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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. The genome of one strain of Cronobacter sakazakii (BAA-894) has been sequenced and annotated.[3] According to multilocus sequence analysis (MLSA) the genus originated ~40 MYA, and the most clinically significant species, C. sakazakii, was distinguishable ~15-23 MYA. .[4]

Clinical significance[edit]

All Cronobacter species, except C. condimenti, have been linked retrospectively to clinical cases of infection in either adults or infants. The majority of Cronobacter cases occur in adults, most often bacteraemia and have not been studied in detail. However the majority of neonatal and infant infections have been associated with C. sakazakii and have received considerable attention.[5] Additionally, Cronobacter spp. are associated as causative agents of neonatal bacteraemia, meningitis and necrotising enterocolitis. However, multilocus sequence typing[6] has shown that the majority of neonatal meningitis 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',[7] and therefore this clone appears to be of greatest concern with infant infections.

Two cases of infants infected with Cronobacter sakazakii were reported to the Missouri Department of Health and Senior Services during the month leading up to Dec 18, 2011. One of the infants died from the infection. Enfamil announced that one lot of their newborn baby formula was pulled off of shelves (recalled) following the death of the infant, but Enfamil says their product has been tested and is safe.[8] CDC analysis of the two cases, using PFGE, revealed the cases were unrelated, and that one of the strains was isolated from both an opened infant formula tin, nursery water and reconstitution feed. No Cronobacter were isolated from unopened tins of infant formula from the same batch.[9] It is notable that the isolates of C. sakazakii from meningitis cases were from the ST4 clonal complex, and therefore support the previously retrospect study.[7]


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.[10] This proposal was validly published in 2008 with 5 species and 3 subspecies named.[1] The genus definition was further revised in 2012 with seven named species. This used the seven loci MLST data to support the definition of two new species; C. universalis and C. condimenti. .[4] Genetic and biochemical analysis has most recently shown that Cronobacter turicensis is not actually a member of the Cronobacter species and a new genus Siccibacter has been proposed.


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.[11]

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.[11]

Cronobacter turicensis (tŭ.rĭ.sĕn'sĭs) is from the L. masc. adj. turicensis, pertaining to Turicum, the Latin name of Zurich, Switzerland.[12]

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.[13][14][15][16][17]

Cronobacter dublinensis (dŭb.lĭn.ĕn'sĭs, from the N.L. masc. adj. dublinensis, pertains to Dublin, Ireland, the origin of the type strain.[10]

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.[10]

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.[10]

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.". IJSEM. 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". IJSEM. 62: 1277–1283. doi:10.1099/ijs.0.032292-0. 
  3. ^ Kucerova, E; et al. (2010). "Genome sequence of Cronobacter sakazakii BAA-894 and comparative genomic hybridization analysis with other Cronobacter species". PLoS ONE. 5 (3): e9556. doi:10.1371/journal.pone.0009556. PMC 2833190Freely accessible. PMID 20221447. 
  4. ^ a b Joseph, E; et al. (2012). "Diversity of the Cronobacter genus as revealed by multi locus sequence typing". J Clin Microbiol. 50 (9): 3031–3039. doi:10.1128/JCM.00905-12. PMC 3421776Freely accessible. PMID 22785185. 
  5. ^ Kucerova, E; et al. (2011). "Cronobacter: diversity and ubiquity". Quality Assurance and Safety of Foods and Crops. 3 (3): 104–122. doi:10.1111/j.1757-837X.2011.00104.x. 
  6. ^ Baldwin, A; et al. (2009). "Multilocus sequence typing of Cronobacter sakazakii and Cronobacter malonaticus reveals stable clonal structures with clinical significance which do not correlate with biotypes". BMC Microbiology. 9: 223. doi:10.1186/1471-2180-9-223. 
  7. ^ a b Joseph, S; Forsythe, JS (2011). "Association of Cronobacter sakazakii ST4 with neonatal infections". Emerging Infectious Diseases. 17 (9): 1713–1715. doi:10.3201/eid1709.110260. 
  8. ^ Reuters (27 December 2011). "Mead Johnson Says Retesting Show Enfamils is Safe". Fox News. Retrieved 29 December 2011. 
  9. ^ "FDA and CDC Update: Investigation of Cronobacter bacteria illness in infants" (Press release). CDC Media Relations. 30 December 2011. Retrieved 2012-02-24. 
  10. ^ a b c d 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. 
  11. ^ 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. 
  12. ^ . Genetic and biochemical analysis has shown that this species is not actually a member of the Cronobacter species and a new genus Siccibacter has been proposed. Essers, B; et al. (2006). "Neonatal sepsis with Enterobacter sakazakii in premature twins". Swiss Medical Weekly. 136 (Suppl. 151): 22S. 
  13. ^ 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. 
  14. ^ 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. 
  15. ^ 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. 
  16. ^ 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. 
  17. ^ Muytjens, HL; Kollee, LAA (1990). "Enterobacter sakazakii meningitis in neonates: Causative role of formula". Pediatric Infectious Disease. 9 (5): 372. doi:10.1097/00006454-199005000-00016. 

External links[edit]