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Pneumonia Bacterium Becoming More Resistant to Antibiotics

© Neal Rolfe Chamberlain

Streptococcus pneumoniae (S. pneumoniae) is a common cause of pneumonia, ear infections, sinus infections, and meningitis (infection of the membranes surrounding the brain). Just 10 years ago it was very sensitive to killing by many inexpensive antibiotics. However, now a little over 1 in 3 isolates of S. pneumoniae from patients infected with S. pneumonia are resistant to penicillin. Which means that penicillin can not be used in these patients.

A recent study in the June 2001 issue of the journal Antimicrobial Agents and Chemotherapy by scientists at University of Iowa College of Medicine indicates that more S. pneumoniae strains are now resistant to antibiotics like penicillin than they were in a 1994-1995 study. This present study demonstrated that antibiotic resistance rates for Streptococcus pneumoniae infections have been on the rise over the past five years, increasing as much as 10% to 16% in the case of some commonly prescribed antibiotics like penicillin and erythromycin.

In the study, researchers collected and tested over 1,500 clinical isolates of S. pneumoniae from 33 medical centers nationwide during the winter of 1999-2000 for resistance to 32 antibiotics. The results were then compared to a similar nationwide study conducted in 1994-1995. Over the last five years resistance rates of S. pneumoniae have increased dramatically. Resistance to penicillin increased over 10% from 24% to 34%. Resistance to erythromycin increased over 16% from 9% to 25% and multidrug resistance increased over 13% from 9% to 22%. Multdrug resistance means that the bacteria were resistant to killing by more than one class of antibiotic. There are several classes of antibiotics based on their chemical structure and on how they kill or stop the growth of bacteria. Penicillin for instance belongs to the beta-lactam antibiotic class and erthromycin belongs to the macrolide class of antibiotics.

The first antibiotic-resistant infection by S. pneumoniae in the United States was reported in 1974. S. pneumoniae antibiotic-resistant infections occurred at low levels in the 1980s. It wasn't until the early 1990s that resistance became widespread.

This is a real concern. S. pneumoniae is the most common cause of pneumonia in older adults and leads to death in 20% of the cases of pneumonia even when appropriate antibiotics are used. If more and more strains of S. pneumoniae becoming resistant to more and more antibiotics this will lead to more treatment failures and more unfortunate outcomes for patients with this bacterial infection.

This is not the end of the world and please do not be overly alarmed. S. pneumoniae is still sensitive to a number of antibiotics and it can still be treated. However, by asking your physician for an antibiotic

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