Microbes strike back: Q&A with Professor Andrew Simor

Thursday, February 25, 2016
Professor Andrew Simor
Professor Andrew Simor

For decades, physicians have relied on antimicrobial drugs to treat infections. However, these drugs are becoming less effective as microbes find clever ways to circumvent human drug design.

The recent emergence of a gene that makes bacteria resistant to colistin, a last-resort drug, set off alarm bells across the medical community. The gene has now been found in twelve countries including Canada, where researchers detected it late last year.

Among scientists battling the global crisis of drug resistance is Andrew Simor, a Professor in the Department of Laboratory Medicine and Pathobiology (LMP). Simor is also the Head of the Division of Infectious Diseases and the Department of Microbiology at Sunnybrook Health Sciences Centre.

Simor spoke with LMP writer Michelle Lee about the principles behind the emergence and spread of antimicrobial resistance, and how his work contributes to the development of preventive strategies and treatments.

Why does antimicrobial resistance arise? Some germs are intrinsically resistant to antibiotics due to their genetic makeup. Because chemical components of many antibiotics are naturally found in the environment, germs with this genetic makeup have a survival advantage. Germs can also acquire new genetic information, either from other organisms in the environment or by a random mutation of their gene. All of this may occur in response to the presence of antibiotics in the organism’s environment, which means that antibiotic use is a major driver. Many antibiotics that we consume are prescribed, but there’s also lots of antibiotic use in the agricultural and veterinary industries. When microorganisms that are exposed to these antibiotics develop resistance, they can spread and cause illnesses in healthcare settings and in the community.

What is the biggest threat today? It’s hard to pick one because they all have significant potential. But in 2013, the Centers for Disease Control and Prevention (CDC) published an update regarding antibiotic resistance cases in the United States. They picked two types of antimicrobial resistance as their most urgent crises. One is Clostridium difficile, which is prevalent in health care facilities and in the community. The second is a group called carbapenem-resistant organisms. I would personally add to this list MRSA (methicillin-resistant Staphylococcus aureus), because it’s so common, potentially extremely virulent, and difficult to treat.

How do your local and international works relate to these issues? Locally, my research here at Sunnybrook aims to understand the epidemiology of antibiotic resistant organisms — how common they are, incidence, prevalence, and what interventions are effective. With this knowledge, we can develop strategies that limit the emergence and spread of these organisms. I’ve also been trying to optimize rapid diagnosis of antibiotic resistance because the sooner you recognize it, the sooner you can treat or prevent it. The organisms I primarily focus on are MRSA and C. difficile.

Regarding international work, I went to Sierra Leone last January and February to work as a World Health Organization (WHO) consultant. One of the main tasks that I was given was to improve infection control and management of Ebola and we’ve seen that it’s very important to develop long-term strategies. Prior to Ebola, there was virtually no culture or knowledge of infection control in hospitals in most of West Africa. Ebola certainly triggered the idea that infection prevention and control practices should be sustained in these countries even after Ebola is gone. I also visited some of the healthcare facilities in the country to make recommendations about their infection control strategies. This included basic measures like how to implement good hand hygiene, use of isolation and barrier precautions and appropriate disinfection of the environment — many things we take for granted here in North America.

How far have we come in fighting antimicrobial resistance? There’s both good news and bad. There is definitely a much greater awareness that antibiotic resistance is a major threat to public health. As a result of this awareness, there are more efforts put towards ensuring effective infection prevention and control measures, and antibiotic stewardship programs are implemented in healthcare facilities. We’re now seeing that MRSA rates are falling and rates of C. difficile in most of Canada have either stabilized or decreased.  On the other hand, there has been an increase in ESBL (extended-spectrum beta lactamases). Carbapenem resistance also has great potential to spread in Canada, as it has already in the US and in many parts of Europe.

Do you think that drug resistance will ever be completely contained? No. There will always be new forms of resistance emerging. Microorganisms such as bacteria, virus and fungi have been around for billions of years. They have been able to survive over time because they can rapidly evolve and respond to the environment. Antibiotics, which have only been around for 60-70 years, are the most recent challenge from the microorganism’s perspective. They have a tremendous ability to respond to this new change, and will continually develop new resistance mechanisms.

What is the future of our battle against antimicrobial-resistant organisms? We have to think broadly to combat antibiotic resistance. New drug development is important, but it’s not the ultimate answer. Strategies like vaccines are quite promising because they reduce overall risk of any infection, which naturally helps decrease infection by an antimicrobial-resistant organism.

What is the future of research in this field? This is one of the most exciting fields within medicine and the fields of microbiology and infectious diseases because we’re always discovering new infectious agents and novel mechanisms of antimicrobial resistance. There will always be new resistance determinants emerging. This creates exciting opportunities for young investigators to better understand the mechanisms of resistance and to begin to develop unique strategies to treat and prevent these infections from occurring.