The World Health Organisation (WHO) has ranked 12 of the world’s deadliest antibiotic-resistant bacteria or “superbugs” based to the threat they pose to human health and has warned that the world could be running out of options to treat common infections.
Close to 700,000 people die worldwide each year due to drug-resistant infections and, if infection-control measures are not followed and new antibiotics not developed, casualty numbers are projected to cross 10 million people by 2050.
Among the three deadliest bacteria that need to be controlled with “critical priority” is carbapenem-resistant enterobacteriaceae that made news recently for killing a woman of septic shock in Nevada. She got the superbug infection in India last year, which led to multiple hospitalizations in India and the US, confirmed the US Centers for Disease Control in January this year.
Her carbapenem-resistant enterobacteriaceae infection was so deadly that it was resistant to 26 different antibiotics, including polymixins and tigecycline, two potent drugs for treating highly-resistant infection.
The US CDC confirmed the resistance was caused by the presence of New Delhi metallo-beta-lactamase (NDM-1), an enzyme that directly breaks down carbapenems, a powerful class of antibiotics used to treat multidrug-resistant infections.
Superbugs to stay
With several bacteria becoming resistant to antibiotics, untreatable hospital-acquired infections are increasing making routine infections, medical procedures and surgeries -- such as influenza, pneumonia, caesarean sections, heart surgeries, chemotherapy etc -- life-threatening for patients.
The “critical priority” group includes multi-drug resistant bacteria that spread easily in hospital settings because immunity is the lowest when people are sick or recovering from medical procedures or surgery. These bacteria worsen disease and cause death from septic shock after the superbugs enter the bloodstream and reach the heart, lungs, kidneys, bones or joints to cause multi-organ failure.
“Bacteria have a quicksilver ability to adapt and find new ways to resist treatment and pass on genetic material that makes other bacteria to become drug-resistant as well. Hospitals and clinicians must follow strict sterilisation and prescription protocols to ensure antibiotics are used correctly,” said laparoscopic and bariatric surgeon Dr Pradeep Chowbey, executive vice-chairman, Max Healthcare.
Surprisingly, Mycobacterium tuberculosis is not included in the list, and neither are some other common infection-causing bacteria such as Chlamydia and streptococcus A and B because they are either targeted by other programmes or have low resistance to existing treatments and are yet not uncontrollable.
The threat, however, is real because treating drug-resistant infections takes longer, cost more money and produces more toxic side effects. India is battling multidrug-resistant TB, with about 2.5% of all new TB cases in the country being resistant to rifampicin, or to both rifampicin and isoniazid – the two most commonly used anti-TB drugs. At the end of 2015, India had 79,000 cases of drug-resistant TB, 11% more than in 2014.
Drug-resistance happens when a weak or an incomplete course of antibiotics knocks the bacteria down but does not kill it, causing it to mutate and emerge stronger. Experts fear that with an increasing number of bacteria developing drug resistance, we are headed towards the pre-penicillin era a century ago when even the mildest infection could kill.
Drug-resistant superbugs thrive in hospitals with poor infection control. “Without effective drugs, doctors cannot treat patients as antibiotic resistance can make lifesaving treatments and surgeries potentially life-threatening,” said Dr Chowbey. “Misuse because of self-medication, non-compliance to the full course for the indication being treated and using strong antibiotics when simple ones are needed all lead to resistance, where antibiotics are anyway misused to feed livestock.
An enzyme that makes bacteria drug resistant is NDM-1 (New Delhi Metallo-beta-lactamase-1), which got the ‘New Delhi’ moniker because it was first detected in 2008 in Swedish patient of Indian origin who had travelled to India. Since then, it has been detected in bacteria in the UK, US, India, Pakistan, Croatia, Canada and Japan. NDM-1 makes bacteria resistant to a wide range of powerful antibiotics, including the carbapenem, which is used to treat other superbugs such as methicillin-resistant Staphyloccus aureus (MRSA).
The most common bacteria that make this enzyme are E. Coli and K. pneumoniae, which cause of stomach and lung infections. “When uncomplicated, these infections can be easily managed, but when the infecting agent is resistant to powerful antibiotics, the infection becomes difficult to treat and spreads easily within the body, especially in people who are ill or recuperating from an illness or a surgery,” said Dr Chowbey.
“This list is a new tool to ensure R&D [research and development] responds to urgent public health needs. If we leave it to market forces alone, the new antibiotics we most urgently need are not going to be developed in time,” said Dr Marie-Paule Kieny, WHO’s assistant director-general for health systems and innovation.
The world is fast running out of options but new drug discovery is not the only solution. “Along with focusing on new drug research, nations must regulate misuse and overuse of antibiotics, both in the medical and livestock industry,” says Dr Srinath Reddy, president, Public Health Foundation of India (PHFI).