SUPERBUGS
Antibiotic-resistant bacteria
Battling germs that keep getting stronger
Last Updated: Monday, October 26, 2009 | 1:25 PM ET
CBC News
An employee displays MRSA bacteria strain inside a petri dish containing agar jelly for bacterial culture in a microbiological laboratory in Berlin. MRSA is a drug-resistant 'superbug', which can cause deadly infections. (Fabrizio Bensch/Reuters)They're in millions of homes and workplaces across the country: antibacterial wipes that are designed to kill germs and protect you and your family from getting sick.
The Canadian Medical Association wants the federal government to ban them.
Some researchers suggest the wipes aren't very good at killing germs. They may remove them from your counter, but the germs stay on the wipe and are either deposited on the next surface you wipe, or enter the environment when the wipe is tossed out with the trash or flushed down the toilet.
Most of the wipes — and other household antibacterial products — contain a chemical compound called triclosan, which is supposed to kill the bacteria that lurk on your counter.
The Canadian Medical Association has called for a ban on household products that contain antibiotics. (Johnson & Johnson Consumer Companies, Inc./Associated Press )There's a growing body of researchers, however, who argue that triclosan is contributing to the problem of antibiotic-resistance bacteria. By passing a resolution at its August 2009 convention calling on Ottawa to act, the CMA said it agreed that antibacterial wipes may cause more harm than good.
The Canadian Paediatric Society says handwashing remains the most effective way to fight the spread of germs. As for antimicrobial products, the society says while they’ve been shown to work in the laboratory, their effectiveness in the home has not been proven.
The society says if you want to go beyond soap and water, a solution of diluted bleach – nine parts water to one part bleach – is an effective germ killer.
Superbugs behind surge in hospital-acquired infections
Bacteria that develop resistance to common antibiotics mean trouble for more than a quarter million Canadians every year. Most develop infections while in hospital. About 8,000 of them die from those infections — more than will die of breast cancer, AIDS and car accidents combined.
A study published in the American Journal of Infection Control in December 2008 found that rates of hospital-acquired infections soared in Canada between 1999 and 2005.
Rates of MRSA (methicillin resistant Staphylococcus) more than doubled in the period from 1999 to 2005, said the study, which was based on a survey of hospitals with 80 or more beds.
There were 5.2 cases of MRSA per 1,000 hospital admissions in 2005, up from two per 1,000 in 1999. There was also an upward trend in C. difficile infections, and the number of hospitals reporting new cases of infection with VRE (vancomycin-resistant enterococci) soared.
More people are picking up antibiotic resistant bugs outside of hospitals. In 2006, 893 Canadians contracted MRSA infections in the community - outside of hospitals. That represented 15 per cent of all MRSA infections recorded. A year later, the total number of MRSA infections rose by one per cent - but the number contracted outside of hospitals rose by almost 50 per cent, according to the Canadian Nosocomial Infection Surveillance Program.
A study published in the Journal of Antimicrobial Chemotherapy in 2003, found that most of the antibiotics that get into the environment had not degraded. "If the drugs are not degraded or eliminated during sewage treatment, in soil or in other environmental compartments, they will reach surface water and ground water, and, potentially, drinking water," the authors wrote.
The researchers noted that antibiotics in the environment make it easier for drug-resistant bacteria to multiply and enter the food chain.
In a study published in the journal Applied and Environmental Microbiology, researchers at the University of Michigan, reported that they found antibiotic-resistant bacteria in drinking water at several sites in Michigan and Ohio — as well as in source water and water that had gone through treatment plants.
The researchers noted that the levels were low. However, they added, "water treatment might increase the antibiotic resistance of surviving bacteria, and water distribution systems may serve as an important reservoir for the spread of antibiotic resistance to opportunistic pathogens."
The most common superbugs include:
MRSA
MRSA — methicillin-resistant Staphylococcus aureus — is a common bacterium that has become resistant to certain types of antibiotics.
It's often found on the skin and in the noses of healthy people - and is usually harmless — but it can cause infection if it gets into the body through a cut or during surgery.
This image, captured with an electron micrograph, shows clumps of methicillin-resistant Staphylococcus aureus bacteria, magnified nearly 10,000 times. (Canadian Press)MRSA is usually transmitted to other people through human hands, especially the hands of healthcare workers, which have been contaminated with MRSA bacteria by contact with infected or colonized patients. The easiest way to prevent transmission is through hand washing with soap and water or using an alcohol-based hand sanitizer.
When penicillin was first used, it was highly effective against Staphylococcus aureus infections, but most strains of the bacterium are now resistant to the antibiotic.
MRSA rarely infects healthy people, and is most often seen in hospitals. The infection can develop in an open wound such as a bedsore or when there is a tube such as a urinary catheter that enters the body. People with long-term illnesses or who have compromised immune systems are at increased risk of infection.
MRSA infections are treated with an antibiotic called vancomycin, which is derived from soil bacteria found in India and Indonesia. Vancomycin is extremely irritating to human tissue, so it is only used as a last resort. Still, some bacteria have become resistant even to this antibiotic, such as vancomycin-resistant Staphylococcus aureus (VRSA) and vancomycin-resistant enterococcus (VRE).
A hospital patient who develops an MRSA infection can expect the length of his or her hospital stay to triple.
While MRSA outbreaks are fairly common in North America, some European countries - including the Netherlands, Finland and Sweden - have been very aggressive in dealing with the bacteria. The Netherlands has adopted a "search-and-destroy" campaign: you're considered infected until tests prove you're not. Infected people are put in isolation and hand-washing orders are enforced. Rates of infection have dropped dramatically, even while they have remained higher in neighbouring countries.
Vancomycin-resistant enterococci (VRE)
Enterococcus is a normally benign bacterium that lives in the intestine. Enterococcus infections can occur in the urinary tract, in the blood and in wounds, including surgical wounds.
While these infections can usually be treated with antibiotics such as ampicillin and vancomycin, a strain that is resistant to both was first discovered in France in 1986. Similar strains can now be found all over the world.
Vancomycin-resistant enterococcus (VRE) is thought to be passed to people through contact with animals or by eating meat. Once the meat is eaten, the bacteria sit dormant in the person's gut until they come into contact with an antibiotic. At that point the VRE can spread to the rest of the body.
Since many patients in hospitals are put on some kind of antibiotic therapy during the course of their treatment, VRE infections often occur in hospitals.
What are ESBL-producing bacteria?
ESBL stands for extended spectrum beta-lactamase, which are enzymes that have developed a resistance to antibiotics like penicillin.
Enzymes are proteins produced by living organisms. The proteins speed up biochemical reactions. ESBL enzymes are most commonly produced by two bacteria - Escherichia coli (otherwise known as E. coli) and Klebsiella pneumoniae. But ESBL enzymes can also be found in bacteria such as salmonella, proteus, morganella, enterobacter, citrobacter, serratia and pseudomonas.
In most cases, the body successfully fights off ESBL-producing bacteria. However, because of the enzymes' ability to fight off antibiotics, people with weak immune systems are at risk. This includes children, the elderly and people with other illnesses.
On May 30, 2007, Toronto's Mount Sinai Hospital closed its neonatal intensive-care unit after a premature baby died of bacteremia — also known as blood poisoning — after contracting serratia. Four other babies tested positive for serratia, which is a naturally occurring bacterium.
ESBL-producing bacteria are spread through feces either by self-infection or direct contact with feces of an infected person. It can, for example, spread from patient to patient on the hands of healthcare workers or the patients themselves. This is why hospitals and seniors' homes are particularly prone to outbreaks.
Washing hands and anything else that comes into contact with an infected person is important to preventing the spread of bacteria.
ESBL enzymes can also spread by passing from one bacterium to another.
Pseudomonas aeruginosa
Pseudomonas aeruginosa is notorious for its resistance to antibiotics and is, therefore, a particularly dangerous and dreaded pathogen.
It is common in soil and water and on vegetation. It's also found on the skin of some healthy people. Within a hospital setting, Pseudomonas aeruginosa can be found in disinfectants, respiratory equipment, food, sinks, taps, and mops. It's constantly reintroduced into a disinfected environment through fruits, plants, vegetables, and visitors and patients transferred from other facilities.
It is spread from patient to patient on the hands of hospital personnel, by direct patient contact with contaminated items, and by the ingestion of contaminated foods and water.
Among the problems the bacteria can cause are:
- Endocarditis. The bacteria infect heart valves of IV drug users and prosthetic heart valves through direct invasion from the blood stream. The endocardium is the inner lining of the heart.
- Respiratory infections. These occur almost exclusively in people with a compromised lower respiratory tract or a weakened immune system.
- Gastrointestinal infections. The bacteria can produce disease in any part of the gastrointestinal tract, primarily in people whose immune systems have been compromised.
Only a few antibiotics are effective against the bacteria and even these antibiotics are not effective against all strains. Nearly all cystic fibrosis patients eventually become infected with a strain that is so resistant that it cannot be treated.
Premature babies are also susceptible because of their underdeveloped respiratory systems. At Montreal's St-Justine hospital, six premature babies died after they were infected in the neonatal intensive care unit in 2005. The source was traced to aging, blocked drains that were harbouring colonies of the bacteria.
