EFFECT OF DRY SANITIZATION ON DRY SURFACE BIOFILM OF Cronobacter sakazakii

Cronobacter sakazakii is an opportunistic foodborne pathogen that affects neonates, and has ability to produce dry surface biofilm (DSB). However, little is known about its resistance to dry sanitizers. This study aimed to evaluate the efficiency of dry sanitizers compared with sodium hypochlorite (SH) on DSB of C. sakazakii . DSB were formed on stainless steel or polypropylene coupons (10 cm²) using two cycles of hydrated/dry phases at 25 °C: T1 (48/48 h) or T2 (24/120 h). At DSB endpoint, the coupons were sanitized with 70% ethanol, a commercial product based on isopropyl alcohol (25%) and quaternary ammonium (0.015%), hot air (90±2 °C), UV-C light (254 nm), gaseous ozone (45±2 mg/L), or SH (200 mg/L, pH 6.5). All dry sanitizers showed limited antimicrobial activity (p > 0.05), with reductions ≤ 0.8 log CFU/cm² over 30 min exposure. In contrast, SH was effective against DSB regardless of the DSB formation protocol, with reductions ≥2 and >5 log CFU/cm² after 10 and 30 min, respectively. Interestingly, DSB formed with shorter hydrated phase and longer dry phase (T2) had greater sensitivity to SH, but it was not noted to dry sanitizers. CLSM images suggested the presence of VBNC cells, particularly after SH treatment. In conclusion, our results emphasize the importance of implementing stringent hygiene measures to control C. sakazakii DSB in the low moisture food industry, and indicate that SH is an effective sanitation strategy when the drying line is promptly addressed.