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ARS Home » Southeast Area » Athens, Georgia » U.S. National Poultry Research Center » Poultry Microbiological Safety and Processing Research Unit » Research » Publications at this Location » Publication #405514
Title: Genotypic characterization, antimicrobial susceptibility and virulence determinants of Campylobacter jejuni and Campylobacter coli isolated from pastured poultry farms

Author
item AWAD, AMAL - Mansoura University
item Yeh, Hung-Yueh
item RAMADAN, HAZEM - Mansoura University
item Rothrock, Michael

Submitted to: Frontiers in Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/25/2023
Publication Date: 11/9/2023
Citation: Awad, A., Yeh, H., Ramadan, H., Rothrock Jr, M.J. 2023. Genotypic characterization, antimicrobial susceptibility and virulence determinants of Campylobacter jejuni and Campylobacter coli isolated from pastured poultry farms. Frontiers in Microbiology. 14:1271551. https://doi.org/10.3389/fmicb.2023.1271551.
DOI: https://doi.org/10.3389/fmicb.2023.1271551

Interpretive Summary: Campylobacter is the leading bacterial pathogen that causes foodborne illnesses worldwide. Pasture farming is regarded as an important source of agricultural production for small farming communities. Consumer preference for pasture-raised animal products has increased. However, there is a paucity information on the microbiological quality of pasture-raised poultry products. The purpose of this study was to explore genetic relatedness of thermophilic Campylobacter isolates, to assess antibiotic resistance phenotypically and genotypically, and to screen the presence of virulence determinants of Campylobacter isolates from a pasture-raised poultry farm. Ninety-seven Campylobacter isolates were genotyped by multilocus sequence typing (MLST). Campylobacter isolates were then evaluated for their phenotypic antimicrobial susceptibility against nine antimicrobial agents using Sensititre plates. Additionally, Campylobacter isolates were tested for the presence of antimicrobial resistance associated elements. Furthermore, Campylobacter isolates were screened for the presence of 13 genes encoding putative virulence factors by PCR. Among 97 Campylobacter isolates, C. jejuni (n=79) and C. coli (n=18) were identified. By MLST, C. jejuni isolates were assigned to seven clonal complexes. Among them, ST-353, ST-607 and ST-21 were the most common STs recognized. All C. coli (n=18) isolates were included in CC-828. Interestingly, eight STs identified were not belonging any previous identified clonal complex. Campylobacter isolates displayed a high resistance rate against tetracycline (81.4%), while a low rate of resistance was observed against macrolides (azithromycin and erythromycin), quinolones and fluoroquinolones (naladixic acid, ciprofloxacin), aminoglycosides (gentamicin), ketolide (telithromycin), amphenicol (florfenicol) and lincomycin (clindamycin). Thirteen isolates (13.54%) were pan-susceptible to all tested antibiotics, while nine isolates were multi-antimicrobial resistant (MAR; resist to 3 or more antimicrobial classes). Interestingly, there is no isolates were resistant to all antimicrobial classes. Thr-86'Ile mutation was identified in all quinolones resistant strains. Erythromycin encoding gene (ermB) was identified in 75 % or erythromycin resistant isolates. The A2075 mutation was detected in one erythromycin resistant strain, while A2074 could not be identified. The tetO gene identified in 93.7% of tetracycline resistant isolates and six tetracycline susceptible isolates. In conclusion, the results of this study revealed that Campylobacter isolates from the pasture-raised poultry farm showed the ST relatedness of the Campylobacter isolates to those commonly associated with humans and they act as a potential source for antibiotic-resistant and pathogenic strains of thermophilic Campylobacter to humans.

Technical Abstract: Aim: Campylobacter is the leading bacterial pathogen that causes foodborne illnesses worldwide. Pasture farming is regarded as an important source of agricultural production for small farming communities. Consumer preference for pasture-raised animal products has increased. However, there is a paucity information on the microbiological quality of pasture-raised poultry products. The purpose of this study was to explore genetic relatedness of thermophilic Campylobacter isolates, to assess antibiotic resistance phenotypically and genotypically, and to screen the presence of virulence determinants of Campylobacter isolates from a pasture-raised poultry farm from Georgia, USA. Methods: Ninety-seven Campylobacter isolates previously identified by Q7 BAX® System Real-Time PCR were genotyped by multilocus sequence typing (MLST). Campylobacter isolates were then evaluated for their phenotypic antimicrobial susceptibility against nine antimicrobial agents using Sensititre plates. Additionally, Campylobacter isolates were tested for the presence of antimicrobial resistance associated elements. Furthermore, Campylobacter isolates were screened for the presence of 13 genes encoding putative virulence factors by PCR. These included genes involved in motility (flaA, and flhA), adhesion and colonization (cadF, docC, racR and virB11), toxin production (cdtA, cdtB, cdtC, wlaN and ceuE) and invasion (ciaB and iamA). Results: Among 97 Campylobacter isolates, C. jejuni (n=79) and C. coli (n=18) were identified. By MLST, C. jejuni isolates were assigned to seven clonal complexes. Among them, ST-353, ST-607 and ST-21 were the most common STs recognized. All C. coli (n=18) isolates were included in CC-828. Interestingly, eight STs identified were not belonging any previous identified clonal complex. Campylobacter isolates displayed a high resistance rate against tetracycline (81.4%), while, a low rate of resistance was observed against macrolides (azithromycin and erythromycin), quinolones and fluoroquinolones (naladixic acid, ciprofloxacin), aminoglycosides (gentamicin), ketolide (telithromycin), amphenicol (florfenicol) and lincomycin (clindamycin). Thirteen isolates (13.54%) were pan-susceptible to all tested antibiotics, while, nine isolates were multi-antimicrobial resistant (MAR; resist to 3 or more antimicrobial classes). Interestingly, there is no isolates were resistant to all antimicrobial classes. Thr-86'Ile mutation was identified in all quinolones resistant strains. Erythromycin encoding gene (ermB) was identified in 75 % or erythromycin resistant isolates. The A2075 mutation was detected in one erythromycin resistant strain, while A2074 could not be identified. The tetO gene identified in 93.7% of tetracycline resistant isolates and six tetracycline susceptible isolates. In conclusion, the results of this study revealed that Campylobacter isolates from the pasture-raised poultry farm showed the ST relatedness of the Campylobacter isolates to those commonly associated with humans and they act as a potential source for antibiotic-resistant and pathogenic strains of thermophilic Campylobacter to humans.