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Isolation and identification of Enterobacter sakazakii in infant milk formulas
Edith Torres-Chavolla1, Elsa Ramírez-Cerda, Rosalba Gutiérrez-Rojo
1Department of Molecular Microbiology, Centro de Investigación y Asistencia en Tecnología y Diseño del Estado de Jalisco, Guadalajara, Jalisco, México.
Abstract:
Enterobacter sakazakii is a pathogen of increasing medical concern, due to it being implicated in cases of meningitis, sepis, and necrotizing enterocolitis associated with the consumption of contaminated infant milk formula. At present, the method adopted by the Mexican food industry for the isolation and identification of E. sakazakii is based on the methodology of the United States Food and Drug Administration (FDA). However, this procedure is laborious and requires 7 days to obtain a confirmative result. The objective of this study was to determine the presence of E. sakazakii in two types of powdered infant milk formula, using an alternative method that requires less time and a smaller sample size than the FDA protocol. We adapted Leuschner's procedure by eliminating violet red bile glucose agar (VRBG) plates and instead adopting white light incubation to stimulate yellow pigment development. This allowed for isolation of E. sakazakii from powdered infant milk formula using a smaller sample and requiring only 5 days for analysis. Results showed that 92% of formula 1 and 32% of formula 2 was positive for E. sakazakii. The high contamination level of E. sakazakii suggests the need for monitoring hygienic conditions in the manufacturing plant and to assess the prevalence of E. sakazakii in powdered infant milk formulas sold in México.
Insights
A new, faster method for detecting Enterobacter sakazakii in infant formula found high contamination levels. This pathogen can cause serious illness in infants, highlighting the need for improved food safety monitoring.
Area of Science:
- Microbiology
- Food Safety
- Public Health
Background:
- Enterobacter sakazakii is a significant pathogen linked to severe infant illnesses through contaminated milk formula.
- Current detection methods used in Mexico are time-consuming (7 days) and labor-intensive.
Purpose of the Study:
- To develop and validate a more efficient method for isolating and identifying Enterobacter sakazakii in powdered infant milk formula.
- To compare the efficacy of the adapted method against the standard FDA protocol.
Main Methods:
- Adapted Leuschner's procedure, omitting violet red bile glucose agar (VRBG) plates.
- Utilized white light incubation to enhance yellow pigment development for easier identification.
- Analyzed powdered infant milk formula samples using a reduced sample size and a 5-day timeframe.
Main Results:
- The adapted method successfully isolated Enterobacter sakazakii in 92% of Formula 1 samples.
- Enterobacter sakazakii was detected in 32% of Formula 2 samples.
- The new method significantly reduced analysis time from 7 to 5 days.
Conclusions:
- The adapted method offers a faster and potentially more cost-effective alternative for Enterobacter sakazakii detection.
- High contamination rates underscore the critical need for enhanced hygiene monitoring in formula manufacturing.
- Further assessment of Enterobacter sakazakii prevalence in Mexican infant formulas is recommended.
