Staphylococcus aureus and Staphylococcal Enterotoxin A in Breaded Chicken Products: Detection and Behavior during the Cooking Process

Abstract

In this study we examined the presence of Staphylococcus aureus and staphylococcal enterotoxin A (SEA) in 20 industrial breaded chicken products obtained from different retail butchers and supermarket stores in Italy. The levels of contamination in the products analyzed were quite low, although the pH values and water activities (a w ) in the samples considered were in ranges favorable for S. aureus growth. As demonstrated by phenotypic and molecular characterization, in spite of the high percentage of coagulase-positive Staphylococcus strains, only three strains could be referred to the species S. aureus. Moreover, all the strains were negative in PCR assays targeting staphylococcal enterotoxin genes (seA to seE, seG to seJ, and seM to seO), as well as the toxic shock syndrome toxin 1 gene, and no SEA was detected in the retail breaded chicken samples analyzed by a reversed passive latex agglutination assay or by Western blotting. Hence, we evaluated the thermal resistance of two strains of SEA-producing S. aureus in a laboratory-scale preparation of precooked breaded chicken cutlets. The heat treatment employed in the manufacture determined the inactivation of S. aureus cells, but the preformed SEA remained active during product storage at 4°C. The presence of the staphylococci and, in particular, of S. aureus in the retail breaded chicken products analyzed is a potential health risk for consumers since the pH and a w values of these kinds of products are favorable for S. aureus growth. The thermal process used during their manufacture can limit staphylococcal contamination but cannot eliminate preformed toxins.

Development of Predictive Growth Models for Staphylococcus aureus and Bacillus cereus on Various Food Matrices Consisting of Ready-to-Eat (RTE) Foods

“…However, as most of the PMP models are based on data from the microbial behavior of healthy cells in liquid microbiological media, these models should be validated for each specific food product before they are used (Johnson, 1984;Pepe et al, 2006). In addition, unstressed cells grown in rich media in the laboratory probably do not accurately represent the physiology of cells found in food environments (Leyer and Johnson, 1993).…”

“…If environmental conditions such as time and temperature during food storage and preparation allow the growth of S. aureus, staphylococcal enterotoxins may be produced, offering potential harm to consumers (Sneed et al, 2004). There are several studies reporting the presence of S. aureus in RTE and perishable foods including raw pork or smoked ham (Atanassova et al, 2001), poultry products (Pepe et al, 2006), milk (Fujikawa and Morozumi, 2006), fish (Hiraki et al, 1998), or foods that are pre-pared in advance before consumption and stored after preparation without adequate refrigeration (Roberts, 1986). Furthermore, the presence of S. aureus on the work surfaces and utensils of foodservice outlets has been widely demonstrated by several studies (Gibson et al, 1988;Hiraki and Suzuki, 1999).…”

Staphylococcus aureus Enterotoxin A Gene Isolated From Raw Red Meat And Poultry in Tehran, Iran

“…Staphylococcus aureus produces a group of 21 enterotoxins, many of which are heat-resistant in foods (2,3). Therefore, measures to prevent the growth of S. aureus are critical because normal temperatures used in cooking will not destroy the toxins, and foods containing staphylococcal enterotoxin usually look and taste normal (4,5).…”

“…In a typical processing operation, after slaughtering and de-feathering, fresh chicken carcasses are eviscerated and washed. These procedures, especially de-feathering, increase the contamination by S. aureus (3,17). The bacterial contamination of poultry products occurs due to its improper control that depends on various factors, such as initial level of contamination of carcasses, the duration and temperature of storage, and hygienic practices during handling (9).…”

Food Compounds Inhibit Staphylococcus Aureus Bacteria and the Toxicity of Staphylococcus Enterotoxin A (SEA) Associated with Atopic Dermatitis

“…The enterotoxigenic bacteria and secreted toxins have been reported to cause clinical infections, and it has also been reported that they contaminate a broad variety of foods, including breaded chicken products (Pepe et al, 2006), canned mushrooms (Anderson et al, 1996), cheeses (Ertas et al, 2010;Ostyn et al, 2010;Rosengren et al, 2010), raw milk (Fusco et al, 2011;Heidinger et al, 2009), pork meat (Wallin-Carlquist et al, 2010), and other foods (Balaban & Rasooly, 2000) as well contaminating handles of shopping carts (Mizumachi et al, 2011) causing many foodborne illnesses in the United States each year (Shinefield & Ruff, 2009). Staphylococcal food poisoning is due to the absorption from the digestive tract into the circulation of the enterotoxins preformed in food A toxin level of <1 µg may induce symptoms of food poisoning.…”