English abstract
Enterobacter sakazakii is an emerging pathogen associated with lifethreatening neonatal infections resulting from the consumption of contaminated powdered infant formula (PIF) milk. Recent taxonomic analyses have determined that E. sakazakii comprises a number of genomospecies, and it has been proposed that E. sakazakii be reclassified as a novel genus, "Cronobacter".
E. sakazakii is an opportunistic pathogen and is rarely reported, little is known about the ecology of E. sakazakii. However, E. sakazakii has been found in manufacturing equipment which is a potential source of contamination for powdered infant formula (PIF) after pasteurization. This study was conducted to determine the risk of using infant formula for E. sakazakii infection and to identify any potential risks if the product is mishandled.
Stores in Dubai were surveyed to determine the market availability of PIF and packaging details were recorded. Random samples were analyzed for E. sakazakii and aerobic colony count (ACC). There were 18 different companies exporting their products for sale in Dubai.
The most common method of labelling was direct printing onto the can without any paper. This was observed on 91% of the samples studied. All of the products used bilingual labelling and most of them (91%) were using Arabic and English. Nine samples (6%) were found to be contaminated with E. sakazakii. E. sakazakii contamination did not correlate with ACC results which ranged between <10 CFU/g and 5.6 X 10CFU/g.
The disc diffusion method in addition to the Becton Dickinson Phoenix system was used to determine the antimicrobial susceptibility of E. sakazakii isolates. The E. sakazakii isolates were resistant to the following antibiotics: cephalothin, cefoxitin, ampicillin and amoxicillin/ clavulanate. This could have an influence on treatment.
Growth rates were determined using PIF reconstituted at 23°C and 37°C, the average generation times were 73 min and 25 min respectively. E. sakazakii takes a short time to double at 37°C, a common ambient kitchen temperature in the Gulf.
D-values were determined using the survival curve method at temperatures of 50°C, 60°C, 70°C and 80°C. They were 909; 0.87; 0.32 and 0.15 min respectively. E. sakazakii was significantly tolerant when exposed to 50°C, the recommended reconstitution temperature.
This study concluded that there is a risk, especially if PIF milk is mishandled and therefore E. sakazakii should be included in the Gulf Standard for PIF milk and also correct labelling of cans and instructions should be included in the standard.
