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After a decade of steady decline in the use of antibiotics in Canada, the number of prescriptions is creeping back up, and experts are worried this could spur a rise in deadly, drug-resistant bacterial infections.

"This should serve as a wakeup call to everyone -- physicians, pharmacists and patients -- to be more vigilant about the use of antibiotics," said Dr. François Boucher, a pediatric infectious-disease specialist in Quebec City and chairman of the National Information Program on Antibiotics (NIPA).

He said that while Canada remains a world leader in combatting antibiotic resistance, the issue constitutes a "global public-health threat" that cannot be taken lightly.

Bacteria become resistant to antibiotics when the drugs are used inappropriately -- such as failing to take a full course of antibiotics (which allows bugs to mutate) or using antibiotics to treat viruses (they only work for bacteria).

The most common cause of bacterial infection is Streptococcus pneumonia, which can cause bronchitis, sinusitis, pneumonia, middle-ear infections (otitis media) and bacterial meningitis in children.

Penicillin-resistant Strep pneumo is the most common example of bacterial resistance and serves as a general gauge of success in battling infections.

According to the annual report card released yesterday by NIPA, the rate of resistant Strep pneumo was 15 per cent in Canada last year, which compares favourably to the United States, where it is 37 per cent, and to parts of Asia, where it exceeds 75 per cent.

"Overall, we're doing very well," said Dr. Donald Low, microbiologist-in-chief at Mount Sinai Hospital in Toronto.

But he said he was concerned by two trends. The first is the slight increase in prescriptions for antibiotics. Canadian doctors wrote 63.5 prescriptions for every 100 Canadians in 2005, up from 61.9 per 100 in 2004, according to the report card. The reasons for the increase is not clear but Dr. Low speculated that it was driven by a very bad flu season in 2005. (Influenza is a virus that should not be treated with antibiotics but it can leave people susceptible to bacterial pneumonia.) It should be noted, however, that in 1994, there were almost 120 prescription per 100 Canadians, so drug use is down substantially.

The second worrisome trend he noted was the steady increase in Strep pneumo in children that is resistant to a class of antibiotics called macrolides.

"Strep pneumo resistance to a commonly prescribed macrolide called erythromycin rose to 19.3 per cent in 2005," Dr. Low said. "In 1999, macrolide resistance in Canada was less than 10 per cent." This is particularly worrisome, he said, because more powerful antibiotics, called fluoroquinolones, cannot be used in children because they can cause serious side effects.

Antibiotic-resistant bacteria kill more than 44,000 people a year in North America, and cost an estimated $5.5-billion (U.S.) in additional treatments. Those numbers are expected to soar in coming years as the so-called super bugs get stronger faster, and the new drugs coming to market dry up.

Research published this week in the medical journal Clinical Infectious Diseases warned that the situation is becoming dire, particularly in the U.S.

"These are life-threatening, drug-resistant infections, and we're seeing them every day," said Dr. Martin Blaser, president of the Infectious Diseases Society of America. "What is worse is that our ammunition is running out and there are no reinforcements in sight."

Yesterday, NIPA also released results of a poll that probed Canadians' understanding of antibiotics and antibiotic resistance. It showed that 53 per cent mistakenly believe antibiotics are useful for the treatment of viral infections.

Dr. Boucher described the results as "surprising and disappointing," and said they "clearly underscore the importance of continuing to educate Canadians about the appropriate use of antibiotics."

The supernasties

This week, the medical journal Clinical Infectious Diseases published a "hit list" of the six most dangerous drug-resistant bugs, and bemoaned the fact that treatment options are rapidly disappearing for all of them. The list includes:

Methicillin-resistant Staphylococcus aureus: MRSA is a common hospital-acquired infection but it is now moving into the community, especially where groups of people are in close quarters, including military facilities, sports teams, and prisons.

Several treatment options are available for MRSA, but many have harsh side effects.

Escherichia coli and Klebsiella species: These bacteria are major causes of urinary tract, gastrointestinal tract, and wound infections. They are becoming resistant to a growing number of antibiotic classes at the same time as the frequency of outbreaks is increasing. New therapies are badly needed but few drugs are under development.

Acinetobacter baumannii: The bacterium is a growing cause of hospital-acquired pneumonia. Mortality rates range from 20 to 50 per cent. The number and hardiness of drug-resistant strains are growing. Soldiers are returning from Iraq and Afghanistan with cases of highly resistant Acinetobacter wound infections. Doctors have been forced to resort to an old drug, colistin, which had previously been abandoned as too toxic.

Aspergillus: This fungal infection is a growing problem among immuno-compromised patients, such as cancer patients, organ transplant recipients, and people with HIV. Existing drugs are toxic or interact with other drugs. Even with the best, newly approved antifungals, death rates from Aspergillus infection are 50 per cent to 60 per cent. Few new antifungal drugs are in the pipeline.

Vancomycin-resistant Enterococcus faecium (VRE): VRE is a major cause of bloodstream infections, infections of the heart, meningitis, and intra-abdominal infections. While drugs are available to treat VRE, they have serious shortcomings.

Pseudomonas aeruginosa: This germ causes severe infection that can be life-threatening, particularly in immuno-compromised patients. Rates of P. aeruginosa hospital-acquired pneumonia have nearly doubled, to 18. 1 per cent in 2003 from 9.6 per cent in 1975.

Source: The Infectious Diseases Society of America