Surveillance de la résistance aux antibiotiques des anaérobies stricts à Gram négatif

Abstract

Material and method Using an agar reference method (Norma M11-A5, National Committee for Clinical and Laboratory Standards) the minimal inhibitory concentrations of nine antibiotics were determined for 376 anaerobic strains. The following strains were investigated: 254 Bacteroides fragilis group (including 143 B. fragilis), 122 other gram-negative anaerobes ( Bacteroides spp. , Prevotella, Fusobacterium, Porphyromonas, Suterella, Desulfomonas, Veillonella). Results In the B. fragilis group resistance rates were: coamoxyclav 2.8%, ticarcillin 27.5%, ticarcillin–clavulanic acid 1.9%, piperacillin–tazobactam 1.9%, cefoxitin 6.2%, imipenem 0.8%, clindamycin 28.3%, respectively. Based on previous studies, resistance to imipenem remained low in 2003 and was only observed for B. fragilis. Resistance to clindamycin was maintained around 25%. No metronidazole resistance was observed, but decreased susceptibility was found for B. fragilis, B. merdae and Prevotella, as in 4.3% of gram-negative anaerobes. Discussion This study confirms the high resistance rate of gram-negative anaerobes to clindamycin, the efficient activity of imipenem, β-lactam/β-lactamase inhibitor combinations and metronidazole. However, reduced metronidazole susceptibility seems to be increasing.