Why US woman dying of bacteria that resisted 26 antibiotics is worrying
A woman in the US died in September last year after being infected by a superbug. The infection was caused by carbapenem-resistant Enterobacteriaceae (CRE), a multidrug-resistant organism associated with high mortality. The news has sent doctors across the world, especially India, into a tizzy. Here's why:
1.The 70-year-old patient in the US was admitted to an acute care hospital last year after an extended trip to India, according to a study published in the Morbidity and Mortality Weekly Report of Centers for Disease Control and Prevention (CDC).
2. The patient was given a primary diagnosis of systemic inflammatory response syndrome, likely resulting from an infected right hip seroma. The infection was serious; none of the 14 antibiotics physicians used to treat the woman worked, according to a PTI report. Incidentally, antibiotics misuse in India has led to soaring levels of antimicrobial resistance.
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| Antibiotics misuse in India has led to soaring levels of antimicrobial resistance. |
3. While CRE are not new to the US, what was new in this case is that the superbug could fend off 26 different antibiotics, including all aminoglycosides and polymixins — another class of last-resort antibiotics.
4. After the CRE — identified as Klebsiella pneumoniae — was confirmed by lab testing, an isolate from a wound specimen was sent to the CDC for further susceptibility testing and to determine the mechanism of resistance. That testing confirmed the presence of New Delhi metallo-beta-lactamase (NDM-1), an enzyme that directly breaks down carbapenems, a powerful class of antibiotics that are often used to treat multidrug-resistant infections.
5. Such infections “threaten the return of a pre-antibiotic era in Indian neonatal intensive care units", the study’s authors warned. But Mike Sharland of St George’s, University of London, says it is not just a problem for India. His team has just published their findings that, across Europe, hospital-acquired infections strike an average of 10 to 17 per cent of babies treated in neonatal or intensive care units, and other studies suggest that many of these may be multi-resistant.
6. It was also intermittently resistant to tigecycline, an antibiotic developed specifically to overcome drug-resistant organisms. Essentially, there were no treatment options.
7. CRE have been labelled as a "nightmare" bacteria not only because they are already resistant to most antibiotics, but also because they spread easily in hospital settings. The enzymes that enable resistance are carried on mobile pieces of DNA known as plasmids that can spread to other types of bacteria. NDM-1 enzyme is particularly mobile, researchers say.
8. When CRE bacteria enter the bloodstream, they can be deadly. CRE bacteria kill up to half of patients who get bloodstream infections from them.
9. NDM-1 was originally identified in 2009 in a Swedish patient who had been hospitalised in India.
10. The multi-drug-resistant Klebsiella pneumoniae has been described by the World Health Organization as "an urgent threat to human health".
11. According to an AFP report, the patient's postmortem tests showed her infection might have responded to a treatment called fosfomycin, which is not approved in the United States.
12. According to Nick Thomson, leader of the bacterial genomics and evolution group at the Wellcome Trust Sanger Institute in England, this bacteria is likely to become more and more resistant. "The report highlights international travel and treatment overseas as a feature in the introduction of this pan-resistant isolate into the USA," he says.
13. Laura Piddock, a professor of microbiology at the University of Birmingham, says the case shows that doctors "need the flexibility to use antibiotics licensed for use in other countries and shown to be active in the laboratory against the patient's infecting bacterium".