Enterococci Isolated from One-Day-Old Chickens and Their Phenotypic Susceptibility to Antimicrobials in the Czech Republic

Abstract

Our study describes the prevalence and spectrum of enterococci isolated from one-day-old chickens in the Czech Republic, their level of antimicrobial resistance, and the occurrence of multiresistance. Over a 24-month period from 1 August 2021 to 31 July 2023, a total of 464 mixed samples of one-day-old chicken organs were examined during routine inspections at 12 randomly selected poultry farms in the Czech Republic. The samples were processed via cultivation methods and suspected strains were confirmed using the MALDI–TOF Mass Spectrometry method. Antimicrobial susceptibility was determined using the MIC method for eight antimicrobials. A total of 128 isolates (prevalence of 27.6%) representing 4 species of enterococci were isolated, including Enterococcus faecalis, Enterococcus faecium, Enterococcus gallinarum, and Enterococcus hirae, with prevalence rates of 23.3%, 1.5%, 2.2%, and 0.6%, respectively. Susceptibility tests showed a high percentage of susceptible strains among E. faecalis, E. faecium, and E. gallinarum for penicillin-based antibiotics, sulfamethoxazole with trimethoprim, and florfenicol (80–100% susceptible strains). E. hirae was an exception, displaying complete resistance to enrofloxacin (0% susceptible strains) and a high degree of resistance to other tested antimicrobials (33.3% susceptible strains). Among the isolated strains, a total of 16 isolates (12.5%) showed resistance to 3 or more antimicrobials. Complete resistance to all eight antimicrobials simultaneously was observed in four isolates (3.1%). This research shows the possible sources of pathogenic enterococci and their virulence and resistance genes. The findings hold relevance for both veterinary and human medicine, contributing to a better understanding of enterococcal circulation in the human ecosystem and food chain, as well as the development of their resistance and multiresistance.

In Vitro Evaluation of Phytobiotic Mixture Antibacterial Potential against Enterococcus spp. Strains Isolated from Broiler Chicken

“…This indicates the risk of the further development and spread of the phenotypic resistance of the most common enterococci to these antimicrobials. In other studies, resistance to erythromycin in chickens varied between 31.1% and 61.0% [40] or 40% and 73.1% [39]. It is noteworthy that our findings regarding the E. faecium strain revealed 100% susceptibility to the tested antimicrobials.…”

“…It should be emphasized that no strains of E. cecorum were found in 1-day-old chicks. Bzdil et al [39] also detected in 1-day-old chicks four species of enterococci, E. faecalis, E. faecium, E. gallinarum and E. hirae, but not E. cecorum. The results regarding the drug resistance of the analyzed strains of Enterococcus spp.…”

“…infections and its treatment apply to laying hens [38,56]. In the case of this type of poultry production, the issue of withdrawal period, the danger of drug residues in eggs intended for human consumption but also the increasing drug resistance of the mentioned strains deserve special attention [39,56,57]. It seems that effective phytobiotic products that do not have a withdrawal period have a chance to become permanent in the prevention and control of infections with various strains of Enterococcus spp.…”