Efficiency of a cleaning protocol for the removal of enterotoxigenic Staphylococcus aureus strains in dairy plants

Author(s)

Prado Martin, Jose Guilherme ; de Oliveira e Silva, Gabriela ; da Fonseca, Carolina Rodrigues ; Morales, Caio Baptista ; Pamplona Silva, Caroline Souza ; Miquelluti, Daniel Lima ; Porto, Ernani

• Document type: Journal article
• Source: International Journal of Food Microbiology; v. 238, p. 295-301, DEC 5 2016.
• Web of Science Citations: 8

Abstract

Staphylococci are considered a major concern in dairy plants mainly due to the intensive production flow, automation of, processing plants and increased demand in the microbiological quality of dairy products. This study aimed to identify S. aureus strains isolated from three Brazilian dairy plants, evaluate the influence of time, temperature and contact surface on the bacterial adhesion process, as well as the efficiency of simulated hygiene and sanitation protocol in removing adhered cells. For genotypic analyses, the presence of icaA and icaD in strains was evaluated. Adherence assays were performed in biofilm reactor, comparing the influence of 2 temperatures (5 degrees C and 35 degrees C), 2 surfaces (stainless steel and polypropylene) and 4 contact times (3, 6, 12 h and post-sanitization). To evaluate the process effectiveness in removing adhered cells, neutral detergent and sanitizing agent based on sodium hypochlorite were used in order to simulate the situation observed in one of the dairy plants analyzed. The presence of icaA and icaD genes was determined in 75.3% and 77.6% of strains, respectively; 70.6% of isolates showed both genes, whereas 17.6% showed no genes. Genes for enterotoxin production were found in all samples, relating to SEG and SEH toxins. The number of cells adhered on both surfaces was about 3 and 6 log(10) CFU/cm(2) at temperatures of 5 degrees C and 35 degrees C, respectively, for most situations evaluated, with significant increase over the evaluation period. In general, the temperature of 35 degrees C favored greater adherence of S. aureus. At 5 degrees C, there was a considerable number of adhered cells, but in populations significantly lower than those observed at 35 degrees C. The cleaning and sanitizing protocol was ineffective in removing adhered cells; better performance of sodium hypochlorite was observed at 5 degrees C, which should be related to lower adherence observed at this temperature. Thus, the process was not able to reduce the number of S. aureus bacteria adhered on both surfaces to safe levels under the conditions evaluated. (C) 2016 Elsevier B.V. All rights reserved. (AU)

• FAPESP's process: 11/07192-7 - Genotypic and phenotypic study of staphylococci coagulase positive potencially enterotoxigenic and biofilm formers in Minas Frescal cheese manufacturers
• Grantee: Ernani Porto
• Support Opportunities: Regular Research Grants