Infections due to Clostridium difficile, MRSA or VRE: Introduction

Overview and Implications

Infections due to Clostridium difficile, MRSA or VRE

Healthcare-associated infections result in a substantial burden of disease in Canadians, and are an important public health problem. They are also a burden on Canada's healthcare system and a barrier to timely access to care for all Canadians (Public Health Agency of Canada 2017, "Routine").

While it is important to prevent, and control the spread of all infections, there are certain, antimicrobial resistant organisms that are more prevalent and pose a great risk in healthcare settings.

Antimicrobial Resistance (AMR) occurs when microbes (e.g. bacteria, viruses, fungi and parasites) evolve in ways that reduces or eliminates the effectiveness of antimicrobial medicines (e.g. antibiotics, antivirals, antifungals and antiparasitics) to treat infections. When microbes are exposed to antimicrobials, they adapt and become more resistant (Public Health Agency of Canada 2017, "Tackling"). (These organisms include (but are not limited to) methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococci (VRE) and Clostridium difficile (C. difficile).

The Public Health Agency of Canada (PHAC) estimates that approximately two per cent of patients admitted to large, academic Canadian hospitals will have acquired an infection with an Antibiotic Resistant Organism (ARO) during the course of their hospital stay (Mitchell et al. 2019) and that at any given time, three to 10 per cent of patients who are hospitalized in Canada will either be infected or be a carrier of an ARO (Martin et al. 2019). According to Dr. Tedros Adhanom Ghebreyesus, Director General, World Health Organisation "AMR is one of the most urgent health risks of our time and threatens to undo a century of medical progress" (World Health Organization 2019). Globally, today, 700,000 people die of resistant infections every year; and, if no action is taken, it's estimated that by 2050, 10 million lives are at risk worldwide due to the rise of drug resistant infections (Review on Antimicrobial Resistance, 2016).

The Government of Canada is com mitted to taking action to prevent, limit, and control the emergence and spread of AMR. The Federal Action Plan on Antimicrobial Resistance and Use in Canada (Public Health Agency of Canada, 2015) outlines 3 pillars of action:

Surveillance: Detecting and monitoring trends and threats in order to inform strategies to reduce the risks and impacts of antimicrobial resistance.
Stewardship: Conserving the effectiveness of existing treatments through infection prevention and control guidelines, education and awareness, regulations, and oversight.
Innovation: Creating new solutions to counteract loss in antimicrobial effectiveness through research and development (Public Health Agency of Canada, 2015).

In addition to the Federal Action Plan, a Pan-Canadian Framework for Action (Public Health Agency of Canada 2017, "Tackling") outlines a One Health approach from both the human and agriculture perspectives. The framework encompasses the three pillars listed above, as well as a fourth pillar for Infection Prevention and Control (IPC).

Clostridium difficile Infection (CDI)

Clostridium difficile (C. difficile) is a bacterium that causes mild to severe diarrhea and intestinal conditions like pseudomembranous colitis (inflammation of the colon).

C. difficile bacteria and their spores are found in feces. People can get infected if they touch surfaces contaminated with feces, and then touch their mouth. This may occur as a result of contamination of the patient environment, of shared equipment, or via the hands of healthcare workers. The elderly, those with other co-morbid illnesses, those who are hospitalized, or who are taking antibiotics, are at a greater risk of infection. Certain antibiotics used over a prolonged period of time increase the chance of developing a C. difficile infection (CDI). Nearly all antibiotics have been implicated in CDI, but broad-spectrum antibiotics and certain antibiotic classes, such as cephalosporins, clindamycin, and fluoroquinolones, seem to have a higher risk for placing patients at risk of CDI.

C. difficile spores can exist for five (5) months on hospital surfaces. C. difficile is the most frequent cause of infectious diarrhea in hospitals and long-term care facilities in Canada, as well as in other industrialized countries and it is associated with increased hospital costs, including increased length of stay (Association for Professionals in Infection Control and Epidemiology 2013; Public Health Agency of Canada 2014; McDonald et al. 2018; NICE 2015; Centers for Disease Control and Prevention 2016, "Clostridium difficile").

Methicillin-resistant Staphylococcus aureus (MRSA)

Staphylococcus aureus (Staph) is a type of bacteria that is commonly found on the skin and in the noses of healthy people. Some Staph bacteria are easily treatable while others are not. Staph bacteria that are resistant to the antibiotic methicillin are known as Methicillin-resistant Staphylococcus aureus or MRSA. If left untreated, MRSA infections may develop into serious, life-threatening complications such as infections of the bloodstream, bones and/or lungs (e.g., sepsis, pneumonia, etc.).

Methicillin-resistant Staphylococcus aureus (MRSA) is commonly found in Canadian hospitals and in the community. On one end of the spectrum, individuals can be colonized (carriers) and asymptomatic. On the other end of the spectrum, MRSA can lead to life-threating infection including septic shock and death. MRSA is spread by skin to skin contact or through contact with items contaminated by the bacteria. Those with weakened immune systems, chronic illnesses, hospitalized or having medical procedures are more at risk of acquiring infection. MRSA has been shown to spread easily in healthcare settings. MRSA can cause infections in a number of places, such as skin and soft tissue, blood, bones, joints, heart valves, lungs, and surgical wounds. (Public Health Agency of Canada 2008; Calfee 2012, Centers for Disease Control and Prevention 2016, "MRSA").

Vancomycin-resistant Enterococci (VRE)

Enterococci are bacteria that live in the human intestine and are often found in the environment. Generally, these bacteria do not cause illness; however, when illness does occur, it can usually be treated with antibiotics. Vancomycin-resistant Enterococci (VRE) are strains of enterococci bacteria that are resistant to the antibiotic vancomycin. A person who is colonized with VRE does NOT have symptoms. A person is considered to be infected with VRE when symptoms ARE present.

VRE infections occur primarily in healthcare settings among patients with weakened immune systems, chronic illnesses and medical procedures/instrumentation. Those who have been previously treated with vancomycin or other antibiotics for long periods of time; those who have undergone surgical procedures and those with medical devices such as urinary catheters are at a higher risk of becoming infected with VRE. VRE tends to focus on places like the gastrointestinal tract, urinary tract, heart valves, blood, and any prosthetic devices, such as artificial joints, prosthetic heart valves, and intravenous catheters.

Vancomycin-resistant Enterococci (VRE) is considered a healthcare-associated drug-resistant organism. It can spread from patient to patient when bacteria are carried on the hands of healthcare workers and occasionally through contact with contaminated equipment or other surfaces (e.g. toilet seats, bedrails, door handles, soiled linens, stethoscopes, etc.) (Public Health Agency of Canada 2010; Calfee 2012; Centers for Disease Control and Prevention 2011).