Investigation of gram-negative bacteria resistant to antimicrobials in feces of Nymphicus hollandicus (cockatiel)

Abstract

Introduction: Nymphicus hollandicus (cockatiel) is a domestic bird that lives directly with humans, making contact with their droppings inevitable. The feces of these birds can harbor bacteria, including those resistant to clinically relevant antimicrobials. Objective: To investigate the presence of antimicrobial resistant gram-negative bacteria in feces of N. hollandicus. Methods: A pool of feces from two birds born and kept in domestic captivity was collected and submitted (2g) to culture enriched in 100 mL of BHI broth plus the antimicrobials meropenem, ciprofloxacin, gentamicin and colistin, separately and together, in addition to only in BHI broth (growth control). Antimicrobial concentrations were established according to CLSI (2019) and BrCAST (2020) which define resistance in gram-negative bacteria. After incubation at 35 ±2 ºC/48h, 100, 10 and 1 µL of each culture were inoculated in MacConkey, cetrimide and nutrient agar using the spread plate technique and incubated at 35 ±2 ºC/48h. Results: In this research, growth of gram negative bacteria resistant to the antimicrobials tested was not observed from the cockatiel feces. However, from the control culture, the growth of distinct morphotypes was observed, lactose fermenters (on MacConkey agar) and colonies producing green pigments (on cetrimide agar). Conclusion: In the intestinal microbiota of cockatiels, there are several types of gram-negative bacteria that, although they have morphological characteristics similar to potential human pathogens, suggest a lower clinical impact considering the resistance to the antimicrobials investigated here.