Investigation on the Factors Affecting Cronobacter sakazakii Contamination Levels in Reconstituted Powdered Infant Formula

Abstract

IntroductionCertain strains of Cronobacter sakazakii can cause serious invasive infections in children, mainly those <2 months old and fed with powdered infant formula (PIF). The infectious dose of C. sakazakii is unknown but evidence suggests that it is approximately 1000 colony forming units (CFU). PIF is currently considered safe if its end-product C. sakazakii level is <1 CFU/g. In this study, we determined the lag time, generation time (GT), and growth rate of five pooled C. sakazakii isolates to evaluate the factors affecting contamination levels in reconstituted PIF.Methods1.71 log CFU/ml of C. sakazakii were inoculated into 100 and 3000 ml of reconstituted PIF and incubated at 22 and 35°C. Growth was evaluated over a 24-h period. ComBase was used for modeling.ResultsIn 3000 ml, the growth rate was 0.45 ± 0.02 log CFU/h with a lag phase of 3 ± 0.05 h and GT of 0.67 h at 22°C, while the growth rate was 0.73 ± 0.01 log CFU/h with a lag phase of 0.45 ± 0.03 h and GT of 0.41 h at 35° C.ConclusionCronobacter sakazakii grows rapidly in reconstituted PIF, especially at 35° C.

The Roles of Epidemiologists, Laboratorians, and Public Health Agencies in Preventing Invasive Cronobacter Infection

“…(Of note, in end-product testing, that cluster would appear as one CFU, even though all 10 cells could multiply independently.) Let us be conservative and round up the generation time determined by Dr. Parra Flores in his article in this Frontiers Topic symposium ( 35 ), which is consistent with the value found by others. Using a generation time of a half hour at 35°C (a temperature roughly comparable to the 36–37°C body temperature of an afebrile neonate) and assuming virulent Cronobacter strains thrive in the neonatal gastrointestinal tract, the 10-cell cluster would reach an infectious dose of 1,000 CFU within 3.5 h, a time interval consistent with the time it takes an infant to consume and digest a formula feeding.…”

“…These resulted in a risk assessment model, as well as a series of reports and recommendations [FAO/WHO 1 ]. In this Frontiers Topic symposium, Dr. Parra Flores applies the WHO’s risk assessment tool to explore the effect of temperature on Cronobacter growth ( 35 ). In 2006, WHO stated that “ contaminated PIF has been convincingly shown, both epidemiologically and microbiologically, to be the vehicle and source of infection in infants ” ( 36 ).…”

“…The World Health Organization’s current recommendations related to Cronobacter are that PIF be reconstituted with water that has been boiled and then cooled to 70°C, to inactivate any Cronobacter contaminating the PIF ( 55 , 56 ). There are at least three problems with this recommendation, one of which was highlighted in Dr. Parra Flores’ Frontiers Topic manuscript ( 35 ). First, it is unlikely that this recommendation will be accurately followed in a home setting.…”

Occurrence and molecular characterization of different virulence-associated genes of Cronobacter sakazakii isolates from some foods and dust samples

“…Infant formulas and other cereal-based foods consumed by infants and young children must be free of this pathogen according to national and international authorities. In addition, C. sakazakii contamination has repeatedly been detected in factories processing baby foods and ingredients used for making baby foods (PARRA-FLORES et al, 2015). Dust particles in the air of such a facility may act as a vector of C. sakazakii dissemination.…”

Multiplexed Lateral Flow Test for Detection and Differentiation of Cronobacter sakazakii Serotypes O1 and O2

“…As Cronobacter spp. does not survive the standard pasteurization process, a Cronobacter contamination critical for causing disease can only occur during filling and packaging and/or during reconstitution of PIF (Nazarowec-White and Farber, 1997 ; Parra-Flores et al, 2015 ). Furthermore, a hallmark of Cronobacter spp.…”