Emergence of antimicrobial resistance in New Caledonia: 20-year trends from laboratory-based surveillance (2005-2024)

Antimicrobial resistance (AMR) issues have emerged in New Caledonia, particularly involving methicillin-resistant Staphylococcus aureus (MRSA), and carbapenem-resistant Acinetobacter baumannii (CR-AB). However, a comprehensive overall picture is still required to guide an antimicrobial stewardship.

A prospective collection of antimicrobial susceptibility testing results was performed over a 20-year period (2005-2024) in the Territorial Hospital Center, the main hospital in New Caledonia. This surveillance encompassed 22 different pathogens and 28 antimicrobial agents, covering 157 pathogen-drug combinations. Resistance rates over time were analyzed using logistic models. A focus was placed on high-priority pathogens, including MRSA, CR-AB, vancomycin-resistant Enterococcus faecium, ceftazidime-resistant Pseudomonas aeruginosa, extended-spectrum β-lactamase Enterobacterales (ESBL-E), and carbapenemase-producing Enterobacterales (CPE). Multidrug-resistant (MDR) and possible extensively drug-resistant (pXDR) isolates were also identified and characterized.

Across 111,022 included isolates, emergences of resistance were observed, notably to penicillins, third-generation cephalosporins, tetracycline, and fusidic acid. Temporal resistance trends were described, along with outbreaks of MRSA and CR-AB, and the emergence of ESBL-E and CPE, representing 3.7% [95% CI: 3.5-3.8] (N = 2208), and 0.1% [95% CI: 0.1-0.2] (N = 85) of the 59,954 Enterobacterales isolates, respectively. Overall, 11% [95% CI: 10.8-11.1] were MDR and 0.6% [95% CI: 0.5-0.6] were pXDR.

Through trend analyses, this surveillance highlighted both the emergence and decline of AMR across diverse bacterial pathogens, helping inform which antibiotics may remain appropriate as first-line options and addressing the lack of data from Pacific Island settings.

This work received financial support from the Pierre Ledoux Jeunesse Internationale scholarship (Fondation de France) and the Institut Pasteur, Paris.