The beta-lactamase inhibitors clavulanic acid and sulbactam were combined with mecillinam. beta-Lactamase-containing Escherichia coli resistant to mecillinam was synergistically inhibited by both clavulanic acid and sulbactam. beta-Lactamase-containing Enterobacter was synergistically inhibited, but strains lacking beta-lactamases were not synergistically inhibited. Synergistic inhibition was n...

The activities of beta-lactam antibiotics were compared against Enterobacter cloacae clinical isolates and mutants which had inducible, stably-derepressed, and basal expression of a pI 8.4 subtype of the Ia chromosomal beta-lactamase. These activities were correlated with the results of studies of the beta-lactamase-lability and beta-lactamase-inducer-power of the antibiotics. Cefoxitin and amp...

BACKGROUND Knowledge of the clinical features of infections caused by Escherichia coli strains that produce plasmid-mediated AmpC beta-lactamase is limited. Of the several groups of plasmid-mediated AmpC beta-lactamases, CMY-type beta-lactamase is the most common in the United States. METHODS We prospectively identified patients infected or colonized with E. coli strains that produce CMY-type...

The comparative activities of ampicillin, cefamandole, cefoxitin, cefaclor, and cefatrizine against both beta-lactamase-producing and non-beta-lactamase-producing isolates of Haemophilus influenzae were determined by using an agar dilution susceptibility test procedure. Ampicillin was the most active drug tested against non-beta-lactamase-producing isolates, whereas cefamandole was most active ...

Fifteen beta-lactam antibiotics were divided into four classes based on their antibacterial actions and beta-lactamase-inducing activities in Proteus vulgaris. One of these groups, which included cefmenoxime, ceftriaxone, cefuzonam, and cefotaxime, showed a clear paradoxical antibacterial activity against P. vulgaris. This group showed growth-inhibitory activity at relatively low concentrations...

OBJECTIVES Isolates previously identified as Citrobacter diversus are now known as Citrobacter koseri. We measured sequence variation at the beta-lactamase structural gene among a group of clinical isolates originally identified as C. diversus by API 20E profiling. METHODS beta-Lactamase and 16S rRNA genes were amplified by PCR and sequenced by standard methods. beta-Lactamase induction was a...

Lincomycin increased the TEM-2 beta-lactamase activity of Escherichia coli K-12 cells carrying plasmid RP4 at a concentration which slightly inhibited cell growth. In a control culture beta-lactamase activity reached its maximal level in late log phase, whereas when lincomycin was present beta-lactamase activity continued to increase into the stationary phase. Lincomycin (100 micrograms/ml) inh...

Enzyme-catalyzed therapeutic activation (ECTA) is a novel prodrug strategy to overcome drug resistance resulting from enzyme overexpression. beta-Lactamase overexpression is a common mechanism of bacterial resistance to beta-lactam antibiotics. We present here the results for one of the beta-lactamase ECTA compounds, NB2001, which consists of the antibacterial agent triclosan in a prodrug form ...

OBJECTIVES Group A streptococci (GAS) cause, among other infections, pharyngotonsillitis in children. The species is frequently localized with the Gram-negative respiratory pathogens non-typeable Haemophilus influenzae (NTHi) and Moraxella catarrhalis, which both produce outer membrane vesicles (OMVs). The aim of this study was to investigate whether OMVs isolated from NTHi contain functional β...