tIn this study, 922 consecutive non-duplicate clinical isolates of Enterobacteriaceae obtainedfrom hospitalized and non-hospitalized patients at Bejaia, Algeria were analyzed forAmpC-type -lactamases production. The ampC genes and their genetic environmentwere characterized using polymerase chain reaction (PCR) and sequencing. Plasmidincompatibility groups were determined by using PCR-based replicon typing. Phylogeneticgrouping and multilocus sequence typing were determined for molecular typing of theplasmid-mediated AmpC (pAmpC) isolates.Of the isolates, 15 (1.6%) were identified as AmpC producers including 14 CMY-4-producing isolates and one DHA-1-producing Klebsiella pneumoniae. All AmpC-producingisolates co-expressed the broad-spectrum TEM-1 -lactamase and three of them co-produced CTX-M and/or SHV-12 ESBL. Phylogenetic grouping and virulence genotyping ofthe E. coli isolates revealed that most of them belonged to groups D and B1. Multilocussequence typing analysis of K. pneumoniae isolates identified four different sequence types(STs) with two new sequences: ST1617 and ST1618. Plasmid replicon typing indicatesthat blaCMY-4gene was located on broad host range A/C plasmid, while LVPK repliconwas associated with blaDHA-1. All isolates carrying blaCMY-4displayed the transposon-likestructures ISEcp1/ISEcp1-blaCMY-blc-sugE.Our study showed that CMY-4 was the main pAmpC in the Enterobacteriaceae isolates inAlgeria.©