Cooccurrence of Multiple AmpC β-Lactamases in Escherichia coli,Klebsiella pneumoniae,and Proteus mirabilis in Tunisia

Over a period of 40 months, plasmid-mediated AmpC β-lactamases were detected in Tunis, Tunisia, in 78 isolates (0.59%) of Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis. In 67 isolates, only one ampC gene was detected, i.e., bla_CMY-2-type (n = 33), bla_ACC (n = 23), bla_DHA (n = 6) or bla_EBC (n = 5). Multiple ampC genes were detected in 11 isolates, with the following distribution: bla_MOX-2, bla_FOX-3, and bla_CMY-4/16 (n = 6), bla_FOX-3 and bla_MOX-2 (n = 3), and bla_CMY-4 and bla_MOX-2 (n = 2). A great variety of plasmids carrying these genes was found, independently of the species and the bla gene. If the genetic context of bla_CMY-2-type is variable, that of bla_MOX-2, reported in part previously, is unique and that of bla_FOX-3 is unique and new.