The invention describes a composition for combating beta-lactamase-mediated antibiotic resistance using beta-lactamase inhibitor useful for injection, capable of pharmaceutical application. The invention relates to pharmaceutical composition containing ceftriaxone (normally as ceftriaxone sodium) and sulbactam (normally as sulbactam sodium). Such compositions are found to be useful for intramuscular or intravenous administration as antibiotics for hospitalized patients with serious infections. Specifically, this invention relates to a pharmaceutical composition further including an aminocarboxylic acid chelating agent, for example, ethylenediaminetetraacetic acid (EDTA), or a pharmaceutically acceptable salt thereof. The pharmaceutical compositions of this invention have been found normally to enhance resistance to particulate formation in solutions to be administered parenterally. The invention also gives details of the dosage forms stored in sealed containers to be reconstituted before use. The invention also gives a process to manufacture these compositions. The invention gives a method of treating a subject having a condition or disorder, wherein a treatment with ceftriaxone sodium and sulbactam sodium is indicated.