A study conducted in a university hospital in Salamanca, Spain, collected clinical isolates of various bacteria (E. coli, K. pneumoniae, S. enterica, and K. oxytoca) from 2001 to 2004, identifying 1% to 2.9% of these isolates as extended-spectrum beta-lactamase (ESBL) producers.
Among the ESBL-producing isolates, the most prevalent types were CTX-M 14, TEM-116, and SHV-2, with a novel CTX-M 27 strain also reported for the first time in Spain.
The research found high clonal diversity among the ESBL producers, indicating that even bacteria with the same types of beta-lact