Simultaneous outbreaks of OXA-23 and NDM co-producing Acinetobacter baumannii among northern Parisian hospitals

Carbapenem-resistant Acinetobacter baumannii (CRAB) are rare in France and are usually reported in intensive care units (ICU). In 2021/2022, an unexpected increase in the incidence of CRAB isolates co-producing OXA-23 and NDM carbapenemases (OXA-23/NDM-CRAB) in patients from both medical wards and intensive care units in several hospitals in the north of Paris prompted an investigation. We collected all cases of OXA-23/NDM-CRABs infection/colonization between January 2020 and December 2022 in five northern Paris hospitals. Demographic and clinical data were collected for each patient. Isolates were sequenced using Illumina technologies and the three representative isolates were also sequenced using Nanopore technologies. An OXA-23/NDM-CRAB was detected in 42 patients (mean age 61 years, M/F: 1.3) of whom 58% were hospitalized in medical ward and 42% in ICU. Two clonal strains spread in 3 hospitals: STOx231/Pas1 in hospital 1 (n=12) and hospital 3 (n=13) differing by 0-16 SNPs and STOx1632/Pas600 in hospital 2 (n=11) differing by 0-17 SNPs. WGS and epidemiological investigation identified the index patient for the hospital 1 and 3 outbreaks as a patient repatriated from hospitalization in Cap Verde. This patient was not screened for multi-drug resistant bacteria including CRAB during hospitalization in hospital 1 and was detected positive 5 days after admission to the ICU in hospital 3. All outbreaks were stopped, by intervention of infection control teams. This is the first description of OXA-23/NDM-CRAB outbreaks in metropolitan France. The simultaneous dissemination of OXA-23/NDM-CRABs in Parisian hospitals is unusual, particularly in non-ICU settings. Medical and nursing staffs have to be sensitized to the importance of screening patients returning from abroad, including for CRAB, to prevent future outbreaks.