''Cronobacter sakazakii'', which before 2007 was named ''Enterobacter sakazakii'', is an opportunistic Gram-negative, rod-shaped,

pathogenic In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a germ ...

bacterium that can live in very dry places, otherwise known as xerotolerance. ''C. sakazakii'' utilizes a number of genes to survive

desiccation Desiccation () is the state of extreme dryness, or the process of extreme drying. A desiccant is a hygroscopic (attracts and holds water) substance that induces or sustains such a state in its local vicinity in a moderately sealed container. ...

and this xerotolerance may be strain specific. The majority of ''C. sakazakii'' cases are adults but

low-birth-weight Low birth weight (LBW) is defined by the World Health Organization as a birth weight of an infant of or less, regardless of gestational age. Infants born with LBW have added health risks which require close management, often in a neonatal intensi ...

preterm neonatal and older

infant An infant or baby is the very young offspring of human beings. ''Infant'' (from the Latin word ''infans'', meaning 'unable to speak' or 'speechless') is a formal or specialised synonym for the common term ''baby''. The terms may also be used to ...

s 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
/ref> In infants it can cause

bacteraemia Bloodstream infections (BSIs), which include bacteremias when the infections are bacterial and fungemias when the infections are fungal, are infections present in the blood. Blood is normally a sterile environment, so the detection of microbe ...

meningitis Meningitis is acute or chronic inflammation of the protective membranes covering the brain and spinal cord, collectively called the meninges. The most common symptoms are fever, headache, and neck stiffness. Other symptoms include confusion or ...

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 ''Cronobacter'' is a genus of Gram-negative, facultatively anaerobic, oxidase-negative, catalase-positive, rod-shaped bacteria of the family Enterobacteriaceae. Several ''Cronobacter'' species are desiccation resistant and persistent in dry ...

'' 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 the majority of neonatal

cases in the past 30 years, across 6 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 Mya may refer to: Brands and product names * Mya (program), an intelligent personal assistant created by Motorola * Mya (TV channel), an Italian Television channel * Midwest Young Artists, a comprehensive youth music program Codes * Burmese ...

, 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 ''Citrobacter'' is a genus of Gram-negative coliform bacteria in the family Enterobacteriaceae. The species ''C. amalonaticus'', ''C. koseri'', and ''C. freundii'' can use citrate as a sole carbon source. ''Citrobacter'' species are differentia ...

''. 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 16S rRNA may refer to: * 16S ribosomal RNA 16 S ribosomal RNA (or 16 S rRNA) is the RNA component of the 30S subunit of a prokaryotic ribosome ( SSU rRNA). It binds to the Shine-Dalgarno sequence and provides most of the SSU structure. The g ...

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, ''

'' within the

Enterobacteriaceae Enterobacteriaceae is a large family (biology), family of Gram-negative bacteria. It was first proposed by Rahn in 1936, and now includes over 30 genera and more than 100 species. Its classification above the level of family is still a subject ...

, 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 ''Cronobacter'' is a genus of Gram-negative, facultatively anaerobic, oxidase-negative, catalase-positive, rod-shaped bacteria of the family Enterobacteriaceae. Several ''Cronobacter'' species are desiccation resistant and persistent in dry p ...

'', and a seventh species was described called ''

Cronobacter condimenti ''Cronobacter'' is a genus of Gram-negative, facultatively anaerobic, oxidase-negative, catalase-positive, rod-shaped bacteria of the family Enterobacteriaceae. Several ''Cronobacter'' species are desiccation resistant and persistent in dry p ...

''.

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 Bacteria described in 1980 ja:エンテロバクター・サカザキ