Cronobacter sakazakii: A Pathogen Titan

In February of 2022, Cronobacter sakazakii (C. sakazakii) made new headlines as the bacteria responsible for the deaths of two infants and the severe illness of two others. The gram-negative bacteria were first isolated in 1953 and are now associated with the dangerous contamination of powdered infant formula. Five years later in 1958, the first documented neonatal meningitis from C. sakazakii occurred. First described as Enterobacter sakazakii by John J. Farmer in 1980, it was renamed in 2007 after the Greek titan Cronos, who devoured his children. Common symptoms of a C. sakazakii infection in neonates are sepsis, bacteremia, and meningitis, leading to a mortality rate of 40-80%. However, there is less awareness that C. sakazakii is not only a danger to formula-fed infants. Other infections have been reported in non-formula-fed infants and adults.

In 2018, a case was reported in Australia where a breast milk-fed infant died from a C. sakazakii infection. It was later determined that the infant had been infected by a breast pump that had not been cleaned thoroughly that had been colonized with C. sakazakii. Adult cases of C. sakazakii infections are observed primarily in the elderly and immunocompromised. Symptoms in adult infections have presented beyond the nervous system, with infections observed in the reproductive, urinary, and gastrointestinal systems. One study by Yong et al. traced a food-borne, acute gastroenteritis outbreak in a Chinese high school to a catered meal contaminated with C. sakazakii. These case studies now beg the question, is C. sakazakii prevalent in the environment, and how are adults becoming infected by a bacterium that is publicly associated with infant formula?

A Persistent, Ubiquitous Bacteria

C. sakazakii’s tolerance for extreme environmental stressors presents a unique challenge in preventing contamination. Most notably, C. sakazakii has demonstrated a high drying tolerance that allows it to remain viable for up to two years; providing the opportunity for C. sakazakii to survive the desiccation step in powdered infant formula processing and continue growth when the powder is reconstituted with water. This resistance is thought to be due to the Cronobacter genus’ ability to produce biofilms, allowing water to persist within the biofilm and protect the bacteria from desiccation.

Preventing contamination is further complicated by the Cronobacter genus prevalence in the environment. Having been isolated from consumer-grade foodstuffs, domestic water, and even household sponges. This inherent presence in the environment, coupled with its ability to withstand environmental stressors, may create ideal conditions for easy, persistent contamination in sectors beyond infant formula, like manufacturing, food, and healthcare.

Is Cronobacter in Your Water System?

As widespread as it is in nature, only a few studies have focused on isolating Cronobacter from water, pipelines, and biofilms within those systems. In partnership with IEH, EST is currently in the early stages of researching the prevalence of C. sakazakii in healthcare water systems. Our goal is to raise awareness of this dangerous pathogen in critical care settings such as NICUs, formula preparation areas, and adult ICUs. If you want to stay updated on our research and other educational articles, sign up for our newsletter here.

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