title: Efficiency of a cleaning protocol for the removal of enterotoxigenic Staphylococcus aureus strains in dairy plants.
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°C and 35°C), 2 surfaces (stainless steel and polypropylene) and 4 contact times (3, 6, 12h 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 log10CFU/cm2at temperatures of 5°C and 35°C, respectively, for most situations evaluated, with significant increase over the evaluation period. In general, the temperature of 35°C favored greater adherence of S. aureus. At 5°C, there was a considerable number of adhered cells, but in populations significantly lower than those observed at 35°C. The cleaning and sanitizing protocol was ineffective in removing adhered cells; better performance of sodium hypochlorite was observed at 5°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.
authors.affiliation: Hygiene and Dairy Laboratory, Agri-food Industry, Food and Nutrition Department, Luiz de Queiroz College of Agriculture, University of São Paulo (USP), Av. Pádua Dias, 11, Piracicaba, SP, Brazil. Electronic address: jguilhermepm@usp.br.
authors.forename: José Guilherme Prado
authors.initials: JG
authors.lastname: Martin
authors.affiliation: Hygiene and Dairy Laboratory, Agri-food Industry, Food and Nutrition Department, Luiz de Queiroz College of Agriculture, University of São Paulo (USP), Av. Pádua Dias, 11, Piracicaba, SP, Brazil. Electronic address: silvago84@gmail.com.
authors.forename: Gabriela
authors.initials: G
authors.lastname: de Oliveira E Silva
authors.affiliation: Hygiene and Dairy Laboratory, Agri-food Industry, Food and Nutrition Department, Luiz de Queiroz College of Agriculture, University of São Paulo (USP), Av. Pádua Dias, 11, Piracicaba, SP, Brazil. Electronic address: carolina@iftm.edu.br.
authors.forename: Carolina Rodrigues
authors.initials: CR
authors.lastname: da Fonseca
authors.affiliation: Hygiene and Dairy Laboratory, Agri-food Industry, Food and Nutrition Department, Luiz de Queiroz College of Agriculture, University of São Paulo (USP), Av. Pádua Dias, 11, Piracicaba, SP, Brazil. Electronic address: bcaiomorales@gmail.com.
authors.forename: Caio Baptista
authors.initials: CB
authors.lastname: Morales
authors.affiliation: Economics, Administration and Sociology Department, Luiz de Queiroz College of Agriculture, University of São Paulo (USP), Av. Pádua Dias, 11, Piracicaba, SP, Brazil. Electronic address: carolpamplona@gmail.com.
authors.forename: Caroline
authors.initials: C
authors.lastname: Souza Pamplona Silva
authors.affiliation: Hygiene and Dairy Laboratory, Agri-food Industry, Food and Nutrition Department, Luiz de Queiroz College of Agriculture, University of São Paulo (USP), Av. Pádua Dias, 11, Piracicaba, SP, Brazil. Electronic address: danielmiquelluti@yahoo.com.br.
authors.forename: Daniel Lima
authors.initials: DL
authors.lastname: Miquelluti
authors.affiliation: Hygiene and Dairy Laboratory, Agri-food Industry, Food and Nutrition Department, Luiz de Queiroz College of Agriculture, University of São Paulo (USP), Av. Pádua Dias, 11, Piracicaba, SP, Brazil. Electronic address: eporto@usp.br.
authors.forename: Ernani
authors.initials: E
authors.lastname: Porto
mesh_terms: D001422:Bacterial Adhesion / Q000187:drug effects* / Q000502:physiology; D018441:Biofilms / Q000187:drug effects*; D001938:Brazil; D003612:Dairying; D003902:Detergents / Q000494:pharmacology*; D004202:Disinfectants / Q000494:pharmacology*; D004768:Enterotoxins / Q000235:genetics*; D012973:Sodium Hypochlorite / Q000494:pharmacology*; D013203:Staphylococcal Infections / Q000517:prevention & control; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification
chemical_list: D003902:Detergents; D004202:Disinfectants; D004768:Enterotoxins; C402489:Staphylococcal enterotoxin H; D012973:Sodium Hypochlorite
keywords: Dairy; Enterotoxin; Minas fresh cheese; Staphylococcus aureus; ica genes