Rapid detection of temocillin resistance in Enterobacterales.

The temocillin test solution was prepared with 21.3 mg/L of temocillin and 150 µL was added into one well of a 96-well polystyrene plate; 150 µL of test solution without temocillin was added into a second well. Temocillin is a semi-synthetic 6- -methoxy derivative of ticarcillin, first developed in 1981.[1] Despite being developed over 40 years ago, temocillin's use as an antimicrobial agent was largely overlooked as a treatment option for infections caused by Gram-negative bacteria due to its poor activity against non-fermenters, including I Pseudomonas i spp. and I Acinetobacter i spp.[1] Temocillin has been demonstrated to have an affinity for penicillin-binding protein 3 in I Escherichia coli i [2] and remarkable stability against a plethora of -lactamases including ESBLs and AmpCs (both plasmid and chromosomal);[3],[4] however, it is not clinically useful against bacteria producing class B (e.g. NDM) or class D (e.g. OXA-48-type) carbapenemases, because those latter enzymes readily hydrolyse this antibiotic, often leading to high MICs of temocillin.[5] A recent study evaluating the use of temocillin against ESBL- and AmpC-producing Enterobacterales confirmed the excellent activity of temocillin, and the few high MICs observed were linked mostly to the carriage of multiple -lactamases by corresponding isolates rather than any single -lactamase type.[6] In recent years, a number of countries in Europe, including Belgium, France, Luxembourg and the UK, have revived the use of this antibiotic, predominantly for the treatment of urinary tract infections but also for bloodstream and lower respiratory tract infections.[7],[8] Subsequently, the surveillance of resistance to temocillin is essential and can be easily determined using either routine broth microdilution or disc diffusion testing; however, such tests require 18-24 h to achieve a result. [Extracted from the article]