Mesh : Aztreonam / administration & dosage pharmacokinetics pharmacology therapeutic use Clinical Trials as Topic Drug Therapy, Combination Enterobacteriaceae / drug effects enzymology Gram-Negative Bacteria / drug effects Gram-Negative Bacterial Infections / drug therapy microbiology Humans Microbial Sensitivity Tests beta-Lactamase Inhibitors / administration & dosage pharmacokinetics pharmacology therapeutic use beta-Lactamases / biosynthesis