Abstract
Background: Cronobacter sakazakii is an emerging pathogen shown to be responsible for many neonatal outbreaks with high mortality rate and is remarkably known to resist desiccation and survive in powder infant formula (PIF) for extended period of time. C. pulveris is also important as a newly developed foodborne pathogen but there is not yet enough published data on its surviving behavior. Reconstituted infant milk formula (RIMF) usually stated as the main vehicle associated with neonatal Cronobacter infections. Aim: The aim of this study was to investigate the survival of Cronobacter spp. (C. sakazakii and C. pulveris) in RIMF at various storage temperatures. Methods: The reconstituted formula was inoculated with five C. sakazakii isolates and four C. pulveris isolates separately and stored at room and refrigeration temperatures for 2, 4, 8, 24, 48, 72, and 96 h. Results: The results showed that C. sakazakii and C. pulveris were able to grow and multiply in RIMF at room temperature as the storage time increases. At 4ºC, population of CP4, CP2, and CS4 were remained as the initial levels until the end of storage period. Whereas CS1, CS3, CP1 and CP3 were not detected at 4°C after 72, 24, 72 and 8 h respectively. However, the viable count of CS5 and CS6 had increased by about 1 log at 4ºC after 8 h. Conclusion: This study demonstrated the significant diverse in behavior between the examined isolates in RIMF at room and refrigeration temperatures as highlighted. Furthermore, these results may improve understanding of C. sakazakii and C. pulveris surviving strategies which may lead to create an effective control of Cronobacter infections.