Cronobacter sakazakii in powdered infant formula on sale in Portugal and its behaviour at different temperatures after reconstitution

Cronobacter sakazakii is an emerging foodborne pathogen which causes necrotizing enterocolitis, bacteremia and rarely, meningitis, especially in infants. The infection has commonly been associated with consumption of contaminated powdered infant formula (PIF). The frequency of disease is low, but its mortality rate is high. The main objective of this study was to evaluate the presence of C. sakazakii in PIF commercialized in different retail establishment located in the North of Portugal. Fifty-eight different PIF samples were tested. Their microbiological quality, namely the detection of C. sakazakii, the enumeration of Enterobacteriaceae, coliforms, coagulase-positive staphylococci and detection of Salmonella spp., was evaluated. According to our results, all the tested samples fulfilled the microbiological criteria of the European Union (Regulation (EEC) 2073/2005). The growth of C. sakazakii in two different PIF samples (reconstituted milk and weaning formula), at three different incubation temperatures (4, 22 and 37°C), was evaluated. No significant differences in the growth rate (p > 0.05) for the two tested PIF samples were observed. The growth of the pathogen was prevented during storage of the reconstituted PIF samples at 4 ºC. However, hazardous levels may be attained in less than 4 h at 37°C and 8 h at 22 °C.