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Release: Feb. 1, 2000

UI College of Pharmacy researcher offers guidelines on new antibiotics

IOWA CITY, Iowa -- A new class of antibiotics known as fluoroquinolones can counter infections such as pneumonia, caused by penicillin-resistant strains of a common pathogen. However, caution is necessary for doctors and patients, according to a University of Iowa College of Pharmacy researcher.

Fluoroquinolones are a group of antibiotics increasingly recognized for their ability to treat infections associated with the pathogen Streptococcus pneumoniae. Michael Klepser, Pharm.D., assistant professor in the UI College of Pharmacy, said treatments like fluoroquinolones are expanding in importance as infections from Streptococcus pneumoniae become more resistant to normal antibiotic treatment.

"The issue of resistance to penicillin is more and more problematic," he said. "Streptococcus pneumoniae accounts for a variety of infections affecting lots of people. If these strains are resistant to penicillin, which they are at growing rates, they are often resistant to other antibiotics."

In an article published last November in the journal Infectious Diseases in Clinical Practice, Klepser notes that penicillin became the drug of choice to treat pneumonia and other infections caused by the pathogen in the 1940s. Resistance to penicillin among all bacteria began to occur in small numbers soon after its introduction, but increased to 22 percent of all infections from streptococcus pneumoniae in the United States in the years 1992-93.

The infections associated with this pathogen, including sinusitis and ear infections commonly contracted by children, are frequently encountered, Klepser said. The growing prevalence of penicillin-resistant infections is prompting clinicians and researchers to find other methods of treatment like fluoroquinolones, which originated in the 1960s and were developed into usable medications in the 1980s. Many clinicians are aware of these antibiotics and treatment guidelines exist for their use, Klepser said, but some doctors may not be fully aware of the amounts of resistance to penicillin that exist.

"Doctors probably need to be aware of the susceptibility-to-penicillin patterns in the hospitals they work in and the community around them," he said. "Prior to the 1990s, doctors could assume that penicillin would work for patients. Now they need to know that high-level resistance can be up to 20 percent in some areas, so penicillin and related compounds will not work for everyone."

The use of these fluoroquinolones, or other antibiotics that can be substituted for penicillin, come at no small cost to the patient.

"Patients will probably have to pay for more expensive antibiotics as resistance increases," Klepser said. "Clinicians try to start treatment with the most narrow antibiotic activity, like penicillin. If this fails, the patient goes back and gets another. If this fails, they need to return again. The patient will need to pay for these return trips to the doctor, and for more and more expensive treatments."

Fluoroquinolones show signs of working more effectively in overcoming various degrees of antibiotic resistance in the infections. Klepser stresses, however, that they should not be used as a first line of treatment unless in situations of penicillin allergy, high likelihood of penicillin resistance or deteriorating patient condition.

This caution is necessary because of side effects and some tendency to interact badly with specific medications. In addition, physicians should approach this treatment responsibly and realize the possibility of failure.

"It would be irresponsible to use these potent antibiotics and not take into account the fact that some reports of resistance to the fluoroquinolones has emerged," he said. "The useful life of an antibiotic is not infinite and is often dictated by how frequently the drug is used. It appears that resistance may occur more rapidly if an antibiotic is used more."