3.4. Virulome of ESBL-positive E. coli ST58 colonizing
Brazilian merganser is associated with a virulent behavior
Virulome analysis of ESBL-producing E. coli PMPU strain
highlighted virulence factors, including adherence factors (fim,
eaeH , lpfAO113 , csgBCDEFG ), invasins (iss ,ibeBC ), cytolytic pore-forming toxin (hlyE ), iron
acquisition systems (entBCEFS , fepABCD ) and chemotaxis
(cheABRMWYZ , motAB ), among other virulence factors
commonly found in commensal and pathogenic E. coli strains (Table
1). The virulent potential of PMPU strain was confirmed in the G.
mellonella infection model, where strains inoculated at 1 ×
105 CFU killed 100% of wax moth larvae within 50h,
showing a more virulent behavior than E. coli ATCC 25922, but no
more than hypervirulent meningitis-causing E. coli MNEC RS218
(Figure S1). G. mellonella has been successfully utilized as anin vivo model to assess the pathogenic potential of clinically
important bacterial pathogen. Therefore, responses to bacterial
infections observed in this model could closely mimics responses
displayed by mammalian models (Jander, Rahme, & Ausubel, 2000; Kavanagh
& Reeves, 2004; Lange et al., 2019). In this study, virulent
performance of E. coli PMPU strain was correlated with virulence
factors commonly identified in pathogenic E. coli lineages from
humans and poultry, highlighting adherence factors (fimBCEFGHI,
eaeH , lpfAO113 , csgBCDEFG ) (Osek, Weiner & Hartland,
2003; Dale & Woodford, 2015; Torres, 2016; Sarowska et al., 2019),
invasins (iss , ibeBC ) (Sarowska et al., 2019), toxin
(hlyE ) (Wyborn et al., 2004), iron acquisition systems
(entBCEFS , fepABCD ) (Torres, 2016; Robinson, Heffernan, &
Henderson, 2018) and chemotaxis factors (cheABRMWYZ ,motAB ) (Pettersen, Mosevoll, Lindemann, & Wiker, 2016). In this
regard, adherence factors and invasins found in the E. coli PMPU
strain may have contributed to the colonization in different tissues of
the bird; and, the cytolytic pore-forming toxin hlyE could be
related to hemodynamic disturbances and tissue damage found in the
histopathology (Oscarssonet al, 1999; Lai et al, 2000; Lithgow, Haider,
Roberts, & Green, 2007). On the other hand, the immature immune system
in a 8-day-old Brazilian merganser, the artificial incubation conditions
(Ruiz-Castellano et al., 2016), as well as use of disinfectants may
contributed to the selection of a virulent E. coli resistant to a
wide range of antibiotics and disinfectants, establishing a disseminated
infection with a fatal end. In order to avoid new infections due toE. coli widely resistant to antimicrobials and disinfectants, a
cleaning of the environments was carried out using peracetic acid
concentrated at 0.2%. After this, no new cases of deaths occurred due
to this bacterium.
Virulent pathogens resistant to an increasing number of antimicrobials
cause thousands of deaths in the human population each year (Gu et
al. , 2018; Cassini et al. , 2019; Centers for Disease
Control, 2019). In this concern, wildlife plays an important role in the
epidemiology of antibiotic-resistant pathogens in the environment
(Alcalá et al. , 2016; Vittecoq et al., 2016; Sevilla et
al. , 2020). However, little is known about the impact of these
MDR-pathogens on wildlife, especially on threatened wildlife species
(Gonçalves et al. , 2012; Larsson et al. , 2018; Ramey &
Ahlstrom, 2020). In this study, we isolated a MDR ESBL-producingE. coli with virulent behavior, belonging to international clone
ST58 and serotype O102:H30, causing fatal infection in a critically
endangered Brazilian merganser. Of note, a MDR colistin-resistantE. coli ST58 was recently isolated from a polluted mangrove
ecosystem in Brazil (Sacramento et al. , 2018), being able to
become a serious threat to the associated wildlife and human population.
A better integration of environmental and wildlife issues is necessary
to a successful One Health approach for global AMR crisis (White &
Hughes, 2019). In this context, to understand epidemiologically the
evolution and adaptation of AMR, wildlife veterinarians must
increasingly report the challenges that arise when treating
antimicrobial-resistant pathogenic bacteria in wildlife species. Herein,
we report a fatal colibacillosis by MDR-ESBL-producing E. coli in
critically endangered Brazilian merganser, highlighting that besides
colonization, critical priority pathogens are threatening wildlife.