Enterobacter sakazakii is a Gram-negative

Gram-negative

Gram-negative bacteria are bacteria that do not retain crystal violet dye in the Gram staining protocol. In a Gram stain test, a counterstain is added after the crystal violet, coloring all Gram-negative bacteria with a red or pink color...

 rod-shaped

Bacillus

Bacillus is a genus of Gram-positive, rod-shaped bacteria and a member of the division Firmicutes. Bacillus species can be obligate aerobes or facultative anaerobes, and test positive for the enzyme catalase. Ubiquitous in nature, Bacillus includes both free-living and pathogenic species...

 pathogenic bacterium

Bacteria

Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...

. It is a rare cause of invasive infection with historically high case fatality rates (40–80%) in infant

Infant

A newborn or baby is the very young offspring of a human or other mammal. A newborn is an infant who is within hours, days, or up to a few weeks from birth. In medical contexts, newborn or neonate refers to an infant in the first 28 days after birth...

s.

It can cause bacteraemia, meningitis

Meningitis

Meningitis is inflammation of the protective membranes covering the brain and spinal cord, known collectively as the meninges. The inflammation may be caused by infection with viruses, bacteria, or other microorganisms, and less commonly by certain drugs...

 and necrotising enterocolitis. E. sakazakii infection has been associated with the use of powdered infant formula

Infant formula

Infant formula is a manufactured food designed and marketed for feeding to babies and infants under 12 months of age, usually prepared for bottle-feeding or cup-feeding from powder or liquid . The U.S...

, with some strains able to survive in a desiccated state for more than 2 years.

Taxonomy

E. sakazakii was defined as a species in 1980 by Farmer et al. 1980. DNA-DNA hybridization showed that E. sakazakii was 53–54% related to species in two different genera, Enterobacter and Citrobacter. However diverse biogroups were described and Farmer et al. suggested that these may represent different species.

The taxonomic relationship E. sakazakii strains has since been clarified using f-AFLP

Aflp

AFLP may refer to:*amplified fragment length polymorphism, a highly sensitive tool used in molecular biology to detect DNA polymorphisms*acute fatty liver of pregnancy, a life-threatening liver condition that may occur during pregnancy...

, automated ribotyping

Ribotyping

Ribotyping involves the fingerprinting of genomic DNA restriction fragments that contain all or part of the genes coding for the 16S and 23S rRNA. Conceptually, ribotyping is similar to probing restriction fragments of chromosomal DNA with cloned probes ....

, full-length 16S rRNA gene sequencing and DNA-DNA hybridization. This has resulted in the classification of E. sakazakii as a new genus, Cronobacter

Cronobacter

Cronobacter is a genus of Gram-negative, facultatively-anaerobic, oxidase negative, catalase positive, rod-shaped bacteria of the family Enterobacteriaceae....

, comprising five species.