Cronobacter sakazakii local isolates response to acid stress and their resuscitability

Abstract

Cronobacter spp. has been reported to cause meningitis, necrotizing enterocolitis, and septicemia in a group of infants through the consumption of powder infant formula. These bacteria are reported to withstand various stress conditions such as heating, drying, low water activity, low pH, etc. A local isolate of Cronobacter sakazakii YRt2a was reportedly survived and entered Viable But Non-Culturable (VBNC) conditions during desiccation stress. This study aims to study the behavior of local isolates of Cronobacter spp. in response to acid stress and its resuscitability. C. sakazakii E2 and YRt2a were grown in TSB at pH 3.0±0.2 or 3.5±0.2. The number of culturable cells and viable cells were enumerated by the Total Plate Count and Direct Viable Count methods, respectively. Resuscitation was done by growing the stress or VBNC cells in TSB with or without sodium pyruvate, catalase, Tween 20, or Cronobacter autoinducer. The results showed that C. sakazakii E2 and YRt2a entered VBNC state after 60 mins of exposure to pH 3.0±0.2, while remained culturable after 120 minutes exposure to pH 3.5±0.2. TSB with or without sodium pyruvate, catalase, Tween 20, or Cronobacter autoinducer could resuscitate the stress or VBNC cells of C. sakazakii. Stress or VBNC state experienced by C. sakazakii in response to acid tends to be transient and can be resuscitated. C. sakazakii experiencing stress or VBNC may pose a risk for food safety.