Metallo-beta-lactamase type 1 | |||||||
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Identifiers | |||||||
Organism | |||||||
Symbol | blaNDM-1 | ||||||
UniProt | C7C422 | ||||||
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NDM-1 [1] is an enzyme that makes bacteria resistant to a broad range of beta-lactam antibiotics. These include the antibiotics of the carbapenem family, which are a mainstay for the treatment of antibiotic-resistant bacterial infections. The gene for NDM-1 is one member of a large gene family that encodes beta-lactamase enzymes called carbapenemases. Bacteria that produce carbapenemases are often referred to in the news media as "superbugs" because infections caused by them are difficult to treat. Such bacteria are usually sensitive only to polymyxins and tigecycline. [2]
NDM-1 was first detected in 2008 in a culture plate of Klebsiella pneumoniae isolated from a Swedish patient of Indian origin. It was later detected in bacteria in India, Pakistan, the United Kingdom, [3] the United States, [4] Canada, [5] Japan, [6] Egypt, [7] and Iraq. [8]
The most common bacteria that make this enzyme are gram-negative such as Escherichia coli and Klebsiella pneumoniae, but the gene for NDM-1 can spread from one strain of bacteria to another by horizontal gene transfer. [9]
Carbapenems are a class of beta-lactam antibiotics that are capable of killing most bacteria by inhibiting the synthesis of one of their cell wall layers. The carbapenems were developed to overcome antibiotic resistance mediated by bacterial beta-lactamase enzymes. However, the blaNDM-1 gene produces NDM-1, which is a carbapenemase beta-lactamase - an enzyme that hydrolyzes and inactivates these carbapenem antibiotics.[ citation needed ]
Carbapenemases are particularly dangerous resistance mechanisms, since they can inactivate a wide range of different antibiotics. [10] The NDM-1 enzyme is one of the class B metallo-beta-lactamase; other types of carbapenemase are class A or class D beta-lactamases. [11] (The class A Klebsiella pneumoniae carbapenemase (KPC) is currently the most common carbapenemase, which was first detected in North Carolina, United States, in 1996 and has since spread worldwide. [12] A later publication indicated that Enterobacteriaceae that produce KPC were becoming common in the United States. [13] )
The resistance conferred by this gene (blaNDM-1), therefore, aids the expansion of bacteria that carry it throughout a human host, since they will face less opposition/competition from populations of antibiotic-sensitive bacteria, which will be diminished by the original antibacterial treatment.[ citation needed ]
NDM-1 functions through two zinc ions present in the active site that cause hydrolysis of the beta-lactams, rendering them ineffective. Experimental data has shown that zinc chelators can prevent the hydrolysis of beta-lactams mediated by metallo-beta-lactamases. [14]
The NDM-1 enzyme was named after New Delhi, the capital city of India, as it was first described by Yong et al. in December 2009 in a Swedish national who fell ill with an antibiotic-resistant bacterial infection that he acquired in India. [15] The infection was identified as a carbapenem-resistant Klebsiella pneumoniae strain bearing the novel gene blaNDM-1. The authors concluded that the new resistance mechanism "clearly arose in India, but there are few data arising from India to suggest how widespread it is". [15] Its exact geographical origin, however, has not been conclusively verified. In March 2010, a study in a hospital in Mumbai found that most carbapenem-resistant bacteria isolated from patients carried the blaNDM-1 gene. [16] Later, the journal editor apologized for allowing the name.
NDM-1 β-lactamase was also found in a K. pneumoniae isolate from Croatia, and the patient arrived from Bosnia and Herzegovina. The second geographical origin is considered to be eastern Balkans. [17]
In May 2010, a case of infection with E. coli expressing NDM-1 was reported in Coventry in the United Kingdom. [18] The patient was a man of Indian origin who had visited India 18 months previously, where he had undergone dialysis. In initial assays the bacterium was fully resistant to all antibiotics tested, while later tests found that it was susceptible to tigecycline and colistin. The authors warned that international travel and patients' use of multiple countries' healthcare systems could lead to the "rapid spread of NDM-1 with potentially serious consequences".
As of June 2010 [update] , there were three reported cases of Enterobacteriaceae isolates bearing this newly described resistance mechanism in the US, the Centers for Disease Control and Prevention (CDC) stated that "All three U.S. isolates were from patients having received recent medical care in India." [19] However, US experts stated that it is unclear as to whether this strain is any more dangerous than existing antibiotic-resistant bacteria such as methicillin-resistant Staphylococcus aureus, which are already common in the USA. [20]
In July 2010, a team in New Delhi reported a cluster of three cases of Acinetobacter baumannii bearing blaNDM-1 that were found in the intensive care unit of a hospital in Chennai, India, in April 2010. As previously, the bacteria were fully resistant to all the aminoglycoside, β-lactam, and quinolone antibiotics, but were susceptible to tigecycline and colistin. This particularly broad spectrum of antibiotic resistance was heightened by the strain's expressing several different resistance genes in addition to blaNDM-1. [21]
A study by a multi-national team was published in the August 2010 issue of the journal The Lancet Infectious Diseases . This examined the emergence and spread of bacteria carrying the blaNDM-1 gene. This reported on 37 cases in the United Kingdom, 44 isolates with NDM-1in Chennai, 26 in Haryana, and 73 in various other sites in Pakistan and India. [1] The authors' analysis of the strains showed that many carried blaNDM-1 on plasmids, which will allow the gene to be readily transferred between different strains of bacteria by horizontal gene transfer. All the isolates were resistant to multiple different classes of antibiotics, including beta-lactam antibiotics, fluoroquinolones, and aminoglycosides, but most were still susceptible to the polymyxin antibiotic colistin.
On 21 August 2010, Ontario, Canada, had its first confirmed case of the "superbug" in Brampton. There were other confirmed cases in British Columbia and Alberta. [22] These confirmed NDM-1 infected cases have no relationship with New Delhi, India. The patients or their relatives never travelled to India in the last decade.
On 6 September 2010, Japan detected its first ever case of the NDM-1 enzyme. In May 2009, a Japanese man in his 50s who had recently returned from vacation in India was struck with a fever and hospitalized, later making a full recovery. Hospital officials confirmed that tests carried out after the patient's recovery were positive for the NDM-1 enzyme. [23]
An environmental point prevalence study conducted between 26 September and 10 October 2010 found bacteria with the NDM-1 gene in drinking water and seepage samples in New Delhi. 50 tap water samples and 171 seepage samples were collected from sites within 12 km of central New Delhi. Of these samples, 20 strains of bacteria were found to contain NDM-1 gene in 51 out of 171 seepage samples and 2 out of 50 tap water samples. [24] [8]
On 8 May 2012, the presence of NDM was found in a patient who died at Royal Alexandra Hospital in Edmonton, Alberta. The patient was also found to be carrying an Acinetobacter strain. The patient contracted the bacteria after another patient, who had surgery on the Indian subcontinent, traveled to Canada and was admitted to hospital with an infection. [25]
Science Daily reported on the 16 December 2013 that a team of scientists from Rice, Nankai and Tianjin universities found NDM-1 in two wastewater treatment plants in northern China. [26] [27] In fact, the NDM-1 was unable to be removed after several treatments and attempts to disinfect the plants. Disinfection by chlorine, one of the most effective methods currently, also failed to eradicate the beta-lactamase. [26]
In June 2014 it was reported that the molecule aspergillomarasmine A from the Aspergillus fungus turns off the resistance mechanism of NDM-1 and thus makes bacteria once again sensitive to traditional antibiotics. It has been shown to be effective in mice and rats but has not yet been tested in humans for safety or effectiveness. [28]
In September 2016, a 70-year-old woman in Reno, Nevada, died of septic shock following infection with NDM-producing Klebsiella pneumoniae . [29] She had been on an extended trip to India and was admitted to a hospital there for an infected right hip.[ citation needed ]
Detection of NDM-1 gene depends upon the phenotypic determination of the enzyme activity. These enzymes are zinc dependent and therefore termed as metallo-beta-lactamase. Indian studies have been done which demonstrate their dependency on zinc and the ability of zinc chelating agents like EDTA to decrease their activity. The Modified Hodge Test and the Re-Modified Hodge Test were developed for phenotypical detection on a routine basis in resource limited laboratories. [30] Other tests for phenotypic detection are:
The Indian health ministry has disputed the conclusion of the August 2010 Lancet study that the gene originated in India, describing this conclusion as "unfair" and stating that Indian hospitals are perfectly safe for treatment. [31] [32] Indian politicians have described linking this new drug resistance gene to India as "malicious propaganda" and blamed multinational corporations for what they describe as selective malignancy. [31] [33] A Bharatiya Janata Party politician has instead argued that the journal article is bogus and represented an attempt to scare medical tourists away from India. [34] The Indian Ministry of Health released a statement "strongly refut[ing]" naming the enzyme "New Delhi". [35] A co-author of the 2010 Lancet study, who is based in the University of Madras, has stated that he does not agree with the part of the article that advises people to avoid elective surgeries in India. [36]
In contrast, an editorial in the March 2010 issue of the Journal of Association of Physicians of India blamed the emergence of this gene on the widespread misuse of antibiotics in the Indian healthcare system, stating that Indian doctors have "not yet taken the issue of antibiotic resistance seriously" and noting little control over the prescription of antibiotics by doctors and even pharmacists. [37] The Times of India states that there is general agreement among experts that India needs both an improved policy to control the use of antibiotics and a central registry of antibiotic-resistant infections. [36]
The British journal The Lancet refused to publish a rebuttal from the Indian National Centre for Disease Control, claiming lack of space and that the journal's editors felt it would be better placed elsewhere. [38] However, on 12 January 2011, the editor of The Lancet, Richard Horton, apologized and acknowledged that naming the resistance enzyme after New Delhi was an "error". [38] Following this, Ajai R. Singh, editor of Mens Sana Monographs, demanded that such 'geographic names giving' be abandoned and replaced by 'scientific name giving'. He proposed changing NDM-1 to PCM (plasmid-encoding carbapenem-resistant metallo-beta-lactamase). [39]
The first reported death due to bacteria expressing the NDM-1 enzyme was recorded in August 2010, when a Belgian man infected while undergoing treatment in a hospital in Pakistan died despite being administered colistin. A doctor involved in his treatment said: "He was involved in a car accident during a trip to Pakistan. He was hospitalised with a major leg injury and then repatriated to Belgium, but he was already infected". [40] In another case, an Indian citizen, died in a hospital because of similar infection.
Beta-lactamases (β-lactamases) are enzymes produced by bacteria that provide multi-resistance to beta-lactam antibiotics such as penicillins, cephalosporins, cephamycins, monobactams and carbapenems (ertapenem), although carbapenems are relatively resistant to beta-lactamase. Beta-lactamase provides antibiotic resistance by breaking the antibiotics' structure. These antibiotics all have a common element in their molecular structure: a four-atom ring known as a beta-lactam (β-lactam) ring. Through hydrolysis, the enzyme lactamase breaks the β-lactam ring open, deactivating the molecule's antibacterial properties.
Enterobacteriaceae is a large family of Gram-negative bacteria. It includes over 30 genera and more than 100 species. Its classification above the level of family is still a subject of debate, but one classification places it in the order Enterobacterales of the class Gammaproteobacteria in the phylum Pseudomonadota. In 2016, the description and members of this family were emended based on comparative genomic analyses by Adeolu et al.
β-Lactam antibiotics are antibiotics that contain a β-lactam ring in their chemical structure. This includes penicillin derivatives (penams), cephalosporins and cephamycins (cephems), monobactams, carbapenems and carbacephems. Most β-lactam antibiotics work by inhibiting cell wall biosynthesis in the bacterial organism and are the most widely used group of antibiotics. Until 2003, when measured by sales, more than half of all commercially available antibiotics in use were β-lactam compounds. The first β-lactam antibiotic discovered, penicillin, was isolated from a strain of Penicillium rubens.
Klebsiella pneumoniae is a Gram-negative, non-motile, encapsulated, lactose-fermenting, facultative anaerobic, rod-shaped bacterium. It appears as a mucoid lactose fermenter on MacConkey agar.
Meropenem, sold under the brand name Merrem among others, is an intravenous carbapenem antibiotic used to treat a variety of bacterial infections. Some of these include meningitis, intra-abdominal infection, pneumonia, sepsis, and anthrax.
Carbapenems are a class of very effective antibiotic agents most commonly used for treatment of severe bacterial infections. This class of antibiotics is usually reserved for known or suspected multidrug-resistant (MDR) bacterial infections. Similar to penicillins and cephalosporins, carbapenems are members of the beta-lactam antibiotics drug class, which kill bacteria by binding to penicillin-binding proteins, thus inhibiting bacterial cell wall synthesis. However, these agents individually exhibit a broader spectrum of activity compared to most cephalosporins and penicillins. Furthermore, carbapenems are typically unaffected by emerging antibiotic resistance, even to other beta-lactams.
Cilastatin inhibits the human enzyme dehydropeptidase.
Acinetobacter baumannii is a typically short, almost round, rod-shaped (coccobacillus) Gram-negative bacterium. It is named after the bacteriologist Paul Baumann. It can be an opportunistic pathogen in humans, affecting people with compromised immune systems, and is becoming increasingly important as a hospital-derived (nosocomial) infection. While other species of the genus Acinetobacter are often found in soil samples, it is almost exclusively isolated from hospital environments. Although occasionally it has been found in environmental soil and water samples, its natural habitat is still not known.
Beta-lactamases are a family of enzymes involved in bacterial resistance to beta-lactam antibiotics. In bacterial resistance to beta-lactam antibiotics, the bacteria have beta-lactamase which degrade the beta-lactam rings, rendering the antibiotic ineffective. However, with beta-lactamase inhibitors, these enzymes on the bacteria are inhibited, thus allowing the antibiotic to take effect. Strategies for combating this form of resistance have included the development of new beta-lactam antibiotics that are more resistant to cleavage and the development of the class of enzyme inhibitors called beta-lactamase inhibitors. Although β-lactamase inhibitors have little antibiotic activity of their own, they prevent bacterial degradation of beta-lactam antibiotics and thus extend the range of bacteria the drugs are effective against.
Plasmid-mediated resistance is the transfer of antibiotic resistance genes which are carried on plasmids. Plasmids possess mechanisms that ensure their independent replication as well as those that regulate their replication number and guarantee stable inheritance during cell division. By the conjugation process, they can stimulate lateral transfer between bacteria from various genera and kingdoms. Numerous plasmids contain addiction-inducing systems that are typically based on toxin-antitoxin factors and capable of killing daughter cells that don't inherit the plasmid during cell division. Plasmids often carry multiple antibiotic resistance genes, contributing to the spread of multidrug-resistance (MDR). Antibiotic resistance mediated by MDR plasmids severely limits the treatment options for the infections caused by Gram-negative bacteria, especially family Enterobacteriaceae. The global spread of MDR plasmids has been enhanced by selective pressure from antimicrobial medications used in medical facilities and when raising animals for food.
Multidrug resistant Gram-negative bacteria are a type of Gram-negative bacteria with resistance to multiple antibiotics. They can cause bacteria infections that pose a serious and rapidly emerging threat for hospitalized patients and especially patients in intensive care units. Infections caused by MDR strains are correlated with increased morbidity, mortality, and prolonged hospitalization. Thus, not only do these bacteria pose a threat to global public health, but also create a significant burden to healthcare systems.
Carbapenem-resistant Enterobacteriaceae (CRE) or carbapenemase-producing Enterobacteriaceae (CPE) are gram-negative bacteria that are resistant to the carbapenem class of antibiotics, considered the drugs of last resort for such infections. They are resistant because they produce an enzyme called a carbapenemase that disables the drug molecule. The resistance can vary from moderate to severe. Enterobacteriaceae are common commensals and infectious agents. Experts fear CRE as the new "superbug". The bacteria can kill up to half of patients who get bloodstream infections. Tom Frieden, former head of the Centers for Disease Control and Prevention has referred to CRE as "nightmare bacteria". Examples of enzymes found in certain types of CRE are KPC and NDM. KPC and NDM are enzymes that break down carbapenems and make them ineffective. Both of these enzymes, as well as the enzyme VIM have also been reported in Pseudomonas.
Avibactam is a non-β-lactam β-lactamase inhibitor developed by Actavis jointly with AstraZeneca. A new drug application for avibactam in combination with ceftazidime was approved by the FDA in 2015 for treating complicated urinary tract (cUTI) and complicated intra-abdominal infections (cIAI) caused by antibiotic-resistant pathogens, including those caused by multidrug resistant Gram-negative bacterial pathogens.
Ceftazidime/avibactam, sold under the brand name Avycaz among others, is a fixed-dose combination medication composed of ceftazidime, a cephalosporin antibiotic, and avibactam, a β-lactamase inhibitor. It is used to treat complicated intra-abdominal infections, urinary tract infections, and pneumonia. It is only recommended when other options are not appropriate. It is given by infusion into a vein.
ESKAPE is an acronym comprising the scientific names of six highly virulent and antibiotic resistant bacterial pathogens including: Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp. The acronym is sometimes extended to ESKAPEE to include Escherichia coli. This group of Gram-positive and Gram-negative bacteria can evade or 'escape' commonly used antibiotics due to their increasing multi-drug resistance (MDR). As a result, throughout the world, they are the major cause of life-threatening nosocomial or hospital-acquired infections in immunocompromised and critically ill patients who are most at risk. P. aeruginosa and S. aureus are some of the most ubiquitous pathogens in biofilms found in healthcare. P. aeruginosa is a Gram-negative, rod-shaped bacterium, commonly found in the gut flora, soil, and water that can be spread directly or indirectly to patients in healthcare settings. The pathogen can also be spread in other locations through contamination, including surfaces, equipment, and hands. The opportunistic pathogen can cause hospitalized patients to have infections in the lungs, blood, urinary tract, and in other body regions after surgery. S. aureus is a Gram-positive, cocci-shaped bacterium, residing in the environment and on the skin and nose of many healthy individuals. The bacterium can cause skin and bone infections, pneumonia, and other types of potentially serious infections if it enters the body. S. aureus has also gained resistance to many antibiotic treatments, making healing difficult. Because of natural and unnatural selective pressures and factors, antibiotic resistance in bacteria usually emerges through genetic mutation or acquires antibiotic-resistant genes (ARGs) through horizontal gene transfer - a genetic exchange process by which antibiotic resistance can spread.
Asad Ullah Khan is an Indian microbiologist, biochemist and a professor at the Interdisciplinary Biotechnology Unit of the Aligarh Muslim University. He is known for his studies on multidrug resistant clinical strains as well as for the first sighting in India of Aligarh super bug (NDM-4), a variant of New Delhi metallo-beta-lactamase 1 (NDM-1). He is an elected fellow of the Royal Society of Chemistry, the Biotech Research Society, India and the Indian Academy of Microbiological Sciences. The Department of Biotechnology of the Government of India awarded him the National Bioscience Award for Career Development, one of the highest Indian science awards, for his contributions to biosciences, in 2012.
Cefiderocol, sold under the brand name Fetroja among others, is an antibiotic used to treat complicated urinary tract infections when no other options are available. It is indicated for the treatment of multi-drug-resistant Gram-negative bacteria including Pseudomonas aeruginosa. It is given by injection into a vein.
Timothy Rutland Walsh is a professor working at the University of Oxford. He is a specialist in antimicrobial resistance. Walsh is the Oxford Institute of Antimicrobial Research (IOI) Director of Biology. His work at IOI involves developing new antibiotics to use in animals, to replace use of human antibiotics. His IOI work also involves screening many chemicals to find new antimicrobials that overcome or impede antimicrobial resistance. Also he is involved in documenting the large scale effects of antibiotic resistance in low to middle income countries, such as China, Pakistan Bangladesh, Brazil and several African countries.
Nacubactam is an investigational β-lactamase inhibitor being developed for the treatment of infections caused by carbapenem-resistant Enterobacteriaceae (CRE). It belongs to the diazabicyclooctane (DBO) class of compounds and exhibits a dual mechanism of action. Nacubactam inhibits serine β-lactamases, including classes A and C and some class D enzymes, while also directly inhibiting penicillin-binding protein 2 (PBP2) in Enterobacteriaceae. This unique profile allows nacubactam to both protect partner β-lactam antibiotics from degradation and exert direct antibacterial effects. As of 2024, nacubactam is undergoing clinical trials in combination with other β-lactam antibiotics such as meropenem, cefepime, and aztreonam for the treatment of complicated urinary tract infections and other serious bacterial infections caused by multidrug-resistant pathogens.
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