Detection of AmpC beta-lactamases using sodium salicylate.
AmpC β-lactamases are enzymes that hydrolyze all β-lactam antibiotics except cefipime and imipenem. Currently, there is no standard phenotypic method for detection of such enzymes. This study aims to report the use of sodium salicylate for AmpC β-lactamases detection and to compare its sensitivity and specificity to other commonly known inhibitors. A total of 135 clinical isolates were used to test the effectiveness of sodium salicylate in detection of plasmid- as well as chromosomally encoded AmpC β-lactamases. All isolates were tested by multiplex PCR testing as well as inhibitor-based methods using cloxacillin, phenylboronic acid and sodium salicylate for the detection of AmpC enzymes. Four isolates were confirmed as producers of plasmid-encoded AmpC β-lactamase and a single isolate was confirmed to have both plasmid and chromosomal genes. Cloxacillin and phenylyboronic acid failed to detect most of the plasmid-encoded enzymes. Sodium salicylate was able to detect the Escherichia coli isolates with plasmid-encoded enzymes in addition to few other isolates that were chromosomally mediated. The sensitivity and specificity of sodium salicylate was 50% and 93%, respectively, higher than those of other known inhibitors. We thus conclude that sodium salicylate can be reliably used as an inhibitor in the detection of plasmid-encoded AmpC enzymes in E. coli.
Department of Microbiology and Immunology, Faculty of Pharmacy, Cairo University, Cairo, Egypt.
Mona T
MT
Kashif
Aymen S
AS
Yassin
Alaa El-Dien M S
Ael-D
Hosny
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001419:Bacteria / Q000145:classification / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification; D001424:Bacterial Infections / Q000382:microbiology*; D001426:Bacterial Proteins / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006801:Humans; D010957:Plasmids / Q000235:genetics; D016133:Polymerase Chain Reaction / Q000379:methods*; D012980:Sodium Salicylate / Q000494:pharmacology*; D065093:beta-Lactamase Inhibitors; D001618:beta-Lactamases / Q000235:genetics* / Q000378:metabolism
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D004791:Enzyme Inhibitors; D065093:beta-Lactamase Inhibitors; C048795:AmpC beta-lactamases; D001618:beta-Lactamases; D012980:Sodium Salicylate