Publications by authors named "Lues J"

Bioaerosols are defined as aerosols that comprise particles of biological origin or activity that may affect living organisms through infectivity, allergenicity, toxicity, or through pharmacological or other processes. Interest in bioaerosol exposure has increased over the last few decades. Exposure to bioaerosols may cause three major problems in the food industry, namely: (i) contamination of food (spoilage); (ii) allergic reactions in individual consumers; or (iii) infection by means of pathogenic microorganisms present in the aerosol.

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Background: Food borne illnesses and food poisoning are cause for concern globally. The diseases are often caused by food contamination with pathogenic bacteria due largely to poor sanitary habits or storage conditions.

Objectives: Prevalence of some bacteria on cleaned and sanitised food contact surfaces from eight convenience food plants in Gauteng (South Africa) was investigated with the view to evaluate the efficacy of the cleaning methods used with such food contact surfaces.

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This article reports on the antilisterial properties of selected organic acids and salt derivatives in order to suggest possible alternatives in food preservation and pathogen control in the poultry meat processing industry. The susceptibility of two Listeria monocytogenes isolates was assessed against five organic acids (lactic, acetic, malic, citric, and propionic) and two acid-salt derivatives (sorbic acid [potassium salt] and benzoic acid [sodium salt]) across a series of pH environments. Minimum inhibitory concentrations (MICs) of the acids were tested against the two strains by means of an agar-dilution method.

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This research focused on the influence of selected antimicrobial agents (AMAs) on the lipopolysaccharide (LPS) composition of Pseudomonas aeruginosa, a common causative agent of nosocomial infections. As LPS has been shown to play a role in attachment and virulence, the research is primarily aimed at shedding light on the response of these organisms to cleaning regimens in healthcare settings using various disinfectants. The endotoxicity and viability of the organisms following disinfection were further investigated via propagation in sublethal concentrations of the selected AMAs.

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The purpose of this paper is to assess the compliance of local government (LG) (metropolitan and district municipalities) with legislative requirements concerning the control of milk hygiene at production level. Municipal health services (MHS) managers are playing an increasingly important role through legislation to ensure the health and well-being of consumers and to secure consumer trust in the product. A survey questionnaire targeting 52 MHS managers or designated persons (directly responsible for milk control) at the various metropolitan municipalities (metros) and district municipalities (DMs) in South Africa was conducted.

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This paper presents data on personal- and general-hygiene knowledge and practices among food handlers in the delicatessens of a major retail group in the Western Cape in South Africa. Food handlers were interviewed by means of a structured questionnaire. Although the majority of food handlers adhered to basic hygiene principles, there is definitely a need for proper and continuous training in personal and general hygiene, not only for food handlers, but also for management.

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The effect of typical sanitizers on the composition and toxicity of lipopolysaccharides (LPSs) produced by Salmonella Enteritidis ATCC 13076 was analyzed. Salmonella Enteritidis was propagated up to the late exponential phase in the presence of commercial sanitizing solutions. LPS was extracted and derivatized with trifluoroacetylation, and gas chromatography-mass spectrometry analysis and the chromogenic Limulus amoebocyte lysate assay were used to assess the ultrastructure and toxicity of the LPS.

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The microbial composition of the air in various areas of a high-throughput chicken-slaughtering facility was investigated. Over a 4-mo period, 6 processing areas were sampled, and the influence of environmental factors was monitored. The highest counts of microorganisms were recorded in the initial stages of processing, comprising the receiving-killing and defeathering areas, whereas counts decreased toward the evisceration, air-chilling, packaging, and dispatch areas.

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Air constituency of the delicatessen sections of a retail group was assessed for the presence and distribution of bioaerosols and the correlation with physical parameters. Total viable counts were determined and the total coliforms, Escherichia coli, other members of the Enterobacteriaceae and Staphylococcus aureus were enumerated. These counts were relatively low, with the average total viable counts 1.

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The quality and shelf-life of perishable foodstuffs can be reduced by high concentrations in the processing environment of bioaerosols consisting of spoilage microbiota. A lack of documented literature on the distribution of such bioaerosols has, however, led to the underestimation of their impact. In the study reported here, the deboning rooms of selected South African red-meat abattoirs were investigated for airborne concentrations of staphylococci; the authors studied the distribution of Staphylococcus species in general, as well as the coagulase types of Staphylococcus aureus in particular.

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Street vendors in the city of Bloemfontein were investigated in order to assess the microbiological quality of the food being sold as well as the level of hygiene conditions under which these food stalls operate. The food samples which were collected included beef, chicken and gravy, while surface samples were taken from the food preparation tables and the hands of the vendors. A structured questionnaire and checklist were used in interviews to determine the status of the vending sites and associated food handling practices.

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This study focused on the influence of typical sanitizers on the composition of the lipopolysaccharides (LPS) produced by the verocytotoxin-producing (VTEC) Escherichia coli O111. We also aimed to cast light on the applicability of O-antigen-based serotyping and endotoxin based Limulus Amebocyte Lysate (LAL) assays applied in the food industry for the identification and quantification of Gram-negative bacteria. E.

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The quantity and composition of bioaerosols in a typical automated chicken egg layer management system (LMS) with a controlled internal climate (B) and without (A) were compared. The LMS-A used a fecal matter disposal system featuring a central opening in the floor through which the matter automatically dropped to an open-air lower level; the LMS-B used a conveyer belt below each hen battery set, which removed the fecal matter frequently. Bioaerosols were collected by impaction on agar.

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Developing countries are faced with high incidences of food poisoning outbreaks, with obvious economic consequences. In highly perishable foodstuffs such as fresh red meat the threat of food poisoning is particularly intense. In this study, red meat samples were collected from a deboning room of a high throughput abattoir.

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Lipopolysaccharides (LPS) are major constituents of the cell wall of Gram-negative bacteria. Capillary zone electrophoresis (CZE) was applied to distinguish between lipopolysaccharides extracted from Escherichia coli ATCC 25922 with various techniques. Extraction methods proposed by Westphal and Jann [Methods Carbohydr.

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