Detection Of Culturable And Viable Butnon-Culturable(VBNC) Salmonellafrom Chicken

Our study investigated viable culturable and Viable but non-culturable(VBNC)state of Salmonella spp.from chicken.This study investigated and analyzed prevalence and antibiotic resistance of Salmonella enterica serovar Enteritidis recovered from retail chicken in Tianjin by using modified isolating method of National standard document.A total of 620 retail chicken parts,including chicken wing middle joints(n=139),chicken wing roots(n=142),chicken drumsticks(n=136),chicken breasts(n=144)and 59 chicken giblets consist of hearts(n=25),livers(n=22),gizzards(n=12),were collected from 29 supermarkets and 10 open markets of 9 main districts of Tianjin from November 2015 to October 2016.240 of these chicken parts were contaminated by S.enterica ser.Enteritidis with a positive rate of 38.71%.Incidence from open market(45.33%)was higher than that from supermarket(34.94%).Incidence from nonpacked chicken(39.41%)was higher than packed chicken(33.77%).Out of different chicken parts,the highest incidence was observed in chicken giblets(59.32%),followed by chicken wing roots(42.25%),chicken breasts(40.28%),chicken middle wings(33.81%),chicken drumsticks(29.41%).475 isolates were obtained and tolerances of these isolates resistant to 13 antimicrobial agents belonging to 7 antimicrobial categories were tested in this study.Among these isolates,470(98.95%)isolates were observed to be resistant to at least 1 antimicrobial agent and another 5 isolates were not resistant any of these 13 antimicrobial agents.Nalidixic acid(97.89%)was the most common antimicrobial agent in this study,followed by ampicillin(78.53%),sulfisoxazole(74.11%),streptomycin(64%),tetracycline(42.95%).368 isolates(44.47%)were resistant to 3 or more categories of antimicrobial,which were called MDR.A new technique was developed that combined PMA with real time quantitive loop mediated isothermal amplification(PMA-qLAMP)to detect Salmonella that in Viable but non-culturable state(VBNC).The developed method PMA-qLAMP could specifically and rapidly quantitate Salmonella VBNC.The standard curve of PMA-qLAMP was y=2.1003x+32.869(R2=0.968);the standard curve of PMA-qPCR was y=-3.2836x+33.97(R2=0.995).A liner fitting of Ct value versus Tt value indicated PMA-qLAMP is highly positively correlated(R2=0.978)with PMA-qPCR,a traditional standard method.A spiking test in chicken model indicated chicken matrixes have no effect on PMA-qLAMP,of which limited of detection was 101 CFU/g.