INTRODUCTION The rising prevalence of extended-spectrum beta-lactamases in gram-negative bacillary pathogens is an important clinical problem resulting from the extensive use of broad-spectrum antibiotics. The emergence of the extended-spectrum beta-lactamases increases the possibility that traditional, empiric antimicrobial regimens may be ineffective. The aims of this study are: to determine ...

beta-Lactamases are the main cause of bacterial resistance to penicillins and cephalosporins. Class A beta-lactamases, the largest group of beta-lactamases, have been found in many bacterial strains, including mycobacteria, for which no beta-lactamase structure has been previously reported. The crystal structure of the class A beta-lactamase from Mycobacterium fortuitum (MFO) has been solved at...

TEM- or SHV-type extended-spectrum beta-lactamases(ESBLs) are of clinical concern in Europe and the United States, whereas bacterial strains producing such types of ESBLs had not been reported in Japan for many years. Toho-1, a different type class A ESBL, has been reported in 1995, in which any prototypical enzyme has not been identified so far. At present Toho-1 is the major ESBL in Japan, ho...

Bacteria that simultaneously produce multiple extended-spectrum beta-lactamases are frequently isolated. We report an Enterobacter cloacae isolate, ES24, producing four different beta-lactamases (AmpC type beta-lactamase, TEM-1, SHV-7, and a novel extended-spectrum beta-lactamase, SHV-30). Direct sequencing of bla(SHV) gene products gave a "double peak" at position 703, suggesting the presence ...

OBJECTIVES Recently, resistance to extended-spectrum cephalosporins due to acquired beta-lactamases has been reported in Pseudomonas aeruginosa. The aim of this study was to investigate the prevalence of Ambler class A and D beta-lactamases and their extended-spectrum derivatives and antimicrobial susceptibilities of P. aeruginosa isolated from various parts of Korea. METHODS A total of 252 c...