Short communication: Pasteurization as a means of inactivating staphylococcal enterotoxins A, B, and C in milk

Abstract

Our aim was to assess the effect of pasteurization temperature on inactivation of staphylococcal enterotoxins (SE). Milk samples were inoculated with log 4.38 to 5.18cfu/mL of 40 different Staphylococcus aureus strains having the ability to produce types A, B, or C SE and incubated at 37°C for 24h to develop SE. This incubation was followed by heat treatment for 15 s at 72, 85, and 92°C. Samples were analyzed for Staph. aureus count by plate method and, specifically, for SE presence. An enzyme-linked immunofluorescent assay on a MiniVIDAS analyzer (bioMérieux, Marcy l'Étoile, France) was used to detect SE, which were determined semiquantitatively based on test values. The Staph. aureus count in milk before pasteurization did not affect the amount of SE. Before pasteurization, SEB was detected in the lowest amount compared with other SE types. Staphylococcal enterotoxins were markedly reduced with pasteurization and inactivated at pasteurization temperatures to an extent depending on the amount in the sample before pasteurization. After pasteurization at 72°C, SE were detected in 87.5% of samples (35/40), after pasteurization at 85°C in 52.5% of samples (21/40), and after pasteurization at 92°C in 45.0% of samples (18/40). We determined that SE may still persist in milk even when Staph. aureus bacteria are inactivated through pasteurization. Although pasteurization may partially inactivate SE in milk, a key measure in the prevention of staphylococcal enterotoxicosis linked to pasteurized milk consumption is to avoid any cold chain disruption during milk production and processing.

Staphylococcus aureus and Staphylococcal enterotoxin detection in raw milk and cheese origin coagulase positive isolates

“…According to the matter, Necidova et al (2016) examined the effect of pasteurization inactivating staphylococcal enterotoxins A, B, and C in milk. For this, milk samples were inoculated with log 4.38 to 5.18 cfu/ml of 50 different S. aureus strains having the ability to produce types A, B, or C SE and incubated at 37°C for 24 h to develop SE.…”

Short communication: Search for superantigen genes in coagulase-negative staphylococci isolated from bovine milk in Canada

“…In addition, staphylococcal enterotoxins are highly resistant to heat and will resist treatments that destroy bacterial cells (Le Loir et al, 2003;Podkowik et al, 2013). For example, staphylococcal enterotoxins may persist in milk after pasteurization (Necidova et al, 2016). These potent exotoxins are also secreted by staphylococcal species other than S. aureus (Podkowik et al, 2013;Tuffs et al, 2018).…”

The use of bacteriophages to control and detect pathogens in the dairy industry

“…While pasteurisation of raw milk eradicates this pathogen, which may have originated from milk‐producing animals with subclinical mastitis, enterotoxin‐producing S. aureus is also a common human skin commensal, and thus, contamination of foodstuffs can occur at the handling stage after processing (Argudín et al ). It is worthy of mention that staphylococcal enterotoxins (SEs) are resistant to heat treatments, and some of these superantigens can persist in milk even after pasteurisation (Necidova et al ). Staphylococcal enterotoxin‐producing S. aureus should ideally be eliminated prior to pasteurisation.…”