Overuse by doctors and patients responsible

By Edward Edelson
HealthScout Reporter

THURSDAY, Dec. 28 (HealthScout) -- The problem of resistance to commonly used antibiotics continues to grow, three teams of researchers report.

It is a worrisome trend that could put us back in the days when deaths from bacterial infections such as pneumonia were all too common, unless physicians and patients learn to exercise restraint in the use of antibiotics, says Dr. Richard P. Wenzel, chairman of the department of internal medicine at Virginia Commonwealth University and author of an editorial on two of the studies in today's New England Journal of Medicine.

One of those studies, headed by Dr. Cynthia G. Whitney, an epidemiologist at the Centers for Disease Control and Prevention, describes growing resistance to antibiotics by Streptococcus pneumoniae, the most common bacterial cause of pneumonia, meningitis and ear infections in children.

The CDC researchers collected more than 12,000 samples from patients infected with S. pneumoniae between 1995 and 1998, testing them against nine classes of antibiotics. Over that period, resistance to three or more of the antibiotic classes increased from 9 percent to 14 percent. Resistance to penicillin grew from 21 percent to 25 percent of the samples.

It is a worrisome trend, Whitney says, because "pneumococcal infections are so common. They are among the main complaints that bring people to a doctor's office."

A second study by CDC researchers, reported in The Journal of the American Medical Association, reported the first known cases of resistance to the antibiotic ceftriaxone, which is used to treat severe cases of food poisoning by salmonella bacteria. A group led by Dr. Frederick J. Angulo says it found 13 cases of ceftriaxone-resistant salmonella from 1996 to 1998.

Since most salmonella infections come from meat, poultry, eggs or other food products, it is possible that the resistant strains came from overuse by farmers of antibiotics related to ceftriaxone, the researchers say.

The third report, in the New England Journal of Medicine, comes from the Cleveland Veterans Affairs Administration, where a group led by Dr. Curtis J. Donskey, chairman of infection control, shows that use of some antibiotics can cause a great increase in resistance to vancomycin by enterococci, relatively innocuous bacteria that live in the intestinal tract. Those bacteria can then pass the genes for resistance to more dangerous bacteria, the researchers say, and so physicians should try to use antibiotics that are less likely to promote vancomycin resistance. Vancomycin is considered an antibiotic of last resort to be used for only the toughest cases.

That is just one way in which physicians can help halt the trend to resistance, says Wenzel. A more basic measure is simply to prescribe fewer antibiotics, he says.

"I think that probably half the antibiotics that are prescribed are unnecessary in that they are prescribed for nonbacterial infections," Wenzel says. Those antibiotics sometimes are prescribed with the thought of preventing a bacterial infection that may arise from a viral disease such as influenza and sometimes simply to reduce feelings of discomfort in a patient, he says.

"One of the things that might be effective in reducing antibiotic use is social pressure from the patients themselves," Wenzel says. "They should know about the risk of accepting antibiotics when they are not necessary and not come to a physician with the preconceived idea of getting antibiotics."

Another way for people to reduce antibiotic use is to take advantage of vaccines, he says. "In this season, that certainly means the influenza vaccine, which not only prevents influenza but also prevents complications of influenza such as pneumonia and meningitis caused by secondary bacterial infections. Anyone over 50 and anyone of any age with a chronic medical problem will certainly benefit from the influenza vaccine."

What To Do

The same benefits can come from vaccination against pneumonia, Wenzel says, which is recommended for all older people and high-risk people, especially those infected with HIV, the virus that causes AIDS. Only a third of HIV-infected individuals have received the pneumonia vaccine, he says.

Whitney echoes those thoughts. "First, we have to be careful about using antibiotics," she says. "Second, we can also use vaccines more effectively, particularly the pneumococcal vaccine. And in the past few years, new vaccines have become available, so there are some reasons to be hopeful."

A more basic measure is hand washing, which "prevents not only the spread of bacterial infections person to person but also the spread of viral infections person to person," Wenzel says. "We have gotten lax about hand washing."