Nationwide study of Escherichia coli and Klebsiella pneumoniae producing extended-spectrum beta-lactamases in Spain.

Clonal dissemination of extended-spectrum beta-lactamases (ESBL) in 170 Escherichia coli isolates and 70 Klebsiella pneumoniae isolates from a nationwide study of 40 Spanish centers in 2000 was not observed in most centers. The most prevalent ESBL were CTX-M-9 (27.3%), SHV-12 (23.9%), and CTX-M-14 (20.5%) for E. coli and TEM-3 (16.7%) and TEM-4 (25%) for K. pneumoniae. A new ESBL, TEM-133, with mutations L21F, E104K, and R164S, was identified.