Global spread of antibiotic-resistant bacteria visualized as bacteria-shaped continents swirling out of an open suitcase, symbolizing the connection between travel and the spread of infection.

Superbugs on the Move: How Global Travel Spreads Antibiotic Resistance

Reese Marlowe in Health & Wellness August 2025 • 5 min read.

"A case study highlights the critical role of international travel in the transmission of New Delhi metallo-β-lactamase (NDM-1), a dangerous antibiotic resistance mechanism."

Antibiotic resistance is one of the most pressing threats to public health today. Common infections are becoming increasingly difficult, and sometimes impossible, to treat as bacteria evolve to resist the drugs designed to kill them. Among these resistant bacteria, Enterobacteriaceae, particularly Escherichia coli (E. coli) and Klebsiella pneumoniae, are significant concerns. These bacteria are responsible for many hospital- and community-acquired infections.

Carbapenems, a class of antibiotics, are often the last line of defense against these multidrug-resistant bacteria. However, bacteria have developed carbapenemases, enzymes that inactivate these drugs, leading to a critical reduction in effective treatment options. The New Delhi metallo-β-lactamase (NDM-1) is one such enzyme that has emerged as a major threat, conferring resistance to a wide range of beta-lactam antibiotics, including carbapenems.

A recent case in Canada illustrates just how easily these resistant bacteria can spread across the globe. A patient who had been hospitalized in India returned to Canada and was found to be carrying an E. coli isolate with NDM-1. This case highlights the crucial role of international travel in the dissemination of antibiotic resistance, turning local infections into global threats.

The Case: From India to Canada – A Chain of Resistance

Global spread of antibiotic-resistant bacteria visualized as bacteria-shaped continents swirling out of an open suitcase, symbolizing the connection between travel and the spread of infection.

In 2010, a 32-year-old man was admitted to a hospital in Mysore, India, with hyperglycemia and a urinary tract infection (UTI). Despite initial treatment with ciprofloxacin, his condition did not improve. He was then transferred to a hospital in Alberta, Canada, where he was diagnosed with prostatitis and pyelonephritis.

Before starting ertapenem treatment, a urine sample revealed an E. coli infection with a high bacterial load. Although the patient clinically improved and follow-up cultures showed no bacterial growth after treatment with ertapenem and fosfomycin, the initial E. coli isolate was found to carry the NDM-1 gene, confirming its resistance to carbapenems. The spread of NDM-1 is particularly concerning because it severely limits treatment options and can lead to increased morbidity and mortality.

Initial Infection: The patient contracted a UTI in India, which did not respond to initial antibiotic treatment.
Transfer to Canada: The patient was transferred to a Canadian hospital for further treatment.
Diagnosis of NDM-1 E. coli: An E. coli isolate from the patient was found to carry the NDM-1 gene, indicating carbapenem resistance.
Treatment: The patient was successfully treated with ertapenem and fosfomycin, but the incident highlighted the risk of spreading resistant bacteria.

Further analysis of the E. coli isolate, named MH01, revealed several key characteristics. The isolate was resistant to a broad spectrum of antibiotics, including amoxicillin/clavulanic acid, piperacillin/tazobactam, cefoxitin, ceftriaxone, ceftazidime, aztreonam, meropenem, and ertapenem. Genetic testing confirmed the presence of NDM-1 and CTX-M-15, another beta-lactamase, further compounding the resistance profile. The isolate belonged to sequence type ST101 and phylogenetic group B1, commonly associated with virulent and resistant strains. The presence of multiple plasmids, carrying various resistance genes, indicated the bacteria’s capacity to readily transfer resistance to other bacteria.

Protecting Yourself and Preventing the Spread

The spread of antibiotic-resistant bacteria is a global issue that requires a multifaceted approach, including responsible antibiotic use, improved sanitation and hygiene practices, and international surveillance. Travelers can take several steps to protect themselves and prevent the spread of resistance. When traveling, especially in areas with high rates of antibiotic resistance, it’s crucial to practice good hygiene, including frequent handwashing, and to be cautious about food and water consumption. Avoid unnecessary antibiotic use and always follow the advice of healthcare professionals. By staying informed and taking proactive measures, we can all play a part in slowing the spread of antibiotic resistance and protecting public health.

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This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.3201/eid1702.101313, Alternate LINK

Title: New Delhi Metallo-Β-Lactamase From Traveler Returning To Canada1

Subject: Infectious Diseases

Journal: Emerging Infectious Diseases

Publisher: Centers for Disease Control and Prevention (CDC)

Authors: Gisele Peirano, Jasmine Ahmed-Bentley, Neil Woodford, Johann D. Pitout

Published: 2011-02-01

Everything You Need To Know

What is New Delhi metallo-β-lactamase (NDM-1), and why is it so important?

The New Delhi metallo-β-lactamase (NDM-1) is an enzyme that makes bacteria resistant to a wide array of antibiotics, including carbapenems, which are often a last resort. Its significance lies in severely limiting treatment options for bacterial infections. When bacteria like Escherichia coli (E. coli) produce NDM-1, it can lead to infections that are very difficult, if not impossible, to treat. This can increase the risk of complications, longer hospital stays, and even death. The implications are significant for public health, because it could lead to the situation where common infections become untreatable.

What is antibiotic resistance, and why is it a significant concern?

Antibiotic resistance happens when bacteria evolve to survive the antibiotics designed to kill them. This often occurs through genetic mutations or by acquiring resistance genes. Carbapenem resistance, which is conferred by enzymes like New Delhi metallo-β-lactamase (NDM-1), is a major concern because carbapenems are often the last line of defense against severe bacterial infections. The significance of antibiotic resistance is it threatens the effectiveness of antibiotics, leading to infections that are harder to treat, which can result in more severe illnesses and increased healthcare costs.

How does international travel contribute to the spread of antibiotic-resistant bacteria?

International travel plays a crucial role in the spread of antibiotic-resistant bacteria like those carrying the New Delhi metallo-β-lactamase (NDM-1) gene. When people travel, they can unknowingly carry resistant bacteria from one place to another. The case study shows this as a patient contracted an E. coli infection in India and then brought an NDM-1-producing strain to Canada. This highlights how quickly antibiotic resistance can become a global issue, as local infections turn into a global threat. This dissemination of resistant bacteria through travel leads to the worldwide distribution of antibiotic-resistant infections.

What made the E. coli isolate from the patient in the case study so concerning?

The patient's E. coli isolate, named MH01, was found to carry the NDM-1 gene, which makes the bacteria resistant to carbapenems and a variety of other antibiotics. Besides NDM-1, the isolate also contained the CTX-M-15 gene, which further increased its resistance profile. These genes, along with the bacteria's ability to transfer them to other bacteria, made MH01 a serious threat. This also showed that the bacteria were resistant to multiple types of antibiotics, meaning infections with this strain would be very difficult to treat, posing significant risks to the patient's health and potentially the wider community.

What steps can individuals take to protect themselves from antibiotic-resistant bacteria?

To protect yourself from antibiotic-resistant bacteria, practice good hygiene, especially frequent handwashing. Be cautious about food and water consumption, particularly when traveling to areas with high rates of antibiotic resistance. Avoid unnecessary antibiotic use and always follow the advice of healthcare professionals. International surveillance is essential to monitor and understand the spread of antibiotic resistance. By staying informed and taking these proactive measures, you can reduce your risk of infection and prevent the spread of resistant bacteria like those carrying New Delhi metallo-β-lactamase (NDM-1), contributing to the protection of public health.