Genomic Characterization of Fluoroquinolone-Resistant Thermophilic Campylobacter Strains Isolated from Layer Chicken Feces in Gangneung, South Korea by Whole-Genome Sequencing

Abstract

Thermophilic Campylobacter species of poultry origin have been associated with up to 80% of human campylobacteriosis cases. Layer chickens have received less attention as possible reservoirs of Campylobacter species. Initially, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of two archived Campylobacter isolates (Campylobacter jejuni strain 200605 and Campylobacter coli strain 200606) from layer chickens to five antimicrobials (ciprofloxacin, nalidixic acid, erythromycin, tetracycline, and gentamicin) were determined using broth microdilution while the presence of selected antimicrobial resistance genes was performed by polymerase chain reaction (PCR) using specific primers. Whole-genome sequencing (WGS) was performed by the Illumina HiSeq X platform. The analysis involved antimicrobial resistance genes, virulome, multilocus sequence typing (MLST), and phylogeny. Both isolates were phenotypically resistant to ciprofloxacin (MIC: 32 vs. 32 µg/mL), nalidixic acid (MIC: 128 vs. 64 µg/mL), and tetracycline (MIC: 64 vs. 64 µg/mL), but sensitive to erythromycin (MIC: 1 vs. 2 µg/mL) and gentamicin (MIC: 0.25 vs. 1 µg/mL) for C. jejuni strain 200605 and C. coli strain 200606, respectively. WGS confirmed C257T mutation in the gyrA gene and the presence of cmeABC complex conferring resistance to FQs in both strains. Both strains also exhibited tet(O) genes associated with tetracycline resistance. Various virulence genes associated with motility, chemotaxis, and capsule formation were found in both isolates. However, the analysis of virulence genes showed that C. jejuni strain 200605 is more virulent than C. coli strain 200606. The MLST showed that C. jejuni strain 200605 belongs to sequence type ST-5229 while C. coli strain 200606 belongs to ST-5935, and both STs are less common. The phylogenetic analysis clustered C. jejuni strain 200605 along with other strains reported in Korea (CP028933 from chicken and CP014344 from human) while C. coli strain 200606 formed a separate cluster with C. coli (CP007181) from turkey. The WGS confirmed FQ-resistance in both strains and showed potential virulence of both strains. Further studies are recommended to understand the reasons behind the regional distribution (Korea, China, and Vietnam) of such rare STs.

Investigation of the Effect of Three Commercial Water Acidifiers on the Performance, Gut Health, and Campylobacter jejuni Colonization in Experimentally Challenged Broiler Chicks

“…The rise in annually reported human infections and the evermore frequent isolation of antimicrobial-resistant C. jejuni strains from humans, animals, and the environment [ 8 , 9 ] emphasize the urgent demand for the development of “alternative-to-antibiotics” biocides [ 10 ] and for the establishment of control strategies in line with the “One Health” approach [ 11 ]. Health organizations are showing an increased interest in alternative biocides, including organic acids, phytogenics, probiotics, and prebiotics.…”

Overview of Virulence and Antibiotic Resistance in Campylobacter spp. Livestock Isolates

“…The Campylobacter genus represents a well-known group of foodborne pathogens responsible for causing self-limited gastroenteritis in humans, which sometimes requires antimicrobial treatment due to the potential for serious complications [22]. In the European Union, campylobacteriosis was the most frequently reported zoonosis in humans, It has been observed that various species within the Campylobacter genus can exchange genetic material with one another, as well as with other bacterial genera [15][16][17][18][19][20]. This facilitates the transfer of genes that enhance the virulence of Campylobacter and allow it to withstand exposure to antibiotics.…”

“…Similarities we only identified in regard to genes cheAVW (chemotaxis), gmh, waa, kps (capsule formation), kpsDEFCST (capsular genes) and hldE (LPS-associated gene). Notably, genes expressing capsular biosynthesis were detected in C. coli strain 200606, namely Cj1416c, Cj1417c, Cj1419c and Cj1420c, suggesting potential genetic exchange between C. coli and C. jejuni species [18]. The same authors analysed the presence of virulence factors in 55 Campylobacter (C. jejuni and C. coli) isolates originating from a layer farm in South Korea.…”

“…Therefore, surveillance programs are needed to regulate the use of antibiotics and ensure clinical prescriptions are based on antibiograms in both veterinary and human medicine [14]. It has been observed that various species within the Campylobacter genus can exchange genetic material with one another, as well as with other bacterial genera [15][16][17][18][19][20]. This facilitates the transfer of genes that enhance the virulence of Campylobacter and allow it to withstand exposure to antibiotics.…”