Cronobacter sakazakii is an emerging food borne pathogen which has been associated with outbreaks of a rare form of infant meningitis. Although the origin of the microorganism has not been established, several
infection cases have been associated with the consumption of contaminated powdered infant formula (PIF). In the present study, growth characteristics of three C. sakazakii strains isolated from PIF samples and C.
muytjensii strain ATCC 51329, which was formerly the ATCC Preceptrol™ strain for the quality control of
‘Enterobacter sakazakii’ prior to the taxonomic revision, were investigated in Tryptone Soya broth (TSB) and
reconstituted PIF at 4, 10, 25, 37, 45 and 50ºC. The viability of heat treated cells of Cronobacter strains was
evaluated by plating on Violet Red Bile Glucose agar (VRBGA) and the Druggan-Forsythe-Iversen (DFI)
chromogenic agar followed by incubation at 37ºC. These strains were also subjected to higher temperatures
between 52 to 60ºC to measure their thermal tolerance. The mean generation time of all Cronobacter strains
were slightly lower in PIF than in TSB. C. muytjensii ATCC 51329 showed lower generation time in all culture
media and all temperatures compared to the Cronobacter food isolates, but the results were not significantly
different (P>0.05). The results also indicated that combination of PIF: DFI culture media had higher recovery at
all temperatures compared to other combinations. Survival study also indicated that C. muytjensii ATCC 51329
had higher D-value compared to food isolates at all incubation temperatures.