Skip to main content

Third gene imparting resistance to last resort antibiotic discovered (downtoearth)

Researchers have discovered yet another gene that carries resistance to a crucial, last resort antibiotic called colistin. The mcr-3 gene is the third such gene, which was isolated from pigs who also carried 18 other resistance determinants. The finding has been published by researchers from China Agricultural University, Beijing in journal mBio.

Colistin is used widely as a last resort antibiotic in humans against multi-drug resistant bacteria. It is the “highest-priority” critically important antimicrobial for human medicine as per the World Health Organization (WHO).

Researchers found a sample of E. coli bacteria that was resistant to colistin, but did not carry any of the two known resistant genes (mcr-1and mcr-2). This prompted the discovery of the third gene. The isolated mcr-3 gene is plasmid mediated, meaning it can be transferred among different bacteria in animals as well as humans.

The authors suggest that this novel mobile colistin resistance gene may be widespread, but its prevalence has remained underestimated. They urge for continuous screening for this mobile mcr-3 gene among colistin-resistant pathogens in humans, animals and environment.

Growing concern

In the recently updated Model List of Essential Medicines 2017 for both adults and children,  all polymixin drugs, including colistin has been put in the “Reserve” category, implying such antibiotics should be treated as last-resort options, or should be used for highly specific patients and settings, where other alternatives have been inadequate or ineffective.

A recent article published in journal Nature raises concern over the spread of resistance to this “last-ditch” antibiotic, which has been more rapid than expected. Alarmingly, the genes are no longer limited to animals, but have also been isolated from bacteria in humans. The gene’s spread shows that antibiotic use on farms can lead to resistance in human infections, says Lance Price, an antibiotic researcher at George Washington University. To curb the unregulated use of colistin and control resistance, Brazil and China have banned colistin for agricultural use.

Rampant overuse of colistin in India

Colistin is widely used in production of food animals in India, particularly poultry. Colistin sulphate can be easily procured from veterinary drug dealers without prescription. Such drugs are sold as feed supplements for animals to enhance growth. Veterinarians readily prescribe colistin for treating diseases in poultry, as farmers urge for quick recovery to prevent loss of flock. Antibiotic-based feed supplements are also used in fish for growth promotion.

With rampant use of crucial drug, there is an urgent need for regulations to check antibiotic use (particularly colistin) in the veterinary sector. Drugs used as supplement along with feed do not come under the purview of the drug control agency, thus limiting regulation on antibiotics. Over-the-counter sale of antibiotics is also widespread. The Department of Animal Husbandry, Dairy and Fisheries issued a circular to states to advice veterinarians on judicious use of antibiotics in poultry and that the use of antibiotics in feed is to be stopped. However, it is not mandatory.

The government has finalised the National Action Plan on Antimicrobial Resistance and is gearing up to regulate antibiotic use in the veterinary and livestock sector. However, regulations should be drafted keeping in mind that it does not drastically affect the livelihood of the small farmers. Surveillance of antibiotic use and its correlation with existing resistance trends in humans, animals and environment is important for developing solutions.

Comments

Popular posts from this blog

NGT terminates chairmen of pollution control boards in 10 states (downtoearth,)

Cracking the whip on 10 State Pollution Control Boards (SPCBs) for ad-hoc appointments, the National Green Tribunal has ordered the termination of Chairpersons of these regulatory authorities. The concerned states are Himachal Pradesh, Sikkim, Tamil Nadu, Uttarakhand, Kerala, Rajasthan, Telangana, Haryana, Maharashtra and Manipur. The order was given last week by the principal bench of the NGT, chaired by Justice Swatanter Kumar. The recent order of June 8, 2017, comes as a follow-up to an NGT judgment given in August 2016. In that judgment, the NGT had issued directions on appointments of Chairmen and Member Secretaries of the SPCBs, emphasising on crucial roles they have in pollution control and abatement. It then specified required qualifications as well as tenure of the authorities. States were required to act on the orders within three months and frame Rules for appointment [See Box: Highlights of the NGT judgment of 2016 on criteria for SPCB chairperson appointment]. Having

High dose of Vitamin C and B3 can kill colon cancer cells: study (downtoearth)

In a first, a team of researchers has found that high doses of Vitamin C and niacin or Vitamin B3 can kill cancer stem cells. A study published in Cell Biology International showed the opposing effects of low and high dose of vitamin C and vitamin B3 on colon cancer stem cells. Led by Bipasha Bose and Sudheer Shenoy, the team found that while low doses (5-25 micromolar) of Vitamin C and B3 proliferate colon cancer stem cells, high doses (100 to 1,000 micromolar) killed cancer stem cells. Such high doses of vitamins can only be achieved through intravenous injections in colon cancer patients. The third leading cause of cancer deaths worldwide, colon cancer can be prevented by an intake of dietary fibre and lifestyle changes. While the next step of the researchers is to delineate the mechanisms involved in such opposing effects, they also hope to establish a therapeutic dose of Vitamin C and B3 for colon cancer stem cell therapy. “If the therapeutic dose gets validated under in vivo

SC asks Centre to strike a balance on Rohingya issue (.hindu)

Supreme Court orally indicates that the government should not deport Rohingya “now” as the Centre prevails over it to not record any such views in its formal order, citing “international ramifications”. The Supreme Court on Friday came close to ordering the government not to deport the Rohingya. It finally settled on merely observing that a balance should be struck between humanitarian concern for the community and the country's national security and economic interests. The court was hearing a bunch of petitions, one filed by persons within the Rohingya community, against a proposed move to deport over 40,000 Rohingya refugees. A three-judge Bench, led by Chief Justice of India Dipak Misra, began by orally indicating that the government should not deport Rohingya “now”, but the government prevailed on the court to not pass any formal order, citing “international ramifications”. With this, the status quo continues even though the court gave the community liberty to approach i