OXA-244-producing Escherichia coli isolates: a challenge for clinical microbiology laboratories [PublishAheadOfPrint]

OXA-244 is a single point mutant derivative of OXA-48 displaying reduced carbapenemase activity. Here, we report microbiological features of 7 OXA-244-producing E. coli isolates. Only one isolate grew on the ChromID® CARBA SMART medium (bioMérieux), but 6/7 grew on ChromID® ESBL medium (bioMérieux), as they co-produced either an extended spectrum β-lactamase and or a plasmid-encoded cephalosporinase. The production of a carbapenemase was detected in 57.1%, 71.4%, 71.4%, and 100% of the E. coli isolates using the Carba NP test, the RAPIDEC® CARBA NP (bioMérieux), a MALDI-TOF MS hydrolysis assay (Bruker), and OXA-48 K-SeT® (Coris bioconcept), respectively. Our results indicate that OXA-244-producing E. coli isolates are difficult to detect, which may lead to their silent spread.

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