1998 Volume 40 Issue 6 Pages 641-647
We evaluated the bactericidal activity of 3 antimicrobial agents, minocycline (MINO), tetracycline (TC), and tosufloxacin (TFLX), when periodontopathic bacteria Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis adhered to or invaded cultured human gingival fibroblasts (Gin-1). Minimum bactericidal concentration (MBC) for each antimicrobial agent was obtained using microbroth dilution techniques. MBC for MINO, TC and TFLX against A. actinomycetemcomitans associated with Gin-1 were 6.25μg/ml, 12.5μg/ml and 3.13μg/ml respectively and those against Gin-1 associated P. gingivalis were 12.5μg/ml, 25μg/ml and 12.5μg/ml respectively. MBC significantly increased when these bacterial organisms were associated with Gin-1 cells; 8-16 times resistant in case of A. actinomycetemcomitans and 32-64 times in case of P. gingivalis. These results suggest that microbial adherence to and/or invasion in Gin-1 cells may result in increased resistance to some antibiotics.
