RESUMEN
To investigate the contamination conditions of Campylobacter spp.in duck production chain and its antimicrobial resistance,virulence gene distribution,samples were collected at the duck slaughterhouse according to GB 4789.9-2014.Triplex PCR assay was applied to identify the species of Campylobacter and the recovered Campylobacter strains were tested for the antimicrobial susceptibility against 8 kinds of antimicrobial agents using a broth microdilution method,the susceptibility results were determined according to the NARMS criteria (2011).Subsequently,4 virulence genes were detected by PCR method.The result showed that 187 Campylobacter isolates were obtained from 489 samples,including 160 C.jejuni,130 C.coli and 10 unidentified Campylobacter isolates.The total isolation rate of Campylobacter was 38.24％.The prevalence of Camnpytobacter before slaughtering,at depilation stage,evisceration stage and duck products was 76.33％,5.62％,24.00％,and 0％,respectively.The Campylobacter isolates were most frequently resistant to tetracycline (95.72 ％),followed by resistance to clindamycin(90.91％),the resistance rate of azithromycin (63.64％) was in the middle,the resistance rates of ciprofloxacin(31.02％),gentamicin(34.76％),nalidixic acid (37.43 ％),erythromycin (41.18 ％),chloramphenicol (41.18％) were relatively low.The multi-drug resistance was common among Campylobacter isolates with a rate of 72.19％.The prevalence of adhesion-associated gene cadF,flagellin gene flaA,invasion associated protein gene iamA,toxin regulation gene cdtB was 100％,80.75 ％,71.12％ and 94.65％,respectively.The results indicated that the Campylobacter contamination occurred in the slaughtering procedures of duck,and the antimicrobial resistance of Campylobacter isolates was relatively serious.In addition,the virulence-associated genes were detected widely among Campylobacter isolates.Therefore,the supervision of antimicrobial agents using at rearing stage should be strengthened,along with health management in duck production chain.
RESUMEN
The article summarized the source of phytase,enzyme property and genetic engineering of phytase,discussed the problems existing in phytase genetic engineering and it's application.