A ceftazidime-resistant Salmonella enterica subspecies enterica serotype Othmarschen strain, harboring the plasmid-mediated new extended-spectrum beta-lactamase TEM-27, was involved in a nosocomial outbreak (8 patients) at the Pediatric Cardiology Department of the Ramón y Cajal Hospital in Madrid. Genomic DNA polymorphism analysis, using an arbitrarily primed polymerase chain reaction, demonstrated the clonal nature of all Salmonella isolates. The plasmid encoding TEM-27 (pJMM1) was characterized by EcoRI, SacI, and BglI restriction. An identical restriction pattern was found in plasmid from all S. enterica strains. Possible in vivo intergeneric plasmid spread was suggested by the identification of an identical plasmid in Escherichia coli RYC5H and Enterobacter cloacae RYC39737 strains isolated during the outbreak. Results indicate that this outbreak involved dissemination of a single ceftazidime-resistant Salmonella strain and the spread of a single TEM-27-encoding plasmid among different Enterobacteriaceae.