The in vitro susceptibilities of various causative organisms recently isolated from patients with genital
infections to
BRL 25000 (a formulation with 2 parts of
amoxicillin and 1 part of
potassium clavulanate),
amoxicillin (AMPC),
cefaclor (CCL),
cephalexin (CEX),
cefadroxil (CDX) and
cefroxadine (CXD) were determined.
beta-Lactamase-producing strains were detected by the
nitrocefin disc method. Frequencies of isolation of
beta-lactamase producing strains of E. coli, K. pneumoniae and B. fragilis were 36%, 96% and 100%, respectively. The activity of
BRL 25000 against S. agalactiae and anaerobic GPC (anaerobic Streptococci, Peptostreptococcus spp.) was slightly less than that of AMPC but was 2- to 4-fold higher than CCL and 8- to 16-fold higher than CEX, CDX and CXD. Against E. coli and K. pneumoniae, the activity of
BRL 25000 was superior to that of AMPC and approximately equal to CEX, CDX and CXD but 2-fold less than CCL. Against the B. fragilis group,
BRL 25000 was much more active than AMPC or any of the
cephalosporins tested, clearly demonstrating the
beta-lactamase inhibitory properties of the
clavulanic acid in
BRL 25000. At inocula of 10(6) CFU/ml, MIC values of
BRL 25000 were 12.5-50 micrograms/ml against some strains of E. coli, K. pneumoniae and B. fragilis. A mechanism of resistance other than
beta-lactamase production is obviously prevalent in these strains. It is speculated that the resistance may be due to a low affinity of the
drug to target
proteins.
Mixed infections of B. fragilis and E. coli or K. pneumoniae are commonly found in the obstetric and gynecological patients.
BRL 25000 shows activity against these strains and also against both aerobic and anaerobic GPC. Therefore,
BRL 25000 is considered useful for the treatment of genital
infections.