Antimicrobial resistant Acinetobacter species in wild birds.

Acinetobacter species belonging to the Acinetobacter calcoaceticus-Acinetobacter baumannii (ACB) and not-ACB complex have become of particular concern in veterinary and human medicine because of their antimicrobial resistance phenotypes and their involvement in case of coinfection with the pandemic SARS-CoV-2 [1, 2]. As wildlife is still overlooked in the epidemiology of medical important antibiotic-resistant bacteria, two free-ranging populations of Scarlet macaw (Ara macao cyanoptera) in Guatemala (n=10) and Belize (n=15) and a rescued group of Yellow-headed amazon (Amazona oratrix belizensis) in Belize (n=15) were sampled to investigate the epidemiological role in AMR Acinetobacter species spreading. Faecal samples (n=16), cloacal (n=34) and choanal swabs (n=14) were collected and cultured for Acinetobacter spp. isolation. Colonies were identified at level species (bioscore >2.300) by matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS: SOP Direct Transfer Procedure Revision.4; Bruker Daltonics, Germany). Susceptibility to a panel of 17 human and veterinary antibiotics, belonging to 11 different categories (aminoglycosides, penicillins, antipseudomonal penicillins+β-lactamase inhibitors, 1st 2nd 3rd and 4th generation cephalosporins, antipseudomonal fluoroquinolones, antipseudomonal carbapenems, monobactams, tetracyclines, macrolides, folate pathway inhibitors, polimixins), was assessed by Kirby-Bauer and MIC (E-test) methods, according to the EUCAST guidelines [3]. Data were analyzed using Chi Squared (STATA 13.0). In wild birds, 30 different bacterial species (n=218) were isolated, 67.4% belonging to Gram positive (n=147) and 32.6% to Gram negative (n=71). The family Moraxellaceae (4.2%, n=71) was represented by Acinetobacter spp. strains, cultured from choanae (P=0.0001). Members of ACB-complex (A. dijkshoorniae) accounted for 33.3% of isolates and not ACB complex strains (A. haemolyticus) for 66.7%. While not ACB-complex strains resulted sensitive to all antibacterial categories tested, the AMR strains were significantly represented in ACB-complex (P<0.0001). In particular, according to Magiorakos et al. [4], A. dijkshoorniae resulted multidrug-resistant (MDR), showing a 100% of resistance to penicillins, penicillins+β-lactamase inhibitors, 1st, 2nd, 3rd generation but not to 4th generation cephalosporins, carbapenems, monobactams, tetracyclines, and macrolides. These findings suggest that Scarlet macaw and Yellow-headed amazon populations can harbour Acinetobacter spp. members and not member of ACB-complex. Wild birds could act as carriers of MDR Acinetobacter strains, spreaders in the environment, and vectors of AMR as secondary sources of AMR for humans and other animals, representing sentinels mirroring the presence of AMR in human and animal influenced-environment.