Cronobacter sakazakii

E. sakazakii was defined as a species in 1980 by JJ Farmer III et al. DNA–DNA hybridization showed that E. sakazakii was 53–54% related to species in two different genera, Enterobacter and Citrobacter. However, diverse biogroups within E. sakazakii were described and Farmer et al suggested these may represent different species and required further research for clarification. The initial four named species in 2007 were Cronobacter sakazakii (comprising two subspecies), C. turicensis, C. muytjensii and C. dublinensis (comprising three subspecies) plus an unnamed species referred to as Cronobacter genomospecies I. The taxonomy was revised in 2008 to include a fifth named species C. malonaticus, which in 2007 had been regarded as a subspecies of C. sakazakii. In 2012, Cronobacter genomospecies I was formally renamed Cronobacter universalis, and a seventh species was described called Cronobacter condimenti. ==Etymology==

The first documented isolation of what would become known as Cronobacter sakazakii was from a can of dried milk in 1950, although these organisms have likely existed for millions of years. In 1980, John J. Farmer III, proposed the name Enterobacter sakazakii for what had been known as "yellow-pigmented E. cloacae", in honor of Japanese bacteriologist Riichi Sakazaki. Over the next decades, E. sakazakii was implicated in scores of cases of meningitis and sepsis among infants, frequently in association with powdered infant formula. In 2007, the genus Cronobacter was created to accommodate the biogroups of E. sakazakii, with C. sakazakii as the type species. The genus was named for Cronos, the Titan of Greek myth, who devoured his children as they were born. == Identification ==

Similar to other Enterobactericiae, C. sakazakii is oxidase negative, motile, and catalase positive. The bacterium produces a yellow pigment that is enhanced by incubation at 20 °C. C. sakazakii can be differentiated from Enterobacter spp through positive Vogues-Proskauer, arginine dihydrolase, and ornithine decarboxylase reactions. == Pathogenesis ==

In infants C. sakazakii can cause bacteraemia, meningitis and necrotizing enterocolitis. Most neonatal C. sakazakii infections cases have been associated with the use of powdered infant formula However, not all cases have been linked to contaminated infant formula. In November 2011, several shipments of Kotex tampons were recalled due to a Cronobacter (E. sakazakii) contamination. In one study, the pathogen was found in 12% of field vegetables and 13% of hydroponic vegetables. == Treatment ==

Cronobacter sakazakii is intrinsically resistant to ampicillin and first- and second- generation cephalosporins due to production of an inducible AmpC β-lactamase. ==References==