics driving resistance - pollutants and waste disposal practices may also be contributing to this process. How to get rid of this crisis? By reducing environmental pollutions. Stop misusing antibiotics. Replace conventional antibiotics to peptide antibiotics.