[In vitro sensitivity of strict anaerobic Gram-negative bacilli to thienamycin NF and various cephalosporins].

Minimal inhibitory concentrations of 105 anaerobic Gram negative bacilli were determined by two-fold dilution in Wilkins - Chalgren agar following the reference method proposed by Sutter et al. No resistance was observed with thienamycin, which is especially active against the Bacteroides fragilis group (MIC 50 = 0.125 mg/l). Among the beta-lactams investigated, cefoxitin and moxalactam proved more active than ceftizoxime and ceftriaxone, while cefotiam exhibited poor activity. While most Fusobacteria were susceptible to studied beta-lactams, some Fusobacterium varium demonstrated resistance to cephalosporins and cephamycins .