MICROBIOLOGY FOR STUDENTS (M4S)

GENE XPERT MTB/RIF ASSAY

Preparation of solution: Some Important Formulae S. No. Formulae 1 Mass= molarity X molecular weight X volume of solution in litre 2 Mass= normality X equivalent weight X volume of solution in litre 3 Volume of desired solution in ml = molarity X molecular weight X volume of solution in ml X 100 / [1000 X specific gravity X assay(purity) ] 4 Volume of desired solution in ml = normality X equivalent weight X volume of solution in ml X 100 / [1000 X specific gravity X assay (purity) ] 5 Dilution factor = concentration of stock solution/ concentration of working solution 6 A working solution (lower conce...

 

ESBL refers to Extended Spectrum β-Lactamases. ESBL falls  under Group 2be and Class A by functional and molecular classification respectively of β-Lactamases. Various types of ESBL have been recognized, the number of which is accounted to more than 700 ESBL.

AmpC β-Lactamases | M4S Digital Textbook M4S • MICROBIOLOGY FOR STUDENTS Print Top Bacteriology • Antimicrobial Resistance • Digital Learning Chapter AmpC β-Lactamases AmpC β-lactamases: mechanism, chromosomal and plasmid-mediated forms, detection, phenotypic tests and molecular identification. AmpC β-lactamase AMR Laboratory Identification M4S Student Notes Expand all Collapse all Clear 0 of 7 chapters opened Contents Overview Location Chromosomal & plasmid-mediated Identification Phenotypic tests Boronic acid disk test References β Overview ⌄ AmpC type β-lactamases are such type of beta-lactamases which are not inhibited by clavulanic acid but are inhibited by boronic acid. These are clinically important cephalosporinases encoded on the chromosomes of many Enterobacteriaceae and a few other organisms. In such organisms they mediate resistance to cephalothin, cefazolin, cefoxitin, most penicillins, and β-lactamase inhibitor/β-lactam...

The Ambler classification comprises 4 groups viz. A,B, C and D. Group A, C and D enzymes are serine enzymes while those of group B are metallo-enzymes. Carbapenemase mainly belong to three  groups of beta-lactamases,  A, B and D.

β-lactamases  are the enzymes that brings about the hydrolysis of beta-lactam ring present in related group of antibiotics causing microbial resistance which was previously susceptible to the very group of antibiotics, eg. Penicillin. First bacterial enzyme reported to destroy Penicillin belonged to the β-lactamase of  Escherichia coli  in 1940 [1]. The same β-lactamase is now called the  AmpC β-lactamase . These β-lactamases destroys the ability of β-lactam antibiotics.