What is Enzyme Therapy?

AmpC enzyme is an abbreviation for AmpC beta lactamase. It is a type of -lactamase produced by the chromosomes or plasmids of Enterobacteriaceae or Pseudomonas aeruginosa. It belongs to class C and Bush Jacoby Medeiros functional classification of -lactamase Ambler molecular structure taxonomy. The first group is -lactamase that acts on cephalosporins and is not inhibited by clavulanic acid. Therefore, AmpC enzyme is also called cephalosporinase.

AmpC enzyme

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AmpC enzyme is an abbreviation for AmpC beta lactamase. Enterobacteriaceae or Pseudomonas aeruginosa

AmpC enzymes are divided into three categories according to the way they are produced: induced high-yield enzymes, sustained high-yield enzymes, and sustained low-yield enzymes.

(1) Induced high-yield enzymes: The synthesis of AmpC enzymes is often related to the presence of 2 lactam antibiotics. Most Enterobacteriaceae and Pseudomonas aeruginosa bacteria produce only a small amount of AmpC enzyme under normal conditions (ie, in the absence of beta-lactam antibiotics). And when there is

1) Cefoxitin sensitivity test: AmpC enzyme can hydrolyze cefoxitin (FOX), that is, the strain producing AmpC enzyme is resistant to cefoxitin. And other broad-spectrum -lactamase (ESBLs) and other -lactamase can not break down cefoxitin, that is, ESBLs-producing strains are sensitive to cefoxitin. Using this feature of AmpC enzyme, preliminary screening of AmpC enzyme-producing strains can be performed.

2) Three-dimensional test: The three-dimensional test is also based on the principle that AmpC enzyme can hydrolyze cefoxitin.

Since AmpC enzyme is easily induced and insensitive to -lactam antibiotic inhibitors, it brings new challenges to clinical anti-infective treatment. At present, the drugs that are stable to AmpC enzymes are mainly carbapenems (imipenem) and fourth-generation cephalosporins (cephemime, cefpirome), and certain quinone and aminoglycoside antibiotics [2o]. In vitro p-lactamylase inhibitors clavulanic acid, sulbactam, trizobactam, and p-lactamyl antibiotics in combination experiments found that except for clavulanic acid, sulbactam and trizobactam did not show Due to the antagonism induced by the induction, it was even found that the combination of triazobactam and piperacillin could inhibit the drug-resistant bacteria producing high AmpC enzymes. In addition, some experiments have shown that clozacillin is a better inhibitor of AmpC enzyme. When used in combination with ceftazidime, clozacillin is significantly better than sulbactam, which requires further evidence from clinical data ["]. Some bacteria were found to produce both ESBLs and AmpC enzymes, but it is not necessary to accurately determine whether these two enzymes are produced in the clinic, because both are preferred for treatment with carbapenem antibiotics such as imipenem. The important thing is drug sensitivity. Whether the test accurately detects its drug resistance so that antibiotic treatment can be timely and correctly selected.