NDM-1 (New Delhi metallo-beta-lactamase)

  • Medical Author:

    Sandra Gonzalez Gompf, MD, FACP is a U.S. board-certified Infectious Disease subspecialist. Dr. Gompf received a Bachelor of Science from the University of Miami, and a Medical Degree from the University of South Florida. Dr. Gompf completed residency training in Internal Medicine at the University of South Florida followed by subspecialty fellowship training there in Infectious Diseases under the directorship of Dr. John T. Sinnott, IV.

  • Medical Editor: Charles Patrick Davis, MD, PhD
    Charles Patrick Davis, MD, PhD

    Charles Patrick Davis, MD, PhD

    Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.

What causes NDM-1 to be produced in bacteria?

The blaNDM-1 gene has been found on bacterial chromosomes and plasmids. Plasmids are small segments of genetic material. Plasmids and other mobile genes can pass from one bacterial strain to another and even between completely different kinds.

Bacteria may develop gene mutations causing resistance spontaneously or on mobile genes. When a group of bacteria are exposed to an antibiotic, the ones that are resistant survive to multiply more of that bacteria. The more antibiotics are given, the more resistant bacteria are produced. This is called "antibiotic pressure" toward resistance. Reducing unnecessary antibiotic exposure allows populations of bacteria to revert to more susceptible strains.

What are symptoms and signs of a person infected with bacteria carrying NDM-1?

Bacteria from the Enterobacteriaceae family are the most common cause of urinary infections. They can also cause bloodstream infections (sepsis), pneumonia, or wound infections. Symptoms and signs depend on the location of the infection. Most people will have fever and fatigue and sometimes confusion. If bacteria enter the bloodstream, patients may go into shock. Symptoms do not differ between bacteria that express NDM-1 and those that do not. However, patients who have bacteria producing NDM-1 will not respond to most conventional antibiotics and are at high risk for complications or death.

How are bacteria that produce NDM-1 identified?

Laboratories routinely test bacteria for susceptibility to antibiotics. Strains that produce NDM-1 will show resistance to penicillins, cephalosporins, and carbapenems. Because carbapenem resistance is still uncommon, resistance to these agents raises suspicion of an NDM-1 or CRE strain, although not all will be NDM-1. If the patient has recently been to an area where NDM-1 is common, like India or Pakistan, this increases the probability that the strain is producing NDM-1.

Specific testing for NDM-1 is not routinely available in most laboratories. Fortunately, most NDM-1 or CRE are susceptible to colistin and other drugs. If a carbapenem-resistant isolate is recovered from a patient who has received medical care in India or Pakistan, it is sent to a state public-health laboratory. The state lab forwards it to the Centers for Disease Control and Prevention for specific testing for NDM-1, and the movement of these strains can be closely tracked.

Medically Reviewed by a Doctor on 9/23/2016

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