In vitro activity of cefbuperazone and other antimicrobial agents against isolates from the female genital tract

Tetracycline resistance in Peptostreptococcus species

Of 15 Peptostreptococcus sp. strains isolated between 1975 and 1984, 13 hybridized with the Tet K, Tet M, or Tet O determinant. A donor Peptostreptococcus anaerobius strain carrying the three determinants could transfer Tet M to P. anaerobius and Fusobacterium nucleatum recipients but not to an Enterococcus faecalis recipient, while neither Tet K nor Tet O was transferred.

Cefotetan: a review of the microbiologic properties and antimicrobial spectrum

Cefotetan (formerly ICI 156834 and YM09330) is a 7-methoxy cephalosporin possessing some advantageous antimicrobial spectrum, safety, and pharmacokinetic characteristics compared with other so-called second-generation cephalosporins. The published literature was reviewed and the cefotetan quantitative susceptibility testing data from nearly 31,000 isolates was tabulated. Against 15,769 enteric bacilli, cefotetan was observed to have a potency and spectrum more closely resembling a third-generation cephalosporin and markedly superior to cefoxitin. The mean of all MIC 90s reported for the Enterobacteriaceae ranged from 0.06 to 13 micrograms/ml except for citrobacter species, E. cloacae, Enterobacter species, and C. freundii. The mean MIC 50 for all 22 recorded species was in the susceptible range. Cefotetan was very effective against B. catarrhalis, H. influenzae, and pathogenic Neisseria species. However, cefotetan and cefoxitin were not active against Pseudomonas species, Acinetobacter species, and some rarely isolated species. Cefotetan was moderately active against the staphylococci (mean MIC 50, 7.6 to 26 micrograms/ml) and streptococci (mean MIC 50, 0.9 to 6.6 micrograms/ml). The coagulase-negative staphylococcus species generally had higher cefotetan and cefoxitin minimum inhibitory concentrations compared with the S. aureus isolates. Oxacillin-resistant staphylococci were resistant to cefotetan. The enterococci, JK group diphtheroids, Corynebacterium species, and L. monocytogenes isolates were resistant. A review of 4,751 strict anaerobes showed cefotetan to have a very comparable activity and spectrum to cefoxitin. The 1,291 B. fragilis strains had a mean MIC 50 and MIC 90 of 5.4 and 23 micrograms/ml, respectively. These values were slightly superior to cefoxitin when tested in parallel. More elevated minimum inhibitory concentrations were observed for other B. fragilis group species for cefoxitin and cefotetan. The mean cefotetan MIC 90 for all other anaerobic bacteria except the Eubacterium species and Lactobacillus species predict favorable clinical efficacy. The beta-lactamase stability of cefotetan is very similar to that of other 7-methoxy cephalosporins. Cefotetan also inhibits Type Ia cephalosporinases with high enzyme affinity and is an inducer of these beta-lactamases, although cefotetan is not rapidly hydrolyzed. Synergy between cefotetan and numerous other antibiotics has been reported, but antagonism has also been occasionally observed.

Comparative antimicrobial activity of aminothiazolyl methoxyimino cephalosporins against anaerobic bacteria, including 100 cefoxitin-resistant isolates

Three aminothiazolyl methoxyimino cephalosporins (ceftizoxime, ceftriaxone, and cefotaxime with and without its metabolite) were tested against 500 strains of anaerobic bacteria using the NCCLS reference agar dilution procedure. Eighty-seven percent of all strains tested were from the Bacteroides fragilis group. When tested against a collection of 100 cefoxitin-resistant isolates, ceftizoxime and the cefotaxime/desacetyl-cefotaxime combination were the most active in vitro, inhibiting 32-38% of strains. Ceftriaxone inhibited the greatest number (87%) of cefoxitin-susceptible anaerobes at less than or equal to 32 micrograms/ml. A regional variation in the activity of these drugs was confirmed when an additional 300 isolates were examined from three medical centers. Cefotaxime, ceftizoxime, and ceftriaxone were essentially equal in overall antimicrobial activity, although each drug was judged the best at one of the three locations. Cefoxitin resistance (MIC greater than or equal to 32 micrograms/ml) was consistent among the institutions at a 25% incidence for all organisms tested, and 28% cefoxitin resistance among the B. fragilis group strains. Cefoxitin resistance was not determined to be associated with a beta-lactamase mechanism, but ceftriaxone and other aminothiazolyl cephems were hydrolyzed, thus elevating their MICs. Regional variation in anaerobic organism susceptibility to cephamycins and cephalosporins in company with the variable beta-lactam resistance mechanisms seems to require periodic, epidemiologic monitoring of in vitro drug activity by appropriate methods to assure continued antimicrobial efficacy.

In vitro activity of cefmetazole, cefotetan, amoxicillin-clavulanic acid, and other antimicrobial agents against anaerobic bacteria from endometrial cultures of women with pelvic infections

The MICs of the new antimicrobial agents cefmetazole, cefotetan, and amoxicillin-clauvulanic acid were compared with the MICs of other antimicrobial agents against anaerobic bacteria from endometrial cultures from women with pelvic inflammatory disease or endometritis. The activity of cefmetazole was similar to that of cefoxitin and generally greater than that of cefotetan. Amoxicillin-clavulanic acid was generally more active than all cephamycins tested.