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Mendonça R, Furtado R, Coelho A, Correia CB, Suyarko E, Borges V, Gomes JP, Pista A, Batista R. Raw milk cheeses from Beira Baixa, Portugal-A contributive study for the microbiological hygiene and safety assessment. Braz J Microbiol 2024; 55:1759-1772. [PMID: 38622468 PMCID: PMC11153484 DOI: 10.1007/s42770-024-01332-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Accepted: 04/03/2024] [Indexed: 04/17/2024] Open
Abstract
Due to specific bacterial microbiota, raw milk cheeses have appreciated sensory properties. However, they may pose a threat to consumer safety due to potential pathogens presence. This study evaluated the microbiological contamination of 98 raw milk cheeses from Beira Baixa, Portugal. Presence and enumeration of Coagulase Positive Staphylococci (CPS), Listeria monocytogenes, Salmonella spp., pathogenic Escherichia coli, and indicator microorganisms (non-pathogenic E. coli and Listeria spp.) was attained. E. coli antimicrobial resistance (AMR) was also evaluated. PCR and/or Whole genome sequencing (WGS) was used to characterize E. coli, Salmonella spp. and L. monocytogenes isolates. Sixteen cheeses (16.3%) were classified as Satisfactory, 59 (60.2%) as Borderline and 23 (23.5%) as Unsatisfactory/Potential Injurious to Health. L. monocytogenes, CPS > 104 cfu g-1, Extraintestinal pathogenic E. coli (ExPEC) and Salmonella spp. were detected in 4.1%, 6.1%, 3.1% and 1.0% of the samples, respectively. Listeria innocua (4.1%) and E. coli > 104 cfu g-1 (16.3%) were also detected. AMR E. coli was detected in 23/98 (23.5%) of the cheese samples, of which two were multidrug resistant. WGS identified genotypes already associated to human disease and Listeria spp. cluster analysis indicated that cheese contamination might be related with noncompliance with Good Hygiene Practices during cheese production.
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Affiliation(s)
- Rita Mendonça
- Department of Food and Nutrition, National Institute of Health Doutor Ricardo Jorge, Lisbon, Portugal.
- Faculty of Sciences, University of Lisbon, Lisbon, Portugal.
| | - Rosália Furtado
- Department of Food and Nutrition, National Institute of Health Doutor Ricardo Jorge, Lisbon, Portugal
| | - Anabela Coelho
- Department of Food and Nutrition, National Institute of Health Doutor Ricardo Jorge, Lisbon, Portugal
| | - Cristina Belo Correia
- Department of Food and Nutrition, National Institute of Health Doutor Ricardo Jorge, Lisbon, Portugal
| | - Elena Suyarko
- Department of Infectious Diseases, National Institute of Health Doutor Ricardo Jorge, Lisbon, Portugal
- NOVA School of Science and Technology, 2829-516, Caparica, Portugal
| | - Vítor Borges
- Department of Infectious Diseases, National Institute of Health Doutor Ricardo Jorge, Lisbon, Portugal
| | - João Paulo Gomes
- Department of Infectious Diseases, National Institute of Health Doutor Ricardo Jorge, Lisbon, Portugal
- Animal and Veterinary Research Center (CECAV), Faculty of Veterinary Medicine, Lusófona University-Lisbon University Centre, Lisbon, Portugal
| | - Angela Pista
- Department of Infectious Diseases, National Institute of Health Doutor Ricardo Jorge, Lisbon, Portugal
| | - Rita Batista
- Department of Food and Nutrition, National Institute of Health Doutor Ricardo Jorge, Lisbon, Portugal.
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Bianchi DM, Maurella C, Lenzi C, Fornasiero M, Barbaro A, Decastelli L. Influence of Season and Food Type on Bacterial and Entero-Toxigenic Prevalence of Staphylococcus aureus. Toxins (Basel) 2022; 14:toxins14100671. [PMID: 36287940 PMCID: PMC9611241 DOI: 10.3390/toxins14100671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2022] [Revised: 09/10/2022] [Accepted: 09/21/2022] [Indexed: 11/30/2022] Open
Abstract
Staphylococcus (S.) aureus is a coagulase-positive pathogen of interest for human health and food safety in particular. It can survive in a wide environmental temperature range (7–48 °C, optimum 37 °C). Its enterotoxins are thermostable, which increases the risk of potential contamination in a variety of food products. Here we investigated the influence of seasonality and food type on bacterial count and presence of S. aureus enterotoxins. To do this, we analyzed 3604 food samples collected over a 5-year period (2016–2020). Ordinal logistic regression showed an influence of both seasonality and food type on the bacterial count. Regarding bacterial counts, winter was found to be the season with the highest risk, while with regards to enterotoxin production, the highest risk was found in autumn, specifically in October. The risk of contamination with S. aureus was greatest for dairy products. Our findings may inform food epidemiologists about foodborne illness prevention and risk to human health.
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Affiliation(s)
- Daniela Manila Bianchi
- Istituto Zooprofilattico Sperimentale del Piemonte Liguria e Valle d’Aosta, 10154 Turin, Italy
- National Reference Laboratory for Coaugulase-Positive Staphylococci including S. aureus, Istituto Zooprofilattico Sperimentale del Piemonte Liguria e Valle d’Aosta, 10154 Turin, Italy
- Correspondence: (D.M.B.); (C.M.)
| | - Cristiana Maurella
- Istituto Zooprofilattico Sperimentale del Piemonte Liguria e Valle d’Aosta, 10154 Turin, Italy
- Correspondence: (D.M.B.); (C.M.)
| | - Christian Lenzi
- Department of Mathematics, Physics and Natural Sciences, University of Eastern Piedmont Amedeo Avogadro, 13100 Vercelli, Italy
| | - Massimo Fornasiero
- Istituto Zooprofilattico Sperimentale del Piemonte Liguria e Valle d’Aosta, 10154 Turin, Italy
| | - Antonio Barbaro
- Istituto Zooprofilattico Sperimentale del Piemonte Liguria e Valle d’Aosta, 10154 Turin, Italy
| | - Lucia Decastelli
- Istituto Zooprofilattico Sperimentale del Piemonte Liguria e Valle d’Aosta, 10154 Turin, Italy
- National Reference Laboratory for Coaugulase-Positive Staphylococci including S. aureus, Istituto Zooprofilattico Sperimentale del Piemonte Liguria e Valle d’Aosta, 10154 Turin, Italy
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Huang Z, Yu X, Yang Q, Zhao Y, Wu W. Aptasensors for Staphylococcus aureus Risk Assessment in Food. Front Microbiol 2021; 12:714265. [PMID: 34603242 PMCID: PMC8483178 DOI: 10.3389/fmicb.2021.714265] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Accepted: 08/17/2021] [Indexed: 12/30/2022] Open
Abstract
Staphylococcus aureus (S. aureus) is the top ordinary pathogen causing epidemic and food poisoning. The authentication of S. aureus has great significance for pathologic diagnosis and food hygiene supervision. Various biosensor methods have been established for identification. This paper reviews the research progress of aptasensors for S. aureus detection, focusing on the classification of aptamer technologies, including optical aptasensors and electrochemical aptasensors. Furthermore, the feasibility and future challenges of S. aureus detection for aptamer assays are discussed. Combining aptasensors with nanomaterials appears to be the developing trend in aptasensors.
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Affiliation(s)
- Ziqian Huang
- College of Food Science and Engineering, Qingdao Agricultural University, Qingdao, China
| | - Xin Yu
- Qingdao Municipal Hospital, Qingdao, China
| | - Qingli Yang
- College of Food Science and Engineering, Qingdao Agricultural University, Qingdao, China
| | - Ying Zhao
- Department of Anesthesiology, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Qingdao, China
| | - Wei Wu
- College of Food Science and Engineering, Qingdao Agricultural University, Qingdao, China
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Kuo FY, Lin WL, Chen YC. Affinity capture using peptide-functionalized magnetic nanoparticles to target Staphylococcus aureus. NANOSCALE 2016; 8:9217-9225. [PMID: 27087258 DOI: 10.1039/c6nr00368k] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Staphylococcus aureus, a commonly found pathogen, can cause food poisoning and infections. Thus, it is necessary to develop analytical methods for the rapid screening of S. aureus in suspicious samples. Magnetic nanoparticles (MNPs) are widely used as affinity probes to selectively enrich target species from complex samples because of their high specific surface area and magnetic properties. The MNP surface should be functionalized to have the capability to target specific species. We herein propose a straightforward method to functionalize aluminum oxide-coated iron oxide (Fe3O4@Al2O3) MNPs with the peptide HHHHHHDEEGLFVD (D). The peptide D was comprised of three domains: polyhistidine (H6) used as the linker, DEE added as the spacer, and GLFVD used for targeting S. aureus. D was immobilized on the surface of Fe3O4@Al2O3 MNPs through H6-Al chelation. Our results showed that the D-functionalized Fe3O4@Al2O3 MNPs (D-Fe3O4 MNPs) possess the capability to target S. aureus. The selective trapping experiments were conducted under microwave-heating for only 60 s, and sufficient bacterial cells were trapped by the MNPs to be identified by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). We demonstrated that the D-Fe3O4@Al2O3 MNPs combined with MALDI-MS can be used to rapidly characterize trace amounts of S. aureus in complex juice and egg samples.
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Affiliation(s)
- Fang-Yin Kuo
- Department of Applied Chemistry, National Chiao Tung University, Hsinchu 300, Taiwan.
| | - Wei-Lien Lin
- Institute of Molecular Science, National Chiao Tung University, Hsinchu 300, Taiwan
| | - Yu-Chie Chen
- Department of Applied Chemistry, National Chiao Tung University, Hsinchu 300, Taiwan. and Institute of Molecular Science, National Chiao Tung University, Hsinchu 300, Taiwan
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Oguttu JW, McCrindle CM, Makita K, Grace D. Investigation of the food value chain of ready-to-eat chicken and the associated risk for staphylococcal food poisoning in Tshwane Metropole, South Africa. Food Control 2014. [DOI: 10.1016/j.foodcont.2014.04.026] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Gustafson JE, Muthaiyan A, Dupre JM, Ricke SC. WITHDRAWN: Staphylococcus aureus and understanding the factors that impact enterotoxin production in foods: A review. Food Control 2014. [DOI: 10.1016/j.foodcont.2014.10.016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Abstract
ABSTRACT
As the manufacture of cheese relies in part on the select outgrowth of microorganisms, such conditions can also allow for the multiplication of unwanted contaminants. Milk ultimately becomes contaminated with microorganisms originating from infection, the farm environment, and feedstuffs, as well as milking and processing equipment. Thus, poor sanitation, improper milk handling, and animal health issues can result in not only decreased yield and poor quality but also sporadic cases and outbreaks of dairy-related disease. The entry, establishment, and persistence of food-borne pathogens in dairy processing environments also present a considerable risk to products postprocessing. Food safety management systems coupled with regulatory policies and microbiological standards for milk and milk products currently implemented in various nations work to reduce risk while improving the quality and safety of cheese and other dairy products. With that, cheese has enjoyed an excellent food safety record with relatively few outbreaks of food-borne disease considering the amount of cheese produced and consumed worldwide. However, as cheese production and consumption continue to grow, we must remain vigilant in ensuring the continued production of safe, high-quality cheese.
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Rajkovic A. Incidence, growth and enterotoxin production of Staphylococcus aureus in insufficiently dried traditional beef ham “govedja pršuta” under different storage conditions. Food Control 2012. [DOI: 10.1016/j.foodcont.2012.03.028] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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10
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Ahn SH, Lee YJ, Lee JY, Paik HD. Microbiological Investigation of Ready-to-cook Pork Bulgogi on Korean Markets. Korean J Food Sci Anim Resour 2012. [DOI: 10.5851/kosfa.2012.32.4.441] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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Hennekinne JA, De Buyser ML, Dragacci S. Staphylococcus aureus and its food poisoning toxins: characterization and outbreak investigation. FEMS Microbiol Rev 2011; 36:815-36. [PMID: 22091892 DOI: 10.1111/j.1574-6976.2011.00311.x] [Citation(s) in RCA: 536] [Impact Index Per Article: 41.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2010] [Revised: 09/15/2011] [Accepted: 10/03/2011] [Indexed: 11/29/2022] Open
Abstract
Staphylococcal food poisoning (SFP) is one of the most common food-borne diseases and results from the ingestion of staphylococcal enterotoxins (SEs) preformed in food by enterotoxigenic strains of Staphylococcus aureus. To date, more than 20 SEs have been described: SEA to SElV. All of them have superantigenic activity whereas half of them have been proved to be emetic, representing a potential hazard for consumers. This review, divided into four parts, will focus on the following: (1) the worldwide story of SFP outbreaks, (2) the characteristics and behaviour of S. aureus in food environment, (3) the toxinogenic conditions and characteristics of SEs, and (4) SFP outbreaks including symptomatology, occurrence in the European Union and currently available methods used to characterize staphylococcal outbreaks.
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Affiliation(s)
- Jacques-Antoine Hennekinne
- French Agency for Food, Environmental and Occupational Health & Safety (Anses), Food Safety Laboratory of Maisons-Alfort, European Union Reference Laboratory for Coagulase Positive Staphylococci, Maisons-Alfort, France.
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Schelin J, Wallin-Carlquist N, Cohn MT, Lindqvist R, Barker GC, Rådström P. The formation of Staphylococcus aureus enterotoxin in food environments and advances in risk assessment. Virulence 2011; 2:580-92. [PMID: 22030860 PMCID: PMC3260550 DOI: 10.4161/viru.2.6.18122] [Citation(s) in RCA: 213] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2011] [Revised: 09/15/2011] [Accepted: 09/16/2011] [Indexed: 01/02/2023] Open
Abstract
The recent finding that the formation of staphylococcal enterotoxins in food is very different from that in cultures of pure Staphylococcus aureus sheds new light on, and brings into question, traditional microbial risk assessment methods based on planktonic liquid cultures. In fact, most bacteria in food appear to be associated with surfaces or tissues in various ways, and interaction with other bacteria through molecular signaling is prevalent. Nowadays it is well established that there are significant differences in the behavior of bacteria in the planktonic state and immobilized bacteria found in multicellular communities. Thus, in order to improve the production of high-quality, microbiologically safe food for human consumption, in situ data on enterotoxin formation in food environments are required to complement existing knowledge on the growth and survivability of S. aureus. This review focuses on enterotoxigenic S. aureus and describes recent findings related to enterotoxin formation in food environments, and ways in which risk assessment can take into account virulence behavior. An improved understanding of how environmental factors affect the expression of enterotoxins in foods will enable us to formulate new strategies for improved food safety.
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Affiliation(s)
- Jenny Schelin
- Applied Microbiology, Department of Chemistry, Lund University, Lund, Sweden.
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13
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White R. Wound dressings and other topical treatment modalities in bioburden control. J Wound Care 2011; 20:431-9. [DOI: 10.12968/jowc.2011.20.9.431] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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Nicolaou N, Xu Y, Goodacre R. Fourier transform infrared and Raman spectroscopies for the rapid detection, enumeration, and growth interaction of the bacteria Staphylococcus aureus and Lactococcus lactis ssp. cremoris in milk. Anal Chem 2011; 83:5681-7. [PMID: 21639098 DOI: 10.1021/ac2008256] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Staphylococcus aureus is one of the main pathogenic microorganisms found in milk and dairy products and has been involved in bacterial foodborne outbreaks in the past. Current enumeration techniques for bacteria are very time-consuming, typically taking 24 h or longer, and bacterial antagonism in the form of lactic acid bacteria (LAB) may inhibit the growth of S. aureus . Therefore, the aim of this investigation was to establish the accuracy and sensitivity of rapid nondestructive metabolic fingerprinting techniques, such as Fourier transform infrared (FT-IR) spectroscopy and Raman spectroscopy (RS), in combination with multivariate analysis techniques, for the detection and enumeration of S. aureus in milk, as well as to study the growth interaction between S. aureus and Lactococcus lactis ssp. cremoris , a common LAB. The two bacterial species were investigated both in a pure monoculture and in a combined inoculated coculture after inoculation into ultraheated milk during the first 24 h of growth at 37 °C. Plating techniques were used to obtain primary reference data for viable bacteria counts. Principal component discriminant function analysis, canonical correlation analysis, partial least-squares (PLS), and kernel PLS (KPLS) multivariate statistical techniques were employed to analyze the data. FT-IR provided very reasonable quantification results both with PLS and KPLS, the latter providing marginally better predictions, with correlation coefficients in the test set (Q(2)) and training set (R(2)) varying from 0.64 to 0.76 and from 0.78 to 0.88 for different bacterial sample combinations. RS results were less encouraging with high degrees of error and poor correlation to viable bacterial counts. S. aureus growth was not inhibited by the presence of the LAB, but metabolic fingerprinting of the coculture indicated that the phenotype of this dual bacterial culture was closer to that of pure LAB cultures. In conclusion, FT-IR spectroscopy in combination with the above multivariate techniques appears to be a promising discrimination and enumeration analytical technique for the two bacterial species. In addition, it has been demonstrated that the L. cremoris metabolic effect in milk dominates that of S. aureus even though there was no growth antagonism observed.
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Affiliation(s)
- Nicoletta Nicolaou
- School of Chemistry and Manchester Interdisciplinary Biocentre, The University of Manchester, Manchester, United Kingdom
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Argudín MÁ, Mendoza MC, Rodicio MR. Food poisoning and Staphylococcus aureus enterotoxins. Toxins (Basel) 2010; 2:1751-73. [PMID: 22069659 PMCID: PMC3153270 DOI: 10.3390/toxins2071751] [Citation(s) in RCA: 609] [Impact Index Per Article: 43.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2010] [Revised: 06/24/2010] [Accepted: 06/30/2010] [Indexed: 01/31/2023] Open
Abstract
Staphylococcus aureus produces a wide variety of toxins including staphylococcal enterotoxins (SEs; SEA to SEE, SEG to SEI, SER to SET) with demonstrated emetic activity, and staphylococcal-like (SEl) proteins, which are not emetic in a primate model (SElL and SElQ) or have yet to be tested (SElJ, SElK, SElM to SElP, SElU, SElU2 and SElV). SEs and SEls have been traditionally subdivided into classical (SEA to SEE) and new (SEG to SElU2) types. All possess superantigenic activity and are encoded by accessory genetic elements, including plasmids, prophages, pathogenicity islands, vSa genomic islands, or by genes located next to the staphylococcal cassette chromosome (SCC) implicated in methicillin resistance. SEs are a major cause of food poisoning, which typically occurs after ingestion of different foods, particularly processed meat and dairy products, contaminated with S. aureus by improper handling and subsequent storage at elevated temperatures. Symptoms are of rapid onset and include nausea and violent vomiting, with or without diarrhea. The illness is usually self-limiting and only occasionally it is severe enough to warrant hospitalization. SEA is the most common cause of staphylococcal food poisoning worldwide, but the involvement of other classical SEs has been also demonstrated. Of the new SE/SEls, only SEH have clearly been associated with food poisoning. However, genes encoding novel SEs as well as SEls with untested emetic activity are widely represented in S. aureus, and their role in pathogenesis may be underestimated.
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Affiliation(s)
- María Ángeles Argudín
- Department of Functional Biology (Section of Microbiology) and University Institute of Biotechnology of Asturias (IUBA), University of Oviedo, Oviedo, Spain.
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Sakai F, Ihara H, Aoyama K, Igarashi H, Yanahira S, Ohkubo T, Asao T, Kozaki S. Characteristics of enterotoxin H-producing Staphylococcus aureus isolated from clinical cases and properties of the enterotoxin productivity. J Food Prot 2008; 71:1855-60. [PMID: 18810869 DOI: 10.4315/0362-028x-71.9.1855] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Staphylococcal enterotoxin H (SEH) is predicted to be involved in staphylococcal food poisoning. To characterize SEH-producing Staphylococcus aureus isolates from staphylococcal food poisoning cases in Japan, we investigated the relationship between SEH production and coagulase serotype, which is an epidemiological marker, and compared the properties of SEH production with those of staphylococcal enterotoxins A (SEA) and B (SEB). SEH production was determined by a newly developed sandwich enzyme-linked immunosorbent assay. Eighty-six (59.7%) of 144 isolates from staphylococcal food poisoning cases produced SEH. Seventy-one of the SEH-producing isolates simultaneously produced SEA, SEB, or both. All SEH-producing isolates belonged to coagulase type VII, which was the predominant type, representing 99 (68.8%) of 144 isolates. The amount of SEH produced in brain heart infusion was almost the same as the amount of SEA and approximately 10-fold lower than that of SEB. SEH and SEA were produced mainly during the late exponential phase of growth, whereas SEB was produced mostly during the stationary phase. The production levels of SEH and SEA were gradually affected by decreases in water activity, but the production of SEB was greatly reduced under conditions of low water activity. These findings indicate that SEH-producing S. aureus isolates are of high prevalence in staphylococcal food poisoning cases. Given the unique epidemiological characteristic of these isolates, SEH and SEA probably are responsible for food poisoning.
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Affiliation(s)
- Fumihiko Sakai
- Institute of Food Hygiene, Snow Brand Milk Products Co., Ltd., Kawagoe, Saitama 350-1165, Japan.
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Pepe O, Blaiotta G, Bucci F, Anastasio M, Aponte M, Villani F. Staphylococcus aureus and staphylococcal enterotoxin A in breaded chicken products: detection and behavior during the cooking process. Appl Environ Microbiol 2006; 72:7057-62. [PMID: 17088378 PMCID: PMC1636142 DOI: 10.1128/aem.00198-06] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2006] [Accepted: 07/10/2006] [Indexed: 11/20/2022] Open
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 degrees 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.
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Affiliation(s)
- Olimpia Pepe
- Dipartimento di Scienza degli Alimenti, Università degli Studi di Napoli Federico II, I-80055 Portici, Italy.
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