What are the tasks of the NARA?

26.06.2025 - The Swiss National Reference Center for Emerging Antibiotic Resistance (NARA) collects multidrug-resistant Gram-negative and Gram-positive bacteria recovered across all Switzerland. Its main tasks are to identify corresponding resistance mechanisms, either already known or newly emerging, and to alert the stakeholders about any clinically significant threat. Furthermore, NARA aims to support clinical labs in their surveillance task by developing diagnostic tests and support epidemiological investigations at the country level.

Switzerland has historically been considered relatively spared from the problem of antibiotic resistance. However, in line with trends observed in neighboring European countries, Switzerland has experienced a steady increase in the isolation of multidrug-resistant (MDR) bacterial strains over the past decade. In particular, the emergence of resistant Gram-negative bacteria has become more prominent. Specifically, the isolation of carbapenemase-producing Enterobacterales, Pseudomonas aeruginosa, or Acinetobacter baumannii is no longer considered uncommon—especially in patients hospitalized in university hospitals.

To monitor the occurrence and spread of MDR bacteria classified as major threats within Switzerland—whether isolated from infections (clinical samples) or colonization (e.g. rectal or nasal screening, depending on the species)— the National Reference Center for Antibiotic Resistance (NARA) was established in 2017 in Fribourg. As a centralized expert laboratory, NARA provides a unique opportunity to maintain continuous surveillance of the most concerning bacterial species and resistance mechanisms circulating at the national level, ultimately supporting efforts to prevent and control their dissemination.

The NARA as an expert reference center to track “superbugs”*

In November 2024, a new mandate from the Federal Office of Public Health (FOPH) expanded the NARA framework. In addition to the central diagnostic laboratory at the University of Fribourg (Medical and Molecular Microbiology Unit) which focuses on Gram-negative bacteria, and the Institute of Microbiology at the University Hospital of Lausanne (CHUV) which focuses on Gram- positive bacteria, a third partner was added: the Institute of Medical Microbiology (IMM) at the University Hospital of Zürich. This expansion enhances NARA’s molecular capacities, particularly in genomic analyses, thereby improving the molecular epidemiological surveillance of MDR bacteria. Hence, detailed molecular epidemiology (e.g. identify transmission routes, identify hospital-based or community-based spread) is reinforced. Representative MDR strains are sequentially sequenced, contributing to the Swiss biobank shared across public institutions.

The NARA’s mission encompasses a broad range of activities, including:

  • Collect potential MDR isolates to identify resistance mechanisms and build a biobank of MDR bacteria circulating in Switzerland.
  • Verify or complement the initial phenotypic observations (e.g. susceptibility testing confirmation, determination of minimal inhibitory concentrations [MIC] values) as reported by referring laboratories.
  • Assess and confirm the nature of carbapenemase determinants in Gram-negative bacteria using multiple techniques, including:
    • Biochemical tests (e.g. Carba NP test for rapid detection of carbapenemase activity),
    • Immunochromatographic tests (for protein identification),
    • Molecular techniques such as PCR (to detect resistance genes).
  • Provide susceptibility testing for new antibiotics, particularly when corresponding methods are not yet available in referring labs. For example, NARA offers MIC testing for novel β-lactam/β-lactamase inhibitor combinations such as aztreonam-avibactam (effective against metallo-β-lactamase producers), ceftolozane-tazobactam, imipenem-relebactam, and meropenem-vaborbactam. Due to the technical challenge of determining MICs for the siderophore cephalosporin cefiderocol (which requires iron-depleted media), NARA also performs these tests when needed.
  • Develop rapid diagnostic techniques to determine susceptibility/resistance profiles for newly available drugs. These tools aim to reduce turnaround time and support timely treatment decisions. All methods developed at NARA are freely shared with colleagues upon request.
  • Investigate uncommon resistance phenotypes in Gram-positive bacteria, especially Staphylococci and Enterococci. This includes susceptibility testing for drugs like teicoplanin, linezolid, and daptomycin, and perform molecular characterization of resistance mechanisms when needed.
  • Monitor the emergence and spread of resistance traits and clones across hospitals and cantons. The nationwide collection of isolates allows NARA to detect patterns of clonal dissemination.
  • Provide expert medical advice for managing challenging infections, including evaluating the relevance of standard treatments based on in vitro data or suggesting alternative therapeutic options, including less conventional antibiotics, based on susceptibility testing.

In summary, NARA’s main services aim to support clinical centers to evaluate the suitability of new drugs for treating MDR infections, especially those caused by carbapenemase producers. This work supports the identification of the main MDR threats in Switzerland and contribute to national surveillance in collaboration with international public bodies. Moreover, in collaboration with partners like Swissnoso and ANRESIS, NARA facilitates the detection, the investigation and the management of potential outbreaks involving specific bacterial strain types.

*”superbug”: a strain of bacteria that has become resistant to antibiotic drugs and that can cause hard-to-treat infections.