Increased minimum inhibitory concentrations with anaerobiasis for tobramycin, gentamicin, and amikacin, compared to latamoxef, piperacillin, chloramphenicol, and clindamycin.

Minimum inhibitory concentrations (MICs) were determined under both routine aerobic and anaerobic conditions for a total of 93 organisms representing nine genera. MICs for the aminoglycosides amikacin, gentamicin, and tobramycin were significantly increased under anaerobic conditions. Tobramycin was most sensitive to the loss of antimicrobial activity with anaerobiasis. MICs for staphylococci were increased by a higher factor than were MICs for gram-negative rods, but even within the latter group increases in MICs for Proteus species were greater than for Salmonella, Klebsiella and Escherichia coli. No change of anaerobic versus aerobic activity was seen for latamoxef, piperacillin, chloramphenicol, or clindamycin.