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1.
Folia Microbiol (Praha) ; 64(6): 845-855, 2019 Nov.
Article in English | MEDLINE | ID: mdl-30888635

ABSTRACT

Staphylococcus aureus (S. aureus) is an important causative agent of contagious intermammary infections in dairy cattle. S. aureus is also considered as an important foodborne pathogen and cause of food poisoning cases and outbreaks worldwide. In order to understand the molecular ecology of S. aureus, the present study compared phenotypic and genotypic characteristics of 70 S. aureus isolates from bovine mastitis milk samples collected during the period from August 2001 to March 2014 in different regions of Northern Germany. The S. aureus isolates were characterised phenotypically, as well as genotypically for their genetic diversity using multi-locus sequence typing (MLST), spa typing and the presence of virulence genes encoding 16 staphylococcal enterotoxins (sea-selu), toxic shock syndrome toxin (tst), thermonuclease (nuc), clumping factor (clfA and clfB), coagulase (coa) and the methicillin resistance gene mecA. A total of 16 sequence types were grouped into eight clonal complexes (CCs), and 17 spa types were identified. These included six novel sequence types and one novel spa type. The majority of bovine mastitis milk-associated sequence types belonged to the clonal complex CC5, CC97, CC133, and CC151 and showed closely related genotypes or lineages with sequence types of human origin. The genotype CC133 (ST133-t1403) was predominant, constituting 27.1% of the isolates. In addition, the S. aureus isolates displayed nine different enterotoxigenic profiles. All S. aureus were methicillin-susceptible (MSSA). The current study provides new information on phenotypic and genotypic traits of S. aureus isolates from bovine mastitis. The comparison of characteristics of isolates from the present study originating from mastitis milk showed similarities with human isolates. This might help to better understand the distribution of S. aureus in the one health context.


Subject(s)
Mastitis, Bovine/microbiology , Milk/microbiology , Penicillin-Binding Proteins/deficiency , Staphylococcus aureus/isolation & purification , Animals , Bacterial Proteins , Cattle , Drug Resistance, Bacterial/genetics , Enterotoxins/genetics , Female , Food Microbiology , Genes, Bacterial/genetics , Genotype , Germany/epidemiology , Humans , Multilocus Sequence Typing , Phenotype , Staphylococcal Infections/microbiology , Staphylococcus aureus/classification , Staphylococcus aureus/genetics , Virulence Factors/genetics
2.
Food Sci Technol Int ; 24(8): 699-704, 2018 Dec.
Article in English | MEDLINE | ID: mdl-30019591

ABSTRACT

Industrialising edible insects goes along with quality control and hazard analysis and critical control points. One of those steps is assessing heat treatment. For the present contribution, the potential of enzymatic heat assessment tests used in the dairy industry (alkaline phosphatase and lactoperoxidase) to detect heat treatment in several insect species ( Acheta domesticus, Gryllus assimilis, Gryllus bimaculatus, Locusta migratoria, Schistocerca gregaria, Chilecomadia moorei, Galleria mellonella, Bombyx mori, Pachnoda marginata, Tenebrio molitor, Zophobas atratus, Apis mellifera, and Hermetia illucens) was evaluated. Insect material was homogenised, diluted, and the enzymatic tests (Lactognost®, Peroxtesmo®) were carried with these liquids as if they were milk. All species but C. moorei, B. mori, P. marginata, and A. mellifera showed alkaline phosphatase activity in raw samples and none in heated (10 min at 100 ℃) ones, while only G. mellonella, T. molitor, and Z. atratus reacted accordingly with lactoperoxidase. In trial 2 focusing only on alkaline phosphatase activity, inactivation of the enzyme after 5, 10, and 15 min of heating occurred species specific within a range of 60-86 ℃, i.e. within ordinary pasteurisation schemes. Thus and for the time being, heat treatment in many edible insect species can be assessed using alkaline phosphatase activity test kits. In contrast to milk samples, positive results may display bluish or greenish colours, and the time until a reliable reading is possible is extended to 1-1.5 h (24 h in the case of Gryllidae).


Subject(s)
Alkaline Phosphatase/analysis , Diet , Food Preservation , Insecta , Lactoperoxidase/analysis , Pasteurization , Animals , Bees/enzymology , Bombyx/enzymology , Food Preservation/standards , Gryllidae/enzymology , Humans , Insecta/enzymology , Locusta migratoria/enzymology , Milk/enzymology , Pasteurization/standards , Tenebrio/enzymology
3.
Crit Rev Food Sci Nutr ; 57(9): 1852-1862, 2017 Jun 13.
Article in English | MEDLINE | ID: mdl-26176586

ABSTRACT

Honey has been considered a relatively safe foodstuff due to its compositional properties, with infant botulism caused by Clostridium botulinum being the most prominent health risk associated with it. Our review is focused on the honey microflora along the food chain and evaluates the pathogenic potential of those microorganisms found in honey. This product may contain a great variety of bacteria and, particularly, fungi that eventually entered the food chain at an early stage (e.g., via pollen). For many of these microorganisms, opportunistic infections in humans have been recorded (e.g., infections by Staphylococcus spp., Citrobacter spp., Escherichia coli, Hafnia alvei, Aspergillus spp., Fusarium spp., Trichoderma spp., Chaetomium spp.), although direct infections via honey were not registered.


Subject(s)
Bacteria/classification , Food Microbiology , Foodborne Diseases/microbiology , Honey/microbiology , Bacteria/isolation & purification , Food Technology , Humans
4.
Mol Cell Probes ; 30(5): 320-325, 2016 10.
Article in English | MEDLINE | ID: mdl-27495132

ABSTRACT

Staphylococcus (S.) aureus is one of the most important animal pathogens causing bovine mastitis. Also, it is a major human pathogen that may produce a variety of toxins which cause staphylococcal food poisoning. In the present study a LAMP assay based on gene nuc to identify S. aureus was developed and validated. The specificity of the LAMP assay was confirmed by using 70 S. aureus isolates and 21 non-S. aureus strains. The optimal temperature-time combination to amplify gene nuc successfully was 65 °C and 30 min. The analytical sensitivity of the developed LAMP assay was 0.26 pg of S. aureus DNA per reaction. The limit of detection evaluated with milk spiked with S. aureus was 9 × 102 CFU mL-1. The final results of this assay were available within less than 2 h. The present study showed that the LAMP assay based on gene nuc appeared to be rapid and simple, and could also be used to identify S. aureus isolates from mastitis milk of dairy cows.


Subject(s)
Mastitis, Bovine/microbiology , Milk/microbiology , Polymerase Chain Reaction/methods , Staphylococcus aureus/genetics , Staphylococcus aureus/isolation & purification , Animals , Cattle , Female , Genes, Bacterial , Limit of Detection , Predictive Value of Tests , Reference Standards , Sensitivity and Specificity
5.
Food Sci Technol Int ; 19(3): 235-41, 2013 Jun.
Article in English | MEDLINE | ID: mdl-23478913

ABSTRACT

Extended shelf life milk is a relatively new kind of fluid milk, generally manufactured by high-temperature treatment and/or micro-filtration. Being advertised as 'pasteurized milk with an extended shelf life', its flavour, compositional quality and labelling was questioned. Extended shelf life (high-temperature treatment), pasteurized ('traditionally produced') and ultrahigh-temperature milk were, therefore, compared at the beginning and end of shelf life. In triangle tests, panellists distinguished clearly between all products. High-temperature treatment milk's flavour was closer to ultrahigh-temperature and traditionally produced milk in the beginning and at the end of shelf life, respectively. Physicochemically and bacteriologically, all three types could be distinguished. Since 'extended shelf life' comprises many process varieties (each affecting flavour differently), consumer information and appropriate package labelling beyond 'long-lasting' is necessary, e.g. by mentioning the heat treatment applied.


Subject(s)
Food Handling/methods , Food Storage , Hot Temperature , Milk/chemistry , Animals , Food Microbiology , Milk/microbiology , Time Factors
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