Antimicrobial resistance and virulence profiles of Enterobacterales isolated from two-finger and three-finger sloths (Choloepus hoffmanni and Bradypus variegatus) of Costa Rica

Abstract

Background: Wildlife has been recently recognized as an environmental reservoir for antimicrobial resistance (AMR). However, less information on this topic is available in animals released back into the wild after rehabilitation in wildlife facilities, compared with studies performed exclusively in captive or free-ranging wildlife. This study aimed to evaluate the potential influence of captivity and/or treatment while in captivity of wild sloths on the AMR and virulence profiles of sloths' Enterobacterales.

Methods: Oral and rectal swab samples were collected from 39 two-finger (Choloepus hoffmanni) and three-finger sloths (Bradypus variegatus) of Costa Rica (n = 78) and analyzed using conventional bacteriological techniques. A generalized linear mixed model was applied to estimate the isolates' multiple antimicrobial resistance and virulence indices as a function of animal status.

Results: A considerable level of resistance was detected, especially for Citrobacter youngae and Escherichia coli, with 17.5% of isolates classified as multidrug-resistant. Virulence indices of isolates from rehabilitated sloths were significantly higher than the ones from sloths being hand-reared for shorter periods.

Conclusions: To our knowledge, this is the first description of sloths' antimicrobial resistant Enterobacterales, suggesting that sloths' rehabilitation and consequent exposure to humans, may promote the selection of bacteria with higher virulence. Ultimately, these bacteria may represent a threat to human and animal health due to their zoonotic potential and AMR and virulence profiles.

Keywords: Antimicrobial resistance; Bacterial virulence factors; Bradypus variegatus; Choloepus hoffmanni; One health; Wildlife bacteria.

Figure 1. Mirror bar chart of the Virulence Index (V. Index) and MAR index mean values for the isolates of the identified bacterial species.

Shigella sonnei (SS), Salmonella enterica subspecies arizonae (SA), Citrobacter youngae (CY), Escherichia coli (ESC), Enterobacter cloacae (EC), Enterobacter amnigenus (EAM), Enterobacter aerogenes (EAE). The bacterial species with the highest V. Index and MAR index mean values are highlighted in dark grey.

Figure 2. Results from boxplots analysis for MAR and Virulence index (V. Index) for isolates from sloths of each animal status group.

(A) MAR index and (B) V. index mean values calculated for the isolates obtained from sloths of the different animal status groups: ‘hand-reared’ (1), ‘rehabilitated and released’ (2), and ‘wild’ (3). The sensitivity level between V. Index mean values of isolates from samples of ‘hand-reared’ (1) and ‘rehabilitated and released’ (2) sloths is indicated by * p < 0.05. The boxplots were created using Rpackage “ggplot2” (Wickham, 2016).