Fig. 12.

Inhibitory effects of 2-mercaptopropionic acid (2-MPA) on IMP-1 producers and non-IMP-1 producers. Three CAZ-resistant strains belonging to the gram-negative bacterial species P. aeruginosa, S. marcescens, and K. pneumoniae and producing IMP-1 metallo-β-lactamase or serine-β-lactamases (SHV-12 or AmpC) were tested. For each IMP-1 producer, a distinct growth inhibitory zone appeared between the KB disk containing CAZ and the filter disk containing 2-MPA (left column). No change is evident around the two KB disks containing CAZ with or without 2-MPA for each serine b-lactamase producer (right column).