Induction potential of clavulanic acid toward L1 and L2 β-lactamases of Stenotrophomonas maltophilia

Excerpt

Clavulanic acid is firstly noticed for its potent inhibitory activity against plasmid-mediated β-lactamases among gram-negative organisms [1]. Plasmid-mediated β-lactamases, which belong to Bush groups 2a, 2b, 2c, or 2d, are generally constitutively expressed in microorganisms [2]. In clinical practice, the combination of β-lactam and clavulanic acid has been proposed to be an effective treatment for bacterial infections. Clavulanic acid is also recognized as a potential inducer for chromosomal AmpC β-lactamases (Bush group 1/Amber C) of the family Enterobacteriaceae [3, 4] and Pseudomonas aeruginosa [5]. And, more importantly, clavulanate is not an efficient inhibitor to β-lactamases of Bush group 1. Stenotrophomonas maltophilia owns two chromosomal-medicated inducible β-lactamases, L1 and L2, which belong, respectively, to Bush group 3c/Amber B and Bush group 2e/Amber A [2]. Clavulanic acid is known to be the most potent inhibitor against the L2 activity [6]. In contrast, clavulanate shows no inhibition effect on the activity of L1 β-lactamase [7]. …