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Cronobacter: For health professionals

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What health professionals need to know about Cronobacter

Cronobacter is a bacterium found in a variety of dried foods, including powdered infant formula, powdered milk and starches. Although Cronobacter infections are rare, they can cause serious and potentially fatal disease, especially in newborns and infants.

Cronobacter is a genus consisting of opportunistic bacterial pathogens that have caused serious human infection. Cronobacter spp. are gram-negative, facultative anaerobes and can live in very dry environments.

Cronobacter was formerly known as Enterobacter sakazakii, but has since been reclassified as a genus encompassing 7 species:

All 7 species of Cronobacter are considered capable of causing human infection.

Clinical manifestations of Cronobacter differ based on patient characteristics, and may include signs of systemic infection, sepsis and meningitis. Empiric antibiotic treatment should be initiated immediately for suspected Cronobacter cases at high risk of invasive infection. Laboratory culture and sensitivity can confirm a diagnosis of Cronobacter and identify the optimal treatment.

Historically, Cronobacter infection has been rarely reported in Canada. However, reports have suggested that global cases may be on the rise. As Cronobacter is not nationally notifiable in Canada, it is difficult to establish the true incidence of disease.

It's important for health care providers to learn about Cronobacter and to educate parents and caregivers about the risks of infection.

Transmission

Cronobacter infection has been associated with the consumption of the following foods:

Cronobacter bacteria have also been identified on various environmental surfaces, including:

The most commonly identified source of exposure is powdered infant formula, placing newborns and infants at an increased risk of infection. Although less common, stroke patients may also be exposed to Cronobacter through starch powders used as food thickening agents.

It is not known if Cronobacter spreads from person to person.

Clinical manifestations

Although rare, Cronobacter can cause illness in individuals of all ages. Due to the source of exposure, infants are at an increased risk of infection.

The spectrum of illness varies, ranging from asymptomatic to fatal disease. The case fatality rate of Cronobacter infection is approximately 40 percent. People who are at higher risk of developing invasive and severe Cronobacter infection include:

Cronobacter bacteria have also been isolated from the respiratory fluids and stools of asymptomatic individuals, suggesting colonization rather than infection.

In patients of all ages, Cronobacter infection may manifest as urinary tract or wound infections.

In infants, early signs of infection with Cronobacter may include:

If Cronobacter bacteria enter the bloodstream or central nervous system, infants may develop more severe manifestations, including:

Previous reports have indicated that infants born prematurely may be at an increased risk of bacteremia, whereas meningitis was more common in late pre-term or full-term infants. Although it may be possible for adults to develop bacteremia or meningitis, this is more likely in infant cases of Cronobacter infection.

Diagnosis

A diagnosis of Cronobacter infection is confirmed by culture. Cronobacter bacteria may be detected in the blood or cerebrospinal fluid from patients with bacteremia or meningitis.

It is important to note that if samples are delayed until after antibiotic administration, cerebrospinal fluid culture may be negative. In this case, other cellular abnormalities in the cerebrospinal fluid or a positive blood culture can confirm a diagnosis of bacterial meningitis.

Some complications of Cronobacter infection (such as cerebral abscess) can be detected from brain imaging studies.

Health professionals are encouraged to contact their local public health authority for guidance when suspecting a case of Cronobacter infection. If infection is confirmed, subsequent testing of contaminated environments may be recommended.

Treatment

Patients of all ages presenting with urinary tract or wound infections due to Cronobacter can be treated with antibiotics.

Infants with suspected Cronobacter infection should be monitored for sepsis or meningitis. If invasive infection is suspected, the infant should be admitted to the hospital and provided empiric antimicrobials without delay.

Multidrug-resistant strains of Cronobacter spp. have been identified. If a diagnosis of Cronobacter is confirmed, the antimicrobial susceptibility of bacterial isolates should be assessed to select the appropriate therapeutic agent.

Treatment isn't indicated in patients presenting with colonization of Cronobacter bacteria rather than infection.

Prevention

Powdered infant formula may become contaminated with Cronobacter during production, manufacturing or preparation by caregivers. Cross-contamination during preparation by caregivers may arise from leaving powdered infant formula mixed with water at room temperature or higher for long periods of time. If not used, prepared formula must be refrigerated immediately.

Breastfeeding and using commercial liquid infant formulas can reduce the risk of Cronobacter infection in infants.

Consult Health Canada's advice on preparing and handling powdered infant formula for more information.

Surveillance

Historically, Cronobacter infection has rarely been reported in Canada. Cronobacter infection is not a nationally notifiable disease, and there is currently no federal surveillance established for this bacterium.

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