On the assumption of the theory that the sulfone of a penam derivative should effectively act as a suicide substrate against beta-lactamases to which the parent compound is a poor substrate, the action of cloxacillin sulfone on four different types of beta-lactamases was studied. As we expected, cloxacillin sulfone showed strong mechanism-based irreversible inactivation against type Ib penicill...

A highly cephem-resistant Escherichia coli strain, FP1546, isolated from the fecal flora of laboratory dogs previously administered beta-lactam antibiotics was found to produce a beta-lactamase, FEC-1, of 48-kilodalton size and pI 8.2. FEC-1 hydrolyzed cefuroxime, cefotaxime, cefmenoxime, and ceftriaxone, as well as the enzymatically less-stable antibiotics cephaloridine, cefotiam, and cefpiram...

The Sterne and Ames strains of Bacillus anthracis carry chromosomal genes bla1 and bla2, which confer beta-lactam resistance when expressed in Escherichia coli. MIC measurements and steady-state kinetic analyses indicate that Bla1 possesses penicillinase activity while Bla2 possesses penicillinase, cephalosporinase, and carbapenem-hydrolyzing activities.

The nucleotide sequence of the gene encoding a novel cephalosporinase (LAT-1), carried by a non-self-transferable plasmid from Klebsiella pneumoniae, has been determined. It was found that the sequence shares a high degree of homology with the Citrobacter freundii OS60 ampC structural gene.

The sulbactam resistance rate in Acinetobacter baumannii has increased worldwide. Previous reports have shown that the β-lactamase bla TEM-1 confers resistance to sulbactam in A. baumannii. The purpose of this study was to examine whether other β-lactamases, including the Acinetobacter-derived cephalosporinase (ADC), OXA-23, OXA-24/72, and OXA-58 families, also contribute to sulbactam resistanc...

We described plasmid mediated transfer of resistance to beta-lactam antibiotics between Bacteroides fragilis strains. Ampicillin-resistance was transferred from B. fragilis strain GAI-10150 to a B. fragilis strain JC-101 with a frequency of 10(-6)/input donor by a filter mating technique. A common plasmid band, named pBFKW1, was found in both the donor and the transconjugants. The plasmid was p...

β-Lactam resistance in Acinetobacter baumannii presents one of the greatest challenges to contemporary antimicrobial chemotherapy. Much of this resistance to cephalosporins derives from the expression of the class C β-lactamase enzymes, known as Acinetobacter-derived cephalosporinases (ADCs). Currently, β-lactamase inhibitors are structurally similar to β-lactam substrates and are not effective...