Reported October 2006

BACKGROUND: Researchers at the University of Rochester Medical Center in New York found a short treatment of a newer class of antibiotics is more effective than the traditional 10-day dose of older antibiotics like penicillin and amoxicillin to treat strep throat. The Rochester scientists reviewed over 47 studies over the past 35 years involving more than 11,000 children and found that 25 percent of children treated for strep throat with penicillin ended up back in the doctor's office within three weeks.

HOW ANTIBIOTICS WORK: Infections are caused by single-celled organisms called bacteria, which can sometimes evade the body's immune system and begin reproducing. Antibiotics kill those harmful bacteria in various ways, such as preventing a bacterium from turning glucose into energy, or preventing it from construct a cell wall. The bacteria die instead of reproducing. Antibiotics are like selective poisons, because they target bacteria and not the body's own cells.

They are not effective against viruses, however. Unlike bacteria, a virus isn't a living, reproducing life form, just a piece of DNA or RNA. A virus injects its DNA into a living cell and the cell itself reproduces more of the viral DNA. There is nothing to "kill," so antibiotics don't work on viruses.

ABOUT STREP THROAT: Viruses cause most sore throats and most generally clear up without medical treatment. Strep throat is an infection caused by a type of bacteria and thus needs treatment with antibiotics. Symptoms include fever, stomach pain and red swollen tonsils. People with the strep throat bacteria can transfer it to others by sneezing, coughing or shaking hands. A doctor will usually take a throat culture to test for strep throat. Lack of treatment can lead to other health problems, such as rheumatic fever (which can damage the heart), scarlet fever, blood infections, or kidney disease.

DRUG RESISTANCE: Bacteria are highly adaptive, and over time they naturally develop resistance, protecting them from incoming germs (and antibiotics) and making them harder to kill. Repeated exposure to penicillin and amoxicillin can result in a throat full of bacteria that can shield strep germs from the older drugs. The surviving bacteria then reproduce more and become more dominant. Sometimes parents discontinue antibiotic medication prematurely when their children begin to feel better, so the strep germ isn't entirely killed off, leading to much more severe infections requiring the use of even stronger drugs later on.

If you would like more information, please contact:

Michael Pichichero, M.D.
Professor of Microbiology & Immunology
University of Rochester
Rochester, NY
(585) 275-1534
michael_pichichero@urmc.rochester.edu

FACTOID...

Alexander Fleming discovered penicillin by accident in London in 1928, when he left plates of bacteria cultures unwashed in his lab for several weeks. When he returned, he found that mold had grown on one of the plates, and the bacteria were not growing around it.

ON THE WEB...

University of Rochester News Article