Abstract
The aim of this study was to reveal the molecular mechanism involved in multidrug resistance and virulence of Campylobacter jejuni isolated from broiler chickens. The virulence of six multidrug resistant C. jejuni was determined by in vitro and in vivo methods. The de novo whole genome sequencing technology and molecular biology methods were used to analyze the genomic features associated with the multidrug resistance and virulence of a selected isolate (C. jejuni 1655). The comparative genomic analyses revealed a large number of single nucleotide polymorphisms, deletions, rearrangements, and inversions in C. jejuni 1655 compared to reference C. jejuni genomes. The co-emergence of Thr-86-Ile mutation in gyrA gene, A2075G mutation in 23S rRNA gene, tetO, aphA and aadE genes and pTet plasmid in C. jejuni 1655 contributed its multidrug resistance to fluoroquinolones, macrolides, tetracycline, and aminoglycosides. The combination of multiple virulence genes may work together to confer the relative higher virulence in C. jejuni 1655. The co-existence of mobile gene elements (e.g., pTet) and CRISPR-Cas system in C. jejuni 1655 may play an important role in the gene transfer and immune defense. The present study provides basic information of phenotypic and genomic features of C. jejuni 1655, a strain recently isolated from a chicken displaying multidrug resistance and relatively high level of virulence.
Highlights
Campylobacter jejuni is one of the most important foodborne pathogens worldwide (Abril et al, 2010)
The C. jejuni isolates were grown on Mueller-Hinton (MH) agar supplemented with 5% sheep blood at 42◦C under microaerobic conditions (5% O2, 10% CO2, and 85% N2) for 24–48 h
C. jejuni RM1221 (ATCC BAA1032) was isolated from chicken and showed low virulence (Fouts et al, 2005). 1655 was a multidrug resistant strain isolated from chicken fecal samples that exhibited relative higher virulence, as evidence by its higher pathogenicity to chickens, colonization of the chicken intestinal tract, cytotoxin production, biofilm formation, adhesion/invasion/intracellular survivability to macrophage cell and higher motility
Summary
Campylobacter jejuni is one of the most important foodborne pathogens worldwide (Abril et al, 2010). The National Antimicrobial Resistance Monitoring System (NARMS) in the USA and Danish Integrated Antimicrobial Resistance Monitoring and Research Program (DANMAP) data showed that multidrug resistance in C. jejuni has been very rare (0.3-0.7%) from retail chicken meat (DANMAP, 2014; NARMS, 2015). Multidrug resistant C. jejuni have been isolated from chicken. Genome of Virulent Campylobacter Strain farms in China recently (Chen et al, 2010; Hao et al, 2015; Wang et al, 2016). The multidrug resistant C. jejuni in chicken may greatly threaten food safety and human public health, it is important to investigate the virulence potential and mechanism involved in multidrug resistance and virulence of C. jejuni
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