Development of a routine laboratory direct detection system of staphylococcal enterotoxin genes.
(17/73)
A novel direct detection system has been developed for eight staphylococcal enterotoxin (SE)-encoding genes (sea, seb, sec, sed, see, seg, seh and sei) in milk. Specific detection by real-time PCR was successful for all SE-encoding genes in the reference strains. Furthermore, a novel DNA-preparation method with good reproducibility [coefficients of variation 0.31, 0.99 and 1.21 % at 10(6), 10(4) and 10(2) c.f.u. (ml milk sample)(-1), respectively] was developed to overcome PCR inhibition in the milk samples. The combination of this DNA-preparation method and real-time PCR resulted in high sensitivity [between 1.1 x 10(2) and 1.0 x 10(4) c.f.u. (ml milk sample)(-1)] and allowed the completion of the entire procedure within 4 h. Results of an evaluation of this method for the detection of SE-encoding genes using known outbreak milk samples produced results showing good correspondence with the reversed passive latex agglutination assay. In addition, this newly developed system can be applied to clinical samples such as faeces and vomit. Consequently, the system should be useful in the routine direct detection of SE-encoding genes in food-borne-poisoning samples. (+info)
Immunoquantitative real-time PCR for detection and quantification of Staphylococcus aureus enterotoxin B in foods.
(18/73)
A real-time immunoquantitative PCR (iqPCR) method for detection of Staphylococcus aureus enterotoxin B (SEB) was developed and evaluated using both pure cultures and foods. The assay consisted of immunocapture of SEB and real-time PCR amplification of the DNA probe linked to the detection antibody. iqPCR was compared to an in-house enzyme-linked immunosorbent assay (ELISA) using the same couple of capture-detection antibodies and to commercial kits for detection of S. aureus enterotoxins (SE). The iqPCR was approximately 1,000 times more sensitive (<10 pg ml(-1)) than the in-house ELISA and had a dynamic range of approximately 10 pg ml(-1) to approximately 30,000 pg ml(-1). iqPCR was not inhibited by any of the foods tested and was able to detect SEB present in these foods. No cross-reactivity with SE other than SEB was observed. Application of iqPCR for detection of SEB in cultures of S. aureus revealed the onset of SEB production after 4 h of incubation at 22, 37, and 42 degrees C, which was in the first half of the exponential growth phase. The total amounts of SEB produced by the two strains tested were larger at 42 degrees C than at 37 degrees C and were strain dependent. (+info)
Expression of enterotoxin genes in Staphylococcus aureus isolates based on mRNA analysis.
(19/73)
Staphylococcus aureus strains are important foodborne pathogens that produce various toxins. To evaluate the risk of the enterotoxins, four S. aureus strains from kinbap and two clinical samples were isolated and identified, and their expression of the enterotoxin genes were analyzed using a reverse transcription real-time PCR. Various enterotoxin genes were detected, including sea, seg, seh, sei, sen, seo, and sem, where each isolate contained one or two. When the mRNA detection of the enterotoxin genes was analyzed using a reverse transcriptase PCR, various levels of expression were found depending on the species and enterotoxin gene. Therefore, it is reasonable to suggest that the poisoning risk of S. aureus can be effectively evaluated based on the gene expression at the mRNA level. (+info)
A study of the enterotoxigenicity of coagulase-negative and coagulase-positive staphylococcal isolates from food poisoning outbreaks in Minas Gerais, Brazil.
(20/73)
Prevalence and characteristics of meticillin-resistant Staphylococcus aureus in humans in contact with farm animals, in livestock, and in food of animal origin, Switzerland, 2009.
(23/73)
A total of 2,662 samples, collected from March to September 2009 in Switzerland, were tested for the presence of meticillin-resistant Staphylococcus aureus (MRSA). The collection comprised nasal swabs from 148 pig farmers, 133 veterinarians, 179 slaughterhouse employees, 800 pigs, 300 calves, 400 cattle, 100 pooled neck skin swabs from chicken carcasses, and 460 food samples of animal origin. Moreover, 142 S. aureus strains, isolated from bovine mastitis milk, were included in the study. Twenty samples (< 1%; four veterinarians, 10 pigs, three calves, one young bull, and two mastitis milk samples) tested positive for MRSA. Genotyping of the MRSA strains was performed by multilocus sequence typing, spa- and SCCmec-typing, and revealed ST398 (n=18), ST8 (n=1), ST 1 (n=1), spa types t011 (n=7), t034 (n=11), t064 (n=1), t127 (n=1), and SCCmec types IV (n=4) and V (n=16). The 20 MRSA strains were subjected to antibiotic susceptibility testing and pulsed-field gel electrophoresis using the restriction enzyme EagI. Supplementary PCR reactions were performed to investigate the presence of Panton-Valentine leukocidin and staphylococcal enterotoxins A to D. (+info)
A large outbreak of food poisoning of unknown aetiology associated with Stilton cheese.
(24/73)
Between November 1988 and January 1989, a total of 155 people in 36 reported outbreaks suffered gastrointestinal symptoms associated with eating Stilton cheese, produced from unpasteurized cow's milk in the English midlands. Symptoms were suggestive of a staphylococcal illness but extensive laboratory testing of cheeses implicated in several of the outbreaks failed to detect any pathogen, toxin or chemical. Control measures were implemented, and included a voluntary withdrawal of the implicated Stilton cheese from sale on 23 January 1989 and a subsequent decision to use pasteurized milk in production of the cheese. (+info)