Susceptibilities of streptococcal strains associated with infective endocarditis to nine antibiotics.

The susceptibilities of 121 streptococcal strains isolated from patients with infective endocarditis to mezlocillin, piperacillin, ceftizoxime, ceftriaxone, ceftazidime, imipenem, ciprofloxacin, ofloxacin and pefloxacin were determined by the agar dilution technique. Viridans streptococci, Streptococcus bovis and Enterococcus faecalis were susceptible to imipenem, mezlocillin and piperacillin. All the strains, except E. faecalis were sensitive to ceftriaxone, ceftizoxime and ceftazidime and resistant to ciprofloxacin, ofloxacin and pefloxacin. E. faecalis strains were moderately resistant to the new quinolons.