NEW YORK, Jul 22 (Reuters Health) -- Between 1993 and 1998, Canada experienced an increase in antibiotic-resistant Streptococcus pneumoniae, a bacteria that is the most common cause of pneumonia, meningitis, ear infections, and sinus infections.

A class of antibiotics called fluoroquinolones are commonly used to treat infections due to S. pneumoniae. But a new report attributes the rise in bacterial resistance to overuse of these antibiotics, and suggests that steps must be taken to curb their use.

In 1993-1994, only 1.5% of the S. pneumoniae samples tested were resistant to fluoroquinolones, a class of antibiotic that is used increasingly often in Canada. By 1997-1998, 2.9% of bacteria samples were resistant to the drugs.

The use of fluoroquinolones rose from less than 1 prescription per 100 persons per year in 1988 to 5.5 per 100 in 1997, according to the report in the July 22nd issue of The New England Journal of Medicine.

"What we've found is that by looking back over 10 years, there's not only been a dramatic increase in the percentage of strains that are less susceptible, but also a higher and higher level of resistance year after year," said Dr. Donald E. Low of the Mount Sinai Hospital in Toronto, Ontario, in an interview with Reuters Health.

"These data are telling us two things: we have to use all antibiotics more judiciously, but also rethink our paradigm on how we're using them. We need to go in and kill the partially resistant strains while we can -- the more we leave around, the more trouble we're going to have in the future," he added.

Low and a team of researchers from the Canadian Bacterial Surveillance Network tested 7,551 isolates of S. pneumoniae obtained throughout Canada during 1988 and from 1993 to 1998. The team also analyzed patterns of antibiotic prescriptions from Canadian retail pharmacies.

"Our study demonstrates that the prevalence of pneumococci with reduced susceptibility to fluoroquinolones not only increased over time, but was associated with the age group (persons 65 or older) and geographic location (Ontario) with the highest per capita use of fluoroquinolones," the investigators concluded.

Low and colleagues add that "it is essential" to control inappropriate use of antibiotics, and also to determine the doses and courses of fluoroquinolones that minimize the development of bacterial resistance.

SOURCE: The New England Journal of Medicine 1999;341:233-239.

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