C. Sakazakii

''Cronobacter sakazakii'', which before 2007 was named ''Enterobacter sakazakii'', is an opportunistic Gram-negative, rod-shaped, pathogenic bacterium that can live in very dry places, a phenomenon known as xerotolerance. ''C. sakazakii'' utilizes a number of genes to survive desiccation and this xerotolerance may be strain specific. Most ''C. sakazakii'' cases are adults but low-birth-weight preterm neonatal and older infants are at the highest risk. The pathogen is a rare cause of invasive infection in infants, with historically high case fatality rates (40–80%).Free full text
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In infants it can cause bacteraemia, meningitis and necrotizing enterocolitis. Most neonatal ''C. sakazakii'' infections cases have been associated with the use of powdered infant formula with some strains able to survive in a desiccated state for more than two years. 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.

All ''Cronobacter'' species, except '' C. condimenti'', have been linked retrospectively to clinical cases of infection in either adults or infants. However multilocus sequence typing has shown that most neonatal meningitis cases in the past 30 years, across six countries, have been associated with only one genetic lineage of the species ''Cronobacter sakazakii'' called 'Sequence Type 4' or 'ST4', and therefore this clone appears to be of greatest concern with infant infections.

The bacterium is ubiquitous, being isolated from a range of environments and foods; the majority of ''Cronobacter'' cases occur in the adult population. However it is the association with intrinsically or extrinsically contaminated powdered formula which has attracted the main attention. According to multilocus sequence analysis (MLSA) the genus originated ~40 MYA, and the most clinically significant species, ''C. sakazakii'', was distinguishable ~15-23 MYA.

Taxonomy

''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 taxonomic relationship between ''E. sakazakii'' strains has been studied using full-length 16S rRNA gene sequencing, DNA–DNA hybridization, multilocus sequence typing (MLST), f- AFLP, automated ribotyping. This resulted in the classification of ''E. sakazakii'' as a new genus, ''Cronobacter'' within the Enterobacteriaceae, initially comprising four named species in 2007. The taxonomy was expanded to five named species in 2008, and more recently (2011) to seven named species.

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.

References

External links

An international meeting on ''Cronobacter''Type strain of ''Cronobacter sakazakii'' at Bac''Dive'' - the Bacterial Diversity Metadatabase

{{Taxonbar, from=Q25841585

Enterobacteriaceae
Food microbiology
Bacteria described in 1980

ja:エンテロバクター・サカザキ