A five-year multicenter study of the susceptibility of the Bacteroides fragilis group isolates to cephalosporins, cephamins, penicillins, clindamycin, and metronidazole in the United States.

Over 2800 clinical strains of the Bacteroides fragilis group were collected during a 5-year period from ten geographically separate sites and tested for their susceptibility to various antimicrobial agents using a broth microdilution method. Among the cephalosporins, ceftizoxime was the most active (13% resistance) and importantly exhibited relatively equal activity against both B. fragilis species and non-B.

In-vitro study of the susceptibility of cefoxitin/cefotetan resistant Bacteroides fragilis group strains to various other antimicrobial agents.

The in-vitro activity of various beta-lactam antibiotics, beta-lactam/beta-lactamase inhibitor combinations, clindamycin, and metronidazole was determined against Bacteroides fragilis group isolates that were resistant to both cefoxitin and cefotetan. Among the cephalosporins tested ceftizoxime was the most active with 80% of the strains susceptible, followed by cefotaxime (65% susceptible), and cefoperazone (47% susceptible). Piperacillin and clindamycin showed comparable activity to ceftizoxime with 80% and 81% susceptible, respectively.

Discordant results between the broth disk elution and broth microdilution susceptibility tests with Bacteroides fragilis group isolates.

Susceptibility testing of 161 clinical isolates of the Bacteroides fragilis group was performed to compare interpretive results generated by the broth disk elution and broth microdilution methods recommended by the National Committee for Clinical Laboratory Standards. Among the cephalosporin-cephamycin compounds tested, correlation was poorest for ceftizoxime (71%), ceftriaxone (57%), and cefotaxime (47%); when the tests did not correlate, false resistance was seen 92, 95, and 93% of the time, respectively. Cefotetan and cefoperazone showed lack of correlation in 19 and 20% of the tests, respectively.

Lomefloxacin, a new fluoroquinolone. Studies on in vitro antimicrobial spectrum, potency, and development of resistance.

Lomefloxacin (NY-198; SC-47111), a potent new difluoroquinolone, was studied to compare its in vitro activity with that of other antimicrobials against 2194 clinical isolates. Lomefloxacin showed excellent inhibitory and bactericidal activity against strains of Enterobacteriaceae and inhibited greater than 99% of the isolates at a concentration of 4 micrograms/ml or less. Lomefloxacin exhibited good-to-moderate activity against strains of Acinetobacter (MIC90 4 micrograms/ml) and Pseudomonas aeruginosa (MIC90 8 micrograms/ml), but poor activity for Pseudomonas cepacia (MIC90 greater than 16 micrograms/ml).

Lomefloxacin (SC 47111 or NY-198), a new difluorinated quinolone: comparison of the in vitro activity with other broad spectrum antimicrobials against Enterobacteriaceae, Acinetobacter spp, Aeromonas spp, and Pseudomonas aeruginosa.

Using a broth microdilution method, we compared the in vitro activity of lomefloxacin to other broad spectrum antimicrobials against clinical strains of Enterobacteriaceae, Acinetobacter spp, Aeromonas spp, and P. aeruginosa. Against the Enterobacteriaceae and A.

Biosynthetic origin of aflatoxin G1: confirmation of sterigmatocystin and lack of confirmation of aflatoxin B1 as precursors.

The origin of aflatoxin G1 was studied using mutant strains of Aspergillus parasiticus blocked early in the pathway and by tracing 14C-labelled aflatoxin B1 (AFB1) in wild-type A. flavus and A. parasiticus strains.