background :   ampc beta lactamases play a significant role in creating resistance to third generation cephalosporins worldwide. they mostly express on chromosome of enterobacteriaceae especially escherichia coli and cause consequential problem in clinical treatment and lead to failure in diagnosis and phenotypic test recommended by clinical and laboratory standards institute.   methods : total...

Broilers and broiler meat products are highly contaminated with extended spectrum beta-lactamase (ESBL) or plasmid-mediated AmpC beta-lactamase producing Escherichia coli and are considered to be a source for human infections. Both horizontal and vertical transmission might play a role in the presence of these strains in broilers. As not much is known about the presence of these strains in the ...

An AmpC-type beta-lactamase conferring high-level resistance to expanded-spectrum cephalosporins and monobactams was characterized from an Acinetobacter baumannii clinical isolate. This class C beta-lactamase (named ADC-33) possessed a Pro210Arg substitution together with a duplication of an Ala residue at position 215 (inside the Omega-loop) compared to a reference AmpC cephalosporinase from A...

Pseudomonas aeruginosa exhibits high intrinsic resistance to penem antibiotics such as faropenem, ritipenem, AMA3176, sulopenem, Sch29482, and Sch34343. To investigate the mechanisms contributing to penem resistance, we used the laboratory strain PAO1 to construct a series of isogenic mutants with an impaired multidrug efflux system MexAB-OprM and/or impaired chromosomal AmpC beta-lactamase. Th...

Background and Objective: A large group of genes associated with extended-spectrum beta-lactamases (ESBL) and AmpC expression is involved in inducing antibiotic resistance in various bacteria. Identifying these genes and assessing their harboring will be crucial in determining the pattern of antibiotic resistance. This study aimed to characterize genetic variants in extended-spectrum beta-lacta...

In the Calgary Health Region during 2000-2003, prospective, active, population-based laboratory surveillance for all cefoxitin-resistant Escherichia coli isolates was performed. Isolates were screened with an inhibitor-based disk test, and plasmid-mediated types were identified by multiplex PCR with sequencing. A total of 369 AmpC beta-lactamase-producing E. coli isolates were identified; annua...

Enterobacter aerogenes resistant to cefepime (MIC, 32 microg/ml) was isolated from a patient treated with cefepime for an infection caused by a strain of E. aerogenes overproducing its AmpC beta-lactamase (MIC of cefepime, 0.5 microg/ml). The AmpC beta-lactamase of the resistant strain had an L-293-P amino acid substitution and a high k(cat)/K(m) ratio for cefepime. Both of these modifications ...

Beta-lactamases are the most widespread resistance mechanism to beta-lactam antibiotics and are an increasing menace to public health. Several beta-lactamase structures have been determined, making this enzyme an attractive target for structure-based drug design. To facilitate inhibitor design for the class C beta-lactamase AmpC, binding site "hot spots" on the enzyme were identified using expe...

BACKGROUND & OBJECTIVE Production of extended spectrum beta-lactamases (ESBLs) and AmpC beta-lactamases are the most common mechanisms of antimicrobial resistance in Gram negative bacilli. A prospective study was undertaken to know the occurrence of ESBL and AmpC producing strains and their antibiotic susceptibilities to newer agents to guide empirical therapy for complicated urinary tract infe...

Development of resistance to the antipseudomonal penicillins and cephalosporins mediated by hyperproduction of the chromosomal cephalosporinase AmpC is a major threat to the successful treatment of Pseudomonas aeruginosa infections. Although ampD inactivation has been previously found to lead to a partially derepressed phenotype characterized by increased AmpC production but retaining further i...