High Prevalence of OXA-23 Carbapenemase-Producing Proteus mirabilis among Amoxicillin-Clavulanate-Resistant Isolates in France

In this multicentric study performed in 12 French hospitals, we reported that 26.9% (14/52) of the amoxicillin-clavulanate-resistant Proteus mirabilis isolates produced the OXA-23 carbapenemase. We found that an inhibition zone diameter of <11 mm around the amoxicillin-clavulanate disc was an accurate screening cutoff to detect these OXA-23 producers. We confirmed by whole-genome sequencing that these OXA-23-producers all belonged to the same lineage that has been demonstrated to disseminate OXA-23 or OXA-58 in P. mirabilis.

Automated summary

This multicentric study in French hospitals found that 26.9% of amoxicillin-clavulanate-resistant Proteus mirabilis isolates produced the OXA-23 carbapenemase. The study also identified a screening cutoff of <11 mm for the inhibition zone diameter around the amoxicillin-clavulanate disc to accurately detect these OXA-23 producers. Whole-genome sequencing confirmed that these OXA-23 producers belonged to the same lineage known to disseminate OXA-23 or OXA-58 in P. mirabilis.