Antibiotic susceptibility testing of Bacteroides

Area of Science:

• Microbiology
• Infectious Diseases
• Pharmacology

Background:

• Bacteroides species are significant opportunistic pathogens in various infections.
• Accurate in vitro susceptibility testing is crucial for guiding effective antimicrobial therapy.
• Evaluating antibiotic efficacy against clinical isolates is essential for patient management.

Purpose of the Study:

• To assess the in vitro susceptibility of clinical Bacteroides strains to nine different antibiotics.
• To compare the predictive value of disc diffusion and agar dilution methods for Bacteroides.

Main Methods:

• Seventy clinical isolates of Bacteroides were tested.
• Modified disc diffusion and agar dilution assays were employed.
• Susceptibility was correlated with achievable serum drug concentrations.

Main Results:

• Over 90% of strains were susceptible to clindamycin, chloramphenicol, carbenicillin, and lincomycin.
• Only 40% of strains demonstrated susceptibility to tetracycline.
• Disc diffusion showed poor predictive value for susceptibility/resistance, except for tetracycline and chloramphenicol.

Conclusions:

• Clindamycin, chloramphenicol, carbenicillin, and lincomycin are effective against most clinical Bacteroides isolates.
• Tetracycline exhibits limited efficacy.
• Agar dilution is more reliable than disc diffusion for predicting Bacteroides susceptibility to these antibiotics.