Two clinical isolates of extended-spectrum beta-lactamase (ESBL)-producing Klebsiella pneumoniae were noted to be less susceptible than expected to imipenem. Both were missing outer membrane proteins that serve as channels for antibiotic entry. The role of beta-lactamase in resistance was investigated by eliminating the original ESBL and introducing plasmids encoding various ESBLs and AmpC beta...

background: ampc type β-lactamases are commonly isolated from extended-spectrum cephalosporin-resistant gram-negative bacteria. also, resistance appeared in bacterial species not naturally producing ampc enzymes. therefore, a standard test for the detection of the plasmid-mediated ampc enzyme and new breakpoints for extended spectrum cephalosporins are urgently necessary. objectives: to detect ...

Many clinical laboratories have problems detecting extended-spectrum beta-lactamases (ESBLs) and plasmid-mediated AmpC beta-lactamases. Confusion exists about the importance of these resistance mechanisms, optimal test methods, and appropriate reporting conventions. Failure to detect these enzymes has contributed to their uncontrolled spread and sometimes to therapeutic failures. Although Natio...

background beta-lactam resistance in gram-negative bacteria, especially escherichia coli, is a main clinical problem. it is often caused by the co-production of β-lactamases, particularly extended-spectrum β-lactamases (esbls) and ampc enzymes. it may lead to a problem for diagnosis via recommended phenotypic tests by the clinical and laboratory standards institute (clsi). conversely, β-lactama...

BACKGROUND NXL104 potentiates ceftazidime and ceftaroline against Enterobacteriaceae with extended-spectrum, AmpC, KPC and OXA β-lactamases. We examined whether similar potentiation was obtained against non-fermenters, which are less permeable than Enterobacteriaceae and have more potent efflux. METHODS MICs of ceftazidime+NXL104 (with NXL104 at 4 mg/L) and comparators were determined by CLSI...

BACKGROUND There is a need for new oral agents active against extended-spectrum beta-lactamase (ESBL) producers, as these increasingly cause community-onset infections. We therefore evaluated faropenem, a penem in Phase III development, against recently collected oxyimino-cephalosporin-resistant bacteria. METHODS We tested 847 consecutive cephalosporin-resistant Enterobacteriaceae collected a...

A major reason for resistance of Enterobacteriaceae to beta-lactam antibiotics is production of ESBLs and AmpC beta-lactamases. As their more detailed description in poultry is unavailable in the Czech Republic, the presented study aimed at assessing their occurrence and molecular characteristics. A total of 154 composite samples from broilers and 150 cloacal swabs from turkeys were examined. P...

Klebsiella pneumoniae is a major cause of nosocomial infections. Emergence of antibacterial resistance and production of beta-lactamases are responsible for the frequently observed empirical therapy failures. The aim of this study was to determine the presence and the prevalence of extended spectrum beta-lactamases (ESBLs) and AmpC beta-lactamases in clinical isolates of K. pneumoniae in Kerman...