Campylobacter jejuni is a major foodborne pathogen and can be transmitted to human beings via the consumption of poultry products. This study aimed to determine antibiotic resistance and virulence potential of one hundred C. jejuni isolates from poultry meat and to explore the correlation between them and the multilocus sequence types (MLST). A total of 29 STs and 13 CCs were identified by MLST, of which 8 STs were first identified. The dominant ST was ST583 (21%), followed by ST42 (15%), ST61 (12%), and ST2276 (10%). Eighty-eight isolates showed resistance to at least one antibiotic. The resistance rate to fluoroquinolones was the highest (81%), followed by tetracycline (59%), whereas all the isolates were susceptible to erythromycin and telithromycin. Multi-antibiotic resistance was detected in 18 C. jejuni isolates. Great variability in the adhesion and invasion ability to Caco-2 cells was observed for the 100 isolates, with adhesion rates varying between 0.02% and 28.48%, and invasion rates varied from 0 to 6.26%. A correlation between STs and antibiotic resistance or virulence was observed. The ST61 isolates were significantly sensitive to CIP, while the TET resistance was significantly associated with ST354 and ST6175 complex. ST11326 showed substantially higher resistance to gentamicin and higher adhesion and invasion abilities to Caco-2 cells. The results helped improve our understanding of the potential hazard of different genotypes C. jejuni and provided critical information for the risk assessment of campylobacteriosis infection.

Clustered regularly interspaced short palindromic repeats (CRISPR) are widespread in bacterial and archaeal genomes as an adaptive immune system against invading mobile genetic elements. This study investigated the distribution of CRISPR loci and their potential association with antimicrobial resistance (AMR) in 40 foodborne Listeria monocytogenes isolates. CRISPR analysis showed that 18 isolates harbored CRISPR Locus 1, five carried Locus 2, and five possessed both loci. Antimicrobial susceptibility testing against seven antimicrobial agents indicated that most isolates were highly susceptible to the tested agents. Specifically, all isolates were susceptible to gentamicin, ampicillin, penicillin, and tetracycline, whereas resistance was observed in a small subset of isolates: four were resistant to chloramphenicol, five to levofloxacin, and four to ciprofloxacin. Statistical analysis showed no statistically significant association between the presence of CRISPR loci and antimicrobial susceptibility phenotypes. These findings provide baseline information on CRISPR locus distribution and antimicrobial susceptibility profiles in foodborne L. monocytogenes isolates. Further studies based on larger isolate collections, whole-genome sequencing, and characterization of associated cas genes are needed to clarify the potential role of CRISPR-Cas systems in AMR evolution in this species.