We isolated five clinical strains (three Proteus mirabilis and two Klebsiella pneumoniae) with beta-lactam resistance phenotypes consistent with production of an AmpC-type beta-lactamase. The predicted amino acid sequences of the enzymes were typical of class C beta-lactamases. The enzymes were identified as CMY-2, CMY-4 and a new CMY-variant beta-lactamase, CMY-12. The AmpC beta-lactamases fro...

Antimicrobial resistance (AMR) occurs when microorganisms fail to respond the therapeutic onslaught of antibiotics. Extended-spectrum beta-lactamase (ESBL) and AmpC enzymes are important AMR mechanisms that erode efficacy Here, we report on detection susceptibility ESBL- AmpC-producing bacteria from livestock poultry environments. Bacteriological molecular biology tools were used for isolation ...

β-Lactamases are the main cause of bacterial resistance to penicillins, cephalosporins and related β-lactam compounds. These enzymes inactivate the antibiotics by hydrolysing the amide bond of the β-lactam ring. Class A β-lactamases are the most widespread enzymes and are responsible for numerous failures in the treatment of infectious diseases. The introduction of new β-lactam compounds, which...

Staphylococcus aureus is a common cause of hospital-acquired infections. This bacterium is resistant to β-lactam antibiotics. The aim of this study was to evaluate the prevalence of S. aureus strains producing enzymes capable of destroying β-lactam antibiotics in a hospital environment. This descriptive and analytic study was performed in Besat Hospital, Sanandaj, Iran, 2016, on 158 swabs colle...

The mechanisms responsible for reduced susceptibility to imipenem (MIC 2-16 mg/L) were investigated in eight strains of Bacteroides fragilis. All the strains produced elevated levels of beta-lactamase. Four B. fragilis strains produced metallo-beta-lactamase capable of marked imipenem hydrolysis, and these enzymes were shown to be responsible for resistance. There was evidence, from testing sus...

background :   imipenem-resistant gram negative bacteria, resulting from metallo-beta-lactamase (mbls)-producing strains have been reported to be among the important causes of nosocomial infections and of serious therapeutic problem worldwide. because of their broad range, potent carbapenemase activity and resistance to inhibitors, these enzymes can confer resistance to almost all beta-lactams....

TEM-1 1-lactamase is the most prevalent plasmid-mediated 13-lactamase in gram-negative bacteria. Recently, TEM I-lactamase variants with amino acid substitutions in the active-site pocket of the enzyme have been identified in natural isolates with increased resistance to extended-spectrum cephalosporins. To identify other amino acid substitutions that alter the activity of TEM-1 towards extende...

The production of β-lactamase enzymes is the main mechanism of resistance to β-lactam antibiotics in gramnegative bacilli. Therefore, it is important to identify the β-lactamases-producing bacteria for the treatment of caused infections. This article aimed to review the recent literature and guidelines regarding phenotypic detection of β-lactamases in common gram-negative bacilli in clinical sa...

There are many examples of two penicillins acting synergistically, usually by one competitively inhibiting beta-lactamase, thus protecting the other from inactivation. There are few reports on penicillins antagonizing each other. Eight strains of three genera (Proteus, Escherichia, Pseudomonas) isolated at Boston City Hospital or Institut Pasteur, Paris, showed antagonism of carbenicillin or am...

Antibody-directed enzyme prodrug therapy (ADEPT) delivers chemotherapeutic agents in high concentration to tumor tissue while minimizing systemic drug exposure. beta-Lactamases are particularly useful enzymes for ADEPT systems due to their unique substrate specificity that allows the activation of a variety of lactam-based prodrugs with minimal interference from mammalian enzymes. We evaluated ...