Extremely Resistant Superbug Is Spreading Internationally

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Main Category: MRSA / Drug Resistance
Also Included In: Infectious Diseases / Bacteria / Viruses;  Public Health
Article Date: 11 Aug 2010 - 8:00 PDT

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A new superbug that makes an enzyme called NDM-1 which probably travelled back to the UK in patients who went over to India and Pakistan for surgical treatments has entered UK hospitals, experts say. This superbug is resistant to virtually all antibiotics, even the most powerful ones. So far, only 50 cases have been reported in Great Britain. However, there is a significant risk of it spreading worldwide.

NDM-1 (New Delhi metallo-beta-lactamase 1) is a new gene that enables a bacterium to become highly resistant to nearly all antibiotics; it is spread in Enterobacteriaceae taken from patients in India and Pakistan. It has also been found in UK patients who travelled to India for elective surgery.

You can read about this in an Article published Online First and in the September edition of The Lancet Infectious Diseases.

The authors of the report say that the time has come for extremely close international monitoring and surveillance, as antibiotics may become redundant with the rapid emergence of these multi-drug resistant NDM-1 producing bacteria and their potential worldwide spread.

Timothy Walsh, Cardiff University, Wales and an international team first detected the NDM-1 gene in Klebsiella pneumonia and Escherichia coli bacteria taken from a Swedish patient admitted to hospital in India.

Even resistant to powerful antibiotics reserved for emergencies

Of concern is that bacteria that produce NDM-1 are even resistant to carbapenems, a group of antibiotics generally reserved for use in emergencies and the treatment of infections caused by multi-resistant bacteria.

The researchers set out to investigate how common the NDM-1 producing antibiotic resistant bacteria are in the Indian Subcontinent (Bangladesh, India, and Pakistan). They also wanted to determine what the implications might be if/when these bacteria come into the UK via patients returning from that part of the world after elective medical procedures.

They collected samples of bacteria from patients with a wide variety of hospital and community-associated infections in India (Channai and Haryana), and from individuals referred to the UK's national reference laboratory between 2007 and 2009.

They tested the samples for:

• The presence of the NDM-1 gene using polymerase chain reaction (PCR) and sequencing.
• Antibiotic susceptibility

They identified:

• 44 (1.5%) NDM-1-positive bacteria in Chennai
• 26 (8%) in Haryana
• 37 in the UK
• 73 in other sites in Bangladesh, India, and Pakistan

NDM-1 was mostly found in:

• E. coli (36), and
• K pneumoniae (111)

Only tigecycline and colistin (types of antibiotics) had any effect on the NDM-1 producing bacteria. There were some cases in which isolates were resistant to ALL antibiotics.

Worryingly, the NDM-1 gene is present on plasmids - DNA structures which can be copied and transferred between different bacteria easily. The authors wrote:

(there is) an alarming potential to spread and diversify among bacterial populations.

The researchers say that the appearance of NDM-1 producing bacteria could lead to a serious worldwide public health problem. There are not many anti-Gram-negative antibiotics in development, and not one that is effective against NDM-1.

Medicine worldwide may be facing a period in which antibiotics become redundant, the authors say:

Even more disturbing is that most of the India isolates from Chennai and Haryana were from community-acquired infections, suggesting that NDM-1 is widespread in the environment.

The researchers concluded that if several of the NDM-1 positive patients in the UK had travelled to India or Pakistan for surgical procedures, such as cosmetic surgery over the last 12 months..:

..India also provides cosmetic surgery for other Europeans and Americans, and it is likely NDM-1 will spread worldwide.

In a Comment, Johann Pitout from the University of Calgary in Canada warns that patients who have medical procedures in India should be screened for multiresistant bacteria before they receive care in their home country:

If this emerging public health threat is ignored, sooner or later the medical community could be confronted with carbapenem-resistant Enterobacteriaceae that cause common infections, resulting in treatment failures with substantial increases in health-care costs.

Emergence of a new antibiotic resistance mechanism in India, Pakistan, and the UK: a molecular, biological, and epidemiological study
Karthikeyan K Kumarasamy, Mark A Toleman, Timothy R Walsh, Jay Bagaria, Fafhana Butt, Ravikumar Balakrishnan, Uma Chaudhary, Michel Doumith, Christian G Giske, Seema Irfan, Padma Krishnan, Anil V Kumar, Sunil Maharjan, Shazad Mushtaq, Tabassum Noorie, David L Paterson, Andrew Pearson, Claire Perry, Rachel Pike, Bhargavi Rao, Ujjwayini Ray, Jayanta B Sarma, Madhu Sharma, Elizabeth Sheridan, Mandayam A Thirunarayan, Jane Turton, Supriya Upadhyay, Marina Warner, William Welfare, David M Livermore, Neil Woodford
The Lancet Infectious Diseases August 11, 2010. DOI:10.1016/S1473-3099(10)70143-2

Written by Christian Nordqvist
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