Clinical isolate of a Xanthomonas maltophilia strain producing L-1-deficient and L-2-inducible β-lactamases

Xanthomonas maltophilia produces two inducible β-lactamases, L-1 and L-2, and resists the antimicrobial activity of β-lactam antibiotics including carbapenems. L-1 has carbapenemase activity and L-2 is a cephalosporinase. It has been suggested that these β-lactamases share regulatory components. We isolated a recent clinical X. maltophilia strain susceptible to carbapenems and resistant to almost all the other β-lactam antibiotics tested. β-Lactamase induction with cefotaxime showed that the clinical isolate had low-level expression of L-1 β-lactamase but remained inducible for L-2 enzyme. The possible relationship of this enzyme to carbapenem sensitivity is considered.