Phenotypic profiles and detection of target genes by PCR in isolates from different sources and reference strains, identified as Cronobacter spp. (Enterobacter sakazakii)

ABSTRACT

Cronobacter, formerly known as Enterobacter sakazakii, is a novel genus of the Enterobacteriaceae family recognized as a cause of high number of fatal cases in neonates, after consuming infant formula. The conventional methods for detecting these organisms are time-consuming and lack sensitivity. The ISO/TS 229642006 is the most recently standardized methodology for detecting Cronobacter in powderedinfant formula. This study aimed at confirming the Brazilian isolates previously identified as E. sakazakiias Cronobacter spp. by biochemical assays, and also to compare characteristics of 37 Cronobacter andnon-Cronobacter isolates; and the miniaturized kits and the ISO/TS methodology were evaluated. A conventional PCR protocol targeting dna G was also developed and a previously described gluA targeting protocol was used. The majority of the Brazilian isolates were not confirmed as Cronobacter spp., and the selective enrichment step of ISO/TS methodology was inhibitory to some Cronobacter strains. The ID 32 Ewas the most reliable kit. The PCR protocol targeting gluA showed consistent results with ID 32E and the developed dnaG PCR protocol was 100% sensitive and specific. Thus, the PCR protocols targeting gluA and dnaG might be used to complement the Cronobacter spp. detection or identification after performing the conventional isolation and identification methods.