In-vitro evaluation of cefpirome (HR 810), teicoplanin and four other antimicrobials against enterococci

In-vitro activities of cefpirome (HR 810), a fourth generation cephalosporin, and teicoplanin were compared with those of ampicillin, piperacillin, and vancomycin against 56 clinical isolates of enterococci. Cefpirome had good activity with the MIC90 and MBC90 being 4 and 16 mg/l. Ampicillin and piperacillin had MBC90 of 4 and 16 mg/l. Teicoplanin was extremely active with the MIC90 being 1.6 mg/l while vancomycin had poor cidal activity with the MBC90 being 16 mg/l. A decrease in activity of cefpirome was noted when the inoculum size was increased from 10(3) to 10(7) organisms per ml. Synergy was demonstrated against most Streptococcus faecium isolates with a combination of cefpirome and gentamicin or piperacillin. Against Str. faecalis, with a similar combination, synergy was seen in less than 50% isolates. No antagonism was noted with any of the antibiotic combinations.