Thienamycin: New Beta-Lactam Antibiotic with Potent Broad-Spectrum Activity

Thienamycin, a new beta-lactam antibiotic, exhibited potent, broad-spectrum activity in vitro against gram-negative bacilli and gram-positive cocci, including many isolates resistant to currently available antibiotics. All isolates were inhibited at concentrations less than or equal to 25 μg/ml, with the exception of 12% of isolates of Enterobacter spp. and 3% of isolates of Serratia marcescens . Its activity decreased with an increase in inoculum concentration of from 10 5 to 10 7 cells per ml.