Prevalence and multidrug resistance of Enterococcus species isolated from chickens at slaughterhouses in Nakhon Ratchasima Province, Thailand

Abstract

Enterococcus is a commensal bacteria found in humans and animals, which can cause human nosocomial infections. One of the most contaminated enterococcal sources is poultry meat. Therefore, this study examined the prevalence and antimicrobial resistance (AMR) profile of Enterococcus from chickens and their meat products at local slaughterhouses in Nakhon Ratchasima Province, Thailand. Between January 2021 and March 2022, 558 samples from 279 cloacal swabs and breast meat were collected from 31 local slaughterhouses. Then, the samples were screened for Enterococcus using modified de Man, Rogosa, and Sharpe agar. Next, selected Gram-positive, catalase-negative, and cocci-shaped colonies were investigated for enterococcal confirmation using Enterococcosel Agar. However, the disk diffusion method investigated positive Enterococcus resistance profiles to 16 antimicrobial agents. Finally, selected phenotypic multidrug-resistant (MDR) Enterococcus isolates were further assessed to identify AMR genes by polymerase chain reaction. Investigations showed that although the prevalence of Enterococcus isolates from the chicken cloacal swabs and meat samples was 28.85% (161/558), most Enterococcus isolates were resistant to colistin, followed by cefoxitin, cephalexin, and streptomycin. These isolates also showed MDR prevalence (65.22%; 105/161) and 66 patterns. Furthermore, selected MDR Enterococcus (MDRE) from cloacal swabs and meat were positive for the resistant extended-spectrum beta-lactamase TEM (ESBL-TEM) genes at 71.43% (20/28) and 78.26% (18/23), respectively, whereas other AMR genes detected in the selected MDR enterococci from the cloacal swabs and meat were beta-lactamase TEM [blaTEM (0%, 1.96%)], class 1 integrase [intI1 (14.28%, 0%)], colistin [mrc–1 (3.57%, 0%)], and vancomycin [vanA (14.28%, 0%)]. This study indicated that phenotypic MDRE correlated with ESBL-TEM gene presence, leading to an AMR reservoir that can be transferred to other bacteria.