Prevalence And Charactererization Of Campylobacter Jejuni Isolated From Retail Chicken In Tianjin

Campylobacter jejuni is a leading foodborne pathogenic bacterium worldwide. They usually colonize in the intestinal tracts of poultry or other livestock (cattle, sheep, and swine) and poultry is the main bacterium reservoir. People are affected by contaminated animals, water and food. The prevelance of C. jejuni have received considerable attention in other countries, but there is lack of data about the distribution and antibiotic-resistant profile of this microaerobic microbe in China. This study was conducted to determine the prevalence and characteristics of C. jejuni in Tianjin, one of the five national central cities in China, on the retail level.A total of 227 samples including chicken legs, breasts, wing middle joints and wing roots were collected from supermarkets and wet markets. Forty two samples were detected to be positive of Campylobacter bacteria. The contamination rates of C. jejuni and other Campylobacter species were 13.7% (31/227) and 5.7% (13/227), respectively. Two chicken samples were contaminated by both C. jejuni and other Campylobacter species. Multilocus sequence typing (MLST) was conducted to study the population structure of C. jejuni and its relationship with human isolates. A great genetic diversity of poultry isolates was found,with 22 sequence types (ST) belonging to 6 clonal complexes and 11 singletons, besides,the novel STs accounted for 40.9% (9/22). ST 8089 and ST 354 were the most dominant STs which both contained four C. jejuni isolates. The most prevalent clonal complexes in the first three places were ST-354 (19.40%), ST-21 (9.70%) and ST-828 complexes(6.50%). Each of the other three clonal complexes only contained one isolate, accounting for 3.20%. The correlation between antimicrobial resistance traits and certain STs or clonal complexes was determined as well. ST -21, ST-353, ST-354, ST-443, ST-607, and ST-828 complexes were also previously identified from human isolates, indicating that these isolates were potential reservoirs of human C. jejuni infection.A group of 31 C. jejuni isolates were subjected to antimicrobial susceptibility test. The selective isolates were fully (100%) resistant to ciprofloxacin and nalidixic acid, followed by tetracycline (77.4%), doxycycline (67.7%), gentamicin (35.5%), clindamycin and florfenicol (25.8%), chloramphenicol (19.4%), as well as erythromycin and azithromycin(12.9%). In addition,a remarkably high proportion of multidrug resistant isolates (41.9%)was identified, highlighting the necessity of performing enforced interventions to reduce Campylobacter prevalence in China. Generally, isolates with the same ST have the same resistance profile. Different recovered isolates attributed to the identical clonal complex could react differently to antimicrobials. These findings laid foundation for further study.