Nocardicin A, a new monocyclic beta-lactam antibiotic IV. Factors influencing the in vitro activity of Nocardicin A.

Factors influencing the in vitro antimicrobial activity of nocardicin A against Pseudomonas aeruginosa and Proteus mirabilis were investigated. Sodium chloride was identified as a major inhibitor. Some of the amino acids, sugars and divalent cations were found to be minor inhibitors. The presence of potassium phosphates enhanced nocardicin A activity against P. aeruginosa, but antagonized the activity against P. mirabilis.