Cronobacter sakazakii

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Enterobacter sakazakii.tif
Scientific classification
Kingdom: Bacteria
Phylum: Proteobacteria
Class: Gammaproteobacteria
Order: Enterobacteriales
Family: Enterobacteriaceae
Genus: Cronobacter
Binomial name
Cronobacter sakazakii
(Farmer et al. 1980)[1]

Cronobacter is the officially recognised bacterial genus name for the organism which before 2007 was named Enterobacter sakazakii. The name Enterobacter should no longer be used as the genus name as Cronobacter has been accepted in the International Journal of Systematic and Evolutionary Microbiology, along with the description of the new species.[2][3] . This is an opportunistic Gram-negative, rod-shaped, pathogenic bacterium that can live in very dry places. The majority of Cronobacter cases are adults but low-birth-weight preterm neonatal and older infants are highest at risk. The disease is associated with a rare cause of invasive infection infants with historically high case fatality rates (40–80%).


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[5][7] with some strains able to survive in a desiccated state for more than two years.[8] 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. There also was a study done where they found the strands of pathogen in 12% of field vegetables and 13% of hydroponic vegetables.[9][10]

All Cronobacter species, except C. condimenti, have been linked retrospectively to clinical cases of infection in either adults or infants. However multilocus sequence typing [11] 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',[12] 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, and the majority of Cronobacter cases are 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. .[13]


E. sakazakii was defined as a species in 1980 by Farmer 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.[1]

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.[2][3][14]

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.


  1. ^ a b Farmer JJ III, Asbury MA, Hickman FW, Brenner DJ (1980). the Enterobacteriaceae Study Group (USA). "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. 
  2. ^ a b Iversen C; Mullane N; Barbara McCardell; 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. 
  3. ^ a b Joseph; et al. "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". Int J Syst Evol Microbiol. 
  4. ^ Hunter, Catherine J.; Petrosyan, Mikael; Ford, Henri R.; Prasadarao, Nemani V. (2017-04-28). "Enterobacter sakazakii: An Emerging Pathogen in Infants and Neonates". Surgical Infections. 9 (5): 533–539. doi:10.1089/sur.2008.006. ISSN 1096-2964. PMC 2579942Freely accessible. PMID 18687047. 
  5. ^ a b Centers for Disease Control Prevention (CDC) (April 2002). "Enterobacter sakazakii infections associated with the use of powdered infant formula--Tennessee, 2001". MMWR. Morbidity and Mortality Weekly Report. 51 (14): 297–300. PMID 12002167.  Free full text
  6. ^ Lai KK (March 2001). "Enterobacter sakazakii infections among neonates, infants, children, and adults. Case reports and a review of the literature". Medicine. 80 (2): 113–22. doi:10.1097/00005792-200103000-00004. PMID 11307587. 
  7. ^ a b Bowen AB, Braden CR (August 2006). "Invasive Enterobacter sakazakii disease in infants". Emerging Infectious Diseases. 12 (8): 1185–9. doi:10.3201/eid1208.051509. PMC 3291213Freely accessible. PMID 16965695. 
  8. ^ Caubilla-Barron J & Forsythe S (2007). "Dry stress and survival time of Enterobacter sakazakii and other Enterobacteriaceae in dehydrated infant formula". Journal Food Protection. 13: 467–472. 
  9. ^ Ueda, Shigeko (2017-01-01). "Occurrence of Cronobacter spp. in Dried Foods, Fresh Vegetables and Soil". Biocontrol Science. 22 (1): 55–59. doi:10.4265/bio.22.55. ISSN 1884-0205. PMID 28367871. 
  10. ^ "FDA Recall of Kotex Tampons". Seeger Weiss LLP. Retrieved 2012-02-29. 
  11. ^ Baldwin; et al. "Multilocus sequence typing of Cronobacter sakazakii and Cronobacter malonaticus reveals stable clonal structures with clinical significance which do not correlate with biotypes". BMC Microbiology. 
  12. ^ Joseph & Forsythe (2011). "Association of Cronobacter sakazakii ST4 with neonatal infections". Emerging Infectious Diseases. 
  13. ^ Joseph S, Sonbol H, Hariri S, Desai P, McClelland M, Forsythe SJ (September 2012). "Diversity of the Cronobacter genus as revealed by multilocus sequence typing". Journal of Clinical Microbiology. 50 (9): 3031–9. doi:10.1128/JCM.00905-12. PMC 3421776Freely accessible. PMID 22785185. 
  14. ^ Iversen C, Lehner A, Mullane N, Bidlas E, Cleenwerck I, Marugg J, Fanning S, Stephan R, Joosten H (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 Evolutionary Biology. 7: 64. doi:10.1186/1471-2148-7-64. PMC 1868726Freely accessible. PMID 17439656.  Free full text

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