Argentinian collaborative study on prevalence of erythromycin and penicillin susceptibility in Streptococcus pyogenes. The Argentinian Streptococcus Study Group.

Two monthly studies on the prevalence of penicillin and erythromycin susceptibility of Streptococcus pyogenes were performed in May and October of 1994 in Argentina. A total of 58 centers from 27 cities participated in these studies. A total of 1072 isolates were tested by a diffusion method, although 595 isolates were tested both by the diffusion and an agar dilution method (n = 1767 isolates). No penicillin-resistant streptococci were found in our study (MIC100 = 0.03 microgram/ml). Only four isolates were confirmed as erythromycin resistant S. pyogenes (prevalence 0.14 and 0.28% in May and October 1994, respectively). Resistance in three isolates was due to an inducible mechanism, although in one strain a different phenotype was observed.

Antibiotic management of outpatients with endocarditis due to penicillin-susceptible streptococci.

Thirty patients with endocarditis caused by penicillin-susceptible streptococci were enrolled in one of two groups in this study. Fifteen patients received ceftriaxone (2 g once daily) for 4 weeks; the other 15 received the same dosage of ceftriaxone for 2 weeks and then received oral amoxicillin (1 g four times a day) for 2 weeks. For the 27 patients treated predominantly as outpatients, 380 days of hospitalization were avoided. Clinical cure was achieved for all patients in both groups. We conclude that ceftriaxone, alone or followed by a course of amoxicillin, is an efficacious mode of treatment for infective endocarditis caused by penicillin-susceptible streptococci. Treatment with these agents can be administered predominantly on an outpatient basis.