Isolation and Genetic Diversity Identification of Cronobacter spp. (Enterobacter sakazakii) from Dried Foods.

Abstract

Cronobacter spp. (formerly Enterobacter sakazakii) is a group of emerging pathogen that has been implicated as the causative agent of meningitis and necrotizing enterocolitis in certain groups of infants. In Indonesia several isolates have been obtained mostly from powder infant formula and weaning foods. This research aimed to obtain Cronobacter spp. isolates from other dried foods i.e. weaning foods, flours, starches and spices and evaluated the biochemical and genotypic characteristics of the isolates. Isolation was conducted according to FDA method (2002) modified with Iversen and Forsythe (2004), biochemical was conducted by API 20E test and genotypic characterization was conducted by PCR amplification of their 16S rRNA gene using 3 primer pairs respectively, 16 SUNIL/ Saka 2b (Segment 1), ESA1/16 SUNI-R (Segment 2) and 16SUNI-L/16SUNI-R (Universal segment). Results of the DNA amplification were sequenced and then analyzed for their relatedness to reference isolates of C.sakazakii from GenBank using BLAST program. In this study 62 samples of weaning foods, flours, starches and spices were screened for the presence of Cronobacter spp. Twelve typical colonies on DFI were obtained from sample of flours, starches and spices samples. Biochemical test using API 20E suggested that 11 of the 12 presumptives isolates were E. sakazakii while one was identified as E. cloacae. Genotypic analysis revealed that eleven isolates including the one identified as E.cloacae by API test were confirmed as C.sakazakii while one isolates was C.muytjensii. Relationships between strains based on segment 1 was depicted in a dendrogram using the neighbor-joining method showed that the twelve isolates can be differentiated into two groups, meanwhile when universal segment was used, the isolates can be differentiated into three groups.