Group A streptococci and erythromycin resistance - Tips from Other Journals

Date: June, 1992

The resurgence of rheumatic fever, fulminant septicemia and other life-threatening infections caused by group A streptococci has been accompanied by an increasing use of erythromycin, the treatment of choice for patients who are allergic to penicillin. Only a few antibiotics are available to treat infections caused by group A streptococci. Erythromycin has been an effective and safe antimicrobial drug, although gastrointestinal side effects are common. However, studies suggest that the number of erythromycin-resistant strains of group A streptococci are rising. Seppala and colleagues conducted a study to evaluate erythromycin resistance in group A streptococcal isolates.

Samples were collected from regional microbiology laboratories in six areas of Finland. The samples included 272 isolates of group A streptococci obtained from blood cultures from 1988 through 1990, 3,087 isolates from throat swabs in 1990, and 1,349 isolates from pus samples in 1990. Resistance to erythromycin was indicated by growth of group A streptococci on sheep's blood agar containing 2 [mu]g of erythromycin per mL after incubation in 5 percent carbon dioxide.

Results of the blood cultures showed that the frequency of resistance to erythromycin increased from 4 percent in 1988 to 7 percent in 1989 and to 24 percent in 1990. The resistance in isolates from throat swabs increased from 8.2 percent to 20 percent from January to December 1990. Resistance in isolates from pus samples rose from 11 percent to 32 percent during the same period. In addition, erythromycin treatment failed in nine (47 percent) of 19 patients who had throat infections caused by erythromycin-resistant isolates.

The authors suggest that physicians should reduce the unnecessary use of erythromycin when other antibiotics may be effective. In an accompanying editorial, O'Brien recommends that clinical microbiology laboratories worldwide frequently determine the susceptibility of group A streptococci to erythromycin in order to document the rise in resistance and to follow changes in patterns of resistance. (New England Journal of Medicine, January 30, 1992, vol. 326, pp. 292, 339.)

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