Analysis of anaerobic gram-negative rods in Oral infections

Abstract

Most anaerobes isolated in oral infections are anaerobic gram-negative rods such as Prevotella, Porphyromonas and Fusobacterium. However, isolation of these organisms is more difficult than other anaerobes. In particular, the isolation rate of anaerobic gramnegative rods is not sufficient even though they are indigenous oral bacteria. We therefore used Brucella HK Agar w/PV (LR) with basal medium to isolate anaerobic gram-negative rods selectively and examined the usefulness of this technique. A total 132 isolates (55 aerobes and 77 anaerobes) were isolated from 48 cases of oral infections. When we used only modified GAM agar, only 17 anaerobic gram-negative rods were isolated (isolation rate: 15.6%). But when we used Brucella HK Agar w/PV (LR) with modified GAM agar, 40 anaerobic gram-negative rods were obtained (isolation rate: 30.3%). The number of isolated Prevotella and Porphyromonas was 22. Ten of them formed black-pigmented colonies.
More than 95% of strains of anaerobic gram-negative rods were susceptible to CEZ, CMZ, LMOX, IPM, TC and CLDM.