Enterobacter sakazakii

A Microbial Biorealm page on the genus Enterobacter sakazakii

Classification

Higher order taxa

Bacteria; Proteobacteria; Gammaproteobacteria; Enterobacterials; Enteribacteriaceae

Species

Enterobacter skazakii

Description and significance

Describe the appearance, habitat, etc. of the organism, and why it is important enough to have its genome sequenced. Describe how and where it was isolated. Include a picture or two (with sources) if you can find them.

Genome structure

Describe the size and content of the genome. How many chromosomes? Circular or linear? Other interesting features? What is known about its sequence? Does it have any plasmids? Are they important to the organism's lifestyle?

Cell structure and metabolism

Describe any interesting features and/or cell structures; how it gains energy; what important molecules it produces.

Ecology

Describe any interactions with other organisms (included eukaryotes), contributions to the environment, effect on environment, etc.

Pathology

E. sakazakii is a food borne pathogen can produce severe illnesses and death to persons with immunological deficiencies such as neonates, the elderly and persons with severe underlying diseases. In these populations E.sakazakii can successfully colonize, establish and ultimately produce disease. Virulence factors are still largely unknown and pathogenicity mechanisms have only begun to be researched. The adherence aspect of E.sakazakii virulence, maybe furthest along with regard to determining its properties pathenogenicity. (2)(6)

In humans, E. sakazakii has been found to affect specifically the vascular system the gastrointestinal system and the nervous system. Establishment in the human vascular system causes bactereaemia and/or sepsis which often proceeded by colonization beyond the blood brain barrier which results in ceribro spinal fluid infection and meningitis; this progresses into intracerebral infarctions, brain abscess and/or cyst formation resulting in central nervous system deterioration. Necrotizing enterocolitis (NEC), also associated with E. sakazakii infection, and is currently the most common gastrointestinal emergency in neonates, it characterized by necrosis of the gastrointestinal lumen.

Once infected, neonates have been found to have a mortality rate of 40 to 80% when infected and a 20% chance that survival is accompanied with serious neurological complications such as hydrocephalus, quadriplegia, brain abscess and retarded neural development (3)(5)(6).

Application to Biotechnology

Determining the complete genome sequence and allowing time for bioinformatic analysis is necessary in order to identify any practical uses for this species. (5)

Current Research

One of the more crucial types of research concerning E. sakazakii has been in developing novel ways in identifying it in food sources and in the general environment. Fatty Acid profiling seems to hold great promise as rapid GC-FID method that can identify and differentiate food pathogens by up to the species level in clinical, environmental, and food samples. This method of identification analyzes fatty acid compositions of whole bacteria cells to determine it’s (saturated: monounsaturated: cyclopropane) fatty acid ratios. A data base with the ability to identify all 134 strains of E. sakazakii fatty acid profiles has been developed by researchers and can produced reliable species level identification in about 24hrs.(7)

Novel ways of treating contaminated foods has also been an area of current research. Typical commercial sterilizing techniques such as UV radiation and several chemical disinfectants have been known to have a reduced efficacy towards E. sakazakii but, recent experiments have shown great promise in the use of bacteriophages. Four new lytic bacteriophages were isolated from a sewer treatment plant in Switzerland and have shown great efficacy in inhibiting outgrowth in bacteria cultures isolated from infant formula after only 4 hours inoculation; two phages in particular have even exhibited host specificity towards E. sakazakii. Applications of Listera phages as a non-destructive biocontrol method has been approved for use in foods since 2006 by the FDA, as a replacement or supplement to conventional controls; thus, the proposition of using phages to control this bacteria’s ubiquity in the food industry holds promise. Further information pertaining to E.sakazakii such as the genomic sequence, bioinformatic data as well as further tests with the new phage and increasing the number of potential phages is required if this bio-control is ever going to have any practical applications. (4)(5)(7)

New hygienic practices have been an area of research that has progressed slower compared to other areas due E. sakazakii biofilms and adhesive properties. It has been know for quite some time that food contamination for these bacteria often originates from using conventionally clean utensils and equipment for the preparation of infant formula in industrialized production, hospitals, day-care centers, food service kitchens and at home. Commercial liquid chemical disinfectants that so far have shown varying digress of efficacy. This is further complicated because the resiliency of E. sakazakii to disinfectants varies from strain to strain. As of now, data has shown that the best way to prevent biofilms from proliferating on food utensils has been to remove all trace amounts of infant formula or food, then follow with a disinfectant. The theory is that infant formula acts as a protective nourishing layer when left on utensils; therefore, removing all food particles will increase lethality of disinfectants. (2)(4)