ABSTRACT A Klebsiella pneumoniae clinical isolate recovered in Tunisia showed resistance to all β-lactams and decreased susceptibility to carbapenems. K. pneumoniae 204 expressed the carbapenem-hydrolyzing β-lactamase OXA-204, differing from OXA-48 by two amino acid substitutions (Gln98His and Thr99Arg) (class D β-lactamase [DBL] numbering). OXA-48 and OXA-204 shared similar resistance profiles, hydrolyzing carbapenems but sparing broad-spectrum cephalosporins. The bla OXA-204 gene was located on a ca. 150-kb IncA/C-type plasmid, which also carried the bla CMY-4 gene. The bla OXA-204 gene was associated with an IS Ecp1 element, whereas the bla OXA-48 genes are usually associated with IS 1999 .