Comparison of kill-kinetic studies with agar and broth microdilution methods for determination of antimicrobial activity of selected agents against members of the Bacteroides fragilis group

Abstract

Kill-kinetic studies often are used to determine the rate and degree of kiling of aerobic bacteria by antimicrobial agents. Few studies, however, make use of this method for determining antimicrobial activity against anaerobic bacteria. To evaluate kill-kinetic studies for anaerobes, kill-kinetic studies were performed for selected antimicrobial agents against members of the Bacteroides fragilis group and compared with MICs obtained by using a reference agar dilution method and a broth microdilution method. Results of the kill-kinetic studies showed that the degree of killing over a 24-h test period was related to the MIC for the test organism. In general, the higher the MIC of an antimicrobial agent for a test organism, the less the killing observed. In addition, these studies demonstrate subtle differences in bactericidal activity at various concentrations of the antimicrobial agents, which cannot be determined by agar or broth dilution methods. Kill-kinetic studies are a useful addition to dilution methods for the evaluation of antimicrobial agents against anaerobes.

Characterization of bactericidal activity of clindamycin against Bacteroides fragilis via kill curve methods

“…Similar observations have been made with the ␤-lactams (7,9,18). Previously, Aldridge and Stratton reported results from time-kill studies with various agents, including clindamycin, conducted with members of the B. fragilis group (1,21). In those reports, the authors hint that the bactericidal activity of clindamycin may be dependent on the concentration over the range of 0.5 to 4 times the MIC.…”

Antimicrobial activities of silver used as a polymerization catalyst for a wound-healing matrix

“…These polymers are produced in two parts with gelation being catalyzed by ionic silver (Ag) with peroxydiphosphate. This mode of catalysis was chosen as silver is widely used as an antimicrobial [13][14][15] and would distribute through the matrix passively. The other core issues of being biocompatible to living tissues and having hemostatic property are also given importance considering wound repair.…”

Annual incidence, epidemiology, and comparative in vitro susceptibilities to cefoxitin, cefotetan, cefmetazole, and ceftizoxime of recent community-acquired isolates of the Bacteroides fragilis group

“…While this may give grossly relevant clinical data, it may be inadequate for seriously ill patients for whom more specific information is important. Many of the B. fragilis group organisms have MICs that cluster at or near the breakpoint of the various antibiotics (22,24,26 crodilution methods, have become increasingly popular (5,(20)(21)(22)). Adding to this complexity is the fact that numerous new antimicrobial agents with activity against anaerobic bacteria have become available.…”