Enterobacter sakazakii

Enterobacter sakazakii, now reclassified as Cronobacter sakazakii, is a Gram-negative rod-shaped bacterium of the family Enterobacteriaceae. It is an opportunistic pathogen that can cause severe infections, particularly in neonates and immunocompromised individuals.

Taxonomy

Enterobacter sakazakii was originally classified within the genus Enterobacter. However, based on molecular phylogenetic studies, it was reclassified into the genus Cronobacter. The reclassification was based on 16S rRNA gene sequencing and other genetic analyses that demonstrated significant differences from other Enterobacter species.

Morphology and Physiology

Cronobacter sakazakii is a facultative anaerobe, meaning it can grow in both the presence and absence of oxygen. It is a motile bacterium, possessing peritrichous flagella that allow it to move. The bacterium is capable of fermenting a variety of sugars, producing acid and gas as metabolic byproducts.

Pathogenicity

Cronobacter sakazakii is known for its ability to cause neonatal meningitis, sepsis, and necrotizing enterocolitis. The bacterium is particularly dangerous for infants, especially those who are premature or have low birth weight. The mortality rate for infected neonates can be as high as 40-80%.

Virulence Factors

The pathogenicity of Cronobacter sakazakii is attributed to several virulence factors, including:

• Adhesins that facilitate attachment to host cells.
• Invasins that enable the bacterium to penetrate host tissues.
• Capsular polysaccharides that protect against phagocytosis.
• Endotoxins that trigger inflammatory responses.

Epidemiology

Cronobacter sakazakii is found in a variety of environments, including water, soil, and food. It is most commonly associated with powdered infant formula, which can become contaminated during production or preparation. The bacterium can survive in dry conditions, making it a persistent contaminant in dry food products.

Diagnosis

Diagnosis of Cronobacter sakazakii infection involves microbiological culture of blood, cerebrospinal fluid, or other sterile body fluids. The bacterium can be identified by its characteristic growth on selective media and confirmed by biochemical tests or molecular methods such as PCR.

Treatment

Treatment of Cronobacter sakazakii infections typically involves the use of antibiotics. However, the choice of antibiotic may be complicated by the bacterium's resistance to certain drugs. Commonly used antibiotics include ampicillin and gentamicin, but susceptibility testing is recommended to guide therapy.

Prevention

Preventive measures focus on minimizing the risk of contamination in powdered infant formula. This includes:

• Strict hygiene practices during formula preparation.
• Using sterile water to reconstitute formula.
• Storing prepared formula at appropriate temperatures to inhibit bacterial growth.

See Also

• Cronobacter
• Neonatal meningitis
• Food safety

External Links

• CDC - Cronobacter
• WHO - Cronobacter