Abstract
Rapid detection of expanded-spectrum cephalosporins (ESC) hydrolysing enzymes is crucial to implement infection control measures and antibiotic stewardship. Here, we have evaluated three biochemical ESC hydrolysis assays (ESBL NDP test, β-LACTA™ test, LFIA-CTX assay) and the NG-Test® CTX-M MULTI that detects CTX-M enzymes, on 93 well-characterized Gram-negative isolates, including 60 Enterobacterales, 21 Pseudomonas spp. and 12 Acinetobacter spp. The performances were good for all three hydrolysis assays, with the LFIA-CTX being slightly more sensitive and specific on the tested panel of isolates especially with Enterobacterales, without ambiguous results. This study showed that LFIA-CTX may be used for the detection of ESC hydrolysis as a competitive alternative to already available assays (β-LACTA™ test and ESBL NDP test) without any specific equipment and reduced hands-on-time. The lateral flow immunoassay NG-Test® CTX-M MULTI has proven to be a useful, easy, rapid, and reliable confirmatory test in Enterobacterales for detection of CTX-M-type ESBLs, which account for most of the resistance mechanisms leading to ESC resistance in Enterobacterales, but it misses rare ESC hydrolysing β-lactamases (AmpC, minor ESBLs, and carbapenemases). Combining it with the LFIA-CTX assay would yield an assay detecting the most frequently-encountered ESBLs (CTX-M-like β-lactamases) together with ESC hydrolysis.
Highlights
Multi-Drug Resistant (MDR) gram-negative pathogens, and especially Enterobacterales, Pseudomonas aeruginosa, and Acinetobacter baumannii, are emerging worldwide, and are in some cases resistant to all available drugs [2,3]. β-Lactams are among the most frequently prescribed antibiotics used to treat bacterial infections, but β-lactamase-mediated resistance does not spare even the most powerful β-lactams (i.e., expanded-spectrum cephalosporins (ESCs) and carbapenems), whose activity is compromised by extendedspectrum β-lactamases (ESBLs), plasmid and hyperproducing chromosomally-encoded cephalosporinases, and carbapenemases (KPC, OXA-48, NDM)
The ESBL NDP test failed to detect in Enterobacterales seven ESBL producers and an overexpressed
An OXA-13 producing P. aeruginosa was missed, which could be explained by the low level of cefotaxime hydrolysis conferred by OXA-13 oxacillinase [14]
Summary
MDR gram-negative pathogens, and especially Enterobacterales, Pseudomonas aeruginosa, and Acinetobacter baumannii, are emerging worldwide, and are in some cases resistant to all available drugs [2,3]. ESBLs are by far the most prevalent ESC resistance mechanism in Enterobacterales, with CTX-Ms representing the most prevalent ESBLs worldwide. The dissemination of these enzymes is a matter of great clinical concern given the major role of these pathogens as causes of nosocomial infections (and, for E. coli, of community-acquired infections), and the major role of expandedspectrum cephalosporins and carbapenems in the treatment of those infections [4].
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