RESIST ACINETO test for the rapid detection of NDM and OXA acquired carbapenemases directly from blood culture in Acinetobacter species.

Carbapenem-resistant Acinetobacter baumannii (CRAB) are increasingly reported worldwide and a leading cause of mortality associated with antimicrobial resistance. Their early detection, particularly in the cases of bloodstream infections, is crucial in attempting to initiate effective antibiotic treatment. The immunochromatographic assay RESIST ACINETO (Coris BioConcept) is a new test developed for the detection of OXA-23, OXA-40/58, and New-Delhi Metallo-beta-lactamase (NDM) carbapenemases in Acinetobacter spp. We evaluated this test on a collection of 121 Acinetobacter spp. clinical isolates, including 104 carbapenemase producers (97 carbapenemases targeted by the test) and 17 non-carbapenemase producers. The performance of the RESIST ACINETO test was evaluated according to the manufacturer's recommendations from bacterial and blood cultures. The strains producing the carbapenemases OXA-23, -40, -58, or/and NDM were accurately detected from bacterial cultures and directly from blood cultures, with the exception of one OXA-23/NDM-1-positive Acinetobacter radioresistens isolate (only detected through standard culture). None of the non-carbapenemase producers tested positive. The RESIST ACINETO test demonstrated sensitivity/specificity of 100%/100% and 99%/100% on bacterial and blood cultures, respectively. IMPORTANCE: The incidence of bloodstream infections with carbapenem-resistant Acinetobacter baumannii (CRAB) could be very high in some countries such as the Balkans or Southeast Asia. In case of positive blood cultures with Gram-negative bacteria, the use of the RESIST ACINETO test could prove highly beneficial for the rapid identification of these imipenem-resistant bacteria and their antibiotic resistance mechanisms. In addition, it is now well established that New-Delhi Metallo-beta-lactamase (NDM) carbapenemase-producing isolates can have increased MICs of cefiderocol, which is an alternative treatment for these infections. This test may also allow the optimization of treatment based on the type of carbapenemase present. Finally, the RESIST ACINETO test is a rapid, easy-to-use, and cost-effective assay that demonstrates excellent performance in detecting the major acquired carbapenemases present in the Acinetobacter species.

Adaptive resistance to cefiderocol in carbapenem-resistant Acinetobacter baumannii (CRAB): Microbiological and clinical issues.

Objectives: Determining the best available therapy for carbapenem-resistant Acinetobacter baumannii (CRAB) infections is a challenge. Cefiderocol is an attractive alternative drug effective against many resistance mechanisms in Gram-negative bacteria. However, its place in the treatment of Acinetobacter baumannii infections remains unclear and much debated, with contradictory results. Methods: We describe here the case of a 37-year-old man with ventilator-associated bacteraemic CRAB pneumonia in an intensive care unit. He was initially treated with a combination of colistin and tigecycline, and was then switched onto colistin and cefiderocol. We then used a new accessible protocol to test 30 CRAB isolates (OXA-23/OXA-24/OXA-58/NDM-1) for adaptive resistance to cefiderocol (ARC) after exposure to this drug. Results: After clinical failure with the initial combination, we noted a significant clinical improvement in the patient on the second combination, leading to clinical cure. No ARC was detected in the two OXA-23 case-CRAB isolates. All NDM-1 CRAB isolates were resistant to cefiderocol in standard tests; the OXA-23, OXA-24 and OXA-58 CRAB isolates presented 84.2 %, 50 % and 0 % ARC, respectively. Conclusions: ARC is not routinely assessed for CRAB isolates despite frequently being reported in susceptible isolates (69.2 %). Subpopulations displaying ARC may account for treatment failure, but this hypothesis should be treated with caution in the absence of robust clinical data. The two main findings of this work are that (i) cefiderocol monotherapy should probably not be recommended for OXA-23/24 CRAB infections and (ii) the characterisation of carbapenemases in CRAB strains may be informative for clinical decision-making.

Microplastics in the insular marine environment of the Southwest Indian Ocean carry a microbiome including antimicrobial resistant (AMR) bacteria: A case study from Reunion Island.

The increasing threats to ecosystems and humans from marine plastic pollution require a comprehensive assessment. We present a plastisphere case study from Reunion Island, a remote oceanic island located in the Southwest Indian Ocean, polluted by plastics. We characterized the plastic pollution on the island's coastal waters, described the associated microbiome, explored viable bacterial flora and the presence of antimicrobial resistant (AMR) bacteria. Reunion Island faces plastic pollution with up to 10,000 items/km2 in coastal water. These plastics host microbiomes dominated by Proteobacteria (80 %), including dominant genera such as Psychrobacter, Photobacterium, Pseudoalteromonas and Vibrio. Culturable microbiomes reach 107 CFU/g of microplastics, with dominance of Exiguobacterium and Pseudomonas. Plastics also carry AMR bacteria including ß-lactam resistance. Thus, Southwest Indian Ocean islands are facing serious plastic pollution. This pollution requires vigilant monitoring as it harbors a plastisphere including AMR, that threatens pristine ecosystems and potentially human health through the marine food chain.