  Cronobacter sakazakii is an opportunistic pathogen associated with outbreaks
of neonatal necrotizing enterocolitis, septicemia, and meningitis.
Reconstituted powdered infant formulae (PIF) is the most common vehicle of
infection. Plate count methods do not provide direct information on the
physiological status of cells. Flow cytometry (FC) has been used to gain
insights into the physiological states of C. sakazakii after heat treatments,
and to compare FC results with plate counts. The percentage of compromised
cells increased as the percentage of live cells increased after the 100 C
treatment. However, the number of compromised cells after 60 or 65 C treatments
decreased as the percentage of live cells increased, showing that both mild
temperatures would not be completely effective eliminating all bacteria but
compromising their membranes, and showing that mild heat treatments are not
enough to guarantee the safety of PIF. FC was capable to detect C. sakazakii
compromised cells that cannot be detected with classical plate count methods,
thus it could be used to decreasing the risk of pathogenic viable but
non-culturable cells to be in the ingested food. Linear regression analysis
showed good correlations between plate count results vs FC results.
