RESEARCHERS URGING WIDER USE OF PNEUMONIA VACCINE.

Byline: Jason Kahn Medical Tribune News Service

In a snapshot view of what is taking place nationwide, a new study shows that the rate of antibiotic-resistant bacterial pneumonia has steadily risen over a three-year period at 10 Ohio hospitals.

Based on the findings, health experts called for more liberal use of bacterial pneumonia vaccines, which currently are recommended only for those over age 65 or people who have chronic diseases.

In the study of 590 patients with severe pneumonia caused by the Streptococcus pneumoniae bacteria, resistance to penicillin rose by 10 percent over the study period, while resistance to other antibiotics rose by as much as 12 percent, Ohio researchers reported in Wednesday's issue of the Journal of the American Medical Association.

The overall death rate from pneumonia remained steady at 19 percent over the three-year period, with the elderly being particularly susceptible - 38 percent of patients age 85 or older died. But patients infected with drug-resistant strains of S. pneumoniae averaged four days longer in the hospital, noted lead study author Dr. Joseph Plouffe, of Ohio State University Medical Center in Columbus.

The researchers noted that in Franklin County, Ohio, where the 10 hospitals studied are located, immunization rates are as low as 19 percent in those who should have received the vaccine. Almost all - 90 percent - of the S. pneumoniae strains would have been killed by the current form of the vaccine, according to the report.

S. pneumoniae is a major cause of the roughly 500,000 cases of pneumonia - 50,000 of which are severe - that occur each year in the United States, said the study authors.

The disorder causes filling of the lungs with fluid in addition to fever, chills and chest pain.

"In terms of drug resistance, what's happening in this study is probably what's happening everywhere else in the country," said Dr. Richard Wenzel, chair of internal medicine at the Medical College of Virginia in Richmond. "This is our best estimate, and the study ended in 1994, so it's probably worse now."

Wenzel urged doctors to be more aggressive in getting patients immunized, and recommended that the criteria for determining those who need the vaccine be changed. The age cutoff should be reduced to at least 55, he said, and all smokers should be targeted.

"If you look at smokers, they tend to have more S. pneumonia in their throat cultures," he said. "If we included this group, that would be a tremendous increase in immunization rates."

Wenzel explained that antibiotics are normally prescribed to kill the S. pneumoniae bacteria after a patient is treated in the critical care unit. But if the microbes are drug-resistant, they will continue to grow and multiply, steadily worsening the patient's condition, he said.

Bacteria acquire resistance to specific antibiotics according to the laws governing all natural evolution: survival of the fittest. When an antibiotic attacks a bacterium, it kills off all the susceptible bacterial cells, leaving only the antibiotic-resistant bacterial cells to flourish. These resistant bacteria then replicate, or they may mutate, exchanging DNA with other bacterial cells, creating entire new generations of bacteria impervious to existing antibiotic medication.

Doctors and patients may also play a role in creating resistant bacteria, Plouffe said. Prescribing an antibiotic for an infection for which it is not effective - such as a viral infection - serves to help bacteria build resistance to the antibiotic. In addition, patients often only take their antibiotic for a few days, stopping as soon as they feel better. At this point, however, only the weakest bacteria have been eradicated; other, stronger bacteria that are able to resist the antibiotic may remain.