The indiscriminate use and overuse of various antibiotics have caused the rapid emergence of antibiotic-resistant bacteria (ARB) in poultry products and the surrounding environment, giving rise to global public health issues. This study aimed to determine the prevalence of multidrug-resistant (MDR) Gram-negative bacteria (GNB) found in the environment of poultry farms and to evaluate the risk of contamination in these farms based on multiple antibiotic resistance (MAR) index values. Soil and effluent samples were collected from 13 poultry farms. The VITEK 2 system was used for bacterial identification and susceptibility testing of the isolates. The identified Gram-negative isolates were Acinetobacter spp., Aeromonas spp., Enterobacter spp., Klebsiella pneumoniae, Proteus spp., Providencia spp., Pseudomonas spp., and Sphingomonas paucimobilis. The results showed that Enterobacter spp., Aeromonas spp., and Providencia spp. exhibited the highest MDR rates and MAR indices; 14% of K. pneumoniae isolates (3/21 isolates) were resistant to 13 antibiotics and found to be extended-spectrum β-lactamase (ESBL)-producing bacteria. As for the tested antibiotics, 96.6% of the isolates (28/29 isolates) demonstrated resistance to ampicillin, followed by ampicillin-sulbactam (55.9% [33/59 isolates]) and cefazolin (54.8% [57/104 isolates]). The high percentage of MDR bacteria and the presence of ESBL-producing K. pneumoniae strains suggested the presence of MDR genes from the poultry farm environment, which poses an alarming threat to the effectiveness of the available antibiotic medicines to treat infectious diseases. Therefore, the use of antibiotics should be regulated and controlled, while studies addressing One Health issues are vital for combating and preventing the development and spread of ARB. IMPORTANCE The occurrence and spread of ARB due to high demand in poultry industries are of great public health concern. The widespread emergence of antibiotic resistance, particularly MDR among bacterial pathogens, poses challenges in clinical treatment. Some pathogens are now virtually untreatable with current antibiotics. However, those pathogens were rarely explored in the environment. In alignment with the concept of One Health, it is imperative to study the rate of resistance in the environment, because this domain plays an important role in the dissemination of bacteria to humans, animals, and other environmental areas. Reliable data on the prevalence of MDR bacteria are crucial to curb the spread of bacterial pathogens that can cause antimicrobial-resistant infections.
Keywords: ESBL; Gram-negative bacteria; antibiotics; multidrug resistance; poultry.