Progress 07/01/10 to 06/30/12
Outputs
OUTPUTS: Staphylococci are a worldwide cause of human and animal infections including life-threatening cases of bacteraemia, wound infections, pyogenic lesions and mastitis. Enterotoxins produced by some staphylococcal species were recognized as causative agents of staphylococcal food poisoning (SFP), being also able to interrupt human and animal immune responses. Only enterotoxins produced by Staphylococcus aureus were as yet well characterized. Much less is known about enterotoxigenic potential of coagulase-negative species of genus Staphylococcus (CNS). The pathogenic role of CNS and their enterotoxigenicity in developing SFP has not been well established. Although it has been reported that enterotoxigenic CNS strains have been associated with human infections and food poisoning, most of research lacked a deeper insight into structure of elements encoding CNS enterotoxins. Recent studies provided us with strong evidence for the presence and localization of enterotoxin-coding elements in CNS genomes and production of enterotoxins. Thus, the importance of pathogenic potential of CNS has been highlighted in human and animal infections as well as food poisoning. PARTICIPANTS: Keun Seok Seo, Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University TARGET AUDIENCES: Cattle farmers and Korean government are interested in developing a vaccine. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
We investigated the presence of staphylococcal enterotoxins (SE) in 148 CNS isolated from samples subjected to diagnostic laboratory using multiplex PCR established in our laboratory. We found that 15 isolates are SE positive. Eight isolates harbor seb, sen, and seq genes. Four isolates harbor sec, sel, and tst genes. Three isolates harbor sek and seq genes. We then tested for enterotoxin gene transfer by prophages. Out of 15 isolates, 6 isolates induced lytic prophage by mitomycin C treatment. We inserted an antibiotic resistant cassette to the enterotoxin genes to test the transferability. However, none of isolates were able to transfer enterotoxin genes. In order to test enterotoxin gene transfer from S. aureus to CNS, an antibiotic gene cassette was inserted to the enterotoxin gene cluster in S. aureus isolate, the strain RF122. We found that the enterotoxin gene cluster was transferred to S. epidermidis and S. chromogens. These results suggest that current status of knowledge is not sufficient to draw definite conclusions on enterotoxigenic potential of CNS. Since staphylococcal enterotoxins are considered an important virulence factor in human and animal infections as well as food safety issues, more attention must be paid to SE produced by CNS. Additional research should be conducted to answer the questions for the characteristics of enterotoxigenic potential of CNS as well as their pathogenic role in regards to human and animal infections as well as SFP.
Publications
- Magdalena Podkowik, Joo Youn Park, Jarosław Bystroń, Keun Seok Seo, Jacek Bania, publication in progress 2013 Enterotoxigenic potential of coagulase-negative staphylococci, International Journal of Food Microbiology.
|
Progress 01/01/11 to 12/31/11
Outputs
OUTPUTS: Coagulase-negative staphylococci (CNS) are a heterogeneous group that is composed of more than 30 Staphylococcus spp. CNS have been considered minor pathogens because they are not usually as virulent as the major pathogens such as S. aureus; yet as a group, the CNS are the most prevalent agents associated with bovine mastitis and some clinical samples. CNS may have a potential impact on the public health that CNS could cause food poisoning by producing staphylococcal superantigen (SAg) or spread SAg to other mastitis and food pathogens. However, direct evidence supporting that CNS could be a possible source of SAg is limited. Our study provides evidence that CNS does possess potential virulence factors such as SAg and could transfer these virulence factors to Staphylococcus aureus and other CNS. This is an important finding that we need to pay more attention to CNS and there is a need to investigate the role of CNS in several important staphylococcal diseases such as bovine mastitis. We submitted a research grant to Korean government and awarded a research fund for three years and are currently writing a scientific report on our findings. PARTICIPANTS: Keun Seok Seo, Department of Basic Sciences, Mississippi State University, College of Veterinary Medicine TARGET AUDIENCES: Cattle Farmers and Korean governement is interested in developing a vaccine. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
We investigated a potential mechanism of virulence gene transfer among S. aureus and other CNS. We found that there are several phages from S. aureus that carry virulence factors such as SAg and other cytotoxins. Importantly, several phages isolated from S. aureus can be transferred to CNS and vice versa. This is clear evidence that CNS could be evolved to potential pathogens or contributes the dissemination of virulence factors to S. aureus and other CNS. These data were used to write a research proposal to Korean government who is interested in developing novel vaccine for bovine mastitis. In connection with another project investigating the role of SAg in bovine mastitis, we demonstrated the importance of CNS in the bovine mastitis and justify the fitness of SAg as novel vaccine candidate. Currently, we are generating non-toxic SAg for novel vaccine application.
Publications
- No publications reported this period
|
|