Antimicrobial resistance is a growing threat to global public health. Gram-negative bacilli stand out in this context due to their high resistance rates and associated mortality. In the Amazon region, little is known about the presence and spread of these microorganisms in wild animals and the environment. The objective was to evaluate the occurrence of resistant Gram-negative bacilli in water, soil, and fecal samples from wild animals in the Metropolitan Region of Manaus, from the perspective of the One Health approach.

Rectal samples were collected from 34 animals from the Wildlife Screening Center, as well as environmental samples (water and soil) from their places of origin. Samples were cultured on selective media, and bacterial isolates were identified by colony morphology, Gram staining, and conventional biochemical tests. Antimicrobial susceptibility was determined by disk diffusion (CLSI, 2023) using 12 antimicrobials: amoxicillin + clavulanic acid, cefoxitin, amikacin, ceftazidime, meropenem, ampicillin, cephalothin, cefuroxime, ciprofloxacin, sulfamethoxazole/trimethoprim, gentamicin, and cefepime. The project was approved by CEUA/FIOCRUZ, Protocol n° 4/23-5.

From the collected samples, 438 isolates of Gram-negative strains were obtained, of which 29.7% were from fecal samples, 36.1% from water, and 34.2% from soil. Most isolates were identified as Escherichia coli (18%), Klebsiella pneumoniae (11.4%), Enterobacter cloacae (11%), Proteus mirabilis (8.2%), Klebsiella aerogenes (5%), Shigella spp.(4.8%), Klebsiella oxytoca (3.4%), and Salmonella spp. (3.2%). The highest sensitivity levels were observed for gentamicin (95.3%), ciprofloxacin (89.3%), and sulfamethoxazole/trimethoprim (84.2%). Resistance was highest for amoxicillin + clavulanic acid (66.9%), followed by ampicillin (59%) and cephalothin (43%). The analysis showed that 91% of the strains were resistant to at least one antibiotic, and only 9% were sensitive to all antibiotics tested for Gram-negative isolates.

The findings show the wide dissemination of resistant Gram-negative bacilli in natural environments of the Amazon region, possibly influenced by human activity. The data reinforce the urgency of implementing integrated surveillance actions in line with the principles of One Health.