Crack Found in Armor Against Pneumonia
Resistance to powerful drugs rises, CDC says
FRIDAY, Sept. 21, 2001 (HealthDayNews) -- Health officials say a front-line defense against bacteria that cause pneumonia and ear infections is showing signs of cracks.
A new report from the Centers for Disease Control and Prevention (CDC) shows that strains of Streptococcus pneumoniae resistant to powerful antibiotics called fluoroquinolones are becoming more common in North America, especially in Canada, and are particularly prevalent among older adults who generally take more of the drugs.
As a result, officials say doctors and state epidemiologists should be alert to signs of resistance to these medications. Physicians also should take care to prescribe fluoroquinolones appropriately, limiting the antibiotics to only patients with bacterial infections.
"We have seen that there has been a slight increase [in resistance], so that alone does not tell you that this is a huge problem, but combined with other reports from Canada and other countries, that gives us concern that the same pattern is going to happen here," says Dr. Montse Soriano, a CDC medical epidemiologist and a co-author of the report.
Streptococcus pneumoniae is the leading cause of both community-acquired pneumonia -- as opposed to cases picked up in the hospital -- and middle ear infections, or otitis media.
Between 1987 and 1992, the share of invasive pneumococcal samples resistant to penicillin rose more than 60-fold, from 0.02 percent to 1.3 percent, the CDC says. In some areas of the country, 30 percent or more of samples don't respond to the drug, the agency says.
The National Foundation for Infectious Diseases says drug-resistant pneumococci cause 150,000 cases of pneumonia, more than 1 million ear infections as well as thousands of cases of meningitis and blood infections each year.
Fluoroquinolones, such as ofloxacin, levofloxacin and the most common form, ciprofloxacin, are synthetic compounds that cause irreparable damage to bacterial DNA. Their use rose significantly, from 3.1 to 4.6 prescriptions per 100 people between 1993 and 1998, says the new report. While prescriptions for children have remained relatively steady, those for people over 18 and especially for Americans ages 65 or older surged during that period.
The study shows a gradual increase in ofloxacin-resistant pneumococci between 1995 and 1997, from 2.5 percent to 3.8 percent of germ samples. The rate was even greater among people 18 or older, rising from 3 percent to 4.5 percent in samples of pneumonia that had spread to the blood, spinal fluid or other places where the germs aren't supposed to reside. Resistance to a newer, more effective drug, levofloxacin, stayed roughly the same, at about 0.3 percent, during the period.
"We haven't seen any significant increase for these new drugs, but [their entry into the market] is very recent," Soriano says. "Our experience with these drugs is that because the mechanism for developing resistance is relatively easy, soon after it is widely used they start developing resistance," she says.
Drugs that resist fluoroquinolones are sometimes immune to other antibiotics, such as penicillin, the study says.
Dr. Thomas File Jr., chief of the infectious disease service at Summa Health System in Akron, Ohio, says physicians need to be careful to prescribe antibiotics of any sort only to patients with bacterial illnesses. Many, if not most cases of middle-ear infections are caused by viruses, not bacteria, and the same holds for bronchitis and sinusitis, he says.
Yet patients often clamor for antibiotics when suffering symptoms of these ailments, and doctors often comply.
File, a professor of internal medicine at Northeastern Ohio Universities College of Medicine, says his practice closely monitors patients on fluoroquinolones for signs of resistance. So far this year he has seen two cases in which the drugs haven't worked.
Recent studies have shown that shorter but more intensive courses of antibiotics are just as effective as longer treatment regimens for some bacterial diseases and may better prevent germs from evolving defenses to the drugs.