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Scientific classification
Kingdom: Bacteria
Phylum: Proteobacteria
Class: Gamma Proteobacteria
Order: Enterobacteriales
Family: Enterobacteriaceae
Genus: Cronobacter
(Iversen et al. 2008)[1] (Joseph et al. 2011)[2]

C. sakazakii
C. malonaticus
C. turicensis
C. muytjensii
C. dublinensis
C. universalis
C. condimenti

Cronobacter is a genus of Gram-negative, facultatively anaerobic, oxidase-negative, catalase-positive, rod-shaped bacteria of the family Enterobacteriaceae. They are generally motile, reduce nitrate, use citrate, hydrolyze esculin and arginine, and are positive for L-ornithine decarboxylation. Acid is produced from D-glucose, D-sucrose, D-raffinose, D-melibiose, D-cellobiose, D-mannitol, D-mannose, L-rhamnose, L-arabinose, D-trehalose, galacturonate and D-maltose. Cronobacter spp. are also generally positive for acetoin production (Voges–Proskauer test) and negative for the methyl red test, indicating 2,3-butanediol rather than mixed acid fermentation. The type species of the genus Cronobacter is Cronobacter sakazakii comb. nov.

Clinical significance[edit]

All Cronobacter species, except C. condimenti, have been linked retrospectively to clinical cases of infection. While cases of infection do occur in adults these are generally non-life-threatening and often secondary colonization to underlying health problems. Infection in infants is associated with neonatal bacteraemia, meningitis and necrotising enterocolitis with a high case fatality rate and ongoing disablement of survivors. Increased awareness that Cronobacter are ubiquitous environmental organisms and initiatives by the WHO and FAO in relation to risk assessments and advice on infant feeding (including safe temperatures for reconstitution of powdered infant formula and appropriate hold times post-reconstitution) has drastically reduced the occurrence of infection outbreaks. Additionally the introduction of an ISO standard method for detection of these organisms has aided the infant formula industry to control their presence in manufacturing sites and products further reducing the risk to infants, though isolated cased can still occur not least as Cronobacter are ubiquitous in home environments as well.


Cronobacter was first proposed as a new genus in 2007 as a clarification of the taxonomic relationship of the biogroups found among strains of Enterobacter sakazakii.[3] This proposal was validly published in 2008 with 5 species and 3 subspecies named.[1] The genus definition was further revised in 2012 to seven named species when a name (C. universalis) was given to a group of isolates that were deemed too few in number to accurately describe during the original taxonomic work, and a single additional isolate was also named (C. condimenti). In 2013 Enterobacter helveticus, Enterobacter pulveris and Enterobacter turicensis were reclassified into the genus Cronobacter, however this was corrected in 2014 when Stephan et. al. published evidence that these should be classified as Franconibacter helveticus, Franconibacter pulveris and Siccibacter turicensis respectively.[4]


Cronobacter ('ter) is from the Greek noun Cronos (Κρόνος), one of the Titans of mythology, who swallowed each of his children as soon as they were born, and the New Latin masculine noun bacter, a rod, resulting in the N.L. masc. n. Cronobacter, a rod that can cause illness in neonates.

Cronobacter sakazakii (sak.a.zaki.ī. N.L. gen. n. sakazakii, of Sakazaki) is named in honour of the Japanese microbiologist Riichi Sakazaki.[5]

Cronobacter malonaticus (mă.lō.nă.tĭ'cŭs) is from N.L. n. malonas -atis, malonate; L. suff. -icus, suffix used with the sense of belonging to; N.L. masc. adj. malonaticus, pertaining to the use of malonate. The type strain, CDC 1058-77T, was isolated from a breast abscess.[5]

Cronobacter turicensis (tŭ.rĭ.sĕn'sĭs) is from the L. masc. adj. turicensis, pertaining to Turicum, the Latin name of Zurich, Switzerland.[3]

Cronobacter muytjensii (mœ.tjәn.sĭ.ī), from the N.L. gen. n. muytjensii, of Muytjens, is named in honour of the Dutch microbiologist Harry Muytjens, who performed much of the early work on Enterobacter sakazakii.[6][7][8][9][10]

Cronobacter dublinensis (dŭb.lĭn.ĕn'sĭs, from the N.L. masc. adj. dublinensis, pertains to Dublin, Ireland, the origin of the type strain.[3]

C. dublinensis subsp. lausannensis (lô.săn.ĕn'sĭs) from the L. masc. adj. lausannensis, pertains to Lausanne, Switzerland, the origin of the type strain for this subspecies.[3]

C. dublinensis subsp. lactaridi (lăkt.ărĭd.ī), is from the L. n. lac lactis, milk, L. adj. aridus, dried, to give N.L. gen. n. lactaridi, of a dried milk.[3]

Cronobacter universalis ('lis) is L. masc. adj. universalis, of or belonging to all or universal.[2]

Cronobacter condimenti ('ti) is from the L. gen. n. condimenti, of spice or seasoning.[2]

See also[edit]


  1. ^ a b Iversen, C; et al. (2008). "Cronobacter gen. nov., a new genus to accommodate the biogroups of Enterobacter sakazakii, and proposal of Cronobacter sakazakii gen. nov. comb. nov., C. malonaticus sp. nov., C. turicensis sp. nov., C. muytjensii sp. nov., C. dublinensis sp. nov., Cronobacter genomospecies 1, and of three subspecies, C. dublinensis sp. nov. subsp. dublinensis subsp. nov., C. dublinensis sp. nov. subsp. lausannensis subsp. nov., and C. dublinensis sp. nov. subsp. lactaridi subsp. nov". International Journal of Systematic and Evolutionary Microbiology. 58 (6): 1442–1447. doi:10.1099/ijs.0.65577-0. PMID 18523192. 
  2. ^ a b c Joseph, S; et al. (2011). "Cronobacter condimenti sp. nov., isolated from spiced meat and Cronobacter universalis sp. nov., a novel species designation for Cronobacter sp. genomospecies 1, recovered from a leg infection, water, and food ingredients". International Journal of Systematic and Evolutionary Microbiology. 62: 1277–1283. doi:10.1099/ijs.0.032292-0. 
  3. ^ a b c d e Iversen, C; et al. (2007). "The taxonomy of Enterobacter sakazakii: proposal of a new genus Cronobacter gen. nov. and descriptions of Cronobacter sakazakii comb. nov. Cronobacter sakazakii subsp. sakazakii, comb. nov., Cronobacter sakazakii subsp. malonaticus subsp. nov., Cronobacter turicensis sp. nov., Cronobacter muytjensii sp. nov., Cronobacter dublinensis sp. nov. and Cronobacter genomospecies 1". BMC Evol. Biol. 7: 64. doi:10.1186/1471-2148-7-64. PMC 1868726Freely accessible. PMID 17439656. 
  4. ^ Stephan, R; et al. (2014). "Re-examination of the taxonomic status of Enterobacter helveticus, Enterobacter pulveris and Enterobacter turicensis as members of the genus Cronobacter and their reclassification in the genera Franconibacter gen. nov. and Siccibacter gen. nov. as Franconibacter helveticus comb. nov., Franconibacter pulveris comb. nov. and Siccibacter turicensis comb. nov., respectively". Int. J. Syst. Evol. Microbiol. 64: 3402–3410. doi:10.1099/ijs.0.059832-0. 
  5. ^ a b Farmer, JJ III; et al. (1980). "Enterobacter sakazakii: a new species of "Enterobacteriaceae" isolated from clinical specimens". Int. J. Syst. Bacteriol. 30 (3): 569–84. doi:10.1099/00207713-30-3-569. 
  6. ^ Muytjens, HL; van der Ros-van de Repe, J; van Druten, HAM (1984). "Enzymatic profiles of Enterobacter sakazakii and related species with special reference to the alpha-glucosidase reaction and reproducibility of the test system". J. Clin. Microbiol. 20 (4): 684–6. PMC 271411Freely accessible. PMID 6386874. 
  7. ^ Muytjens, HL; et al. (1983). "Analysis of eight cases of neonatal meningitis and sepsis due to Enterobacter sakazakii". J. Clin. Microbiol. 18 (1): 115–20. PMC 270753Freely accessible. PMID 6885983. 
  8. ^ Muytjens, HL; van der Ros van De Repe, J (1986). "Comparative in vitro susceptibilities of eight Enterobacter species, with special reference to Enterobacter sakazakii". Antimicrobial Agents and Chemotherapy. 29 (2): 367–70. doi:10.1128/aac.29.2.367. PMC 176414Freely accessible. PMID 3636109. 
  9. ^ Muytjens, HL; Roelofs-Willemse, H; Jaspar, GH (1988). "Quality of powdered substitutes for breast milk with regard to members of the family Enterobacteriaceae". J. Clin. Microbiol. 26 (4): 743–6. PMC 266435Freely accessible. PMID 3284901. 
  10. ^ Muytjens, HL; Kollee, LAA (1990). "Enterobacter sakazakii meningitis in neonates: Causative role of formula". Pediatric Infectious Disease Journal. 9 (5): 372. doi:10.1097/00006454-199005000-00016. 

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