Detection Of Cronobacter In Infant Formula Rice Flour And Multilocus Sequence Typing Analysis

Cronobacter was an emerging food borne pathogen that is ubiquitous in theenvironment and vegetal-itas caused such severe diseases as infantile meningitis,septicemia, or necrotizing enterocolitis. The main pollution sources was infantformula in the past poisoning cases.In this study, we have investigated Cronobacterpollution in101infant formula food samples,by MPN,differential medium andrpoB gene sequence typing. Cronobacter was found in7samples.8isolates wereidentified as C.sakazakii and C.malonaticus. The relevant national standardsspecified Cronobacter can’t be detected,the7samples were disqualification. Thesesamples from different brands, which account for each factory exist some problemsin production safety management or production personnels not comply with rulesthat result in microbial contamination. Because of serious consequences for thebaby,the food production must prevent pollution in each link.Traditional molecular typing like Random Amplification PolymorphismDNA(RAPD) can’t distinguish Cronobacter,and low recognition degree,highrepeatability and easy to confuse made it abandon. So the more efficient and fastclassification method multilocus sequence typing(MLST) developed rapidly inrecent years and can distinguish Cronobacter in genes. In comparison of43isolates(from tea drink materials and infant formula food isolates in lab and infantformula food isolates in Yunnan Centers for Disease Control),17STs wereidentified in31isolates,new alleles or new STs were submitted to acquire newnumber in12isolates.gltB，gyrB and pps alleles gene mutation rate was higher,itshows than these alleles distinguish ability was higher.ST4and ST7sequence typewas advantage,which tallies with database. By evolutionary tree can clearlyidentify the evolutionary relationships and genetic relationships,Biofilm’s formation enhanced the resistance of cells to environmental stressand provides protection against drugs and disinfectant.43isolates have been test forbiofilm capability and showed all of Cronobacter have strong biofilm formationcapability.C.dublinensis and C.malonaticus have greater bioflim activity than C.sakazakii. Through11kinds of antibiotics to determine the antibiotics sensitivityof Cronobacter.the resistance of tetracycline and valinomycin is higher,anddifferent area have different antibiotics resistance.